CN204633601U - An adjustable constant voltage and constant current power supply - Google Patents

Abstract

The utility model provides a kind of adjustable constant-voltage constant, it is characterized in that: it comprises: rectification filtering module, controlled switch voltage reduction module, 5V switch buck module, electric current and voltage adjustment module, electric current and voltage sampling module, OLED display module, described rectification filtering module is connected to civil power by transformer, rectification filtering module is connected with controlled switch voltage reduction module, 5V switch buck module, controlled switch voltage reduction module, 5V switch buck module are connected with electric current and voltage sampling module, controlled switch voltage reduction module are connected with electric current and voltage adjustment module.The utility model uses constant pressure and flow step-down two kinds of control methods, power supply constant voltage can not only be exported, all right constant current output, and can automatically switch under both modes.

Description

An adjustable constant voltage and constant current power supply

technical field

The utility model relates to the field of power supply, in particular to an adjustable constant voltage and constant current power supply.

Background technique

With the development of semiconductor technology, at present, the working voltage of many ARM core processors, DSP, FPGA, etc. is getting lower and lower, but because the internal transistors are always increasing with Moore's law, the required current is also constantly increasing. External power supplies can no longer meet this demand. For example, the Exynos 5422, a processor with a Cortex-A15 architecture and integrated GPU, has an operating voltage of only 1.1V and a full-load current of more than 6A. In actual use, it is necessary to integrate a PMU on the circuit board to convert the voltage of about 5V into the low-voltage and high-current power supply required by the chip. However, in the pre-development environment, it is often necessary to repeatedly test the power supply voltage and current to determine the power supply circuit of the PMU. The chip power supply in the early stage can only be provided externally, but the existing power supplies on the market can no longer provide such a large current at low voltage. The existing method is to design a temporary external power supply by reserving a large margin by estimating the parameters, but this method increases the workload of the developer, prolongs the development cycle, and is extremely difficult to troubleshoot once a power supply problem occurs.

In addition, most of the existing DC power supplies are designed for constant voltage and current limiting, which cannot be used as a constant current source, or the output current is too small when used as a constant current source. However, with the continuous development of electronic products, there are more and more occasions that require constant current power supply, or constant voltage/constant current automatic switching power supply. For example, high-power LEDs need constant current power supply, and the charging process of lithium batteries requires constant current first. And then constant voltage power supply. In addition, in both applications, a constant current source is required to output a large current, and the existing power supply cannot meet the demand. For example, Chinese patent 201210241608.4 provides a constant voltage and current limiting power supply, which cannot output constant current. For example, Chinese patent 201410032376.0 provides a power supply capable of constant voltage or constant current output, but it uses LM2596 as the step-down main control chip, and the maximum output current is only 3A, which cannot meet the demand for high current output.

Utility model content

The technical problem solved by the utility model is to provide an adjustable constant voltage and constant current power supply to solve the problems raised in the above-mentioned background technology.

The technical problems solved by the utility model are realized by the following technical solutions: an adjustable constant voltage and constant current power supply, including: a rectification filter module, a controlled switch step-down module, a 5V switch step-down module, a voltage and current regulation module, Current sampling module, OLED display module, the rectification and filtering module is connected to the mains through a transformer, the rectification and filtering module is connected with a controlled switch step-down module, a 5V switch step-down module, a controlled switch step-down module, a 5V switch step-down module A voltage and current sampling module is connected to the module, and a voltage and current regulation module is connected to the controlled switch step-down module.

The voltage and current sampling module is connected with an OLED display module, an adjustable output interface, and a USB output interface.

