TWI879080B - Power supply device with high output stability - Google Patents

Abstract

A power supply device with high output stability includes a voltage divider circuit, a switch circuit, a transformer, a first capacitor, an output stage circuit, and a detection and control circuit. The voltage divider circuit generates a divided voltage according to an input voltage. The switch circuit generates a switching voltage according to the input voltage, a first driving voltage, and a second driving voltage. The first capacitor provides a capacitive voltage. The output stage circuit generates an output voltage and an output current. The detection and control circuit determines whether to reduce a voltage level of the first driving voltage or the second driving voltage according to the divided voltage, the capacitive voltage, the output voltage, and the output current.

Description

High output stability power supply

The present invention relates to a power supply, and more particularly to a power supply with high output stability.

Power supplies are indispensable components in the field of notebook computers. However, when the power supply performs high-frequency switching, the internal resonant current will often be distorted, which will cause problems such as electromagnetic interference (EMI). In view of this, it is necessary to propose a new solution to overcome the difficulties faced by previous technologies.

In a preferred embodiment, the present invention provides a power supply with high output stability, including: a voltage divider circuit, which generates a voltage divider potential according to an input potential; a switching circuit, which generates a switching potential according to the input potential, a first drive potential, and a second drive potential; a transformer, including a main coil, a first secondary coil, and a second secondary coil, wherein the transformer has a built-in leakage inductor and an excitation inductor, and the main coil receives the switching potential through the leakage inductor. ; a first capacitor coupled to the excitation inductor and providing a capacitance potential; an output stage circuit coupled to the first sub-coil and the second sub-coil and generating an output potential and an output current; and a detection and control circuit generating the first driving potential and the second driving potential; wherein the detection and control circuit further determines whether to reduce the potential level of the first driving potential or the second driving potential according to the voltage division potential, the capacitance potential, the output potential, and the output current.

In some embodiments, the voltage divider circuit includes: a first resistor having a first end and a second end, wherein the first end of the first resistor is coupled to an input node to receive the input potential, and the second end of the first resistor is coupled to a first node to output the divided potential; and a second resistor having a first end and a second end, wherein the first end of the second resistor is coupled to the first node, and the second end of the second resistor is coupled to a ground potential.

In some embodiments, the switching circuit includes: a first transistor having a control end, a first end, and a second end, wherein the control end of the first transistor is used to receive the first driving potential, the first end of the first transistor is coupled to a second node to output the switching potential, and the second end of the first transistor is coupled to the input node to receive the input potential; and a second transistor having a control end, a first end, and a second end, wherein the control end of the second transistor is used to receive the second driving potential, the first end of the second transistor is coupled to the ground potential, and the second end of the second transistor is coupled to the second node.

In some embodiments, the leakage inductor has a first end and a second end, the first end of the leakage inductor is coupled to the second node to receive the switching potential, the second end of the leakage inductor is coupled to a third node, the main coil has a first end and a second end, the first end of the main coil is coupled to the third node, the second end of the main coil is coupled to a fourth node, the excitation inductor has a first end and a second end, the first end of the excitation inductor is coupled to the third node, the second end of the excitation inductor is coupled to the fourth node, and the The first capacitor has a first end and a second end, the first end of the first capacitor is coupled to the fourth node to output the capacitance potential, the second end of the first capacitor is coupled to the ground potential, the first sub-coil has a first end and a second end, the first end of the first sub-coil is coupled to a fifth node, the second end of the first sub-coil is coupled to a common node, the second sub-coil has a first end and a second end, the first end of the second sub-coil is coupled to the common node, and the second end of the second sub-coil is coupled to a sixth node.

In some embodiments, the output stage circuit includes: a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to the fifth node, and the cathode of the first diode is coupled to an output node to output the output potential; a second diode having an anode and a cathode, wherein the anode of the second diode is coupled to the sixth node, and the cathode of the second diode is coupled to the output node; a second diode having an anode and a cathode, wherein the anode of the second diode is coupled to the sixth node, and the cathode of the second diode is coupled to the output node; a capacitor having a first end and a second end, wherein the first end of the second capacitor is coupled to the output node, and the second end of the second capacitor is coupled to a seventh node; and a third resistor having a first end and a second end, wherein the first end of the third resistor is coupled to the common node, and the second end of the third resistor is coupled to the seventh node; wherein the output current flows through the second capacitor and the third resistor.

