CN104682355B - A kind of lithium battery protection circuit - Google Patents

Abstract

The invention discloses a lithium battery protection circuit, which includes a battery and a lithium battery protection chip, the battery is connected to the lithium battery protection chip, the lithium battery protection chip includes a bias and reference circuit and a control submodule, and the bias and reference circuit generates a bias Voltage and reference voltage, the control sub-module generates an overcharge control signal and an overdischarge control signal according to the battery voltage, bias voltage and reference voltage; the lithium battery protection chip also includes a substrate switching circuit, a gate control circuit and a field effect transistor; The substrate switching circuit generates the substrate switching signal according to the overcharge control signal or the overdischarge control signal, the gate control circuit generates the gate control signal according to the overcharge control signal and the overdischarge control signal, and the field effect transistor generates the gate control signal according to the substrate switching signal and the gate The pole control signal controls the opening or closing of the lithium battery charging and discharging circuit. Through the lithium battery protection circuit, the invention improves the integration degree of the lithium battery protection chip and reduces the cost of the lithium battery protection circuit.

Description

A lithium battery protection circuit

technical field

The invention relates to the technical field of semiconductor integrated circuits, in particular to a lithium battery protection circuit.

Background technique

The existing lithium battery protection circuit is shown in Figure 1. The lithium battery protection chip contains two parts: a control module and a detection module. The detection module compares the lithium battery voltage VDD with the overcharge detection voltage and overdischarge detection voltage, and compares the VM terminal The voltage is compared with the overcurrent detection voltage, the short circuit detection voltage, and the charging detection voltage to obtain a comparison signal. The control module processes the comparison signal, judges the working state of the lithium battery, and cuts off the charging or discharging switch according to the actual situation to protect the lithium battery.

The existing lithium battery protection chip has too many peripheral components, the integration level is too low, and the cost is too high.

Contents of the invention

The embodiment of the present invention provides a lithium battery protection circuit, aiming at solving the problem of many peripheral components and high cost in the existing lithium battery protection circuit.

An embodiment of the present invention provides a lithium battery protection circuit, including a battery and a lithium battery protection chip, the battery is connected to the lithium battery protection chip, the lithium battery protection chip includes a bias and reference circuit and a control submodule, The bias and reference circuit generates a bias voltage and a reference voltage, and the control submodule generates an overcharge control signal and an overdischarge control signal according to the voltage of the battery, the bias voltage and the reference voltage; the The lithium battery protection chip also includes a substrate switching circuit, a gate control circuit and a field effect transistor;

The first output terminal of the control submodule is connected to the input terminal of the substrate switching circuit, the second output terminal of the control submodule is connected to the first input terminal of the gate control circuit, and the control submodule The third output terminal of the module is connected to the second input terminal of the gate control circuit, the output terminal of the substrate switching circuit is connected to the substrate of the field effect transistor, and the output terminal of the gate control circuit is connected to the The gate of the field effect transistor is connected, and the first input terminal of the control submodule is connected to the source of the field effect transistor;

The substrate switching circuit generates a substrate switching signal according to the overcharge control signal or the overdischarge control signal, and the gate control circuit generates a gate control signal according to the overcharge control signal and the overdischarge control signal signal, the field effect transistor controls the opening or closing of the charging and discharging circuit of the lithium battery according to the substrate switching signal and the gate control signal.

The beneficial effects brought by the technical scheme provided by the invention are:

It can be seen from the above-mentioned embodiments of the present invention that since the battery and the lithium battery protection chip are included, the battery is connected to the lithium battery protection chip, the lithium battery protection chip includes a bias and reference circuit and a control submodule, and the bias and reference circuit generates a bias voltage and Reference voltage, the control sub-module generates an overcharge control signal and an overdischarge control signal according to the battery voltage, bias voltage and reference voltage; the lithium battery protection chip also includes a substrate switching circuit, a gate control circuit and a field effect transistor; the substrate The switching circuit generates the substrate switching signal according to the overcharge control signal or the overdischarge control signal, the gate control circuit generates the gate control signal according to the overcharge control signal and the overdischarge control signal, and the field effect transistor generates the gate control signal according to the substrate switching signal and the gate control signal. The signal controls the opening or closing of the charging and discharging circuit of the lithium battery, thus improving the integration of the lithium battery protection chip and reducing the cost of the lithium battery protection circuit.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic structural diagram of a lithium battery protection circuit in the prior art;

