CN106026257B - A kind of mobile terminal - Google Patents

Abstract

The invention discloses a mobile terminal. By simultaneously setting a load switch and a charging chip in a charging line of a battery, the mobile terminal can support two modes of direct charging and charging with a charging chip on hardware. For the selection and switching of the two charging methods, the present invention adopts the method of automatically controlling the load switch and the charging chip to alternately enable the operation according to the battery cell voltage change, and based on the dynamically adjustable output voltage of the charger, the charging chip is automatically switched on. The selection switching of the charging voltage control right is performed between the processor and the processor. The charging strategy thus designed can speed up the charging speed of the battery, improve the charging efficiency, and reduce the temperature rise of the charging while ensuring the safety of charging the mobile terminal. The trouble caused by use improves the user experience.

Description

a mobile terminal

technical field

The invention belongs to the technical field of mobile terminals, and in particular relates to a mobile terminal product supporting two charging modes of direct charging and charging chip charging.

Background technique

With the rapid development of electronic information technology, portable mobile terminal products (such as mobile phones, PADs, notebook computers, etc.) have penetrated into all aspects of people's lives and become the leading force leading the progress of the semiconductor industry. Most of the current mobile terminal products use rechargeable batteries to power the internal system circuits of the products. With the increasing number of functions supported by mobile terminal products, the power consumption of its system circuits also increases. In the case of limited battery capacity, the battery life after charging is gradually shortened, resulting in the charging operation becoming more and more difficult. frequently.

At present, there are two main battery charging methods widely used: one is the SDP charging method, which uses the host (such as a computer) to charge the battery. This charging method is due to the constant charging voltage output by the host and the small charging current , so a longer charging time is required. The other is the DCP charging method, which uses a power adapter (charger) to charge the battery. There are various types of existing chargers, including ordinary 5V chargers with an output voltage of DC 5V, QC2.0, USB PD, MTK PE+ chargers with optional output voltages, and QC3 with freely adjustable output voltages. .0 charger etc. Among them, the QC3.0 charger is a relatively intelligent power adapter released by Qualcomm in 2015. Its output voltage can be adjusted in steps of 0.2V within the range of 3.6V~12V, and a voltage negotiation mechanism is adopted. , achieving optimal power transfer.

When using the QC3.0 charger to charge the built-in battery of mobile terminal products such as mobile phones, the efficiency of the charging chip can be improved by reducing the input voltage of the charging chip inside the mobile phone. However, the efficiency of the mobile phone's built-in charging chip will be limited by the chip manufacturing process, so that the maximum efficiency of the charging chip is generally limited to about 80% to 90%. For high-current charging, even a 10% efficiency loss will translate into a high temperature rise of the mobile phone, which will affect the user's experience. This will also become a bottleneck for the continuous increase of the charging current and hinder the further improvement of the battery charging speed. .

Contents of the invention

The purpose of the present invention is to provide a mobile terminal that supports two charging methods, direct charging and charging chip charging, which can reduce charging temperature rise and improve charging efficiency while speeding up battery charging.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions to achieve:

A mobile terminal is provided with a battery, a charging interface, a charging chip, a load switch and a processor; the battery is used to store electric energy; the charging interface is used for an external charger, and a power pin and a D+ pin are arranged on it , D-pin; the charging chip is connected between the charging interface and the battery, used to receive the charging power output by the charger, and charge the battery; the charging chip is provided with the D+ The first drive pin connected to the pin and the second drive pin connected to the D- pin, when the cell voltage of the battery is outside the preset direct charging threshold range, the charging chip passes The first drive pin and the second drive pin regulate the output voltage of the charger; the load switch is connected between the power supply pin and the battery, and is used to connect or cut off the direct current of the battery. charging path; the processor is provided with a third drive pin connected to the D+ pin and a fourth drive pin connected to the D- pin; When it is outside the range of the preset direct charging threshold, the load switch is controlled to be disconnected, and the charging chip is started to charge the battery; when the cell voltage of the battery is within the preset direct charging threshold range, the charging is turned off. chip, and control the load switch to communicate with the battery and the power supply pin, and adjust the output voltage of the charger through the third drive pin and the fourth drive pin.

Compared with the prior art, the advantages and positive effects of the present invention are: the present invention sets a load switch and a charging chip in the charging line of the battery at the same time, so that the mobile terminal can support two modes of direct charging and charging chip charging on the hardware. . For the selection and switching of the two charging methods, the present invention adopts the method of automatically controlling the load switch and the charging chip to alternately enable the operation according to the battery cell voltage change, and based on the dynamically adjustable output voltage of the charger, the charging chip is automatically switched on. The selection switching of the charging voltage control right is performed between the processor and the processor. The charging strategy thus designed can speed up the charging speed of the battery, improve the charging efficiency, and reduce the temperature rise of the charging while ensuring the safety of charging the mobile terminal. The trouble caused by use improves the user experience.

Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is the circuit block diagram of a kind of embodiment that the mobile terminal proposed in the present invention is connected with the charger with adjustable output voltage;

Fig. 2 is a schematic circuit diagram of another embodiment in which the mobile terminal proposed by the present invention is connected to a charger with adjustable output voltage;

Fig. 3 is a processing flowchart of an embodiment based on the charging method proposed by the mobile terminal shown in Fig. 1 or Fig. 2;

Fig. 4 is the processing flowchart of an embodiment of the battery direct charging process;

Fig. 5 is a processing flowchart of an embodiment of a charger plug-in detection method in the battery direct charging process;

Fig. 6 is a processing flow chart of another embodiment of the charger plug-in/unplug detection method during the battery direct charging process.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

In this embodiment, in order to make full use of the dynamically adjustable output voltage of the QC3.0 charger to significantly increase the charging speed, on the one hand, the hardware of the mobile terminal with a built-in rechargeable battery is modified so that the mobile terminal can support conventional charging. , that is, the battery is charged through the charging chip inside the mobile terminal; it can also support direct charging, that is, the output voltage of the charger is directly transmitted to the battery, and the battery is directly charged with a large current; on the other hand, according to the charging of the battery The real-time change of the cell voltage during the process dynamically adjusts the charging voltage output by the QC3.0 charger, and controls the mobile terminal to enter different charging modes, thereby realizing the rational use of charging power and shortening the charging time of the battery.

Of course, the QC3.0 charger can also be replaced by other chargers with dynamically adjustable output voltage, which can also achieve the same technical effect. The specific types of chargers with adjustable output voltage in this embodiment are not limited to the above example.

In the following, with reference to FIG. 1 and FIG. 2 , firstly, the hardware configuration of the mobile terminal in this embodiment will be described in detail.

As shown in Figure 1, in order to retain the existing traditional charging function of the mobile terminal and ensure that the mobile terminal can be plugged and charged normally with the existing host and conventional chargers, this embodiment keeps the existing charging interface of the mobile terminal unchanged. That is, a multiplexed interface that is also used for charging and data transmission, such as the widely used USB interface J1, to meet the plugging and charging requirements of most conventional power adapters and computer hosts produced by most manufacturers on the market. In this embodiment, the USB interface J1 may be a USB Type-C interface, or may be a Micro USB interface or the like. Since the USB Type-C interface can support a current of up to 5A, in this embodiment, the USB Type-C interface is preferably used as the charging interface of the mobile terminal for an external charger to charge the battery U4 inside the mobile terminal.

A load switch U1 and a charging chip U2 are arranged inside the mobile terminal to support direct charging and charging with a charging chip. In this embodiment, the load switch U1 can use an integrated chip to perform on-off control of the direct charging path of the battery U4, as shown in FIG. 1 ; the load switch U1 can also be constructed using discrete components, For example, a MOS transistor Q2 is used to cooperate with a booster circuit U7, as shown in Figure 2, which can also realize the on-off control of the direct charging path of the battery U4.

In this embodiment, firstly, the specific circuit design and working principle of the charging circuit using an integrated chip as the load switch U1 are described in detail with reference to FIG. 1 .

