A power supply circuit with floating ground control function

Abstract

The embodiment of the present invention provides a power supply circuit with a floating ground control function, including: a power transistor, a driving module, an inductor, a voltage detection module, a comparison module and an energy discharge module; the gate of the power transistor is electrically connected to the driving module, the first pole transmits the output voltage through the inductor, the second pole is connected to the input power supply, and the first pole of the power transistor is connected to the floating ground; the first end of the voltage detection module is connected to the floating ground power supply, the second end is electrically connected to the floating ground, and the third end is electrically connected to the first input end of the comparison module; the second input end of the comparison module is connected to the threshold voltage, and the output end is electrically connected to the control end of the energy discharge module; the first end of the energy discharge module is connected to the output voltage, and the second end of the energy discharge module is grounded. The power supply circuit with a floating ground control function provided by the embodiment of the present invention can improve the problem of power failure of the floating ground power supply when the power supply circuit is unloaded.

Description

Technical Field

[0001] The present invention relates to the field of power supplies, and in particular to a power supply circuit with a floating ground control function. Background Art

[0002] With the development of electronic technology, electronic products have been used more and more. As the energy source of electronic products, power management is an important factor to ensure the stable operation of electronic products.

[0003] In an existing power supply circuit, one end of the power transistor is connected to a high-voltage power supply and the other end is connected to an inductor, so that the power transistor has a voltage withstand problem of the gate-source voltage Vgs. In order to solve this problem, a floating power supply can be connected to adjust the gate-source voltage Vgs to prevent the gate-source voltage Vgs from exceeding the voltage withstand range. Among them, the floating power supply is powered by a high-voltage power supply. When there is a load in the power supply system, the power transistor is repeatedly turned on and off. Intermittent power supply to the floating power supply in the power supply system can prevent the floating power supply from losing power. When there is no load, the power transistor is turned off for a long time, and the floating power supply cannot be powered and loses power. Therefore, the existing power supply circuit has the problem that the floating power supply loses power when there is no load and cannot supply power normally. Summary of the invention

[0004] The power supply circuit with floating control function provided by the embodiment of the present invention can improve the problem of floating power supply power failure when the power supply circuit is unloaded.

[0005] The embodiment of the present invention provides a power supply circuit with a floating ground control function, comprising: a power transistor, a driving module, an inductor, a voltage detection module, a comparison module and an energy discharge module;

[0006] The gate of the power transistor is electrically connected to the driving module, the first pole transmits the output voltage through the inductor, the second pole is connected to the input power supply, and the first pole of the power transistor is connected to the floating ground;

[0007] The first end of the voltage detection module is connected to the floating power supply, the second end is electrically connected to the floating ground, and the third end is electrically connected to the first input end of the comparison module; the voltage detection module is used to detect the voltage difference between the floating power supply and the floating ground;

[0008] The second input terminal of the comparison module is connected to the threshold voltage, and the output terminal is electrically connected to the control terminal of the energy discharge module;

[0009] The first end of the energy discharge module is connected to the output voltage, and the second end of the energy discharge module is grounded; the comparison module is used to control the state of the energy discharge module according to the output signal of the comparison module to control the floating voltage.

[0010] Optionally, the voltage detection module includes a current mirror module and a current-voltage conversion module;

[0011] The current mirror module comprises a first input terminal, a second input terminal and an output terminal, the first input terminal of the current mirror module is connected to the floating power supply, the second input terminal is connected to the floating ground, and the output terminal is electrically connected to the first input terminal of the comparison module;

[0012] The current-voltage conversion module includes a first end and a second end, the first end of the current-voltage conversion module is electrically connected to the output end of the current mirror module, and the second end is grounded; the current-voltage conversion module is used to convert the current of the current mirror module into voltage.