In some embodiments, the detection and control circuit includes: an amplifier that amplifies the capacitor potential to generate an amplified potential.

In some embodiments, the detection and control circuit further includes: a comparison circuit that compares a common potential at the common node with a sensed potential at the seventh node to generate a comparison potential.

In some embodiments, the detection and control circuit further includes: an AND gate having a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, and an output terminal, wherein the first input terminal of the AND gate is used to receive the divided potential, the second input terminal of the AND gate is used to receive the amplified potential, the third input terminal of the AND gate is used to receive the comparison potential, the fourth input terminal of the AND gate is used to receive the output potential, and the output terminal of the AND gate is used to output a logic potential.

In some embodiments, the detection and control circuit further includes: a microcontroller that generates the first driving potential and the second driving potential, wherein if the logic potential has a high logic level, the microcontroller will temporarily reduce the potential level of the first driving potential or the second driving potential by a predetermined ratio within a predetermined time.

In some embodiments, the predetermined time is approximately 0.66 μs, and the predetermined ratio is approximately 70%.

In order to make the purpose, features and advantages of the present invention more clearly understood, specific embodiments of the present invention are specifically listed below and described in detail with reference to the accompanying drawings.

Certain terms are used in the specification and patent application to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and patent application do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criterion for distinction. The words "include" and "including" mentioned throughout the specification and patent application are open terms and should be interpreted as "including but not limited to". The word "substantially" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and achieve the basic technical effect. In addition, the word "coupled" in this specification includes any direct and indirect electrical connection means. Therefore, if a first device is described herein as being coupled to a second device, it means that the first device may be directly electrically connected to the second device, or may be indirectly electrically connected to the second device via other devices or connection means.

FIG. 1 is a schematic diagram showing a power supply 100 according to an embodiment of the present invention. For example, the power supply 100 can be applied to a desktop computer, a laptop computer, or an all-in-one computer. As shown in FIG. 1, the power supply 100 includes: a voltage divider circuit 110, a switching circuit 120, a transformer 130, a first capacitor C1, an output stage circuit 140, and a detection and control circuit 150. It should be noted that, although not shown in FIG. 1, the power supply 100 may further include other components, such as: a voltage regulator or (and) a negative feedback circuit.

The voltage divider circuit 110 can generate a voltage divider voltage VD according to an input potential VIN. For example, the input potential VIN can be a DC potential, and its potential level can be between 360V and 440V, but it is not limited thereto. The voltage divider voltage VD can be lower than the input potential VIN. The switching circuit 120 can generate a switching potential VW according to the input potential VIN, a first driving potential VG1, and a second driving potential VG2. The transformer 130 includes a main coil 131, a first sub-coil 132, and a second sub-coil 133. The transformer 130 may further have a built-in leakage inductor LR and a magnetizing inductor LM, wherein the leakage inductor LR, the magnetizing inductor LM, and the main coil 131 may all be located on the same side of the transformer 130, and the first sub-coil 132 and the second sub-coil 133 may all be located on the opposite side of the transformer 130. The main coil 131 may receive a switching potential VW via the leakage inductor LR, and the first sub-coil 132 and the second sub-coil 133 may operate in response to the switching potential VW. The first capacitor C1 is coupled to the magnetizing inductor LM, wherein the first capacitor C1 may provide a capacitance potential VP. In some embodiments, the leakage inductor LR, the magnetizing inductor LM, and the first capacitor C1 may together form a resonant tank of the power supply 100. The output stage circuit 140 is coupled to the first sub-coil 132 and the second sub-coil 133, and can generate an output potential VOUT and an output current IOUT. For example, the output potential VOUT can be another DC potential, and its potential level can be between 18V and 20V, but it is not limited thereto. The detection and control circuit 150 can generate a first drive potential VG1 and a second drive potential VG2. In addition, the detection and control circuit 150 can be used to monitor the operating status of the remaining circuit elements, wherein the detection and control circuit 150 can further determine whether to reduce the potential level of the first drive potential VG1 or the second drive potential VG2 according to the voltage division potential VD, the capacitor potential VP, the output potential VOUT, and the output current IOUT. According to actual measurement results, the power supply 100 of the present invention can effectively suppress its non-ideal distortion phenomenon, thereby greatly improving its own output stability.

The following embodiments will introduce the detailed structure and operation of the power supply 100. It must be understood that these drawings and descriptions are only examples and are not intended to limit the scope of the present invention.