When the load switch U1 is a controllable switch chip, the input pin VIN of the load switch U1 can be connected to the power pin VBUS of the USB interface J1, and the output pin VOUT can be connected to the positive pole of the battery U4. During the direct charging process, the load switch U1 connects its input pin VIN and its output pin VOUT to connect the direct charging path of the battery U4.

In order to realize the on-off control of the load switch U1, a processor U3 is also provided in the mobile terminal in this embodiment, and the processor U3 is used to output a valid or invalid enable to the enable pin EN of the load switch U1. signal, and then control the load switch U1 to enable or suspend (non-enable), so as to realize accurate switching between the two charging modes.

In this embodiment, in order to ensure the safety of charging the battery U4, the mobile terminal is further provided with a battery voltage monitoring unit U5 and a logical AND gate U6, as shown in FIG. 1 . Wherein, the battery voltage monitoring unit U5 is used to detect the terminal voltage of the battery U4. Specifically, a voltage dividing circuit (such as a voltage dividing circuit composed of resistors R10 and R11) can be connected between the positive pole of the battery U4 and the input terminal of the battery voltage monitoring unit U5. Circuit) method, the terminal voltage of the battery U4 is divided by the voltage dividing circuit, and then transmitted to the input terminal of the battery voltage monitoring unit U5, and the battery voltage monitoring unit U5 is effective for the terminal voltage of the battery U4 through conversion. monitor. If the terminal voltage of the battery U4 does not exceed the preset threshold (for a battery with a maximum cell voltage of 4.4V, the threshold of the terminal voltage can be set to 4.6V), the battery voltage monitoring unit U5 outputs a high level through its output terminal The signal is transmitted to one of the input pins of the logic AND gate U6. Connect the other input pin of the logical AND gate U6 to the first GPIO port of the processor U3, for example, the GPIO1 port, and receive the enable signal output by the processor U3 for controlling the enable of the load switch U1. When the battery U4 needs to be directly charged, the processor U3 outputs a high-level active enable signal through its GPIO1 port. At this time, if the terminal voltage of the battery U4 does not exceed the preset threshold, the two input pins of the logical AND gate U6 are both at high level. The logic AND gate U6 performs an AND operation on the two received high-level signals, outputs a high-level signal and transmits it to the enable pin EN of the load switch U1, controls the load switch U1 to enable, and connects its input pins VIN and The output pin VOUT connects the direct charging path of the battery U4, and uses the output voltage of the charger to directly charge the battery U4. During the direct charging process, the processor U3 always outputs a high-level active enable signal through its GPIO1 port. When the battery voltage monitoring unit U5 detects that the terminal voltage of the battery U4 exceeds the preset threshold, it sets its output terminal to low power. level, so that the output signal of logic AND gate U6 changes from high level to low level, and then the load switch U1 is suspended (that is, the load switch U1 is controlled to enter a non-enabled non-working state), so that the input lead of the load switch U1 The pin VIN and the output pin VOUT are disconnected, cutting off the direct charging path of the battery U4, and preventing the battery U4 from being overcharged and damaged.

The output signal of the battery voltage monitoring unit U5 is simultaneously sent to another GPIO port of the processor U3, such as the GPIO2 port, so that the processor U3 can monitor the terminal voltage of the battery U4 in real time.

In this embodiment, a battery voltage monitoring unit U5 and a logic AND gate U6 are set in the mobile terminal. Even if the mobile terminal crashes during the charging process, the low-level signal output by the battery voltage monitoring unit U5 can be used to control the logic AND gate U6. Set the enable pin of the load switch U1 to a low level, and then enter a non-enabled state, cut off the direct charging path of the battery U4, and realize the hardware overvoltage protection function.

In order to prevent the load switch U6 from being unable to be turned off due to an abnormal logic AND gate U6, this embodiment utilizes the second GPIO port of the processor U3, such as the GPIO3 port, to directly connect the enable pin EN of the load switch U1. . The processor U3 sets its GPIO3 port as an input state by default. Once it is found that the logic AND gate U6 fails and cannot control the load switch U1 to cut off the direct charging path as required, the GPIO3 port can be set to a low level. In this way, the load switch U1 is controlled to enter the non-enabled state, and then the direct charging path of the battery U4 is cut off, and the protection mechanism for hardware abnormality is implemented.

The load switch U1 of this embodiment also has overvoltage protection and current limiting functions, and an overvoltage protection pin OVP and a current limiting pin ILIM are provided on it, as shown in FIG. 1 . The overvoltage protection pin OVP of the load switch U1 is connected to the power pin VBUS of the USB interface J1 through a resistor divider network to monitor the output voltage of the charger. In this embodiment, the resistor divider network can be composed of two divider resistors R4, R5 connected in series between the power supply pin VBUS of the USB interface J1 and the system ground, and the divider resistors R4, R5 The middle node of the load switch U1 is connected to the overvoltage protection pin OVP. By configuring the resistance values of the voltage dividing resistors R4 and R5, the charging voltage connected through the power supply pin VBUS (that is, the output voltage of the charger) exceeds the preset voltage. When the direct charging voltage safety threshold V _safe is set, the load switch U1 is triggered to perform an overvoltage protection action, cutting off the direct charging path of the battery U4, and preventing the battery U4 from being subjected to an overvoltage impact.

In this embodiment, the direct charging voltage safety threshold V _safe may consider the cell voltage V _{bat_real} of the battery U4, the maximum charging current value I _{max_bat} supported by the battery U4, the internal resistance of the battery U4, and the system in the direct charging path The line resistance and other factors are determined in detail. Specifically, V _safe = V _{bat_real} + I _{max_bat} *R+△V can be set; where, R is the sum of the internal resistance of the battery U4 and the line resistance of the system in the direct charging path, △V is the voltage deviation threshold, and △ V≥1V. In this embodiment, it is preferable to set ΔV=1V to improve the timeliness of the overvoltage protection action response while protecting the battery U4 from overvoltage.

For the current-limiting pin ILIM of the load switch U1, in this embodiment, it is preferable to ground one of the pins through the resistor R8, and ground the other through the resistor R6 and a switch path of the switch tube Q1, and connect the control terminal of the switch tube Q1 to the processor U3 , for example, on the GPIO5 port of the processor U3, the selective access of the resistor R6 is controlled by controlling the on-off of the switch tube Q1. Specifically, the switch tube Q1 can be selected from various switch elements such as transistors, power tubes, silicon controlled rectifiers, etc. This embodiment uses an NPN triode as an example for illustration. The base of the NPN transistor Q1 is connected to the GPIO5 port of the processor U3, the emitter is grounded, and the collector is connected to the current limiting pin ILIM of the load switch U1 through the resistor R6 in series with it. Configure the resistance value of the resistor R8 so that the load switch U1 limits the current to 500mA in the default state. When it is necessary to enter the direct charging process, the processor U3 first outputs a high level through its GPIO1 port, controls the load switch U1 to conduct, and connects the direct charging path of the battery U4; then outputs a high level through its GPIO5 port to control the NPN type triode Q1 is saturated and turned on. At this time, the resistance value R _(ILIM) of the equivalent resistance connected to the current limiting pin ILIM of the load switch U1 is the parallel resistance value of the resistance R6 and the resistance R8. The resistance value of the resistance R6 is configured so that the load Switch current limit. Wherein, the I _safe is a preset direct charging current safety threshold I _safe , and the I _safe may be determined by considering factors such as the maximum charging current value I _{max_bat} supported by the battery U4. As a preferred design solution of this embodiment, I _safe = I _{max_bat} + ΔI may be set, wherein ΔI is the current deviation threshold, and ΔI≥500mA. In this embodiment, △I=500mA is preferably set, which not only protects the battery U4 from overcurrent, but also improves the timeliness of the current limiting response action.