[0013] Optionally, it is characterized in that the current mirror module includes a first transistor, a second transistor and a first resistor;

[0014] The gate of the first transistor is electrically connected to the gate of the second transistor, the first electrode is electrically connected to the first electrode of the second transistor, and the second electrode is electrically connected to the first end of the first resistor;

[0015] The first end of the first resistor is electrically connected to the gate of the first crystal, and the second end is electrically connected to the first end of the inductor;

[0016] A first electrode of the second transistor is electrically connected to the floating power supply, and a second electrode of the second transistor is electrically connected to the first end of the comparison module.

[0017] Optionally, it is characterized in that the first transistor and the second transistor are P-type transistors.

[0018] Optionally, it is characterized in that the current-voltage conversion module includes a third transistor and a second resistor;

[0019] The gate of the third transistor is electrically connected to the first end of the second resistor, the first electrode is electrically connected to the first end of the comparison module, and the second electrode is electrically connected to the first end of the second resistor;

[0020] A second terminal of the second resistor is grounded.

[0021] Optionally, the energy discharge module includes a fourth transistor and a third resistor;

[0022] The gate of the fourth transistor is electrically connected to the output terminal of the comparison module, the first electrode is grounded, and the second electrode is electrically connected to the first end of the third resistor;

[0023] The second end of the third resistor is electrically connected to the output voltage.

[0024] Optionally, the power transistor is an N-type transistor.

[0025] Optionally, the power supply circuit provided in the embodiment of the present invention further includes a capacitor module, and the capacitor module is electrically connected between the floating power supply and the floating ground.

[0026] Optionally, the driving module includes a first end, a second end and an output end; the first end of the driving module is connected to the floating power supply, the second end is connected to the floating ground, and the output end is electrically connected to the gate of the power transistor.

[0027] Optionally, the power supply circuit provided in the embodiment of the present invention further includes a switching diode, wherein an anode of the switching diode is grounded, and a cathode is electrically connected to the first electrode of the power transistor.

[0028] In an embodiment of the present invention, the first end of a voltage detection module is connected to a floating power supply, the second end is electrically connected to the floating ground, the first pole of the power transistor is also connected to the floating ground, and the power supply circuit includes a voltage detection module, a comparison module and an energy discharge module that cooperate with each other. Among them, the voltage detection module is used to detect the voltage difference between the floating power supply and the floating ground, and the detection result is input to the first input end of the comparison module. The comparison module compares the voltage difference with the threshold voltage and outputs a control signal to control the state of the energy discharge module. In an embodiment of the present invention, when the floating ground voltage is high, the floating ground voltage can be controlled to discharge, thereby avoiding the power transistor from withstanding too high a voltage; when the floating ground voltage is low, the input power supply is controlled to charge the floating ground, and the floating ground power supply can be charged through the floating ground, so that the floating ground power supply will not be powered off. Therefore, the embodiment of the present invention improves the problem of power failure of the floating ground power supply when the power supply circuit is unloaded. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the circuit structure of a power supply circuit with a floating ground control function provided by an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of the circuit structure of another power supply circuit with floating ground control function provided by an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of the circuit structure of another power supply circuit with floating ground control function provided by an embodiment of the present invention;

[0032] Figure 4 A structural schematic diagram of the relationship between the voltage difference between the floating power supply and the floating ground and the output voltage in the prior art;

[0033] Figure 5 A schematic structural diagram of the relationship between a floating power supply, a floating voltage difference and an output voltage in a power supply circuit with a floating control function provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention, rather than to limit the embodiments of the present invention. It is also necessary to explain that, for ease of description, only parts related to the embodiments of the present invention are shown in the accompanying drawings, rather than all structures.

