Low-power constant voltage and constant current circuit based on VIOC

Abstract

The application provides a low-power constant-voltage and constant-current circuit based on VIOC, wherein a VIOC differential acquisition module is used for acquiring the difference between the output voltage of a DCDC switching power supply and the output voltage of an LDO module; an LDO feedback module is used for feeding back the voltage output by the LDO module to the LDO module or converting the current output by the LDO module into a corresponding voltage signal and then feeding back to the LDO module; a voltage and current monitoring module is used for measuring the voltage and current of the direct current output by the LDO module and outputting a digital communication signal and a fault protection interrupt signal to an MCU module according to the measured voltage and current; and the MCU module is used for adjusting the output voltage of the LDO module according to the digital communication signal and the fault protection interrupt signal. The application meets the real-time switching of constant-voltage and constant-current power supply in OLED CELL testing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated circuits, and particularly relates to a low-power constant-voltage constant-current circuit based on a VIOC. BACKGROUND

[0002] In the screen display industry, as the market share of OLED screens gradually increases and the application range gradually expands, the testing of OLED screen CELL processes is becoming more and more comprehensive and strict. If an OLED screen needs to be lit, in addition to necessary small signals, it also needs two-way power supply of +VDD and -VSS. To meet the needs of different products, +VDD and -VSS have two different combination modes in the output type. One is that a constant-voltage source and a constant-voltage source are combined, that is, +VDD and -VSS are both constant-voltage sources. The other is that a constant-voltage source and a constant-current source are combined, that is, one of +VDD and -VSS is a constant-voltage source and the other is a constant-current source. According to the needs of display screen manufacturers, the output type may be changed in real time during actual lighting.

[0003] In order to meet the requirements of low ripple and low power consumption, the common method in engineering at present is to adopt the series connection mode of a DCDC switching power supply and a discrete LDO linear voltage stabilizer. The DCDC and the LDO are respectively controlled by independent DACs. In the power-on sequence, the DCDC power supply is first started to output, at this time the LDO module is still in the off state, since the two modules are connected in series, so the whole system has no voltage output at this time. When the DCDC reaches the rated output voltage, the LDO module is started according to the instruction of the main control, at this time the system voltage or current starts to output. Note that the DCDC always outputs in the mode of a constant-voltage source, while the LDO can output in the mode of a constant-voltage source or a constant-current source.

[0004] In the switching of the LDO constant-voltage constant-current output type, the main method is digital switching based on ADC (analog-to-digital converter) sampling. In order to reduce the calculation amount of the master control unit and the complexity of the hardware circuit, the actual method adopted is a pseudo constant-current mode of digital regulation. This mode is still essentially a constant-voltage source, and the difference is that ADC is used to simultaneously collect the output voltage and current. The working steps of the master microprocessor in the normal working state of the constant-voltage source are: ① reading the load current in the constant-voltage source mode. ② calculating the load impedance according to the output voltage and the load current. ③ taking the load impedance as the proportional coefficient of the PID control, and outputting a new set voltage after the master control calculation. ④ monitoring the output current of the LDO module, and if there is an error with the set value, continue to iterate and adjust, and finally achieve the purpose of constant current. The reason why it is called pseudo constant-current mode is that, due to cost considerations, in the screen testing industry, the voltage and current sampling ADC generally adopts a general low-speed ADC or even only a current monitoring chip integrated with an ADC, which cannot achieve fast sampling adjustment. The main disadvantages are: ① long adjustment time. The single adjustment time needs tens of milliseconds, and if multiple iterations are required, the adjustment time may be as high as hundreds of milliseconds. ② voltage impact. The essence of adjustment is to adjust the DAC module of DCDC and LDO. If the actual value and the set value differ too much, and the algorithm is not well optimized, it is possible that the single adjustment step is too large, which may cause the voltage to jump suddenly, the waveform to be not smooth, and may cause adverse effects on equipment or products. SUMMARY

[0005] The present application provides a low-power constant-voltage constant-current circuit based on VIOC.

[0006] The present application provides a low-power constant-voltage constant-current circuit based on VIOC, comprising: a DCDC switching power supply, an LDO module, a VIOC differential acquisition module, an LDO feedback module, a voltage and current monitoring module, and an MCU module.

[0007] The DCDC switching power supply is used to convert the input voltage to a first target direct current voltage and output to the LDO module.