Connect the power pin VBUS of the USB interface J1 to the power input terminal VBUS of the charging chip U2 inside the mobile terminal at the same time. When the charging chip U2 needs to be used to charge the battery U4, the processor U3 first outputs a low level through its GPIO1 port Invalid enable signal, control the load switch U1 to disconnect; then through its control port, such as its GPIO4 port, output a high-level signal to the EN pin of the charging chip U2, control the charging chip U2 to enable operation, and switch the charging mode Charge to the charging chip U2, use the charging chip U2 to receive the output voltage of the charger, and switch the control power of the output voltage of the charger to the charging chip U2, and use the charging chip U2 to dynamically adjust the output voltage of the charger. Specifically, the charging chip U2 can adjust the output voltage of the charger according to the change of the cell voltage of the battery U4, connect the output terminal ChgOut of the charging chip U2 to the positive pole of the battery U4, and use the power output by the charging chip U2 to charge the battery U4 .

In order to detect the battery cell voltage, charging current and other parameters of the battery U4, in this embodiment, a metering chip is preferably built in the battery U4, and the metering chip is used to detect parameters such as the battery cell voltage, charging current, and battery temperature rise of the battery U4, And transmit to the processor U3 through bus communication (for example, through I ² C bus). The processor U3 can send the received cell voltage, charging current and other parameters to the charging chip U2, for example, through the SPMI bus to the charging chip U2, and the charging chip U2 determines what kind of charging to perform according to the cell voltage of the battery U4. mode (such as trickle charging or constant voltage charging, etc.). In addition, the B+ and B- pins of the charging chip U2 can be correspondingly connected to the positive pole and the negative pole of the battery U4 for detecting the terminal voltage of the battery U4. Connect the sampling resistor R9 in series between the output terminal ChgOut of the charging chip U2 and the positive pole of the battery U4, such as a high-power precision resistor of 10 milliohms, and connect the C+ and C- pins of the charging chip U2 to the sampling resistor R9 correspondingly The output current of the charging chip U2 can be calculated by detecting the voltage drop across the sampling resistor R9 and combining the resistance value of the sampling resistor R9.

The load switch U1 is also provided with a current monitoring pin IMON, and the current monitoring pin IMON generates a proportionally reduced monitoring current output according to the output current of the charger. The charging chip U2 can be connected to the current monitoring pin IMON of the load switch U1 through an ADC interface, and grounded through a resistor R3, as shown in FIG. 1 . Use the resistor R3 to convert the monitoring current output by the current monitoring pin IMON into a voltage, and perform analog-to-digital conversion through the ADC interface to calculate the output current of the charger, and realize the real-time monitoring of the output current of the charger by the charging chip U2. Of course, the charging chip U2 can also transmit the detected output current value of the charger to the processor U3 through the SPMI bus, so as to realize the comprehensive monitoring of the charging safety of the system by the processor U3.

In order to dynamically adjust the output voltage of the QC3.0 charger connected to the USB interface J1, this embodiment connects the third drive pin (such as the differential pin D+) and the fourth drive pin (such as the differential pin D+) of the processor U3 D-) respectively connected to the differential pins of the USB interface J1, that is, the D+ pin and the D- pin, and the first drive pin (such as the differential pin D+) and the second drive pin (such as the differential pin D+) of the charging chip U2 (such as The differential pin D-) is connected to the D+ pin and D- pin of the USB interface J1 through the isolation resistors R1 and R2 respectively, and the signal on the differential signal line is realized between the charging chip U2 and the processor U3 through the resistors R1 and R2 isolation. Specifically, when the processor U3 or the charging chip U2 detects that the charger inserted into the USB interface J1 is a QC3.0 charger, it can charge the QC3.0 through its differential pin D+ or differential pin D- The device sends a pulse signal to adjust the output voltage of the QC3.0 charger.

The QC3.0 charger uses its interface chip to receive signals transmitted through its differential pin D+ and differential pin D-. Whenever its differential pin D+ receives a pulse signal, the interface chip controls the AC- The DC unit raises its output voltage by 0.2V; whenever its differential pin D- receives a pulse signal, the interface chip controls the AC-DC unit to lower its output voltage by 0.2V, thus charging the QC3.0 The dynamic adjustment of the output voltage of the tor.

In order to accurately identify whether the external charger is a standard QC3.0 charger, you can set the detection pin ID on the USB interface J1 of the mobile terminal and the USB interface J0 of the standard QC3.0 charger, and use the processing The device U3 detects the level change of the ID pin to realize the identification of the standard QC3.0 charger. As a preferred design scheme of this embodiment, it is possible to change the detection pin ID by setting a pull-up circuit or a grounding circuit inside the standard QC3.0 charger. time level status. For example, when the standard QC3.0 charger is not plugged into the USB interface J1 of the mobile terminal, configure the interface circuit inside the mobile terminal so that the potential of the detection pin ID of the USB interface J1 is in the second level state (such as low power level); when a standard QC3.0 charger is inserted into the USB interface J1, use the internal circuit (such as a pull-up circuit) of the standard QC3.0 charger to change the potential of the detection pin ID When the processor U3 detects that the potential of the ID pin has jumped from the second level state to the first level state, it determines that there is a standard QC3.0 charging Plug in the charger and enter the charging management process.

For the ground pin GND in the USB interface J1, it should be well connected with the system ground of the mobile terminal, and when the mobile terminal is plugged into the external device, ensure that the mobile terminal and the external device share the same ground.

The specific circuit design and working principle of the load switch U1 built with discrete components and the charging circuit formed by the load switch U1 will be described in detail below in conjunction with FIG. 2 .

As shown in FIG. 2 , the load switch U1 of this implementation example can be constructed by using a MOS pair transistor Q2 and a boost circuit U7 . Specifically, the switch path of the MOS transistor Q2 can be connected in series between the power supply pin VBUS of the USB interface J1 and the positive pole of the battery U4, and the gate of the MOS transistor Q2 can be connected to the output terminal of the boost circuit U7, through The drive voltage output by the booster circuit U7 is used to control the on-off of the MOS transistor Q2, and further on-off control of the direct charging path of the battery U4.

In order to realize overvoltage protection and overcurrent protection during direct battery charging, the load switch U1 built with discrete components can be further provided with a current monitoring chip U9 and a controller U8, as shown in FIG. 2 . The controller U8 can be realized by a single-chip microcomputer, and an ADC interface AD2 of the single-chip microcomputer is connected to the positive pole of the battery U4 through a voltage divider circuit composed of resistors R26 and R27, so as to detect the terminal voltage of the battery U4. The other ADC interface AD3 of the controller U8 is connected to the direct charging path of the battery U4 through a voltage divider circuit composed of resistors R28 and R29 to detect the output voltage of the charger. In the direct charge path of the battery U4, the sampling resistor R23 is connected in series (preferably using a high-power precision resistor as the sampling resistor R23), and the positive and negative input terminals +NI and -NI of the current monitoring chip U9 are correspondingly connected to the The two ends of the sampling resistor R23 are used to calculate the output current of the charger by collecting the voltage drop across the sampling resistor R23, and then the output of the output terminal OUT of the current monitoring chip U9 can reflect the monitoring of the output current. After the voltage is divided by the voltage dividing resistors R24 and R25, it is transmitted to the ADC interface AD1 of the controller U8 and the ADC interface of the charging chip U2 respectively, so as to realize the accuracy of the output current of the charger by the controller U8 and the charging chip U2 monitor.

In the controller U8, the overvoltage protection threshold (such as the direct charging voltage safety threshold V _safe ), the overcurrent protection threshold (such as the direct charging current safety threshold I _safe ) and the maximum terminal voltage can be preset. During the battery direct charging process, The controller U8 judges whether each parameter exceeds its preset threshold according to the detected output voltage and current of the charger and the terminal voltage of the battery U4, and then outputs a corresponding control signal through its control pin CTL to realize the control of the booster. Enable control of voltage circuit U7.