The controlled switch step-down module uses a synchronous Buck switch topology for step-down, and replaces the diode of the lower bridge arm of the traditional Buck topology with a full N-channel MOS tube to realize a fully-controlled chopper rectification, which is comparable to other linear regulators. Compared with the voltage converter or non-synchronous step-down topology, it significantly reduces the switching loss and heat generation, so that it can output 20V voltage and 10A current. A current sampling resistor is added between the step-down inductor and the output filter capacitor, and the current feedback is realized by sampling the voltage at both ends of the amplifying resistor through the current feedback network, thereby realizing the function of constant current output. A resistor divider network is used to sample the voltage between the output capacitor and the power ground to realize voltage feedback, thereby realizing the function of constant voltage output. The parameters of the resistor divider network and the current feedback network can be changed by using the voltage and current sampling module, so that the voltage and current can be adjusted.

The 5V switch step-down module also uses a synchronous Buck topology to provide a 5V constant voltage power supply with a maximum output of 3A current. Because the 5V voltage source is widely used in various environments, the voltage source In addition to supplying power to the voltage and current sampling module and the OLED display module of the system, it is also exported for external use.

The voltage and current adjustment module uses a potentiometer to adjust the resistance value, changes the feedback resistance value of the voltage feedback network to change the output voltage, and changes the comparison voltage of the current feedback network to change the output current, so that the voltage and current can be adjusted.

The voltage and current sampling module uses a resistor divider network to sample the output voltage, provides output voltage information to the OLED display module, and uses a current sampling resistor to sample the output current, but since the sampled signal is too weak, in order to improve the accuracy, A program-controlled amplifier is used to amplify the sampling signal, and then sent to the OLED module for output current sampling.

The transformer uses a 24V, 200W single-output power frequency transformer to provide energy for the work of the entire system.

The rectification and filtering module uses a diode bridge for full-bridge rectification and a π-type CLC filter network for filtering to provide a stable DC power supply for subsequent circuits.

The OLED display module acquires the voltage and current information from the voltage and current sampling module, processes them, decodes them and sends them to the OLED screen for display.

Compared with the prior art, the beneficial effects of the utility model are: 1. The utility model uses two control methods of constant voltage and constant current step-down, so that the power supply can not only output constant voltage, but also output constant current, and can be used in this Automatic switching between the two modes.

2. The utility model uses a synchronous high-frequency Buck switch step-down topology, and uses an all-N channel low internal resistance MOS tube as a switch power stage, which greatly reduces switching losses and improves step-down efficiency. Compared with traditional power supplies, it can output a large current.

3. The utility model uses a highly integrated 5V power supply as an auxiliary power supply, which can not only provide energy for the system control and display parts, but also lead out for external use.

4. The utility model uses a program-controlled amplifier to amplify the current sampling signal on the current sampling resistor, which solves the disadvantages of the previous current sampling signal being too small and inconvenient for quantization processing, and realizes high-precision current measurement, and compared with other solutions, it greatly reduces the internal resistance of the power supply.

5. The utility model uses a self-luminous OLED display screen to display the current output voltage and current of the power supply, which is small in size, high in contrast, low in power consumption, and has an eye-catching display effect.

Description of drawings

Fig. 1 is the structure schematic diagram of the utility model.

Fig. 2 is a circuit diagram of the controlled switch step-down module of the present invention.

Fig. 3 is a circuit diagram of the 5V switch step-down module of the present invention.

Fig. 4 is a circuit diagram of the voltage and current regulation module of the present invention.

Fig. 5 is a circuit diagram of the voltage and current sampling module of the present invention.

FIG. 6 is a circuit diagram of the OLED display module of the present invention.

FIG. 7 is a circuit diagram of a transformer of the present invention.

Fig. 8 is a circuit diagram of the rectifying and filtering module of the present invention.

Detailed ways

In order to make the technical means, creative features, goals and effects of the present invention easy to understand, the present invention will be further elaborated below in conjunction with specific illustrations.

As shown in Figure 1, an adjustable constant voltage and constant current power supply includes: a rectification filter module, a controlled switch step-down module, a 5V switch step-down module, a voltage and current adjustment module, a voltage and current sampling module, and an OLED display module. The rectification and filtering module is connected to the mains through a transformer. The rectification and filtering module is connected with a controlled switch step-down module and a 5V switch step-down module. The controlled switch step-down module and the 5V switch step-down module are connected with a voltage and current sampling module. A voltage and current regulation module is connected to the controlled switch step-down module.