Fig. 2 is the structural representation of a kind of lithium battery protection circuit of the present invention;

3 is a schematic circuit diagram of a lithium battery protection circuit substrate switching circuit of the present invention;

FIG. 4 is a circuit schematic diagram of a gate control circuit of a lithium battery protection circuit according to the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

A schematic structural diagram of a lithium battery protection circuit according to the present invention, as shown in FIG. 2 , includes a battery 02 and a lithium battery protection chip 01. The battery 02 is connected to the lithium battery protection chip 01. The lithium battery protection chip 01 includes a bias and reference circuit 011 and a control circuit. Sub-module 012, bias and reference circuit 011 generates bias voltage and reference voltage, control sub-module 012 generates overcharge control signal and over-discharge control signal according to battery voltage, bias voltage and reference voltage; lithium battery protection chip also includes Substrate switching circuit 013, gate control circuit 014 and field effect transistor M1;

The first output terminal of the control submodule 012 is connected to the input terminal of the substrate switching circuit 013, the second output terminal of the control submodule 012 is connected to the first input terminal of the gate control circuit 014, and the third output terminal of the control submodule 012 terminal is connected to the second input terminal of the gate control circuit 014, the output terminal of the substrate switching circuit 013 is connected to the substrate of the field effect transistor M1, and the output terminal of the gate control circuit 014 is connected to the gate of the field effect transistor M1, The first input end of the control sub-module 012 is connected to the source of the field effect transistor M1;

The substrate switching circuit 013 generates a substrate switching signal according to the overcharge control signal or the overdischarge control signal, the gate control circuit 014 generates the gate control signal according to the overcharge control signal and the overdischarge control signal, and the field effect transistor M1 switches according to the substrate The signal and gate control signal control the opening or closing of the lithium battery charge and discharge circuit.

In specific implementation, the control sub-module 012 may include a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first capacitor C1, Multi-way switch 121, over-discharge protection circuit 122, over-charge protection circuit 123, delay circuit 124, system sleep circuit 125, over-current protection circuit 126, over-charge protection circuit 127 and logic circuit 128; the first resistor R1 terminal is the second input terminal of the control sub-module 012, the second terminal of the first resistor R1 is connected with the second power supply, the first terminal of the first capacitor C1 and the first terminal of the third resistor R3, and the first terminal of the third resistor R3 Two ends are connected with the first end of the fourth resistor R4 and the first input end of the multi-way switch 121, the second end of the fourth resistor R4 is connected with the first end of the fifth resistor R5 and the second input end of the multi-way switch 121 connected, the second end of the fifth resistor R5 is connected with the first end of the sixth resistor R6 and the third input end of the multi-way switch 121, the second end of the sixth resistor R6 is connected with the first end of the seventh resistor R7 and the multi-way switch 121 The fourth input end of the multi-way switch 121 is connected, the second end of the seventh resistor R7 and the second end of the first capacitor C1 are connected to the power ground, the first output end of the multi-way switch 121 is connected to the input of the over-discharge protection circuit 122 The second output terminal of the multi-way switch 121 is connected to the input terminal of the overcharge protection circuit 123, the output terminal of the overcurrent protection circuit 126 is connected to the third input terminal of the delay circuit 124, and the output terminal of the short circuit protection circuit 127 It is connected with the fourth input end of the delay circuit 124, the first end of the second resistor R2 is connected with the input end of the overcurrent protection circuit 126 and the input end of the short circuit protection circuit 127, and the second end of the second resistor R2 is a control sub The first input end of module 012, the output end of delay circuit 124 is connected with the input end of logic circuit 128, the output end of delay circuit 124 is connected with the input end of system dormancy circuit 125, and the first output end of logic circuit 128 is The first output terminal of the control sub-module 012 , the second output terminal of the logic circuit 128 is the second output terminal of the control sub-module 012 , the third output terminal of the logic circuit 128 is the third output terminal of the control sub-module 012 .