Specifically, the control pin CTL of the controller U8 can be set to output a high level by default, the control pin CTL of the controller U8 can be connected to one of the input pins of the logical AND gate U6, and the input pin of the logical AND gate U6 The other input pin is connected to the GPIO1 port of the processor U3, and receives the enable signal output by the processor U3 through its GPIO1 port. When it is necessary to switch to the direct charging mode, the processor U3 outputs a high-level active enable signal through its GPIO1 port. Since the control pin CTL of the controller U8 outputs a high level by default, the output terminal of the logical AND gate U6 Output a high-level signal to control the boost circuit U7 to enable operation, output a driving signal to control the conduction of the MOS transistor Q2, and connect the direct charging path of the battery U4. During the direct charging process of the battery U4, the controller U8 detects the output voltage, output current and the terminal voltage of the battery U4 in real time, as long as one of the parameters exceeds the preset threshold, it immediately sets its control pin CTL to low power. level, so that the boost circuit U7 stops running, and the MOS transistor Q2 is controlled to turn off, so as to cut off the direct charging path of the battery U4 and ensure the charging safety of the battery U4. At the same time, the controller U8 can transmit the detected parameters such as the output voltage and current of the charger and the terminal voltage of the battery U4 to the processor U3 through a bus (such as a UART bus), so as to realize the overall control of the system circuit by the processor U3.

When it is necessary to switch the charging method of the battery U4 from direct charging to charging chip charging, the processor U3 can set its GPIO1 port to low level, and then control the logic AND gate U6 to output a low level signal to control the boost circuit U7 Stop the operation, cut off the direct charging path of the battery U4, and then the processor U3 outputs a high-level signal to the EN pin of the charging chip U2 through its control port (such as its GPIO4 port), and controls the charging chip U2 to enable operation to start charging Chip U2 charges battery U4.

In FIG. 2 , the connection relationship between the charging chip U2 , the processor U3 and the battery U4 and the connection relationship with the charging interface J1 can follow the circuit design shown in FIG. 1 , and this embodiment will not be further described here.

After the above-mentioned hardware transformation is performed on the mobile terminal, the charging management process performed by the mobile terminal will be described in detail below with reference to FIG. 3 and FIG. 4 .

As shown in Figure 3, the charging management process of this embodiment mainly involves the following steps:

S301. Detecting the plug-in state of the charger;

In this embodiment, the mobile terminal can use its charging chip U2 or processor U3 to detect whether there is a charger inserted on its USB interface J1, if no charger is detected, then repeat the detection process of this step; When there is a charger plugged in, go to the next step.

S302. Identify the type of the charger;

The mobile terminal can identify the charger plugged into its USB interface J1 according to the traditional charger type identification method, and keep the direct charging path of the battery U4 disconnected during the identification process (that is, control the load switch U1 in Figure 1 Disable; or control the boost circuit U7 in Figure 2 to disable, so that the MOS transistor Q2 remains off), and the charging chip is used for charging by default.

When the mobile terminal detects that the charger plugged in is a charger with a fixed output voltage, such as a normal 5V charger, QC2.0 charger, USB PD charger or MTK PE+ charger, etc., it will keep the charging chip Charging, that is, always using the charging chip U2 to charge the battery U4. If a charger with a dynamically adjustable output voltage is plugged in (this embodiment uses a QC3.0 charger as an example for illustration), then perform the next steps.

In this embodiment, when it is detected that the QC3.0 charger is plugged in, it is also possible to further identify whether the QC3.0 charger is a standard charger according to the design requirements. The level status of the detection pin ID on the interface J1 is used to determine whether the inserted QC3.0 charger is a standard charger, and if so, perform the next steps; otherwise, even if the inserted QC3.0 charger is The charging of the terminal is safe, and the charging chip is also used to charge the battery U4. That is to say, the mobile terminal selectively enters the direct charging mode only when it detects that the charger plugged into its USB interface J1 is a standard QC3.0 charger, otherwise, the charging chip U2 is used to charge the battery U4.

In this embodiment, the standard QC3.0 charger can be set to output a 5V voltage by default, which is the same as the charging voltage output by the host and a conventional power adapter, so as to meet the requirements of the charging chip U2 in the mobile terminal for the input power supply. Require.

S303. Detect the cell voltage of the battery, and select and enter different charging modes according to the cell voltage of the battery;

In this embodiment, the processor U3 can obtain the cell voltage V _{bat_real} of the battery U4 by communicating with the metering chip built in the battery U4 _; If it is within the range [S1, S2], execute the subsequent steps; otherwise, jump to step S305 for execution.

In this embodiment, the direct charge threshold (low voltage threshold S1, high voltage threshold S2) can be specifically determined according to the actual situation of the battery, and is preferably the same as that under the standard DCP charging method (that is, the traditional charging of the battery by a conventional charger). The battery voltage range corresponding to the constant current charging phase is the same. For example, for a 4.4V battery (that is, a rechargeable battery with a maximum cell voltage of 4.4V), you can set its low-voltage threshold S1=3.2V and high-voltage threshold S2=4.2V.

S304, entering the battery direct charging process;

When the processor U3 detects that the cell voltage V _{bat_real} of the battery U4 is within the preset direct charging threshold range [3.2, 4.2], it first controls the charging chip U2 to suspend, that is, enters a non-enabled non-working state, and will The charging mode is switched from charging with the charging chip to direct charging, and the control of the output voltage of the charger is switched from being performed by the charging chip to being performed by the processor U3. Then, look up the preset initial relationship comparison table, and obtain the output voltage target value V _targ and the charging current target value I _targ corresponding to the interval segment of the cell voltage V _{bat_real} of the battery.

Specifically, according to the set direct charging threshold range [S1, S2], several intervals can be divided for the cell voltage of the battery, for example, with a span of 100mV, N intervals can be divided, N=(S2-S1 )/100mV. The output voltage target value V _targ and the charging current target value I _targ corresponding to the cell voltage of each interval segment are determined in advance for each interval segment to form the initial relationship comparison table, which is stored in the processor U3, Or stored in a memory connected to the processor U3 in the mobile terminal for calling by the processor U3.

In this embodiment, it is preferable to divide two interval segments within the range [3.2,4.2] of the direct charging threshold:

The battery cell voltage V _{bat_real} corresponding to the first section is between 3.2V~4V, the charger output voltage target value V _targ =V _max-1 , and the charging current target value I _targ =I _{max_bat} . That is, the charging current target value I _targ corresponding to the first interval can be determined according to the maximum charging current value I _{max_bat} supported by the battery U4 , for example, I _targ =4.5A can be set. The V _max-1 can be determined according to the cell voltage V _{bat_real} of the battery U4, the I _{max_bat} , the internal resistance of the battery U4, and the line resistance of the system in the direct charging path, for example, V _max-1 = I _{max_bat} * can be set R+V _{bat_real} , the R is the sum of the internal resistance of the battery U4 and the line resistance of the system in the direct charging path;

The cell voltage corresponding to the second interval is between 4V~4.2V, the output voltage target value V _targ =V _max-2 of the charger, and the charging current target value I _targ =I _{max_IC} . That is, the charging current target value I _targ corresponding to the second interval can be determined according to the maximum output current value I _{max_IC} supported by the charging chip U2, for example, I _targ = 3A can be set, so that when the charging mode changes from direct charging to charging When the chip is charging, it can keep the charging current stable. The V _max-2 can be determined according to the cell voltage V _{bat_real} of the battery U4, the I _{max_IC} , the internal resistance of the battery U4, and the line resistance of the system in the direct charging path, for example, V _max-2 =I _{max_IC} * can be set R+V _{bat_real} .

The direct charging process will be described in detail below with reference to FIG. 4 .

S401, the processor U3 looks up the interval segment in the initial relationship comparison table according to the detected cell voltage V _{bat_real} of the battery U4, and adjusts the QC3.0 charger according to the output voltage target value V _targ corresponding to the interval segment The output voltage V _out until V _out =V _targ ;

Specifically, the processor U3 can compare the output voltage target value V _targ with the 5V voltage output by the QC3.0 charger by default, calculate the number of pulses that need to be output through its differential pin D+ or D-, and then send the The differential pin D+ or D- of the .0 charger outputs a corresponding number of pulses to adjust the output voltage V _out of the QC3.0 charger to V _targ .