[0008] The LDO module is used to suppress the ripple and noise of the direct current output by the DCDC switching power supply, and output a second target direct current voltage to the LDO feedback module.

[0009] The VIOC differential acquisition module is used to acquire the difference between the output voltage of the DCDC switching power supply and the output voltage of the LDO module, and transmit the difference to the DCDC switching power supply.

[0010] The LDO feedback module is configured to feed back the voltage output by the LDO module into the LDO module or convert the current output by the LDO module into a corresponding voltage signal and then feed back the voltage signal into the LDO module, so as to output a constant current source or a constant voltage source;

[0011] The voltage and current monitoring module is configured to measure the voltage and current of the direct current output by the LDO module, and output a digital communication signal and a fault protection interrupt signal to the MCU module according to the measured voltage and current;

[0012] The MCU module is configured to adjust the output voltage of the LDO module according to the digital communication signal and the fault protection interrupt signal.

[0013] Optionally, the LDO module comprises a MOS tube and a first comparator.

[0014] The source of the MOS tube is electrically connected to the output end of the DCDC switching power supply and the first input end of the VIOC differential acquisition module, the drain is electrically connected to the input end of the LDO feedback module and the second input end of the VIOC differential acquisition module, and the gate is electrically connected to the output end of the first comparator.

[0015] The first input end of the first comparator is electrically connected to the output end of the MCU module, and the second input end is electrically connected to the output end of the LDO feedback module.

[0016] Optionally, the VIOC differential acquisition module comprises a first operational amplifier, a fifth resistor and a sixth resistor.

[0017] The first input end of the first operational amplifier is electrically connected to the output end of the DCDC switching power supply, and the second input end is electrically connected to the drain of the MOS tube; one end of the output end of the first operational amplifier is electrically connected to one end of the fifth resistor; one end of the fifth resistor away from the first operational amplifier is electrically connected to the FB pin of the DCDC switching power supply and one end of the sixth resistor; and the other end of the sixth resistor away from the fifth resistor is grounded.

[0018] Optionally, the LDO feedback module comprises a first resistor, a second comparator, a multiplexer, a second operational amplifier, a second resistor and a third resistor.

[0019] One end of the first resistor is electrically connected to the drain of the MOS tube and the first input end of the second comparator, and the other end of the first resistor is electrically connected to the second input end of the second comparator and the first input end of the second operational amplifier; the output end of the second comparator is electrically connected to the first input end of the multiplexer; the second input end of the second operational amplifier is electrically connected to the output end of the second operational amplifier; the output end of the second operational amplifier is electrically connected to one end of the second resistor; the other end of the second resistor is electrically connected to the second input end of the multiplexer and one end of the third resistor; the other end of the third resistor is grounded; and the output end of the multiplexer is electrically connected to the second input end of the first comparator.

[0020] Optionally, the voltage and current monitoring module comprises a fourth resistor, a third comparator and a monitoring chip.

[0021] One end of the fourth resistor is electrically connected to the other end of the first resistor and the first input end of the third comparator; the other end of the fourth resistor is electrically connected to the second input end of the third comparator and the first input end of the monitoring chip; the output end of the third comparator is electrically connected to the second input end of the monitoring chip; and the output end of the monitoring chip is electrically connected to the input end of the MCU module.

[0022] Optionally, the first output end of the MCU module is electrically connected to the third input end of the multiplexer; the second output end of the MCU module is electrically connected to the input end of the subsequent digital-to-analog conversion module; and the output end of the subsequent digital-to-analog conversion module is electrically connected to the first input end of the first comparator.

[0023] Optionally, the differential pressure V1 of the LDO module is calculated according to the following formula:

[0024] V1=V fb ×(R5+R6) / R6;

[0025] wherein, V fb is the internal reference voltage of the DCDC switching power supply chip; R5 is the resistance value of the fifth resistor; and R6 is the resistance value of the sixth resistor.

[0026] Optionally, the output voltage V dc of the DCDC switching power supply is calculated according to the following formula:

[0027] V dc =V fb ×(R5+R6) / R6+V2;

[0028] wherein, V fbThe internal reference voltage of the DCDC switching power supply chip; R5 is the resistance value of the fifth resistor; R6 is the resistance value of the sixth resistor; V2 is the output voltage of the LDO module.

[0029] Optionally, the MOS tube is a P-channel metal-oxide-semiconductor (PMOS) transistor.