FIG. 2 is a circuit diagram of a power supply 200 according to an embodiment of the present invention. In the embodiment of FIG. 2, the power supply 200 has an input node NIN and an output node NOUT, and includes: a voltage divider circuit 210, a switching circuit 220, a transformer 230, a first capacitor C1, an output stage circuit 240, and a detection and control circuit 250. The input node NIN of the power supply 200 can receive an input potential VIN from an external input power source (not shown), and the output node NOUT of the power supply 200 can be used to output an output potential VOUT to an electronic device (not shown).

The voltage divider circuit 210 includes a first resistor R1 and a second resistor R2. The first resistor R1 has a first end and a second end, wherein the first end of the first resistor R1 is coupled to the input node NIN, and the second end of the first resistor R1 is coupled to a first node N1 to output a divided voltage VD. The second resistor R2 has a first end and a second end, wherein the first end of the second resistor R2 is coupled to the first node N1, and the second end of the second resistor R2 is coupled to a ground potential VSS (e.g., 0V). In some embodiments, the relationship between the divided voltage VD and the input potential VIN can be as described in the following equation (1):

………………………………(1) Wherein “VD” represents the potential level of the divided potential VD, “VIN” represents the potential level of the input potential VIN, “R1” represents the resistance value of the first resistor R1, and “R2” represents the resistance value of the second resistor R2.

The switching circuit 220 includes a first transistor M1 and a second transistor M2. For example, the first transistor M1 and the second transistor M2 may each be an N-type Metal-Oxide-Semiconductor Field-Effect Transistor (NMOSFET). The first transistor M1 has a control terminal (e.g., a gate), a first terminal (e.g., a source), and a second terminal (e.g., a drain), wherein the control terminal of the first transistor M1 is used to receive a first driving potential VG1, the first terminal of the first transistor M1 is coupled to a second node N2 to output a switching potential VW, and the second terminal of the first transistor M1 is coupled to the input node NIN. The second transistor M2 has a control terminal (e.g., a gate), a first terminal (e.g., a source), and a second terminal (e.g., a drain), wherein the control terminal of the second transistor M2 is used to receive a second driving potential VG2, the first terminal of the second transistor M2 is coupled to the ground potential VSS, and the second terminal of the second transistor M2 is coupled to the second node N2. In some embodiments, the first driving potential VG1 and the second driving potential VG2 may have the same switching frequency and complementary logic level.

The transformer 230 includes a main coil 231, a first secondary coil 232, and a second secondary coil 233, wherein the transformer 230 may further have a built-in leakage inductor LR and an excitation inductor LM. The leakage inductor LR and the excitation inductor LM may be inherent components generated when the transformer 230 is manufactured, and are not external independent components. The leakage inductor LR, the main coil 231, and the excitation inductor LM may all be located on the same side of the transformer 230 (e.g., the primary side), while the first secondary coil 232 and the second secondary coil 233 may all be located on the opposite side of the transformer 230 (e.g., the secondary side, which may be isolated from the primary side). The leakage inductor LR has a first end and a second end, wherein the first end of the leakage inductor LR is coupled to the second node N2 to receive the switching potential VW, and the second end of the leakage inductor LR is coupled to a third node N3. The main coil 231 has a first end and a second end, wherein the first end of the main coil 231 is coupled to the third node N3, and the second end of the main coil 231 is coupled to a fourth node N4. The excitation inductor LM has a first end and a second end, wherein the first end of the excitation inductor LM is coupled to the third node N3, and the second end of the excitation inductor LM is coupled to the fourth node N4. The first capacitor C1 has a first end and a second end, wherein the first end of the first capacitor C1 is coupled to the fourth node N4 to output a capacitance potential VP, and the second end of the first capacitor C1 is coupled to the ground potential VSS. In some embodiments, the leakage inductor LR, the magnetizing inductor LM, and the first capacitor C1 may together form a resonant tank of the power supply 200, wherein a resonant current IR may simultaneously flow through the leakage inductor LR, the magnetizing inductor LM, and the first capacitor C1 of the resonant tank. The first sub-coil 232 has a first end and a second end, wherein the first end of the first sub-coil 232 is coupled to a fifth node N5, and the second end of the first sub-coil 232 is coupled to a common node NCM. For example, the common node NCM may provide a common potential VCM, which may be regarded as another ground potential, and may be the same as or different from the aforementioned ground potential VSS. The second sub-coil 233 has a first end and a second end, wherein the first end of the second sub-coil 233 is coupled to the common node NCM, and the second end of the second sub-coil 233 is coupled to a sixth node N6.