S402, connecting the direct charging path of the battery U4, using the output voltage of the charger to directly charge the battery U4;

Specifically, for the direct charging path designed with the load switch U1 (as shown in Figure 1), the processor U3 can be used to control the load switch U1 to enable operation to connect the direct charging path of the battery U4; The designed direct charging path (as shown in Figure 2) can use the processor U3 to control the boost circuit U7 to enable operation, and then drive the MOS transistor Q2 to conduct, and connect the direct charging path of the battery U4 to realize the charging of the battery U4. Direct charge.

S403. Real-time detection of the charging current I of the battery U4, and by comparing the charging current I with the charging current target value I _targ of the interval, to determine whether to increase or decrease the output voltage V _out of the charger, so that the charging current of the battery U4 I reaches or approaches the charging current target value I _targ ;

Specifically, during the process of directly charging the battery U4, the charging current I of the battery U4 is detected in real time, and if I<I _targ , the output voltage V _out of the charger is gradually increased until the charging current I=I _targ ; if If I>I _targ , the output voltage V _out of the charger is gradually lowered until the charging current I=I _targ . After that, continue to detect the charging current I of the battery U4, as long as the charging current I is close to I _targ , for example, the charging current I is within the interval of [I _targ -△I, I _targ ], keep the current output voltage V _out of the charger unchanged , Carry out high-current constant-current direct charging to the battery U4. The ΔI is the current deviation threshold, and its value is preferably not less than 500mA. In this embodiment, it is preferable to set ΔI=500mA to avoid repeated adjustment of the output voltage V _out of the charger.

S404. When the battery cell voltage V _{bat_real} of the battery U4 enters from an interval segment with a lower voltage level to an interval segment with a higher voltage level, search the initial relationship comparison table to obtain the charging current target value I _targ of the interval segment, And adjust the output voltage V _out of the charger, so that the charging current I of the battery U4 reaches or approaches the charging current target value I _targ of the interval;

Specifically, during the process of direct charging the battery U4, the cell voltage V _{bat_real} of the battery U4 keeps rising _. The processor U3 obtains the charging current target value I _targ corresponding to the higher-level interval segment by looking up the initial relationship comparison table; then, the processor U3 dynamically reduces the output voltage V _out of the charger, Until the charging current I of the battery U4 is equal to the charging current target value I _targ of the interval.

For example, when the cell voltage V _{bat_real} of the battery U4 rises from the first interval to the second interval, only the charging current target value corresponding to the second interval is read I _targ =I _{max_IC} =3A, that is Yes, the output voltage V _out of the charger is adjusted according to the charging current target value I _targ of the second interval, and it is not necessary to adjust the output voltage V _out of the charger according to the output voltage target value V _targ corresponding to the second interval, so as to ensure The charging current changes smoothly. In this embodiment, the output voltage target value V _targ corresponding to the second interval is only read when the cell voltage V _{bat_real} of the battery U4 is just in the second interval when the mobile terminal is plugged into a standard charger. , as the basis for the initial adjustment of the charger output voltage.

When the battery cell voltage V _{bat_real} of the battery U4 enters from an interval segment with a lower voltage level to an interval segment with a higher voltage level, and is close to the critical point of the two interval segments (for example, for the case where two interval segments are set , when the battery cell voltage V _{bat_real} of the battery U4 just exceeds 4V), since the charging current target value corresponding to the interval section with one level higher voltage is lower than the target charging current value corresponding to the interval section with one level lower voltage, it is necessary The output voltage V _out of the charger is adjusted down. When the output voltage V _out of the charger is dynamically reduced, the battery cell voltage V _{bat_real} of the battery U4 may drop from the interval segment with one level higher voltage to the interval segment with one level lower voltage (for example , the cell voltage V _{bat_real} becomes less than 4V), this is due to the existence of the internal resistance of the cell, after the charging current I decreases, the cell voltage V _{bat_real drops} instantly and returns to the previous interval. In this case, in order to ensure the stability of the direct charging process, as long as it is detected that the charging current I of the battery U4 is not zero, it will not return to the previous interval, but continue to dynamically reduce the output voltage V of the charger. _out , until the charging current I of the battery reaches the charging current target value I _targ corresponding to the interval segment of the higher level (for example, for the case of two interval segments designed in this embodiment, continue to lower the output of the charger voltage V _out until I=3A). Afterwards, in order to avoid repeated adjustments of the output voltage V _out , as long as the processor U3 detects that the charging current I is close to I _targ , for example, I is between 2.5A and 3A, the current output voltage V _out of the charger remains unchanged, which is beneficial to the battery. U4 performs high-current constant-current direct charging. In this embodiment, the current deviation threshold is preferably designed to be 500mA. Of course, it can also be set to other values according to the actual design requirements of the mobile terminal, which is not specifically limited in this embodiment.

S405. When the cell voltage V _{bat_real} of the battery U4 rises beyond the preset direct charging threshold range [S1, S2], switch the charging mode from direct charging to charging with a charging chip;

Specifically, when it is detected that the battery cell voltage V _{bat_real} of the battery U4 increases continuously with the direct charging process and exceeds the high voltage threshold S2, the direct charging path of the battery U4 is cut off. For the direct charging path designed with load switch U1 (as shown in Figure 1), the processor U3 can be used to control the load switch U1 to suspend, that is, to control the load switch U1 to be disabled and enter the non-operating state to cut off the direct charging of the battery U4. charging path; for the direct charging path designed with MOS pair tube Q1 (as shown in Figure 2), the processor U3 can be used to control the boost circuit U7 to disable, and then control the MOS tube Q2 to turn off, so as to cut off the power of the battery U4 Direct charge path. After the direct charging path of the battery U4 is cut off, the processor U3 controls the charging chip U2 to enable, switches to the charging chip for charging, uses the charging chip U2 to receive the output voltage V _out of the charger, charges the battery U4, and jumps to the step S306 is executed.

S305. Determine whether the cell voltage V _{bat_real} of the battery is lower than the low-voltage threshold S1, and if so, trickle charge the battery U4 through the charging chip U2 until the cell voltage V _{bat_real} of the battery = S1, return to step S304, and enter the battery direct charge Process; if the cell voltage V _{bat_real} of the battery is greater than the high voltage threshold S2, step S306 is executed;

In this embodiment, when the processor U3 detects that the cell voltage V _{bat_real} of the battery U4 is outside the preset direct charging threshold range [S1, S2], it first controls the load switch U1 to turn off, and cuts off the battery U4. In the direct charging channel, the charging mode is switched to the charging chip charging, and the charging chip U2 is used to charge the battery U4, and the output voltage control right of the charger is switched to the charging chip U2, and the charging chip U2 is used to adjust the output voltage of the charger.

The charging chip U2 can obtain the cell voltage V _{bat_real} of the battery U4 by communicating with the processor U3. When the charging chip U2 detects that the cell voltage V _{bat_real} of the battery U4 is lower than S1, it adjusts the output voltage V _out of the QC3.0 charger to 5V to supply power to the charging chip U2. At this time, the charging chip U2 can output a small current of 200mA to trickle charge the battery U4 until the cell voltage V _{bat_real} of the battery U4 = S1 .

S306. Detect whether the cell voltage V _{bat_real} of the battery U4 is higher than S2 and lower than the maximum cell voltage S3 corresponding to the battery U4, if yes, execute step S307; otherwise, execute step S308;

In this embodiment, for the case of using a 4.4V battery, the S3 is 4.4V.

S307. Dynamically adjust the output voltage V _out of the charger, find out the minimum output voltage of the charger when the output current of the charging chip U2 satisfies its expected output current _Ith , and use the minimum output voltage to supply power to the charging chip U2, until the cell voltage V _{bat_real} of the battery U4 reaches its maximum cell voltage;

In this embodiment, considering that in the case of the same charging current, the higher the input voltage of the charging chip (that is, the output voltage of the charger), the lower the efficiency of the charging chip and the greater the heat loss, so when using When the charging chip U2 is charging the battery U4, the basic principle of adjusting the output voltage V _out of the charger is to reduce the output voltage V _out of the charger as much as possible and increase the input current I _in under the condition of satisfying the charging power, so as to keep the charging chip The input power and output power of U2 are conserved.