[0030] Advantages:

[0031] 1. The constant voltage and constant current real-time switching can meet the positive and negative voltage power supply in the OLED CELL test.

[0032] 2. The hardware feedback loop switching time is short, which can improve the OLED CELL test speed.

[0033] 3. The hardware feedback loop switching can ensure the smoothness of the output waveform, and the current impact is small.

[0034] 4. In the case of unknown load, the output voltage of the DCDC switching power supply can be automatically adjusted according to the voltage output by the LDO module, reducing additional software operation.

[0035] 5. The DCDC switching power supply output voltage can be kept fixed through feedback during the switching process, minimizing heat dissipation. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described in the following are only embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0037] Figure 1 The structure diagram of the low-power constant voltage and constant current circuit based on VIOC provided by the embodiment of the present application;

[0038] Figure 2 The circuit diagram of the low-power constant voltage and constant current circuit based on VIOC provided by the embodiment of the present application;

[0039] Figure 3 The circuit diagram of the LDO feedback module provided by the embodiment of the present application;

[0040] Figure 4 The circuit diagram of the VIOC differential acquisition module provided by the embodiment of the present application;

[0041] Figure 5 The circuit diagram of the LDO module provided by the embodiment of the present application;

[0042] Figure 6A circuit diagram of the voltage and current monitoring module provided in the embodiment of the present application. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0044] Embodiment 1

[0045] As shown in Figure 1 and Figure 2 , the present embodiment provides a low-power constant-voltage constant-current circuit based on VIOC, which includes a DCDC switching power supply 1, an LDO module 2, a VIOC differential acquisition module 3, an LDO feedback module 4, a voltage and current monitoring module 5, and an MCU module 6.

[0046] The DCDC switching power supply 1 is used to convert an input voltage to a first target direct-current voltage and output to the LDO module.

[0047] The DCDC switching power supply 1 converts the device input voltage into a suitable set voltage with high efficiency. Specifically, DCDC output voltage = LDO output voltage + drop out voltage. Its essence is a direct-current constant-voltage source, the input is a system voltage, and the output is a specific voltage power supply after voltage reduction by the system voltage power supply. The DCDC direct-current output ripple and noise are relatively large, which will affect the test accuracy for display screen test equipment, so the LDO module needs to be used in the later stage to further suppress the ripple and noise.

[0048] Drop out voltage, usually refers to in a power converter or voltage regulator, when the load current passes through, the output voltage drops below the minimum value of the normal output voltage. This phenomenon is particularly common in low-dropout linear voltage regulators (LDO), because LDO needs to maintain a certain voltage difference at the output end to ensure that the internal adjustment elements (such as transistors) can work normally.

[0049] In LDO, drop out voltage refers to the minimum voltage difference between the output voltage and the input voltage under the minimum load current. For example, if the drop out voltage of an LDO is 0.3V, when the output voltage is 3.0V, the input voltage should be at least 3.3V (3.0V+0.3V). If the input voltage is lower than this value, the LDO may not be able to maintain its output voltage, resulting in a drop in output voltage, which may affect the normal operation of electronic devices connected to the LDO output.

[0050] The LDO module 2 is used to suppress the ripple and noise of the DC output of the DCDC switching power supply 1 and output a second target DC voltage to the LDO feedback module 4.

[0051] As shown in Figure 5 The LDO module 2 includes a MOS tube Q1 and a first comparator U1; the source of the MOS tube Q1 is electrically connected to the output of the DCDC switching power supply 1 and the first input of the VIOC differential acquisition module 3, the drain is electrically connected to the input of the LDO feedback module 4 and the second input of the VIOC differential acquisition module 3, and the gate is electrically connected to the output of the first comparator U1.

[0052] The first input of the first comparator U1 is electrically connected to the output of the MCU module 6, and the second input is electrically connected to the output of the LDO feedback module 4.

[0053] The LDO module 2 is a low dropout regulator. The core of the LDO module 2 is a first comparator U1 (i.e. error comparator) and a high-power MOS tube Q1 (for positive voltage circuit, MOS tube Q1 is generally P-MOSFET device, i.e. P-channel metal oxide semiconductor PMOS transistor). The function of the error comparator is to compare the feedback of the output load with the set DAC voltage, adjust the gate voltage of the MOS tube Q1, make the MOS tube Q1 work in the variable resistance area, achieve the purpose of outputting specific voltage and suppressing the DC ripple of the DCDC switching power supply 1 output, and finally get DC with relatively low ripple and noise level to meet the power demand of the screen to be tested. The input of the LDO module 2 is the output of the DCDC switching power supply 1, and the output is a specific voltage power supply after ripple suppression.