The voltage and current sampling module is connected with an OLED display module, an adjustable output interface, and a USB output interface.

The controlled switch step-down module uses a synchronous Buck switch topology for step-down, and replaces the diode of the lower bridge arm of the traditional Buck topology with a full N-channel MOS tube to realize a fully-controlled chopper rectification, which is comparable to other linear regulators. Compared with the voltage converter or non-synchronous step-down topology, it significantly reduces the switching loss and heat generation, so that it can output 20V voltage and 10A current. A current sampling resistor is added between the step-down inductor and the output filter capacitor, and the current feedback is realized by sampling the voltage at both ends of the amplifying resistor through the current feedback network, thereby realizing the function of constant current output. A resistor divider network is used to sample the voltage between the output capacitor and the power ground to realize voltage feedback, thereby realizing the function of constant voltage output. The parameters of the resistor divider network and the current feedback network can be changed by using the voltage and current sampling module, so that the voltage and current can be adjusted.

The 5V switch step-down module also uses a synchronous Buck topology to provide a 5V constant voltage power supply with a maximum output of 3A current. Because the 5V voltage source is widely used in various environments, the voltage source In addition to supplying power to the voltage and current sampling module and the OLED display module of the system, it is also exported for external use.

The voltage and current adjustment module uses a potentiometer to adjust the resistance value, changes the feedback resistance value of the voltage feedback network to change the output voltage, and changes the comparison voltage of the current feedback network to change the output current, so that the voltage and current can be adjusted.

The voltage and current sampling module uses a resistor divider network to sample the output voltage, provides output voltage information to the OLED display module, and uses a current sampling resistor to sample the output current, but since the sampled signal is too weak, in order to improve the accuracy, A program-controlled amplifier is used to amplify the sampling signal, and then sent to the OLED module for output current sampling.

The transformer uses a 24V, 200W single-output power frequency transformer to provide energy for the work of the entire system.

The rectification and filtering module uses a diode bridge for full-bridge rectification and a π-type CLC filter network for filtering to provide a stable DC power supply for subsequent circuits.

The OLED display module acquires the voltage and current information from the voltage and current sampling module, processes them, decodes them and sends them to the OLED screen for display.

The first preferred solution of the utility model is that the controlled switch step-down module uses the LT3741 constant voltage constant current synchronous Buck controller of Linear Company, and its step-down topology is driven by all N-channel MOS tubes, which greatly reduces the Heat generation, so that it can output high voltage and high current, and can realize constant voltage and constant current operation under any voltage/current. The switching frequency is set to 300KHz, which significantly reduces the inductance of the external filter inductor and the capacitance of the capacitor, and reduces the volume and weight of the power supply.

The second preferred solution of the present utility model is that the controlled switch step-down module, wherein the upper bridge arm of the Buck power stage uses the AOD4184N channel MOS transistor of AOSMD Company, the on-resistance is 8 milliohms, the withstand voltage is 40V, and the maximum current 50A, the lower bridge arm uses the AOD438 N-channel MOS tube of AOSMD Company, the on-resistance is 3.5 milliohms, the withstand voltage is 30V, and the maximum current is 85A. By using all N-channel MOS tubes, the switching loss and The conduction loss reduces the calorific value and improves the step-down efficiency, so that the power supply can output 20V voltage and 10A current.

The third preferred solution of the present utility model is that the 5V switch step-down module uses the TPS54335 synchronous Buck switching regulator of TexasInstrument Company, which integrates the switch MOS tube itself, and only needs to configure the external inductance capacitor and voltage feedback resistor in use , which can provide 5V 3A output under the input voltage of 7V to 28V, and reduce the volume.