[0035] Figure 1 A schematic diagram of a circuit structure of a power supply circuit with a floating ground control function provided by an embodiment of the present invention, referring to Figure 1 The power supply circuit with floating ground control function provided by the embodiment of the present invention includes: a power transistor 110, a driving module 120, an inductor L, a voltage detection module 130, a comparison module 140 and an energy discharge module 150; the gate of the power transistor 110 is electrically connected to the driving module 120, the first electrode transmits the output voltage Vout through the inductor L, the second electrode is connected to the input power supply Vin, and the first electrode of the power transistor 110 is connected to the floating ground Lx; the first end of the voltage detection module 130 is connected to the floating ground power supply Vboot, and the second end is electrically connected to the floating ground Lx , the third end is electrically connected to the first input end of the comparison module 140; the voltage detection module 130 is used to detect the voltage difference between the floating power supply Vboot and the floating ground Lx; the second input end of the comparison module 140 is connected to the threshold voltage Vth, and the output end is electrically connected to the control end of the energy discharge module 150; the first end of the energy discharge module 150 is connected to the output voltage Vout, and the second end of the energy discharge module 150 is grounded; the comparison module 140 is used to control the state of the energy discharge module 150 according to the output signal of the comparison module 140 to control the voltage of the floating ground Lx. Optionally, the power transistor 110 is an N-type transistor, the drain of the power transistor 110 is connected to the input power supply Vin, and the source is electrically connected to the floating ground Lx. When the gate-source voltage of the power transistor 110 is positive and greater than its threshold voltage, the power transistor 110 is turned on.

[0036] Exemplarily, the working principle of the power supply circuit to control the floating ground Lx is that when the power supply circuit is unloaded, the power transistor 110 is disconnected, and the function of the inductor L is to continue the current. When the floating ground Lx voltage is greater than the output voltage Vout, the floating ground Lx will charge the current into the inductor L. The first input terminal of the comparison module 140 inputs the voltage difference between the floating ground power supply Vboot and the floating ground Lx, and the comparison module 140 is used to compare the voltage input to the first input terminal with the threshold voltage Vth connected to the second input terminal. When the voltage input to the first input terminal in the comparison module 140 is less than the threshold voltage value Vth connected to the second input terminal, the comparison module 140 outputs a control signal, and the control signal can make the energy discharge module 150 discharge the output voltage Vout, thereby reducing the floating ground Lx voltage. When the floating ground Lx voltage is reduced to a certain extent, the first pole voltage of the power transistor 110 will be less than the gate voltage. When the voltage difference reaches the threshold voltage Vth, the power transistor 110 is turned on, and the input power supply Vin supplies power to the floating ground Lx. It can be seen that the embodiment of the present invention can control the discharge of the floating ground Lx voltage when the floating ground Lx voltage is high, thereby avoiding too high a withstand voltage of the power transistor 110; when the floating ground Lx voltage is low, the input power supply Vin is controlled to charge the floating ground Lx voltage, and the floating ground power supply Vboot can be charged through the floating ground Lx voltage, so that the floating ground power supply Vboot will not be powered off.

[0037] The setting of the threshold voltage Vth can be set as needed. Specifically, if the threshold voltage Vth is large, the floating ground Lx voltage is released before it is fully charged, the output voltage Vout discharges slowly, and the energy of the input power supply Vin is wasted. If the threshold voltage Vth is small, the floating ground Lx voltage will be very high, so that the input power supply Vin cannot continue to supply power to the floating ground power supply Vboot, causing the floating ground power supply Vboot to lose power. Exemplarily, the size of the threshold voltage Vth can be obtained by computer simulation calculation to make the output voltage Vout discharge faster.