Specifically, when S2<V _{bat_real} ≤ S3 , the charging chip U2 adjusts its output current (ie, the charging current I of the battery U4 ) to reach its expected output current I _th . In this embodiment, it is preferable to set the expected output current I _th equal to the maximum output current supported by the charging chip U2 , for example, set I _th =3A, so as to further shorten the charging time.

In the process of charging the battery U4 by the charging chip U2, the processor U3 can control the charging chip U2 to gradually adjust the output voltage V _out of the charger, and at the same time detect the output current of the charging chip U2 to find out when the expected output current I _th is met. The minimum input voltage (that is, the minimum output voltage of the charger when the expected output current I _th of the charging chip U2 is met), the input voltage at this time is the best efficiency under the current battery voltage. Thereafter, as the cell voltage V _{bat_real} of the battery U4 gradually increases, the output voltage V _out of the charger is synchronously adjusted to maintain the charging current I of the battery U4 to meet the above-mentioned I _th until the cell voltage V _{bat_real} of the battery U4 When the turning point of constant voltage charging is reached, that is, V _{bat_real} = S3, the subsequent constant voltage charging stage is entered.

S308. Keep the output voltage of the charging chip U2 equal to the maximum cell voltage S3 of the battery U4, charge the battery U4 at a constant voltage, and adjust the output voltage V _out of the charger by 200mV when the charging current I decreases by 500mA and When the minimum adjustment is 5V, it will not be adjusted downward until the charging is completed;

In this embodiment, when the charging process enters the constant voltage charging stage, the charging current I of the battery U4 will gradually decrease. In order to maintain a high charging efficiency during the constant voltage charging process, this embodiment designs Every time the charging current I is reduced by 500 mA, the output voltage V _out of the charger is controlled to decrease by 200 mV (this value can be calculated according to the specific conditions of the mobile terminal), until the charging is completed, the output voltage V _out of the charger is adjusted to the default value 5V.

Thus, the entire charging process is completed.

In order to ensure the safety of charging the mobile terminal, this embodiment also proposes the following abnormal charging mechanism:

(1) For a mobile terminal designed using an integrated chip as the load switch U1, as shown in Figure 1, this embodiment preferably adopts the following security protection mechanism:

①Using the current limiting function of the load switch U1, the system defaults to 500mA current limiting when powered on (realized by configuring the resistance value of resistor R8), so as to ensure that the charging current under abnormal conditions will not damage the mobile terminal;

② Use the current monitoring pin IMON of the load switch U1 to monitor in real time the total input current I _in entering the mobile terminal during the direct charging process (that is, the output current of the charger), if the total input current I _in exceeds the preset direct charging current The safety threshold I _safe (realized by configuring the parallel resistance of resistor R6 and resistor R8, preferably setting I _safe =5A), reduces the output voltage V _out of the charger, thereby reducing its output current (that is, the total input current I _in ), until I _in < I _safe ;

③ Use the overvoltage protection function of the load switch U1 to keep the total input voltage into the mobile terminal during the direct charging process from exceeding the set threshold. That is, the output voltage V _{out of the charger is detected in real time, and if the output voltage V out of} the charger exceeds the preset direct charging voltage safety threshold V _safe , the direct charging path of the battery U4 is cut off to prevent the battery U4 from receiving overvoltage shock. In this embodiment, for a 4.4V battery, it is preferable to set V _safe =6V;

④ Use the built-in metering chip in the battery U4 to detect the cell voltage V _{bat_real} and the charging current I of the battery U4 in real time. If one of them exceeds the maximum threshold specified in the battery specification (that is, the maximum charge specified in the battery specification voltage value and maximum charging current value), then reduce the output voltage V _out of the charger, and cut off the direct charging path of the battery U4;

⑤ Monitor the terminal voltage of the battery U4, and once it exceeds the maximum threshold (it can be determined according to the maximum terminal voltage specified in the battery specification, this embodiment preferably sets the maximum threshold to 4.6V for the 4.4V battery U4), then reduce the output voltage V _out of the charger, and cut off the direct charging path of the battery U4;

⑥Hardware protection mechanism: When the logical AND gate U6 in Figure 1 is abnormal and cannot control the normal disconnection of the load switch U1, set the GPIO3 port of the processor U3 to a low level, control the load switch U1 to disconnect, and cut off the power supply of the battery U4. Direct charging path to avoid damage to the battery.

(2) For the load switch U1 designed with the MOS pair transistor Q2 and the booster circuit U7, as shown in Figure 2, this embodiment preferably adopts the following safety protection mechanism:

①Detect the total input current I _in entering the mobile terminal (that is, the output current of the charger) through the current monitoring chip U9, and transmit the detected total input current I _in to the charging chip U2 and the controller U8 at the same time, and the processor U3 The total input current I _in entering the mobile terminal during the direct charging process is obtained by the charging chip U2. When the processor U3 or the controller U8 detects that I _in exceeds a preset threshold (for example, the direct charging current safety threshold I _safe , it is preferable to set I _safe = 5A), output a low-level signal to the logic AND gate U6, cut off the direct charging path, and play the role of double protection;

② Use the built-in metering chip in the battery U4 to detect the cell voltage V _{bat_real} and the charging current I of the battery U4 in real time. If one of them exceeds the maximum threshold specified in the battery specification (that is, the maximum charge specified in the battery specification voltage value and maximum charging current value), then reduce the output voltage V _out of the charger, and cut off the direct charging path of the battery U4;

③ Monitor the terminal voltage of the battery U4, and once it exceeds the maximum threshold (it can be determined according to the maximum terminal voltage specified in the battery specification, this embodiment preferably sets the maximum threshold to 4.6V for the 4.4V battery U4), then reduce the output voltage V _out of the charger, and cut off the direct charging path of the battery U4;

④ The controller U8 simultaneously detects the terminal voltage of the battery U4 through its ADC interface AD2, and once it exceeds the maximum threshold, it notifies the processor U3 through its UART interface to reduce the output voltage V _out of the charger, or even cut off the direct current of the battery U4. filling channel;

⑤ During the direct charging process, the controller U8 and the processor U3 adopt a timing handshake mechanism. Once it is found that one party does not perform signal handshaking regularly, the direct charging path of the battery U4 is cut off;

⑥During the direct charging process, the controller U8 detects in real time the total input voltage V _in entering the mobile terminal through its ADC interface AD3, that is, the output voltage V _out of the charger. Once V _in exceeds the set threshold, such as exceeding the preset direct The charging voltage safety threshold V _safe (for a 4.4V battery is preferably set to V _safe = 6V), the processor U3 is notified to reduce the output voltage V _out of the charger, and even cut off the direct charging path of the battery U4.

By adopting the dual protection mechanism of the processor U3 and the controller U8, the safety of charging the mobile terminal can be further ensured.

With the above-mentioned design scheme proposed in this embodiment, if the charger is unplugged or powered off during the direct charging process, since the input pin VIN and output pin VOUT of the load switch U1 are in the open state (for the MOS pair tube Q2 The designed direct charging path, because the source and drain of the MOS transistor Q1 are connected), the voltage of the battery U4 will act on the power pin VBUS of the USB interface J1 through the direct charging path, resulting in the power pin VBUS of the USB interface J1 The voltage of the battery is maintained at a high level, so that the system cannot detect that the charger has been unplugged, and the charger icon on the user interface will remain.