As shown in FIG. 3 , the substrate switching circuit includes a first level conversion circuit, a first field effect transistor Q1 , a second field effect transistor Q2 , a third field effect transistor Q3 and a fourth field effect transistor Q4 .

The input terminal of the first level conversion circuit is the input terminal of the substrate switching circuit 013, the first output terminal of the first level conversion circuit is connected to the gate of the first field effect transistor Q1, and the first output terminal of the first level conversion circuit is connected to the gate of the first field effect transistor Q1. The two output ends are connected to the gate of the second field effect transistor Q2, the third output end of the first level shifting circuit is connected to the gate of the third field effect transistor Q3, and the fourth output end of the first level shifting circuit is connected to the gate of the third field effect transistor Q3. The gate of the fourth FET Q4 is connected, the source of the first FET Q1 is connected to the power ground, the drain of the first FET Q1 is connected to the source of the second FET Q2, and the second FET The drain of Q2 and the source of the third field effect transistor Q3 are the output terminals of the substrate switching circuit, the drain of the third field effect transistor Q3 is connected to the source of the fourth field effect transistor Q4, and the source of the fourth field effect transistor Q4 The drain is the second input terminal of the substrate switching circuit 013 .

In specific implementation, it can be assumed that the negative terminal voltage of the external circuit of the lithium battery protection circuit is B-, the battery voltage is VDD, the second input terminal of the substrate switching circuit is connected to the negative terminal voltage B- of the external circuit, and the first level conversion circuit The voltage domain of the first output terminal of the first level conversion circuit is 0 to VDD, the voltage domain of the second output terminal of the first level conversion circuit is B- to VDD, the voltage domain of the third output terminal of the first level conversion circuit is 0 to VDD, the second The voltage domain of the fourth output terminal of the level conversion circuit is from B- to VDD.

When the input terminal of the substrate switching circuit is connected to the overcharge control signal OC, the voltage of the first output terminal of the first level conversion circuit, the voltage of the second output terminal of the first level conversion circuit and the overcharge control signal of the original circuit The OC signal is in the same phase, the voltage of the third output terminal of the first level conversion circuit, the voltage of the fourth output terminal of the first level conversion circuit and the overcharge control signal OC signal of the original circuit are out of phase. When the overcharge control signal OC is 0, the system is overcharged, and the potential of the output terminal of the substrate switching circuit is connected to the B- terminal. When the overcharge control signal OC is 1, the system is not overcharged, and the potential of the output terminal of the substrate switching circuit is Connect to ground.

When the input terminal of the substrate switching circuit is connected to the over-discharge control signal OD, the voltage of the first output terminal of the first level conversion circuit, the voltage of the second output terminal of the first level conversion circuit and the over-discharge control signal of the original circuit The OD signals are in the same phase, the voltage of the third output terminal of the first level conversion circuit, the voltage of the fourth output terminal of the first level conversion circuit and the over-discharge control signal OD signal of the original circuit are out of phase. When the over-discharge control signal OD is 0, the system overshoots, and the potential of the output terminal of the substrate switching circuit is connected to the B- terminal. When the over-discharge control signal OD is 1, the system is not overcharged, and the potential of the output terminal of the substrate switching circuit is Connect to ground.

Since the protection circuit of the lithium battery is turned off through 4 FETs, it is ensured that the charging and discharging circuit of the lithium battery can be completely closed no matter when the charging power supply or the load is connected.

As shown in Figure 4, the gate control circuit includes a second level conversion circuit, a third level conversion circuit, a NAND gate U1, a fifth field effect transistor Q5, a sixth field effect transistor Q6, and a seventh field effect transistor Q7 , the eighth field effect transistor Q8 and the ninth field effect transistor Q9.

