Adjustable linear low-noise power supply circuit

Abstract

This application relates to an adjustable linear low-noise power supply circuit, including a DC-DC converter module, an LDO module, a first feedback network module, and a second feedback network module. The input terminal of the DC-DC converter module is connected to a power input terminal, the output terminal of the DC-DC converter module is connected to the input terminal of the LDO module, the output terminal of the LDO module is connected to a load, the first feedback network module connects the output terminal and the feedback terminal of the DC-DC converter module, and the second feedback network module connects the output terminal and the feedback terminal of the LDO module. All or part of the resistors in the first feedback network module are programmable resistors. The resistance value of the programmable resistors can be adjusted according to actual needs to change the voltage output of the DC-DC converter module, achieving linear adjustment of the output voltage. Combined with the LDO module for DC-DC conversion, it achieves low-noise and stable voltage output, improving the ease of use and reliability of the power supply circuit.

Description

Technical Field

[0001] This application relates to the field of power supply technology, and in particular to an adjustable linear low-noise power supply circuit. Background Technology

[0002] A DC-DC (Direct-to-DC) chip is an integrated circuit that converts electrical energy to voltage in a DC circuit. Its core function is to convert one DC voltage value to another, performing both step-down and step-up conversions, as well as polarity reversals. Traditional power supply circuits rely on external fixed feedback resistors to maintain the DC-DC chip's voltage output at a set value. This method cannot dynamically adjust to actual load requirements, necessitating frequent resistor replacements or circuit redesigns, resulting in poor flexibility and low ease of use. Utility Model Content

[0003] Therefore, it is necessary to provide an adjustable linear low-noise power supply circuit that can improve the flexibility of use in addressing the above problems.

[0004] The first aspect of this application provides an adjustable linear low-noise power supply circuit, including a DC-DC module, an LDO (Low Dropout Regulator) module, a first feedback network module, and a second feedback network module. The input terminal of the DC-DC module is connected to a power input terminal, the output terminal of the DC-DC module is connected to the input terminal of the LDO module, the output terminal of the LDO module is connected to a load, the first feedback network module is connected to the output terminal of the DC-DC module and the feedback terminal of the DC-DC module, and the second feedback network module is connected to the output terminal of the LDO module and the feedback terminal of the LDO module.

[0005] All or part of the resistors in the first feedback network module are programmable resistors. The DC-DC module converts the DC power input to the power input terminal according to the signal fed back by the first feedback network module and outputs the converted DC power to the LDO module. The LDO module converts the received DC power into a stable DC voltage and delivers it to the load according to the signal fed back by the second feedback network module.

[0006] In one embodiment, the DC-DC module includes a DC-DC chip, a first peripheral circuit, and an inductor. The Vin pin of the DC-DC chip serves as the input terminal of the DC-DC module and is connected to the power supply input terminal. The Vout pin of the DC-DC chip is connected to the first end of the inductor. The second end of the inductor serves as the output terminal of the DC-DC module and is connected to the input terminal of the LDO module and the first feedback network module. The FB pin of the DC-DC chip serves as the feedback terminal of the DC-DC module and is connected to the first feedback network module. The GND pin of the DC-DC chip is grounded. The first peripheral circuit is connected to the Vin pin, EN pin, and RT pin of the DC-DC chip.

[0007] In one embodiment, the first feedback network module includes resistors Rx1 and Rx2, with a first end of resistor Rx1 connected to a second end of the inductor, a second end of resistor Rx1 connected to the FB pin of the DC-DC chip and a first end of resistor Rx2, and a second end of resistor Rx2 grounded; resistors Rx1 and / or Rx2 are programmable resistors.

[0008] In one embodiment, the first peripheral circuit includes resistors R1 and R2. The first end of resistor R1 is connected to the Vin pin of the DC-DC chip, the second end of resistor R1 is connected to the EN pin of the DC-DC chip, the first end of resistor R2 is connected to the RT pin of the DC-DC chip, and the second end of resistor R2 is grounded.

[0009] In one embodiment, the number of LDO modules is one or more, and the LDO modules increase the current delivered to the load by output current sharing; the number of second feedback network modules is the same as the number of LDO modules, and the second feedback network modules are connected to the corresponding LDO modules.