In order to ensure that the system can accurately detect the unplugged state of the charger during the direct charging process, so as to control the accurate cut-off of the direct charging path, this embodiment preferably proposes the following two design schemes:

One solution is to use a fixed pin of the charging interface J1 for the detection of the charger being pulled out. In this embodiment, the detection pin ID of the charging interface J1 is taken as an example for illustration. Connect the detection pin ID of the charging interface J1 to the charger detection port of the processor U3, for example, an interrupt interface ID1 with an interrupt function, as shown in FIG. 1 and FIG. 2 . The level change on the ID1 interface is triggered by plugging and unplugging the charger, thereby triggering an interrupt, and the following identification process is performed, as shown in Figure 5:

S501. When the processor U3 detects that the level on its ID1 interface changes, an interrupt is triggered;

In this embodiment, a grounding circuit or a pull-up circuit may be provided on one side of the standard charger to change the level state of the detection pin ID when the charger is plugged in or out. For example, when the charging interface J1 is connected to a standard charger, configure the detection pin ID to be in the first level state (such as a high level) through the standard charger (such as a pull-up circuit); when the charging interface J1 is not connected When a standard charger is configured, the detection pin ID is configured to be in a second level state (eg low level) by an interface circuit (eg pull-down circuit) on the mobile terminal side.

S502. During the interruption process, if the processor U3 detects that the potential on the ID1 interface jumps from the first level state to the second level state, it preliminarily determines that the charger may be pulled out;

S503, cutting off the direct charging path of the battery U4;

Specifically, when the processor U3 detects that the level on its ID1 interface jumps from the first level state to the second level state, it first outputs a low level through its GPIO1 port, and then controls the logical AND gate U6. The output level changes from high level to low level, and then controls the load switch U1 (as shown in Figure 1) or the boost circuit U7 (as shown in Figure 2) to disable, thereby realizing the cut-off of the direct charging path. Since the direct charging path is cut off, the voltage of the battery U4 will not affect the potential on the power pin VBUS of the charging interface J1;

S504. Using a conventional charger plug-in state detection mechanism to detect the plug-in state of the charger;

Since the direct charging path has been cut off, if the charger is pulled out, the voltage on the power pin VBUS of the charging interface J1 will drop to zero, and the potential on the power pin VBUS can be detected by the processor U3, and if it is zero, then judge The charger has been unplugged, the charging process is ended, and the processor U3 is used to control the elimination of the charger icon on the user interface; if it is not zero, it is determined that the charger is not unplugged.

Another solution is to detect the total current input through the charging interface J1 (that is, the total input current I _in ) and the current I _bat entering and leaving the battery U4, and judge whether the charger is unplugged during the direct charging process according to the changes of I _in and I _bat out.

Combined with Figure 6, the specific process includes:

S601. Detect the total current input through the charging interface J1, that is, the total input current I _in ;

In this embodiment, for the load switch U1 designed with an integrated chip, as shown in FIG. 1 , the total input current I _in can be calculated by detecting the monitoring current output by the current monitoring pin IMON of the load switch U1 . For the load switch designed with MOS pair transistor Q2 and boost circuit U7, as shown in Figure 2, the total input current I _in can be detected by the current monitoring chip U9, and the corresponding voltage can be output according to the size of the total input current I _in , after the voltage is divided by the voltage dividing resistors R24 and R25, it is collected by the controller U8 to calculate the size of the total input current I _in and notify the processor U3.

S602. If I _in is smaller than the preset value, then perform subsequent steps; otherwise, consider that the charger is not pulled out, and maintain the current direct charging process;

In this embodiment, preferably, the preset value is set to 100mA.

S603. Detect the flow direction of the current I _bat of the battery U4 (that is, the charging current I). If it flows out from the battery U4, it means that the battery U4 is discharged. It is preliminarily determined that the charger may be pulled out, and the subsequent steps are performed; otherwise, it is considered that the charger is not pulled out. out, keep the current direct charging process;

In this embodiment, the built-in metering chip of the battery U4 can be used to detect the current _Ibat of the battery U4. If the current _Ibat is a positive value, it means that the battery U4 is discharged, and subsequent steps are performed to further judge the plugging and unplugging state of the charger; If the current I _bat is a negative value, it means that the battery U4 is being charged, and it is considered that the charger is not pulled out, and the current direct charging process is maintained.

S604, cutting off the direct charging path of the battery U4;

Specifically, when the processor U3 determines that the charger may be pulled out during the direct charging process, it outputs a low level through its GPIO1 port, and the output level of the control logic AND gate U6 changes from high level to low level, Then control the load switch U1 (as shown in Figure 1) or the boost circuit U7 (as shown in Figure 2) to disable, thereby realizing the cut-off of the direct charging path. Since the direct charging path is cut off, the battery voltage will not affect the potential on the power supply pin VBUS of the charging interface J1.

S605. Using a conventional charger plug-in state detection mechanism to detect the plug-in state of the charger;

Since the direct charging path has been cut off, if the charger is pulled out, the voltage on the power pin VBUS of the charging interface J1 will drop to zero, and the potential on the power pin VBUS can be detected by the processor U3, and if it is zero, then judge The charger has been unplugged, the charging process is ended, and the processor U3 is used to control the elimination of the charger icon on the user interface; if it is not zero, it is determined that the charger is not unplugged.

The charging method proposed by the present invention can be widely used in mobile terminals such as mobile phones, tablet computers, notebook computers, mobile power supplies, etc., so as to meet different charging needs of users.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (13)