[0038] In the embodiment of the present invention, the first end of the voltage detection module 130 is connected to the floating power supply Vboot, the second end is electrically connected to the floating ground Lx, the first pole of the power transistor 110 is also connected to the floating ground Lx, and the power supply circuit includes a voltage detection module 130, a comparison module 140 and an energy discharge module 150 that cooperate with each other. Among them, the voltage detection module 130 is used to detect the voltage difference between the floating power supply Vboot and the floating ground Lx, and the detection result is input to the first input end of the comparison module 140. The comparison module 140 compares the voltage difference with the threshold voltage Vth and outputs a control signal to control the state of the energy discharge module 150. The embodiment of the present invention can control the floating ground Lx voltage discharge when the floating ground Lx voltage is high, thereby avoiding the power transistor 110 from having too high a withstand voltage; when the floating ground Lx voltage is low, the input power supply Vin is controlled to charge the floating ground Lx, and the floating ground Lx can charge the floating ground power supply Vboot, so that the floating ground power supply Vboot will not be powered off. Therefore, the embodiment of the present invention improves the problem of power off of the floating ground power supply Vboot when the power supply circuit is unloaded.

[0039] Figure 2 A circuit structure diagram of another power supply circuit with floating ground control function provided by an embodiment of the present invention, referring to Figure 2 On the basis of the above embodiments, optionally, the voltage detection module 130 includes a current mirror module 131 and a current-voltage conversion module 132; the current mirror module 131 includes a first input terminal, a second input terminal and an output terminal, the first input terminal of the current mirror module 131 is connected to the floating power supply Vboot, the second input terminal is connected to the floating ground Lx, and the output terminal is electrically connected to the first input terminal of the comparison module 140; the current-voltage conversion module 132 includes a first terminal and a second terminal, the first terminal of the current-voltage conversion module 132 is electrically connected to the output terminal of the current mirror module 131, and the second terminal is grounded; the current-voltage conversion module 132 is used to convert the current of the current mirror module 131 into a voltage.

[0040] Among them, the current mirror module 131 is used to generate a current when there is a voltage difference between the floating ground Lx and the floating ground power supply Vboot, and mirror the current to the first end of the current-voltage conversion module 132, and the current-voltage conversion module 132 generates a corresponding voltage according to the current. That is, the voltage difference between the floating ground Lx and the floating ground power supply Vboot-mirrored current-the voltage generated by the current-voltage conversion module 132 presents a one-to-one correspondence. The voltage generated by the current-voltage conversion module 132 can represent the magnitude of the voltage difference between the floating ground Lx and the floating ground power supply Vboot.

[0041] The embodiment of the present invention realizes the detection of the voltage difference between the floating ground Lx and the floating ground power supply Vboot by setting the voltage detection module 130 including the current mirror module 131 and the current-voltage conversion module 132. The detected voltage difference can be compared with the threshold voltage Vth, so as to better judge the magnitude relationship between the voltage difference between the floating ground Lx and the floating ground power supply Vboot and the threshold voltage Vth.

[0042] Figure 3 A schematic diagram of a circuit structure of another power supply circuit with a floating control function provided by an embodiment of the present invention, referring to Figure 3 In one embodiment of the present invention, optionally, the current mirror module 131 includes a first transistor T1, a second transistor T2 and a first resistor R1; the gate of the first transistor T1 is electrically connected to the gate of the second transistor T2, the first electrode is electrically connected to the first electrode of the second transistor T2, and the second electrode is electrically connected to the first end of the first resistor R1; the first end of the first resistor R1 is electrically connected to the gate of the first transistor T1, and the second end is electrically connected to the first end of the inductor L; the first electrode of the second transistor T2 is electrically connected to the floating power supply Vboot, and the second electrode is electrically connected to the first end of the comparison module 140.

[0043] The first transistor T1 and the first resistor R1 are connected in series between the floating ground Lx and the floating ground power supply Vboot. The connection mode of the first transistor T1 plays the role of a diode. When the voltage of the floating ground power supply Vboot is higher than the voltage of the floating ground Lx, the first resistor R1 plays the role of current limiting. At the same time, the second transistor T2 mirrors the current of the first transistor T1 and outputs it.

[0044] Optionally, the first transistor and the second transistor are P-type transistors. The P-type transistor is turned on when its gate is at a low level, and is suitable for being turned on when the floating power supply is higher than the floating voltage.