The fourth preferred solution of the present utility model is that the voltage and current sampling module uses the INA169 rail-to-rail program-controlled amplifier of Texas Instrument Company, which can set 20 times, 50 times, and 100 times of magnification, and its rail-to-rail characteristics The current sampling can be performed from the positive side of the power supply, which is very suitable for the amplification of the current sampling signal.

The fifth preferred solution of the present utility model is that the OLED display module uses UG-2864HSWEG01 of Univision Company, which is a 0.96-inch 12864 white OLED self-luminous screen, and does not require an external backlight when used, and because of its self-luminous characteristics, the contrast ratio is very high. High, can be viewed in the sun, the viewing angle can reach 170°, the maximum operating current is 28.9mA, which reduces the power consumption of the display module itself.

The working principle of the utility model is: after the device is powered on, the alternating current is transformed into low-voltage alternating current through the transformer module, and the low-voltage alternating current is transformed into low-voltage direct current through the rectification and filtering module. 5V DC, to supply power to the voltage and current sampling module and the OLED display module, and as one output, the voltage and current sampling module supplies power to external devices, and the other channel enters the controlled switch step-down module, and the controlled switch step-down module accepts the voltage and current adjustment module control parameters, the output voltage starts from 0V at startup, and gradually increases within 200ms. During the increase process, the voltage and current are continuously detected. If any item of voltage/current reaches the set value of the voltage and current adjustment module, the increase will stop. Large voltage; in steady state, if the load increases when the module works in constant voltage mode, so that the output current exceeds the set current value, the module will switch the working mode to constant current mode, and reduce the working voltage until the output current is not greater than Set current; if the load decreases when the module works in constant current mode, so that the output current is lower than the set current value, the module will try to increase the output voltage, trying to make the current reach the set current value again, if the output voltage rises to the set current value When the current does not reach the set value at constant voltage, the working state of the module will switch back to the constant voltage mode and output the set voltage. The direct current output by the controlled step-down module is connected to the external load through the voltage and current sampling module. The voltage and current sampling module uses a resistor divider network to sample the output voltage, uses a current sampling resistor to sample the output current through a program-controlled amplifier, and then sends the sampled voltage and current signals to the OLED module. The OLED module quantifies the sampled voltage and current signals and sends them to the OLED screen for display.

The basic principles and main features of the present utility model and the advantages of the present utility model have been shown and described above. Those skilled in the art should understand that the utility model is not limited by the above-mentioned embodiments. The above-mentioned embodiments and descriptions only illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model The new model also has various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The required protection scope of the utility model is defined by the appended claims and their equivalents.

Claims (6)

1. an adjustable constant-voltage constant, it is characterized in that: it comprises: rectification filtering module, controlled switch voltage reduction module, 5V switch buck module, electric current and voltage adjustment module, electric current and voltage sampling module, OLED display module, described rectification filtering module is connected to civil power by transformer, rectification filtering module is connected with controlled switch voltage reduction module, 5V switch buck module, controlled switch voltage reduction module, 5V switch buck module are connected with electric current and voltage sampling module, controlled switch voltage reduction module are connected with electric current and voltage adjustment module.

2. a kind of adjustable constant-voltage constant according to claim 1, is characterized in that: described electric current and voltage sampling module is connected with OLED display module, adjustable output interface, USB output interface.

3. a kind of adjustable constant-voltage constant according to claim 1, is characterized in that: described transformer uses that 24V, 200W are mono-exports Industrial Frequency Transformer, for the work of whole system provides the energy.

4. a kind of adjustable constant-voltage constant according to claim 1, is characterized in that: described rectification filtering module uses diode bridge to carry out full-bridge rectification, uses π type CLC filter network to carry out filtering, for late-class circuit provides galvanic current source.

5. a kind of adjustable constant-voltage constant according to claim 1, is characterized in that: described controlled switch voltage reduction module comprises the synchronous Buck controller of constant pressure and flow.

6. a kind of adjustable constant-voltage constant according to claim 1, is characterized in that: described OLED display module is the 0.96 cun of 12864 spontaneous optical screen of White OLED.