[0054] The VIOC differential acquisition module 3 is used to acquire the difference between the output voltage of the DCDC switching power supply 1 and the output voltage of the LDO module 2, and transmit the difference to the DCDC switching power supply 1.

[0055] As shown in Figure 4 The VIOC differential acquisition module 3 includes a first operational amplifier U2, a fifth resistor R5 and a sixth resistor R6.

[0056] The first input of the first operational amplifier U2 is electrically connected to the output of the DCDC switching power supply 1, and the second input is electrically connected to the drain of the MOS tube Q1; the output of the first operational amplifier U2 is electrically connected to one end of the fifth resistor R5; one end of the fifth resistor R5 away from the first operational amplifier U2 is electrically connected to the FB pin of the DCDC switching power supply 1 and one end of the sixth resistor R6; one end of the sixth resistor R6 away from the fifth resistor R5 is grounded.

[0057] The inputs to the VIOC differential acquisition module 3 are the output voltages of the DC-DC switching power supply 1 and the LDO module 2, respectively. The output of the VIOC differential acquisition module 3 is the difference between the input voltages. The main function of the VIOC differential acquisition module 3 is to acquire the voltages before and after the MOSFET Q1, and then transmit the difference to the preceding switching power supply voltage regulation module after differential calculation. R5 and R6 are both voltage divider resistors. Based on the calculations performed by the VIOC differential acquisition module 3, the voltage difference V1 of the LDO module 2 can be obtained:

[0058] V1 = V fb ×(R5+R6) / R6.

[0059] Among them, V fb R5 is the internal reference voltage of the DC-DC switching power supply chip; R6 is the resistance value of the fifth resistor; R7 is the resistance value of the sixth resistor.

[0060] For ease of design, the differential result can also be directly output to the FB pin of the DCDC switching power supply 1. Through this differential feedback, without the need for a pre-amplifier DAC (digital-to-analog converter), it can be ensured that the output voltage of the pre-amplifier DCDC is always at least one reference value of the internal FB of the switching power supply (typically 0.6V or 0.8V) higher than the output voltage of the LDO module 2.

[0061] The voltage regulation of the pre-amplifier DC-DC converter is controlled by the VIOC differential acquisition module 3, and is automatic. The output voltage V of the DC-DC switching power supply is... dc :

[0062] V dc =V fb ×(R5+R6) / R6+V2.

[0063] V2 is the output voltage of the LDO module. Therefore, the voltage drop loss of LDO module 2 can be kept constant, preventing thermal breakdown of MOSFET Q1.

[0064] LDO feedback module 4 is used to feed the voltage output of LDO module 2 into LDO module, or to convert the current output of LDO module into a corresponding voltage signal and feed it back into LDO module 2 for constant current or constant voltage source output.

[0065] like Figure 3 As shown, the LDO feedback module includes a first resistor R1, a second comparator U3, a multiplexer, a second operational amplifier U4, a second resistor R2, and a third resistor R3. In this embodiment, the multiplexer is a TS5A23160.

[0066] One end of the first resistor R1 is electrically connected to the drain of the MOS tube Q1 and the first input terminal of the second comparator U3, and the other end of the first resistor R1 is electrically connected to the second input terminal of the second comparator U3 and the first input terminal of the second operational amplifier U4 away from the MOS tube Q1; the output terminal of the second comparator U3 is electrically connected to the first input terminal of the multiplexer; the second input terminal of the second operational amplifier U4 is electrically connected to the output terminal of the second operational amplifier U4; one end of the second resistor R2 is electrically connected to the output terminal of the second operational amplifier U4; the other end of the second resistor R2 is electrically connected to the second input terminal of the multiplexer and one end of the third resistor R3 away from the second operational amplifier U4; the other end of the third resistor R3 is grounded; and the output terminal of the multiplexer is electrically connected to the second input terminal of the first comparator U1.