[0045] Continue to refer Figure 3 Optionally, the current-voltage conversion module 132 includes a third transistor T3 and a second resistor R2; the gate of the third transistor T3 is electrically connected to the first end of the second resistor R2, the first electrode is electrically connected to the first end of the comparison module 140, and the second electrode is electrically connected to the first end of the second resistor R2; the second end of the second resistor R2 is grounded.

[0046] Among them, the third transistor T3 is a P-type transistor, and the connection method of the third transistor T3 plays the role of a diode. When the second transistor T2 is turned on, the third transistor T3 is subjected to a forward voltage and turned on. The mirror current of the second transistor T2 flows through the branch formed by the third transistor T3 and the second resistor R2, and the mirror current generates a voltage drop on the second resistor R2. Specifically, the larger the mirror current, the greater the voltage drop on the second resistor R2, and the greater the voltage received by the comparison module 140; on the contrary, the smaller the mirror current, the lower the voltage drop on the second resistor R2, and the smaller the voltage received by the comparison module 140. Optionally, the first resistor R1 and the second resistor R2 are of the same model.

[0047] Continue to refer Figure 3 On the basis of the above embodiments, optionally, the comparison module 140 includes a comparator, a first input terminal of the comparator is connected to the threshold voltage Vth, and a second input terminal of the comparator is electrically connected to the first electrode of the third transistor. Exemplarily, the first input terminal of the comparator is a positive input terminal, and the second input terminal of the comparator is a negative input terminal. When the voltage of the second input terminal is lower than the threshold voltage, the comparator outputs a positive voltage.

[0048] Continue to refer Figure 3 On the basis of the above embodiments, optionally, the energy discharge module 150 includes a fourth transistor T4 and a third resistor R3; the gate of the fourth transistor T4 is electrically connected to the output end of the comparison module 140, the first electrode is grounded, and the second electrode is electrically connected to the first end of the third resistor R3; the second end of the third resistor R3 is electrically connected to the output voltage Vout.

[0049] Exemplarily, the fourth transistor T4 is an N-type transistor. When the voltage at the second input terminal of the comparator is less than the threshold voltage Vth, the comparator outputs a positive voltage, so that the fourth transistor T4 in the energy discharge module 150 is turned on, and the output voltage Vout is discharged through the third resistor R3 and the fourth transistor T4, thereby reducing the output voltage Vout and further reducing the voltage of the floating ground Lx.

[0050] Continue to refer Figure 3 Based on the above embodiments, optionally, the driving module 120 includes a first end, a second end and an output end; the first end of the driving module 120 is connected to the floating power supply Vboot, the second end is connected to the floating ground Lx, and the output end is electrically connected to the gate of the power transistor 110.

[0051] The floating power source Vboot serves as the power supply of the driving module 120. Under the action of the floating power source Vboot, the driving module 120 combines the voltage of the floating ground Lx and the driving logic to output a driving signal to the power transistor 110. The magnitude of the driving signal is related to the magnitude of the floating power source Vboot. If the voltage of the floating power source Vboot decreases, the driving module 120 will be unable to drive the power transistor 110.

[0052] Continue to see Figure 3 On the basis of the above embodiments, optionally, the power supply circuit provided in the embodiment of the present invention further includes a capacitor C, which is electrically connected between the floating power supply Vboot and the floating ground Lx to store the voltage difference between the floating power supply Vboot and the floating ground Lx. Wherein, due to the setting of the capacitor C, when the input power supplies power to the floating ground Lx, the floating power supply Vboot is also boosted, thereby avoiding the problem of being unable to drive the power transistor 110 due to the reduction of the floating power supply Vboot.

[0053] Continue to see Figure 3 On the basis of the above embodiments, optionally, the power supply circuit provided in the embodiment of the present invention further includes a switching diode D, the anode of the switching diode D is grounded, and the cathode is electrically connected to the first electrode of the power transistor 110. The switching diode D is connected in anti-parallel between the first electrode of the power transistor 110 and the ground. Exemplarily, when the floating ground Lx voltage is negative, the switching diode D is turned on, and the floating ground Lx voltage is grounded to avoid the floating ground Lx voltage being negative.