The output stage circuit 240 includes a first diode D1, a second diode D2, a second capacitor C2, and a third resistor R3. The first diode D1 has an anode and a cathode, wherein the anode of the first diode D1 is coupled to the fifth node N5, and the cathode of the first diode D1 is coupled to the output node NOUT. The second diode D2 has an anode and a cathode, wherein the anode of the second diode D2 is coupled to the sixth node N6, and the cathode of the second diode D2 is coupled to the output node NOUT. The second capacitor C2 has a first terminal and a second terminal, wherein the first terminal of the second capacitor C2 is coupled to the output node NOUT, and the second terminal of the second capacitor C2 is coupled to a seventh node N7. The third resistor R3 can provide a relatively low resistance value (e.g., less than or equal to 5Ω). The third resistor R3 has a first end and a second end, wherein the first end of the third resistor R3 is coupled to the common node NCM, and the second end of the third resistor R3 is coupled to the seventh node N7. It should be noted that an output current IOUT of the output stage circuit 240 can flow through the second capacitor C2 and the third resistor R3 at the same time, so that the third resistor R3 can provide a sense potential VE at the seventh node N7.

The detection and control circuit 250 includes an amplifier 252 , a comparison circuit 254 , an AND gate 256 , and a microcontroller unit (MCU) 258 .

The amplifier 252 may amplify the capacitor potential VP according to a gain factor K to generate an amplified potential VA. For example, the gain factor K may be greater than 1. In some embodiments, the relationship between the amplified potential VA and the capacitor potential VP may be as described in the following equation (2):

…………………………………………(2) “VA” represents the potential level of the amplifier potential VA, “VP” represents the potential level of the capacitor potential VP, and “K” represents the value of the gain factor K.

The comparison circuit 254 can compare the common potential VCM at the common node NCM with the sensed potential VE at the seventh node N7 to generate a comparison potential VB. In some embodiments, the comparison circuit 254 can include a subtractor (not shown) that can obtain a potential difference ΔV across the third resistor R3 by subtracting the common potential VCM from the sensed potential VE. According to Ohm's law, the magnitude of the potential difference ΔV can be roughly proportional to the current value of the output current IOUT. Therefore, the comparison circuit 254 can obtain relevant information of the output current IOUT according to the potential difference ΔV. For example, if the sensed potential VE is exactly equal to the common potential VCM (i.e., the potential difference ΔV is exactly equal to 0), it means that the output current IOUT is exactly equal to 0, and the comparison circuit 254 can output the comparison potential VB with a high logic level. On the contrary, if the sensed potential VE is not equal to the common potential VCM (i.e., the potential difference ΔV is not equal to 0), it means that the output current IOUT is not equal to 0, and the comparison circuit 254 can output the comparison potential VB with a low logic level.

The AND gate 256 has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, and an output terminal, wherein the first input terminal of the AND gate 256 is used to receive the divided voltage VD, the second input terminal of the AND gate 256 is used to receive the amplified voltage VA, the third input terminal of the AND gate 256 is used to receive the comparison voltage VB, the fourth input terminal of the AND gate 256 is used to receive the output voltage VOUT, and the output terminal of the AND gate 256 is used to output a logic voltage VL. Generally speaking, when the power supply 200 operates normally and the output current IOUT is equal to 0, the AND gate 256 will generate a logic voltage VL with a high logic level. Otherwise, the AND gate 256 will generate a logic potential VL having a low logic level.

The microcontroller 258 can generate a first driving potential VG1 and a second driving potential VG2. In some embodiments, if the logic potential VL has a low logic level, the microcontroller 258 will not additionally adjust the first driving potential VG1 and the second driving potential VG2; on the contrary, if the logic potential VL has a high logic level, the microcontroller 258 will temporarily reduce the potential level of the first driving potential VG1 or the second driving potential VG2 by a predetermined ratio DR within a predetermined time TD. For example, the predetermined time TD may be approximately 0.66 μs, and the predetermined ratio DR may be approximately 70%, but is not limited thereto.

FIG. 3 shows a signal waveform diagram of a conventional power supply, wherein the horizontal axis represents time (s) and the vertical axis represents potential level (V) or current value (A). As shown in FIG. 3, during the high logic period of the first driving potential VG1, the corresponding resonant current IR may be distorted (as indicated by a first dashed frame 301), and during the high logic period of the second driving potential VG2, the corresponding resonant current IR may also be distorted (as indicated by a second dashed frame 302). Therefore, conventional power supplies often face the problem of insufficient output stability.