[0010] In one embodiment, the LDO module includes an LDO chip and a second peripheral circuit. The Vin pin of the LDO chip serves as the input terminal of the LDO module and is connected to the output terminal of the DC-DC module. The Vout pin of the LDO chip serves as the output terminal of the LDO module and is connected to the load and the second feedback network module. The SET pin of the LDO chip serves as the feedback terminal of the LDO module and is connected to the second feedback network module. The second peripheral circuit is connected to the Vin pin, EN pin, and Ilimt pin of the LDO chip.

[0011] In one embodiment, the second peripheral circuit includes resistors R4 and R5. The first end of resistor R4 is connected to the Vin pin of the LDO chip, the second end of resistor R4 is connected to the EN pin of the LDO chip, the first end of resistor R5 is connected to the Ilimt pin of the LDO chip, and the second end of resistor R5 is grounded.

[0012] In one embodiment, the second feedback network module includes a resistor Rx3, the first end of which is connected to the SET pin of the LDO chip, and the second end of which is connected to the Vout pin of the LDO chip; the resistor Rx3 is a programmable resistor.

[0013] In one embodiment, the second feedback network module is also connected to the input terminal of the LDO module, and the LDO module follows the output voltage of the DCDC module according to the signal fed back by the second feedback network module, and outputs a stable DC voltage to the load.

[0014] In one embodiment, the second feedback network module includes a switch Q1, a diode D1, resistors R6, R7, and R8. The control terminal of the switch Q1 is connected to the first terminal of the resistor R6 and the anode of the diode D1. The second terminal of the resistor R6 is grounded. The cathode of the diode D1 is connected to the Vin pin of the LDO chip. The first terminal of the switch Q1 is connected to the first terminal of the resistor R7. The second terminal of the resistor R7 is connected to the Vout pin of the LDO chip. The second terminal of the switch Q1 is connected to the first terminal of the resistor R8. The second terminal of the resistor R8 is connected to the SET pin of the LDO chip.

[0015] In one embodiment, the power supply circuit further includes a measurement module and a control module. The measurement module is connected to the output terminal of the LDO module and the control module. The control module is connected to the control terminals of the programmable resistors in the first feedback network module and the second feedback network module. The control module adjusts the resistance value of the corresponding programmable resistor according to the output voltage measured by the measurement module.

[0016] In the aforementioned adjustable linear low-noise power supply circuit, all or part of the resistors in the first feedback network module are programmable resistors. The DC-DC module converts the DC power input to the power supply terminal based on the signal fed back from the first feedback network module, and outputs the converted DC power to the LDO module. The LDO module, based on the signal fed back from the second feedback network module, converts the received DC power into a stable DC voltage and delivers it to the load. The resistance value of the programmable resistors can be adjusted according to actual needs to change the voltage output of the DC-DC module, enabling linear adjustment of the output voltage. Combined with the DC-DC conversion by the LDO module, it achieves low-noise and stable voltage output, improving the ease of use and reliability of the power supply circuit. Attached Figure Description

[0017] Figure 1 This is a block diagram of an adjustable linear low-noise power supply circuit in one embodiment;

[0018] Figure 2 This is a schematic diagram of the structure of an adjustable linear low-noise power supply circuit in one embodiment;

[0019] Figure 3 This is a schematic diagram of the adjustable linear low-noise power supply circuit in another embodiment;

[0020] Figure 4 This is a schematic diagram of the adjustable linear low-noise power supply circuit in another embodiment. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0023] It is understood that the terms "first," "second," etc., used in this application may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. In the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have the transmission of electrical signals or data between them.

[0024] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0025] In one embodiment, such as Figure 1 As shown, an adjustable linear low-noise power supply circuit is provided, including a DC-DC module 110, an LDO module 120, a first feedback network module 130, and a second feedback network module 140. The input terminal of the DC-DC module 110 is connected to the power input terminal to receive DC current Vcc. The output terminal of the DC-DC module 110 is connected to the input terminal of the LDO module 120, and the output terminal of the LDO module 120 is connected to the load Rload. The first feedback network module 130 is connected to the output terminal and the feedback terminal of the DC-DC module 110. The second feedback network module 140 is connected to the output terminal and the feedback terminal of the LDO module 120.