[0054] In the above embodiments, the structure of the power supply circuit is described exemplarily, and its qualitative working principle is explained in combination with the structure. The power supply circuit provided by the embodiment of the present invention is further explained from a quantitative perspective below.

[0055] Figure 4 FIG. 1 is a schematic diagram showing the relationship between the voltage difference between the floating power supply and the floating ground and the output voltage in the prior art. Figure 4 , exemplarily, the time required for the maximum value of the floating power supply to drop to the threshold voltage is t0.

[0056] in,

[0057] In the formula, C BOOT0 is the capacitance between the floating power supply and the floating ground, I BOOT0 is the current in the floating power supply when no load is applied, V BOOTMAX0 It is the maximum voltage difference between the floating power supply and the floating ground during charging. In this field, it is required that the voltage difference between the floating power supply and the floating ground will not drop below Vth within the T0 time, so it is obtained:

[0058]

[0059] The method used in the prior art to prevent the floating power supply from losing power is to add a dummy load at the output voltage end, thereby shortening the off time of the power transistor and allowing the floating power supply to obtain sufficient power. The current required for the dummy load in the prior art is calculated as:

[0060]

[0061] Among them, C out0 is the output dummy load capacitance. It can be known through calculation that the current required by the dummy load is higher than the calculated minimum current, so it can be known that in the prior art, adding a dummy load will increase the power consumption of the no-load state.

[0062] Figure 5 A schematic diagram of the relationship between the voltage difference between the floating power supply and the floating ground and the output voltage in a power supply circuit with a floating ground control function provided by an embodiment of the present invention, with reference to Figure 3 and Figure 5 When the voltage difference between the floating power supply Vboot and the floating ground Lx is greater than the threshold voltage Vth, the output voltage Vout remains unchanged. When the voltage difference between the floating power supply Vboot and the floating ground Lx is less than the threshold voltage, the comparison module 140 outputs a control signal to the energy discharge module 150, and the energy discharge module 150 starts to discharge the voltage value of the output voltage Vout. The output voltage is discharged within the time T, so:

[0063]

[0064] Where C is the capacitance between the floating power supply and the floating ground, I BOOT is the current of the floating power supply when no load is applied, V BOOTMAX It is the maximum voltage difference between the floating power supply and the floating ground during charging.

[0065] Furthermore, the average current required by the load in the circuit of the embodiment of the present invention is calculated as:

[0066]

[0067] In the formula, C out is the output load capacitance. disarge is the discharge current. It can be calculated that the magnitude of the average current at this time has nothing to do with R3. At the same time, it can be concluded through calculation that the smaller the floating power supply current is when no-load, the smaller the power consumption of the power supply circuit is. The average current in the embodiment of the present invention is the same as the minimum load current calculated. That is, compared with the method of adding a dummy load in the prior art, the power supply circuit provided by the embodiment of the present invention achieves the effect of minimizing no-load power consumption on the basis of improving the power failure of the floating power supply when the power supply circuit is no-load.

[0068] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the embodiments of the present invention are not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the embodiments of the present invention. Therefore, although the embodiments of the present invention are described in more detail through the above embodiments, the embodiments of the present invention are not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the embodiments of the present invention, and the scope of the embodiments of the present invention is determined by the scope of the appended claims.