The input terminal of the second level conversion circuit and the first input terminal of the NAND gate U1 are the first input terminal of the gate control circuit, and the first output terminal of the second level conversion circuit is connected to the gate of the fifth field effect transistor Q5. pole connection, the second output end of the second level conversion circuit is connected to the gate of the sixth field effect transistor Q6, the input end of the third level conversion circuit and the second input end of the NAND gate U1 are gate control circuits The second input terminal of the third level conversion circuit is connected to the gate of the seventh field effect transistor Q7, the second output terminal of the third level conversion circuit is connected to the gate of the eighth field effect transistor Q8 The output terminal of the NAND gate U1 is connected to the gate of the ninth field effect transistor Q9, the positive pole of the power supply of the NAND gate U1 is connected to the first power supply and the source of the ninth field effect transistor Q9, and the power supply of the NAND gate U1 The negative electrode and the source of the fifth field effect transistor Q5 are connected to the power ground, the drain of the sixth field effect transistor Q6 is connected to the drain of the fifth field effect transistor Q5, the source of the sixth field effect transistor Q6, the eighth field effect transistor The source of the field effect transistor Q8 and the drain of the ninth field effect transistor Q9 are the output terminals of the gate control circuit, the source of the seventh field effect transistor Q7 is the third input terminal of the gate control circuit, and the seventh field effect transistor Q7 The drain is connected to the source of the eighth field effect transistor Q8.

In a specific implementation, the input end of the second level shifting circuit is connected to the over-discharge control signal OD, the voltage domain of the first output end of the second level shifting circuit is 0 to VDD, and the second output of the second level shifting circuit The voltage domain of the terminal is B- to VDD, the voltage of the first output terminal of the second level shifting circuit and the voltage of the second output end of the second level shifting circuit are opposite to the discharge control signal OD. The input terminal of the third level conversion circuit is connected to the overcharge control signal OC, the voltage domain of the first output terminal of the third level conversion circuit is B- to VDD, and the voltage domain of the second output terminal of the third level conversion circuit is 0 To VDD, the voltage of the first output terminal of the third level shifting circuit and the voltage of the second output end of the third level shifting circuit are inverse to the overcharge control signal OC.

In a specific implementation, the above-mentioned first power source and the second power source may be battery voltage.

Through the circuits in Figure 3 and Figure 4, the following functions are realized:

A. When the over-discharge control signal OD is 0, the substrate of the field effect transistor M1 is grounded, and the gate is grounded. At this point, the battery no longer supplies power to the load.

B. When the overcharge control signal OC is 0, the substrate of the field effect transistor M1 is connected to the negative pole B- of the external circuit, and the gate is connected to the negative pole B- of the external circuit. At this point, the external charging voltage no longer charges the battery.

C. When the over-discharge control signal OD is 1 and the over-charge control signal OC is 1, the substrate of the field effect transistor M1 is connected to the negative terminal B- of the external circuit or grounded, and the gate is connected to the first power supply VDD. At this point, the battery supplies power to the load, or the external charging voltage charges the battery.

The present invention includes a battery and a lithium battery protection chip, the battery is connected to the lithium battery protection chip, the lithium battery protection chip includes a bias and reference circuit and a control submodule, the bias and reference circuit generates a bias voltage and a reference voltage, and the control submodule Generate overcharge control signal and overdischarge control signal according to battery voltage, bias voltage and reference voltage; lithium battery protection chip also includes substrate switching circuit, gate control circuit and field effect tube; substrate switching circuit according to overcharge control The signal or over-discharge control signal generates a substrate switching signal, the gate control circuit generates a gate control signal according to the overcharge control signal and over-discharge control signal, and the FET controls the charging and discharging of the lithium battery according to the substrate switching signal and the gate control signal The circuit is opened or closed, therefore, the integration degree of the lithium battery protection chip is improved, and the cost of the lithium battery protection circuit is reduced.