[0026] The DC-DC module 110, based on the signal fed back from the first feedback network module 130, converts the DC power Vcc input to the power input terminal and outputs the converted DC power to the LDO module 120. The LDO module 120, based on the signal fed back from the second feedback network module 140, converts the received DC power into a stable DC voltage and supplies it to the load Rload. All or part of the resistors in the first feedback network module 130 are programmable resistors, and the second feedback network module 140 can also use programmable resistors, or a feedback network can be formed using switching transistors or other devices. Figure 2 As shown, the power supply circuit may further include a control module 150 and a measurement module 160. The measurement module 160 is connected to the output terminal of the LDO module 120 and the control module 150. The control module 150 is connected to the control terminals of the programmable resistors in the first feedback network module 130 and the second feedback network module 140. The control module 150 adjusts the resistance value of the corresponding programmable resistor according to the output voltage measured by the measurement module 160. The control module 150 sends a signal to the programmable resistor to control the programmable resistor to change its resistance value, thereby adjusting the voltage output of the power supply circuit to meet actual needs. The control module 150 can be an FPGA, MCU, CPU, etc., and the measurement module 160 can be an ADC.

[0027] The structure of the DCDC module 110 is not unique; in one embodiment, such as... Figure 2As shown, the DC-DC module 110 includes a DC-DC chip U1, a first peripheral circuit, and an inductor L. The Vin pin of the DC-DC chip U1 serves as the input terminal of the DC-DC module 110 and is connected to the power supply input terminal. The Vout pin of the DC-DC chip U1 is connected to the first end of the inductor L. The second end of the inductor L serves as the output terminal of the DC-DC module 110 and is connected to the input terminal of the LDO module 120 and the first feedback network module 130. The FB pin of the DC-DC chip U1 serves as the feedback terminal of the DC-DC module 110 and is connected to the first feedback network module 130. The GND pin of the DC-DC chip U1 is grounded. The first peripheral circuit is connected to the Vin pin, EN pin, and RT pin of the DC-DC chip U1.

[0028] The DC-DC chip U1 is an integrated circuit that performs power-to-voltage conversion in a DC circuit. Its core function is to convert one DC voltage value to another, enabling both step-down and step-up conversions, as well as polarity reversals. The first peripheral circuit may specifically include resistors R1 and R2. The first end of resistor R1 is connected to the Vin pin of the DC-DC chip U1, and the second end of resistor R1 is connected to the EN pin of the DC-DC chip U1. The first end of resistor R2 is connected to the RT pin of the DC-DC chip U1, and the second end of resistor R2 is grounded.

[0029] The DC-DC module 110 may also include capacitors C1, C2, and C3. The first terminal of each capacitor is connected to the Vin pin of the DC-DC chip U1, and the second terminal is grounded. Capacitors C1, C2, and C3 are used to filter the input DC current Vcc. Furthermore, this adjustable linear low-noise power supply circuit also includes capacitor C4. The first terminal of capacitor C4 is connected to the second terminal of inductor L, and the second terminal of capacitor C4 is grounded. Capacitor C4 is used to filter the DC current output from inductor L.

[0030] Furthermore, the first feedback network module 130 includes resistors Rx1 and Rx2. The first end of resistor Rx1 is connected to the second end of inductor L, and the second end of resistor Rx1 is connected to the FB pin of the DC-DC chip U1 and the first end of resistor Rx2. The second end of resistor Rx2 is grounded. Resistors Rx1 and / or Rx2 are programmable resistors. In this embodiment, both resistors Rx1 and Rx2 are programmable resistors. The control module 150 is connected to the control terminals of resistors Rx1 and Rx2 to adjust their resistance values.

[0031] The structure of the LDO module 120 is not unique; in one embodiment, see below. Figure 2The LDO module 120 includes an LDO chip U2 and a second peripheral circuit. The Vin pin of the LDO chip U2 serves as the input terminal of the LDO module 120 and is connected to the output terminal of the DC-DC module 110. The Vout pin of the LDO chip U2 serves as the output terminal of the LDO module 120 and is connected to the load Rload and the second feedback network module 140. The SET pin of the LDO chip U2 serves as the feedback terminal of the LDO module 120 and is connected to the second feedback network module 140. The GND pin of the LDO chip U2 is grounded. The second peripheral circuit is connected to the Vin pin, EN pin and Ilimt pin of the LDO chip U2.