FIG. 4 is a signal waveform diagram of the power supply 200 according to an embodiment of the present invention, wherein the horizontal axis represents time (s) and the vertical axis represents potential level (V) or current value (A). As shown in FIG. 4, after a first current I1 flowing through the first diode D1 drops to 0, the microcontroller 258 can temporarily reduce the potential level of the first driving potential VG1 by a predetermined ratio DR within a predetermined time TD. For example, if the predetermined ratio DR is 70%, the potential level of the first driving potential VG1 after the reduction will be only 30% of its original potential level. In addition, after a second current I2 flowing through the second diode D2 drops to 0, the microcontroller 258 can also temporarily reduce the potential level of the second driving potential VG2 by a predetermined ratio DR within a predetermined time TD. For example, if the predetermined ratio DR is 70%, the potential level of the second driving potential VG2 after the reduction will be only 30% of its original potential level. It should be noted that the first driving potential VG1 after the reduction or the second driving potential VG2 after the reduction can prevent the switching circuit 220 from being fully turned on, thereby buffering the resonant current IR of the power supply 200. According to the measurement results of FIG. 4, under the design of the present invention, the resonant current IR of the power supply 200 will hardly have the phenomenon of non-ideal distortion, so the overall output stability will be greatly improved.

The present invention proposes a novel power supply. According to actual measurement results, the overall output stability of the power supply using the above design will be significantly improved, so it is very suitable for application in various types of devices.

It is worth noting that the potential, current, resistance, inductance, capacitance, and other component parameters described above are not limiting conditions of the present invention. Designers can adjust these settings according to different needs. The power supply of the present invention is not limited to the states shown in Figures 1-4. The present invention may only include any one or more features of any one or more embodiments of Figures 1-4. In other words, not all of the features shown in the diagrams need to be implemented in the power supply of the present invention at the same time. Although the embodiments of the present invention use metal oxide semi-conductor field effect transistors as an example, the present invention is not limited to this. People skilled in the art can use other types of transistors, such as junction field effect transistors, or fin field effect transistors, etc., without affecting the effects of the present invention.

Ordinal numbers in this specification and the scope of the patent application, such as "first", "second", "third", etc., have no sequential relationship with each other, and are only used to mark and distinguish two different components with the same name.

Although the present invention is disclosed as above with the preferred embodiments, it is not intended to limit the scope of the present invention. Anyone skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the attached patent application.

100,200: Power supply 110,210: Voltage divider circuit 120,220: Switching circuit 130,230: Transformer 131,231: Main coil 132,232: First secondary coil 133,233: Second secondary coil 140,240: Output stage circuit 150,250: Detection and control circuit 252: Amplifier 254: Comparison circuit 256: AND gate 258: Microcontroller 301: First dashed frame 302: Second dashed frame C1: First capacitor C2: Second capacitor D1: First diode D2: First diode DR: Predetermined ratio I1: First current I2: Second current IOUT: Output current IR: Resonance current K: Gain factor LM: Magnetizing inductor LR: Leakage inductor M1: First transistor M2: Second transistor N1: First node N2: Second node N3: Third node N4: Fourth node N5: Fifth node N6: Sixth node N7: Seventh node NCM: Common node NIN: Input node NOUT: Output node R1: First resistor R2: Second resistor R3: Third resistor TD: Determined time VA: Amplified potential VB: Comparison potential VCM: Common potential VD: Voltage divider potential VE: Sense potential VG1: First drive potential VG2: Second drive potential VIN: Input potential VL: logic potential VOUT: output potential VP: capacitor potential VSS: ground potential VW: switching potential ΔV: potential difference

FIG. 1 is a schematic diagram showing a power supply according to an embodiment of the present invention. FIG. 2 is a circuit diagram showing a power supply according to an embodiment of the present invention. FIG. 3 is a signal waveform diagram showing a conventional power supply. FIG. 4 is a signal waveform diagram showing a power supply according to an embodiment of the present invention.