1. A mobile terminal, characterized in that, is provided with: Batteries, for storing electrical energy; Charging interface, equipped with power supply pin, D+ pin, D- pin, used for external charger; The charging chip is connected between the charging interface and the battery, and is used to receive the charging power output by the charger and charge the battery; the charging chip is provided with a first driver connected to the D+ pin pin, the second drive pin connected to the D-pin, when the cell voltage of the battery is outside the range of the preset direct charge threshold, the charging chip passes the first drive pin Regulating the output voltage of the charger with the second driving pin; The load switch is connected between the power supply pin and the battery, and is used to connect or cut off the direct charging path of the battery; the load switch is an integrated chip, which enables conduction when the enable pin is at a high level; The processor is provided with a first GPIO port, a third driving pin connected to the D+ pin, and a fourth driving pin connected to the D- pin; a battery voltage monitoring unit, connected to the battery, for detecting the terminal voltage of the battery; A logic AND gate, one of its input pins is connected to the first GPIO port of the processor, the other input pin is connected to the output terminal of the battery voltage monitoring unit, and its output pin is connected to the use of the load switch. can pin; Wherein, when the cell voltage of the battery is outside the range of the preset direct charging threshold, the processor starts the charging chip to charge the battery, and outputs a low-level invalid enable signal through its first GPIO port , the enable pin of the load switch is set to a low level through a logic AND gate, and the load switch is controlled to be disconnected; when the battery voltage monitoring unit detects that the terminal voltage of the battery exceeds a preset threshold, it outputs A low-level signal, and then the enable pin of the load switch is set to a low level through the logic AND gate, and the load switch is controlled to be disconnected; the processor is at the preset direct charging threshold when the cell voltage of the battery is at the preset direct charging threshold When within the range, the charging chip is turned off, and an active high level enable signal is output through its first GPIO port. When the battery voltage monitoring unit detects that the terminal voltage of the battery is lower than the preset threshold, it passes Its output terminal outputs a high-level signal, and then the enable pin of the load switch is set to a high level through the logic AND gate, and the load switch is controlled to connect the battery and the power supply pin, and the processor The output voltage of the charger is adjusted through the third driving pin and the fourth driving pin. 2. The mobile terminal according to claim 1, wherein when the cell voltage of the battery is within the range of the preset direct charging threshold, the processor searches its preset initial relationship comparison table, Acquire the output voltage target value and charging current target value corresponding to the interval segment according to the cell voltage of the battery, and determine the output voltage through the third drive pin and the fourth drive pin according to the output voltage target value. Drive the pulse signal output by the pin to adjust the output voltage of the charger to the output voltage target value; detect the charging current of the battery and dynamically adjust the output voltage of the charger so that the charging current of the battery Reach or approach the charging current target value. 3. The mobile terminal according to claim 1, characterized in that a control port is provided on the processor, and when the cell voltage of the battery is outside the range of the preset direct charging threshold, the processor Controlling the charging chip to start through the control port; the processor controls the charging chip to turn off through the control port when the cell voltage of the battery is within the range of the preset direct charging threshold. 4. The mobile terminal according to claim 1, wherein a second GPIO port is also provided on the processor, and the enabling pin of the load switch is connected to the second GPIO of the processor port; the second GPIO port of the processor defaults to an input state, and when an abnormality occurs in the logic AND gate and cannot control the disconnection of the load switch, the processor outputs a low output through the second GPIO port level signal to control the load switch to turn off. 5. The mobile terminal according to claim 1, wherein an overvoltage protection pin and a current limiting pin are arranged on the load switch, and the overvoltage protection pin is connected to the The power supply pin of the charging interface controls the load switch to be disconnected when the output voltage of the charger exceeds the preset direct charging voltage safety threshold by configuring the resistance value of the voltage dividing resistor in the resistor dividing network; The current limiting pin of the load switch is grounded through a first resistor, and grounded through a second resistor and a switch path of a switch tube, and the control terminal of the switch tube receives a control signal output by a processor; When the battery cell voltage is outside the preset direct charging threshold range, the output control signal controls the switching tube to be disconnected, configures the resistance value of the first resistor, and sets the current limiting value of the load switch to 500mA; When the cell voltage of the battery is within the range of the preset direct charging threshold, the processor outputs a control signal to control the switching tube to close, configures the resistance value of the second resistor, and sets the current limiting value of the load switch to is the safe threshold of the direct charging current. 6. The mobile terminal according to claim 2, wherein when the processor controls the load switch to be turned on to charge the battery directly, if it detects that the cell voltage of the battery is within the threshold of the direct charge Within the range and from the interval section with one level lower voltage to the interval section with one level higher voltage, find out the charging current target value corresponding to the interval section with one level higher through the initial relationship comparison table, and dynamically reduce The output voltage of the charger until the charging current of the battery reaches or approaches the charging current target value corresponding to the interval segment of the higher level. 7. The mobile terminal according to claim 6, characterized in that, when the cell voltage of the battery enters an interval section with one level lower than the voltage level to an interval section with one level higher voltage, the processor is close to two At the critical point of the section, if the dynamic reduction of the output voltage of the charger causes the cell voltage of the battery to drop from an interval section with one level higher than the voltage to an interval section with one level lower than the voltage, the battery will be detected. If the charging current is not zero, then continue to dynamically reduce the output voltage of the charger until the charging current of the battery reaches or approaches the target value of the charging current corresponding to the higher interval. 8. The mobile terminal according to any one of claims 1 to 7, characterized in that, When the charging chip detects that the cell voltage of the battery is lower than the preset direct charging threshold range, the output voltage of the charger is adjusted to 5V to supply power for the charging chip, and the battery is trickle charged through the charging chip; When the charging chip detects that the cell voltage of the battery is higher than the preset direct charging threshold range and lower than the maximum cell voltage supported by the battery, it dynamically adjusts the output voltage of the charger to find out the output current of the charging chip The minimum output voltage of the charger in the case of meeting its expected output current, using the minimum output voltage to supply power to the charging chip until the cell voltage of the battery reaches the maximum cell voltage; When the charging chip detects that the cell voltage of the battery reaches the maximum cell voltage, it adjusts its output voltage to the maximum cell voltage, charges the battery at a constant voltage, and detects the battery voltage. The charging current, and every time the charging current is reduced by 500mA, the output voltage of the control charger is lowered by 200mV and adjusted to a minimum of 5V until the charging is completed. 9. A mobile terminal, characterized in that it is provided with: Batteries, for storing electrical energy; Charging interface, equipped with power supply pin, D+ pin, D- pin, used for external charger; The charging chip is connected between the charging interface and the battery, and is used to receive the charging power output by the charger and charge the battery; the charging chip is provided with a first driver connected to the D+ pin pin, the second drive pin connected to the D-pin, when the cell voltage of the battery is outside the range of the preset direct charge threshold, the charging chip passes the first drive pin Regulating the output voltage of the charger with the second driving pin; A load switch, which includes a MOS pair tube and a boost circuit, the switch path of the MOS pair tube is connected between the power supply pin of the charging interface and the battery, and the control terminal of the MOS pair tube is connected to the boost circuit, Using the driving voltage output by the booster circuit to control the on-off of the MOS pair tube; The processor is provided with a first GPIO port, a third driving pin connected to the D+ pin, and a fourth driving pin connected to the D- pin; A controller, which is connected to the power supply pin of the charging interface through a voltage divider circuit, and is used to detect the output voltage of the charger; A current monitoring chip, which is used to detect the output current of the charger, and send the detected current value to the controller; A logic AND gate, one of its input pins is connected to the first GPIO port of the processor, the other input pin is connected to the control pin of the controller, and its output pin is connected to the boost circuit; Wherein, when the cell voltage of the battery is within the range of the preset direct charging threshold, the processor turns off the charging chip, and outputs a high level to the logical AND gate through its first GPIO port; The control pin of the controller outputs a high level by default, and the output pin of the logic AND gate outputs a high level to control the boost circuit to output a driving voltage to control the conduction of the MOS pair tube. During the conduction period of the MOS pair, the processor adjusts the output voltage of the charger through the third drive pin and the fourth drive pin; when the controller detects that the output voltage of the charger When the voltage is higher than the preset direct charging voltage safety threshold, or it is detected that the output current of the charger exceeds the preset direct charging current safety threshold, the control pin outputs a low level to the logic AND gate to control the The booster circuit stops outputting the driving voltage, and then controls the MOS to turn off the tube; when the battery cell voltage is outside the preset direct charging threshold range, the processor sends a signal to the The logic AND gate outputs a low level, controls the MOS pair to turn off, and starts the charging chip to charge the battery. 10. The mobile terminal according to claim 9, wherein when the cell voltage of the battery is within the range of the preset direct charging threshold, the processor searches its preset initial relationship comparison table, Acquire the output voltage target value and charging current target value corresponding to the interval segment according to the cell voltage of the battery, and determine the output voltage through the third drive pin and the fourth drive pin according to the output voltage target value. Drive the pulse signal output by the pin to adjust the output voltage of the charger to the output voltage target value; detect the charging current of the battery and dynamically adjust the output voltage of the charger so that the charging current of the battery Reach or approach the charging current target value. 11. The mobile terminal according to claim 10, wherein when the processor controls the load switch to be turned on and directly charges the battery, if it detects that the cell voltage of the battery is within the threshold of the direct charge Within the range and from the interval section with one level lower voltage to the interval section with one level higher voltage, find out the charging current target value corresponding to the interval section with one level higher through the initial relationship comparison table, and dynamically reduce The output voltage of the charger until the charging current of the battery reaches or approaches the charging current target value corresponding to the interval segment of the higher level. 12. The mobile terminal according to claim 11, characterized in that, when the cell voltage of the battery enters an interval section with one level lower voltage to an interval section with one level higher voltage, the processor is close to two At the critical point of the section, if the dynamic reduction of the output voltage of the charger causes the cell voltage of the battery to drop from an interval section with one level higher than the voltage to an interval section with one level lower than the voltage, the battery will be detected. If the charging current is not zero, then continue to dynamically reduce the output voltage of the charger until the charging current of the battery reaches or approaches the target value of the charging current corresponding to the higher interval. 13. The mobile terminal according to any one of claims 9 to 12, characterized in that, When the charging chip detects that the cell voltage of the battery is lower than the preset direct charging threshold range, the output voltage of the charger is adjusted to 5V to supply power for the charging chip, and the battery is trickle charged through the charging chip; When the charging chip detects that the cell voltage of the battery is higher than the preset direct charging threshold range and lower than the maximum cell voltage supported by the battery, it dynamically adjusts the output voltage of the charger to find out the output current of the charging chip The minimum output voltage of the charger in the case of meeting its expected output current, using the minimum output voltage to supply power to the charging chip until the cell voltage of the battery reaches the maximum cell voltage; When the charging chip detects that the cell voltage of the battery reaches the maximum cell voltage, it adjusts its output voltage to the maximum cell voltage, charges the battery at a constant voltage, and detects the battery voltage. The charging current, and every time the charging current is reduced by 500mA, the output voltage of the control charger is lowered by 200mV and adjusted to a minimum of 5V until the charging is completed.