[0032] The LDO chip U2 is a linear voltage regulator whose main function is to convert the input DC voltage into a stable output DC voltage with a small input-output voltage difference, achieving stable voltage regulation even when the input voltage is close to the output voltage. Based on the linear voltage regulation principle, the LDO chip U2 mainly consists of a regulating transistor (usually a PNP or NPN transistor, MOSFET, etc.), a reference voltage source, an error amplifier, and an internal feedback network. The reference voltage source provides a stable reference voltage. The error amplifier compares the output voltage with the reference voltage, generating an error signal that drives the regulating transistor to adjust its voltage drop, thereby maintaining a stable output voltage. When the input voltage increases or the load current decreases, the voltage drop of the regulating transistor increases to keep the output voltage constant. The second peripheral circuit may include resistors R4 and R5. The first end of resistor R4 is connected to the Vin pin of the LDO chip U2, and the second end of resistor R4 is connected to the EN pin of the LDO chip U2. The first end of resistor R5 is connected to the Ilimt pin of the LDO chip U2, and the second end of resistor R5 is grounded.

[0033] In one embodiment, such as Figure 2 As shown, the second feedback network module 140 includes a resistor Rx3. The first end of the resistor Rx3 is connected to the SET pin of the LDO chip U2, and the second end of the resistor Rx3 is connected to the Vout pin of the LDO chip. The resistor Rx3 is a programmable resistor. Specifically, by replacing resistors Rx1, Rx2, and Rx3 with programmable resistors, adding a control module 150 for control calculations, and adding a measurement module 160 for closed-loop output adjustment, compared with the traditional fixed output scheme, firstly, the output is a system set value, not the original fixed hardware output, providing greater operational flexibility; secondly, the addition of the measurement module 160 makes the entire output system closed-loop, and compared with the traditional scheme where output accuracy relies on resistor consistency during mass production, the power supply circuit provided in this application has higher output accuracy.

[0034] First, the control module 150 obtains the set voltage to be output, which can be derived from the host computer or the internal settings of the control module 150. The control module 150 controls a programmable resistor to set its resistance value. The programmable resistor can be understood as a sliding rheostat / potentiometer resistor controlled by a programming device. Due to changes in the external feedback resistor, the output voltage of the DCDC module 110 is adjusted by the internal feedback network. The control module 150 controls the measurement module 160 to measure the output voltage and compares the returned measured voltage with the set voltage. If the set output requirement is met, the system control output is completed; otherwise, the resistance value of the programmable resistor is adjusted according to the internal output logic until the desired output is achieved.

[0035] The number of LDO modules 120 can be one or more. Each LDO module 120 increases the current delivered to the load Rload by sharing the output current. The number of second feedback network modules 140 is the same as the number of LDO modules, and each second feedback network module is connected to its corresponding LDO module. When there are multiple LDO modules 120, they are interconnected. The input terminals of each LDO module 120 are connected to the output terminals of the DC-DC module 110, and the output terminals of each LDO module 120 are connected to the load Rload. Each LDO module 120 increases the current delivered to the load Rload by sharing the output current. This structure, where one DC-DC module 110 drives multiple LDO modules 120, with one LDO module 120 acting as the master and the others as slaves, uses parallel output for current sharing, expanding the output power. This meets the current requirements of hardware circuits that require low noise, low current ripple, and a sufficiently small circuit area.

[0036] like Figure 3 As shown, in the multi-LDO module 120, both the master and slave units include an LDO chip U2, resistor R4, capacitor C6, and capacitor C5 (capacitor C5 is not shown). The second feedback network module 140 corresponding to the master unit includes resistor Rx3, and the second feedback network module 140 corresponding to the slave unit includes resistor Rx4. Resistors Rx3 and Rx4 are programmable resistors. The Track pin of the LDO chip U2 in the slave unit is connected to the Ilimt pin of the LDO chip U2 in the master unit, and then they share a common resistor R5 for grounding. The slave unit uses the Track pin inside the LDO chip U2 to monitor the output current. By connecting the Ilimt pin of the master LDO chip U2 to the Track pin of the slave LDO chip U2, current sharing between the master and slave units is ensured, thereby expanding the output power.