The serial numbers of the above embodiments of the present invention are for description only, and do not represent the advantages and disadvantages of the embodiments.

Those of ordinary skill in the art can understand that all or part of the steps for implementing the above embodiments can be completed by hardware, and can also be completed by instructing related hardware through a program. The program can be stored in a computer-readable storage medium. The above-mentioned The storage medium mentioned may be a read-only memory, a magnetic disk or an optical disk, and the like.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (2)

1. a kind of lithium battery protection circuit, including battery and Li battery protection IC, the battery and the li-ion cell protection core Piece is connected, and the Li battery protection IC includes biasing and reference circuit and control submodule, and the biasing is given birth to reference circuit Into bias voltage and reference voltage, the control submodule is according to the voltage, the bias voltage and the benchmark of the battery Voltage generation overcharges electric control signal and overdischarge control signal；Characterized in that, the Li battery protection IC also includes lining Bottom switching circuit, grid control circuit and FET；

First output end of the control submodule is connected with the input of the substrate switching circuit, the control submodule Second output end is connected with the first input end of the grid control circuit, the 3rd output end of the control submodule with it is described The second input connection of grid control circuit, the output end of the substrate switching circuit connect with the substrate of the FET Connect, the output end of the grid control circuit is connected with the grid of the FET, the first input of the control submodule End is connected with the source electrode of the FET；

The substrate switching circuit overcharges electric control signal or overdischarge control signal generation substrate switching letter according to Number, the grid control circuit overcharges electric control signal and overdischarge control signal generation grid control letter according to Number, the FET controls opening for charging and discharging lithium battery loop according to the substrate switching signal and the grid control signal Open or close；

The substrate switching circuit includes the first level shifting circuit, the first FET, the second FET, the 3rd field-effect Pipe and the 4th FET；

The input of first level shifting circuit is the input of the substrate switching circuit, the first level conversion electricity First output end on road is connected with the grid of first FET, the second output end of first level shifting circuit with The grid connection of second FET, the 3rd output end and the 3rd FET of first level shifting circuit Grid connection, the 4th output end of first level shifting circuit is connected with the grid of the 4th FET, described First FET source electrode is connected with power supply, and the drain electrode of first FET connects with the source electrode of second FET Connect, the drain electrode of second FET and the output end that the source electrode of the 3rd FET is the substrate switching circuit, The drain electrode of 3rd FET is connected with the source electrode of the 4th FET, and the drain electrode of the 4th FET is institute State the second input of substrate switching circuit.

2. lithium battery protection circuit as claimed in claim 1, it is characterised in that the grid control circuit includes second electrical level Change-over circuit, the 3rd level shifting circuit, NAND gate, the 5th FET, the 6th FET, the 7th FET, the 8th FET and the 9th FET；

The input of the second electrical level change-over circuit and the first input end of the NAND gate are the grid control circuit First input end, the first output end of the second electrical level change-over circuit is connected with the grid of the 5th FET, described Second output end of second electrical level change-over circuit is connected with the grid of the 6th FET, the 3rd level shifting circuit Input and the NAND gate the second input be the grid control circuit the second input, the 3rd level turn The first output end for changing circuit is connected with the grid of the 7th FET, the second output of the 3rd level shifting circuit End is connected with the grid of the 8th FET, and the output end of the NAND gate and the grid of the 9th FET connect Connect, the positive source of the NAND gate is connected with the source electrode of the first power supply and the 9th FET, the electricity of the NAND gate The source electrode of source negative pole and the 5th FET with being connected to power supply altogether, the drain electrode of the 6th FET with described 5th The drain electrode connection of effect pipe, the source electrode of the 6th FET, the source electrode of the 8th FET and described 9th The drain electrode of effect pipe is the output end of the grid control circuit, and the source electrode of the 7th FET is grid control electricity 3rd input on road, the drain electrode of the 7th FET are connected with the drain electrode of the 8th FET.