[0067] The input of the LDO feedback module 4 is the output voltage and output current of the LDO module 2, and the output of the LDO feedback module 4 is a voltage signal. The feedback of the LDO is composed of high-side current feedback and remote voltage feedback, wherein the output current of the LDO module 2 is converted into a corresponding voltage signal through the first resistor R1 (a sampling resistor). The loop switching of the LDO feedback module 4 is completed by the multiplexer controlled by the MCU module 6. The feedback output enters the LDO module 2, is compared with the DAC configured by the MCU module 6, and then controls the MOS tube Q1, which can output as a constant current source or as a constant voltage source.

[0068] The second operational amplifier U4 mainly functions as impedance conversion. By using the high input impedance characteristic of the operational amplifier, the leakage current phenomenon caused by directly using resistance voltage division feedback is reduced. The second resistor R2 and the third resistor R3 are both voltage division resistors, which are placed in the output stage of the second operational amplifier U4 (an instrument operational amplifier) and function to extract the feedback signal, which is sent into the LDO module 2 through the multiplexer and is error amplified with the DAC voltage, so as to control the gate of the MOS tube Q1.

[0069] The voltage and current monitoring module 5 is used for measuring the voltage and current of the direct current output by the LDO module 2, and outputs a digital communication signal and a fault protection interruption signal to the MCU module 6 according to the measured voltage and current.

[0070] As shown in Figure 6 , the voltage and current monitoring module 5 includes a fourth resistor R4, a third comparator U5 and a monitoring chip. In the embodiment, the model of the monitoring chip is INA226.

[0071] One end of the fourth resistor R4 is electrically connected to the first resistor R1 away from the one end of the MOS tube Q1 and the first input end of the third comparator U5; the fourth resistor R4 away from the one end of the first resistor R1 is electrically connected to the second input end of the third comparator U5 and the first input end of the monitoring chip; the output end of the third comparator U5 is electrically connected to the second input end of the monitoring chip; and the output end of the monitoring chip is electrically connected to the input end of the MCU module 6.

[0072] The voltage and current monitoring module 5 is mainly composed of a voltage and current monitoring chip and a current sampling resistor (the fourth resistor R4), and functions to measure the voltage and current of the direct current output by the LDO module 2. The measured data is used as digital feedback on one hand to adjust the output voltage in real time and ensure the output accuracy, and is used to protect against overvoltage and overcurrent and monitor circuit failure on the other hand. The input is low-ripple direct current, and the output is a digital communication signal and a fault protection interrupt signal.

[0073] The MCU module 6 is used to adjust the output voltage of the LDO module 2 according to the digital communication signal and the fault protection interrupt signal.

[0074] The MCU module 6 is mainly composed of a microprocessor chip, and functions to receive measurement values, perform feedback calculation, set the output voltage, and process various circuit protections. The input is the communication data and the protection interrupt output by the voltage and current monitoring module 5, and the output is a loop switching signal to the multiplexer and a digital SPI signal to the data communication of the DAC.

[0075] The low-power constant-voltage constant-current circuit based on VIOC provided in the embodiment can meet the real-time switching of constant-voltage constant-current of positive and negative voltage power supply in OLED CELL testing, the switching time of the hardware feedback loop is short, the OLED CELL testing speed can be improved, the hardware feedback loop switching can ensure the smoothness of the output waveform and the current impact is relatively small, in the case of unknown load, the output voltage of the DCDC switching power supply can be adjusted according to the voltage output by the LDO module, the additional software operation is reduced, and the output voltage of the DCDC switching power supply can be kept fixed through feedback in the switching process, and the heat dissipation is minimized.

[0076] The present application has been described in detail by combining with the specific embodiments and exemplary examples, but these descriptions cannot be understood as limitations on the present application. Those skilled in the art understand that the technical solutions and embodiments of the present application can be variously replaced, modified or improved without departing from the spirit and scope of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A low power constant voltage and constant current circuit based on VIOC, characterized by, The application relates to a voltage and current output circuit, which comprises a DCDC switching power supply, an LDO module, a VIOC differential acquisition module, an LDO feedback module, a voltage and current monitoring module and an MCU module. The DCDC switching power supply is used for converting an input voltage into a first target direct-current voltage and outputting the first target direct-current voltage to the LDO module. The LDO module is used for suppressing ripple and noise of direct-current voltage output by the DCDC switching power supply and outputting a second target direct-current voltage to the LDO feedback module. The VIOC differential acquisition module is used for acquiring a difference between output voltage of the DCDC switching power supply and output voltage of the LDO module and transmitting the difference to the DCDC switching power supply. The LDO feedback module is used for feeding back output voltage of the LDO module into the LDO module or converting current output by the LDO module into a corresponding voltage signal and then feeding back the voltage signal into the LDO module to output a constant current source or a constant voltage source. The voltage and current monitoring module is used for measuring voltage and current of direct-current voltage output by the LDO module and outputting a digital communication signal and a fault protection interruption signal to the MCU module according to the measured voltage and current. The MCU module is used for adjusting output voltage of the LDO module according to the digital communication signal and the fault protection interruption signal. The LDO module comprises a MOS tube and a first comparator.