[0037] In one embodiment, the second feedback network module 140 is also connected to the input terminal of the LDO module 120. The LDO module 120 follows the output voltage of the DC-DC module 110 based on the signal fed back by the second feedback network module 140, and outputs a stable DC voltage to the load Rload. In this embodiment, the output of the LDO module 120 is controlled by the input voltage of the LDO module 120. When the overall output voltage of the power supply circuit needs to change, the output voltage of the DC-DC module 110 is controlled to change first. Due to the follower network, the LDO module 120 ensures that the output voltage is a fixed value relative to the input voltage. When the input voltage decreases, the output voltage decreases accordingly. This "follower LDO" achieves low-noise output by suppressing power ripple. The output of the LDO module 120 is no longer controlled by the programming device and is mainly implemented by the follower network.

[0038] Specifically, such as Figure 4 As shown, the second feedback network module 140 includes a switch Q1, a diode D1, resistors R6, R7, and R8. The control terminal of switch Q1 is connected to the first terminal of resistor R6 and the anode of diode D1. The second terminal of resistor R6 is grounded. The cathode of diode D1 is connected to the Vin pin (input pin) of LDO chip U2. The first terminal of switch Q1 is connected to the first terminal of resistor R7. The second terminal of resistor R7 is connected to the Vout pin (output pin) of LDO chip U2. The second terminal of switch Q1 is connected to the first terminal of resistor R8. The second terminal of resistor R8 is connected to the SET pin (output voltage setting pin) of LDO chip U2. Switch Q1 can be a transistor or a MOSFET. In this embodiment, switch Q1 is a PNP transistor, with the base as the control terminal, the emitter as the first terminal, and the collector as the second terminal. The collector of the transistor is connected to the SET pin of the LDO chip U2 via resistor R8, and the emitter is connected to the Vout pin of the LDO chip U2 via resistor R7. The base of the transistor is connected to a voltage divider circuit consisting of diode D1 and resistor R6, which is connected to the Vin pin of the LDO chip U2. When the input current of the LDO stage changes, the voltage across diode D1 and resistor R6 changes accordingly, resulting in a change in the voltage across the transistor's base. This forward biases the transistor's PN junction, thus controlling the change in the LDO's output voltage.

[0039] Specifically, the switching transistor Q1 is connected to the Vin, Vout, and SET pins of the LDO chip U2, forming a voltage sampling node. This allows the input voltage to directly influence the feedback voltage through changes in the current flowing through the switching transistor Q1. The control terminal of the switching transistor Q1 is connected to the Vin pin of the LDO chip U2 via diode D1. A reference potential is established using the voltage regulation of diode D1, allowing the control terminal potential of the switching transistor Q1 to change linearly with the Vin pin, thus achieving direct control of the switching transistor Q1 by the input voltage. When the input voltage Vin changes, this potential is coupled to the control terminal of the switching transistor Q1 via diode D1, adjusting the conduction level of the switching transistor Q1. By adjusting the forward voltage of diode D1, the current amplification factor β of the switching transistor Q1, and the resistance value, the voltage difference ΔV between Vin and Vout can be precisely controlled to satisfy the dynamic balance relationship ΔV = Vd1 + Vbe - Q1 + IR1 (where Vd1 is the forward voltage of diode D1, and Vbe - Q1 is the base-emitter voltage of the switching transistor Q1).

[0040] Among them, the resistance of resistors R7 and R8 is set during the operation of switch Q1. The control terminal voltage of switch Q1 is a reference voltage relationship established by diode D1 and resistor R6. The first terminal voltage of switch Q1 and LDO chip U2 are current limited by resistor R7, which can improve the stability of LDO and reduce output ripple.

[0041] In this embodiment, by optimizing the LDO control, its output voltage follows the output changes of the DC-DC converter. The follower network can ensure that the LDO output voltage is controlled within the optimal operating range of the LDO (the voltage difference between the input and output voltages can be adjusted by the follower network), thereby ensuring low noise output of the entire system.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. An adjustable linear low-noise power supply circuit, characterized in that, It includes a DC-DC module, an LDO module, a first feedback network module, and a second feedback network module. The input terminal of the DC-DC module is connected to the power input terminal, the output terminal of the DC-DC module is connected to the input terminal of the LDO module, the output terminal of the LDO module is connected to the load, the first feedback network module is connected to the output terminal and the feedback terminal of the DC-DC module, and the second feedback network module is connected to the output terminal and the feedback terminal of the LDO module. All or part of the resistors in the first feedback network module are programmable resistors. The DC-DC module converts the DC power input to the power input terminal according to the signal fed back by the first feedback network module and outputs the converted DC power to the LDO module. The LDO module converts the received DC power into a stable DC voltage and delivers it to the load according to the signal fed back by the second feedback network module.