100: Power supply 110: Voltage divider circuit 120: Switching circuit 130: Transformer 131: Main coil 132: First secondary coil 133: Second secondary coil 140: Output stage circuit 150: Detection and control circuit C1: First capacitor IOUT: Output current LM: Magnetizing inductor LR: Leakage inductor VD: Voltage divider potential VIN: Input potential VG1: First drive potential VG2: Second drive potential VOUT: Output potential VP: Capacitor potential VW: Switching potential

Claims (7)

A power supply with high output stability includes: a voltage divider circuit, which generates a voltage divider potential according to an input potential; a switching circuit, which generates all switching potentials according to the input potential, a first drive potential, and a second drive potential; a transformer, which includes a main coil, a first secondary coil, and a second secondary coil, wherein the transformer has a leakage inductor and an excitation inductor built in, and the main The coil receives the switching potential through the leakage inductor; a first capacitor is coupled to the excitation inductor and provides a capacitance potential; an output stage circuit is coupled to the first sub-coil and the second sub-coil and generates an output potential and an output current; and a detection and control circuit generates the first driving potential and the second driving potential; wherein the detection and control circuit further generates the first driving potential and the second driving potential according to the divided voltage potential, the The detection and control circuit comprises: an amplifier, amplifying the capacitor potential to generate an amplified potential; a comparison circuit, comparing a common potential with a sensed potential to generate a comparison potential; and an AND gate, having a first input terminal, a second input terminal, and a second output current. An input terminal, a third input terminal, a fourth input terminal, and an output terminal, wherein the first input terminal of the AND gate is used to receive the divided potential, the second input terminal of the AND gate is used to receive the amplified potential, the third input terminal of the AND gate is used to receive the comparison potential, the fourth input terminal of the AND gate is used to receive the output potential, and the output terminal of the AND gate is used to output a logic potential. A power supply as claimed in claim 1, wherein the voltage divider circuit comprises: a first resistor having a first end and a second end, wherein the first end of the first resistor is coupled to an input node to receive the input potential, and the second end of the first resistor is coupled to a first node to output the divided potential; and a second resistor having a first end and a second end, wherein the first end of the second resistor is coupled to the first node, and the second end of the second resistor is coupled to a ground potential. A power supply as claimed in claim 2, wherein the switching circuit comprises: a first transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the first transistor is used to receive the first driving potential, the first terminal of the first transistor is coupled to a second node to output the switching potential, and the second terminal of the first transistor is coupled to the input node to receive the input potential; and a second transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the second transistor is used to receive the second driving potential, the first terminal of the second transistor is coupled to the ground potential, and the second terminal of the second transistor is coupled to the second node. A power supply as claimed in claim 3, wherein the leakage inductor has a first end and a second end, the first end of the leakage inductor is coupled to the second node to receive the switching potential, the second end of the leakage inductor is coupled to a third node, the main coil has a first end and a second end, the first end of the main coil is coupled to the third node, the second end of the main coil is coupled to a fourth node, the excitation inductor has a first end and a second end, the first end of the excitation inductor is coupled to the third node, the second end of the excitation inductor is coupled to the fourth node. Node, the first capacitor has a first end and a second end, the first end of the first capacitor is coupled to the fourth node to output the capacitance potential, the second end of the first capacitor is coupled to the ground potential, the first sub-coil has a first end and a second end, the first end of the first sub-coil is coupled to a fifth node, the second end of the first sub-coil is coupled to a common node, the second sub-coil has a first end and a second end, the first end of the second sub-coil is coupled to the common node, and the second end of the second sub-coil is coupled to a sixth node. A power supply as claimed in claim 4, wherein the output stage circuit comprises: a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to the fifth node, and the cathode of the first diode is coupled to an output node to output the output potential; a second diode having an anode and a cathode, wherein the anode of the second diode is coupled to the sixth node, and the cathode of the second diode is coupled to the output node; a second capacitor having a first end and a second end, wherein the first end of the second capacitor is coupled to the output node, and the second end of the second capacitor is coupled to a seventh node; and a third resistor having a first end and a second end, wherein the first end of the third resistor is coupled to the common node, and the second end of the third resistor is coupled to the seventh node; wherein the output current flows through the second capacitor and the third resistor; wherein the common potential comes from the common node, and the sensed potential comes from the seventh node. The power supply of claim 1, wherein the detection and control circuit further comprises: a microcontroller, generating the first driving potential and the second driving potential, wherein if the logic potential has a high logic level, the microcontroller will temporarily reduce the potential level of the first driving potential or the second driving potential by a predetermined ratio within a predetermined time. For example, the power supply of claim 6, wherein the predetermined time is approximately 0.66μs, and the predetermined ratio is approximately 70%.

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