2. The low power constant voltage and constant current circuit based on VIOC according to claim 1, characterized in that, The source of the MOS tube is electrically connected to an output end of the DCDC switching power supply and a first input end of the VIOC differential acquisition module, the drain is electrically connected to an input end of the LDO feedback module and a second input end of the VIOC differential acquisition module, and the gate is electrically connected to an output end of the first comparator. The first input end of the first comparator is electrically connected to an output end of the MCU module, and the second input end is electrically connected to an output end of the LDO feedback module. The VIOC differential acquisition module comprises a first operational amplifier, a fifth resistor and a sixth resistor.

3. The low power constant voltage and constant current circuit based on VIOC according to claim 2, characterized in that, The first input end of the first operational amplifier is electrically connected to an output end of the DCDC switching power supply, and the second input end is electrically connected to the drain of the MOS tube; one end of the output end of the first operational amplifier is electrically connected to one end of the fifth resistor; one end of the fifth resistor, which is away from the first operational amplifier, is electrically connected to an FB pin of the DCDC switching power supply and one end of the sixth resistor; and one end of the sixth resistor, which is away from the fifth resistor, is grounded. The LDO feedback module comprises a first resistor, a second comparator, a multiplexer, a second operational amplifier, a second resistor and a third resistor.

4. The low power constant voltage and constant current circuit based on VIOC according to claim 2, characterized in that, ​ One end of the first resistor is electrically connected to the drain of the MOS tube and the first input end of the second comparator, and the other end of the first resistor is electrically connected to the second input end of the second comparator and the first input end of the second operational amplifier; the output end of the second comparator is electrically connected to the first input end of the multiplexer; the second input end of the second operational amplifier is electrically connected to the output end of the second operational amplifier; the output end of the second operational amplifier is electrically connected to one end of the second resistor; the other end of the second resistor is electrically connected to the second input end of the multiplexer and one end of the third resistor; the other end of the third resistor is grounded; and the output end of the multiplexer is electrically connected to the second input end of the first comparator.

5. The low power constant voltage and constant current circuit based on VIOC according to claim 4, characterized in that, The voltage and current monitoring module comprises a fourth resistor, a third comparator and a monitoring chip; One end of the fourth resistor is electrically connected to the other end of the first resistor and the first input end of the third comparator; the other end of the fourth resistor is electrically connected to the second input end of the third comparator and the first input end of the monitoring chip; the output end of the third comparator is electrically connected to the second input end of the monitoring chip; and the output end of the monitoring chip is electrically connected to the input end of the MCU module.

6. The low power constant voltage and constant current circuit based on VIOC according to claim 4, wherein, The first output end of the MCU module is electrically connected to the third input end of the multiplexer; the second output end of the MCU module is electrically connected to the input end of the subsequent digital-to-analog conversion module; and the output end of the subsequent digital-to-analog conversion module is electrically connected to the first input end of the first comparator.

7. The low power constant voltage and constant current circuit based on VIOC according to claim 3, characterized in that, The differential pressure V1 of the LDO module is calculated according to the following formula: V1 = V fb x (R5 + R6) / R6; Wherein, V fb is the internal reference voltage of the DCDC switching power supply chip; R5 is the resistance value of the fifth resistor; R6 is the resistance value of the sixth resistor.

8. The low power constant voltage and constant current circuit based on VIOC according to claim 3, characterized in that, The output voltage V of the DCDC switching power supply is calculated according to the following formula dc : V dc = V fb × (R5+R6) / R6+V2; Wherein, V fb is the internal reference voltage of the DCDC switching power supply chip; R5 is the resistance value of the fifth resistor; R6 is the resistance value of the sixth resistor; V2 is the output voltage of the LDO module.

9. The low power constant voltage and constant current circuit based on VIOC according to claim 2, wherein, The MOS tube is a P-channel metal-oxide-semiconductor (PMOS) transistor.

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