2. The circuit according to claim 1, characterized in that, The DC-DC module includes a DC-DC chip, a first peripheral circuit, and an inductor. The Vin pin of the DC-DC chip serves as the input terminal of the DC-DC module and is connected to the power supply terminal. The Vout pin of the DC-DC chip is connected to the first end of the inductor. The second end of the inductor serves as the output terminal of the DC-DC module and is connected to the input terminal of the LDO module and the first feedback network module. The FB pin of the DC-DC chip serves as the feedback terminal of the DC-DC module and is connected to the first feedback network module. The GND pin of the DC-DC chip is grounded. The first peripheral circuit is connected to the Vin, EN, and RT pins of the DC-DC chip.

3. The circuit according to claim 2, characterized in that, The first feedback network module includes resistors Rx1 and Rx2. The first end of resistor Rx1 is connected to the second end of the inductor, the second end of resistor Rx1 is connected to the FB pin of the DC-DC chip and the first end of resistor Rx2, and the second end of resistor Rx2 is grounded. Resistor Rx1 and / or resistor Rx2 are programmable resistors.

4. The circuit according to claim 2, characterized in that, The first peripheral circuit includes resistors R1 and R2. The first end of resistor R1 is connected to the Vin pin of the DC-DC chip, the second end of resistor R1 is connected to the EN pin of the DC-DC chip, the first end of resistor R2 is connected to the RT pin of the DC-DC chip, and the second end of resistor R2 is grounded.

5. The circuit according to claim 1, characterized in that, The number of LDO modules is one or more, and the LDO modules increase the current delivered to the load by output current sharing; the number of second feedback network modules is the same as the number of LDO modules, and the second feedback network modules are connected to the corresponding LDO modules.

6. The circuit according to claim 1, characterized in that, The LDO module includes an LDO chip and a second peripheral circuit. The Vin pin of the LDO chip serves as the input terminal of the LDO module and is connected to the output terminal of the DC-DC module. The Vout pin of the LDO chip serves as the output terminal of the LDO module and is connected to the load and the second feedback network module. The SET pin of the LDO chip serves as the feedback terminal of the LDO module and is connected to the second feedback network module. The second peripheral circuit is connected to the Vin pin, EN pin, and Ilimt pin of the LDO chip.

7. The circuit according to claim 6, characterized in that, The second peripheral circuit includes resistors R4 and R5. The first end of resistor R4 is connected to the Vin pin of the LDO chip, and the second end of resistor R4 is connected to the EN pin of the LDO chip. The first end of resistor R5 is connected to the Ilimt pin of the LDO chip, and the second end of resistor R5 is grounded.

8. The circuit according to claim 6, characterized in that, The second feedback network module includes a resistor Rx3, the first end of which is connected to the SET pin of the LDO chip, and the second end of which is connected to the Vout pin of the LDO chip; the resistor Rx3 is a programmable resistor.

9. The circuit according to claim 6 or 7, characterized in that, The second feedback network module is also connected to the input terminal of the LDO module. The LDO module follows the output voltage of the DCDC module based on the signal fed back by the second feedback network module and outputs a stable DC voltage to the load.

10. The circuit according to claim 9, characterized in that, The second feedback network module includes a switch Q1, a diode D1, resistors R6, R7, and R8. The control terminal of the switch Q1 is connected to the first terminal of the resistor R6 and the anode of the diode D1. The second terminal of the resistor R6 is grounded. The cathode of the diode D1 is connected to the Vin pin of the LDO chip. The first terminal of the switch Q1 is connected to the first terminal of the resistor R7. The second terminal of the resistor R7 is connected to the Vout pin of the LDO chip. The second terminal of the switch Q1 is connected to the first terminal of the resistor R8. The second terminal of the resistor R8 is connected to the SET pin of the LDO chip.

11. The circuit according to any one of claims 1 to 8, characterized in that, It also includes a measurement module and a control module. The measurement module is connected to the output terminal of the LDO module and the control module. The control module is connected to the control terminals of the programmable resistors in the first feedback network module and the second feedback network module. The control module adjusts the resistance value of the corresponding programmable resistor according to the output voltage measured by the measurement module.

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