Claims

1. A power supply circuit with floating ground control function, characterized in that: include: Power transistor, drive module, inductor, voltage detection module, comparison module and energy discharge module; The gate of the power transistor is electrically connected to the driving module, the first pole transmits the output voltage through the inductor, the second pole is connected to the input power supply, and the first pole of the power transistor is connected to the floating ground; The first end of the voltage detection module is connected to the floating power supply, the second end is electrically connected to the floating ground, and the third end is electrically connected to the first input end of the comparison module; the voltage detection module is used to detect the voltage difference between the floating power supply and the floating ground; The second input terminal of the comparison module is connected to the threshold voltage, and the output terminal is electrically connected to the control terminal of the energy discharge module; The first end of the energy discharge module is connected to the output voltage, and the second end of the energy discharge module is grounded; the comparison module is used to control the state of the energy discharge module according to the output signal of the comparison module to control the voltage of the floating ground; The power transistor is an N-type transistor; When the power supply circuit is unloaded, the power transistor is disconnected, and the function of the inductor is freewheeling. When the voltage of the floating ground is greater than the output voltage, the floating ground will charge current into the inductor. The first input end of the comparison module inputs the voltage difference between the floating ground power supply and the floating ground. The comparison module is used to compare the voltage input to the first input end with the threshold voltage connected to the second input end. When the voltage input to the first input end of the comparison module is less than the threshold voltage value connected to the second input end, the comparison module outputs a control signal. The control signal enables the energy discharge module to discharge the output voltage to reduce the voltage of the floating ground. When the voltage of the floating ground is reduced to make the first pole voltage of the power transistor less than the gate voltage, when the voltage difference between the first pole voltage and the gate voltage of the power transistor reaches the threshold voltage, the power transistor is turned on, and the input power supply supplies power to the floating ground.

2. The power supply circuit according to claim 1, characterized in that: The voltage detection module includes a current mirror module and a current-voltage conversion module; The current mirror module comprises a first input terminal, a second input terminal and an output terminal, the first input terminal of the current mirror module is connected to the floating power supply, the second input terminal is connected to the floating ground, and the output terminal is electrically connected to the first input terminal of the comparison module; The current-voltage conversion module includes a first end and a second end, the first end of the current-voltage conversion module is electrically connected to the output end of the current mirror module, and the second end is grounded; the current-voltage conversion module is used to convert the current of the current mirror module into voltage.

3. The power supply circuit according to claim 2, characterized in that: The current mirror module includes a first transistor, a second transistor and a first resistor; The gate of the first transistor is electrically connected to the gate of the second transistor, the first electrode is electrically connected to the first electrode of the second transistor, and the second electrode is electrically connected to the first end of the first resistor; The first end of the first resistor is electrically connected to the gate of the first crystal, and the second end is electrically connected to the first end of the inductor; A first electrode of the second transistor is electrically connected to the floating power supply, and a second electrode of the second transistor is electrically connected to the first end of the comparison module.

4. The power supply circuit according to claim 3, characterized in that: The first transistor and the second transistor are P-type transistors.

5. The power supply circuit according to claim 2, characterized in that: The current-voltage conversion module includes a third transistor and a second resistor; The gate of the third transistor is electrically connected to the first end of the second resistor, the first electrode is electrically connected to the first end of the comparison module, and the second electrode is electrically connected to the first end of the second resistor; A second terminal of the second resistor is grounded.

6. The power supply circuit according to claim 1, characterized in that: The energy discharge module includes a fourth transistor and a third resistor; The gate of the fourth transistor is electrically connected to the output terminal of the comparison module, the first electrode is grounded, and the second electrode is electrically connected to the first end of the third resistor; The second end of the third resistor is electrically connected to the output voltage.

7. The power supply circuit according to claim 1, characterized in that: A capacitor module is also included, and the capacitor module is electrically connected between the floating power supply and the floating ground.

8. The power supply circuit according to claim 1, characterized in that: The driving module comprises a first end, a second end and an output end; the first end of the driving module is connected to the floating power supply, the second end is connected to the floating ground, and the output end is electrically connected to the gate of the power transistor.

9. The power supply circuit according to claim 1, characterized in that: It also includes a switching diode, wherein the anode of the switching diode is grounded, and the cathode is electrically connected to the first electrode of the power transistor.

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