TW202347939A - Power supply device for suppressing magnetic saturation - Google Patents

Abstract

A power supply device for suppressing magnetic saturation includes a bridge rectifier, a first transformer, a first power switch element, a second transformer, a second power switch element, an output stage circuit, and a detection and control circuit. The bridge rectifier generates a rectified voltage according to a first input voltage and a second input voltage. The first transformer includes a first main coil and a first secondary coil. The first main coil receives the rectified voltage. The second transformer includes a second main coil and a second secondary coil. The second main coil receives the rectified voltage. The output stage circuit is coupled to the first secondary coil and the second secondary coil, and is configured to generate an output voltage. The detection and control circuit detects a temperature parameter relative to the first transformer, and selectively enables or disables the second transformer and the second power switch element according to the temperature parameter.

Description

Power supply that suppresses magnetic saturation

The present invention relates to a power supply, and in particular to a power supply capable of suppressing magnetic saturation.

In traditional power supplies, the magnetizing inductor is built into the transformer. However, each magnetic component has its hysteresis curve range for normal use. When the temperature of the transformer is too high, the magnetizing inductor may enter a state of magnetic saturation, which will cause its magnetizing characteristics to disappear and cause safety problems. 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 proposes a power supply that suppresses magnetic saturation, including: a bridge rectifier that generates a rectified potential based on a first input potential and a second input potential; a first transformer including a A first main coil and a first auxiliary coil, wherein the first transformer has a built-in first exciting inductor, and the first main coil is used to receive the rectified potential; a first power switch, according to a pulse wave Width modulating the potential to selectively couple the first main coil to a ground potential; a second transformer including a second main coil and a second auxiliary coil, wherein the second transformer has a built-in second a magnetizing inductor, and the second main coil is used to receive the rectified potential; a second power switch to selectively couple the second main coil to the ground potential according to the pulse width modulation potential ; An output stage circuit, coupled to the first secondary coil and the second secondary coil, and generating an output potential; and a detection and control circuit, generating the pulse width modulation potential, and detecting the A temperature parameter of the first transformer, wherein the detection and control circuit further selectively enables or disables the second transformer and the second power switch according to the temperature parameter.

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

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

Figure 1 is a schematic diagram of 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 notebook computer, or an all-in-one computer. As shown in Figure 1, the power supply 100 includes: a bridge rectifier 110, a first transformer 120, a first power switch 130, a second transformer 140, a second power switch 150, and an output stage circuit. 160, and a detection and control circuit 170. 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 bridge rectifier 110 can generate a rectified potential VR according to a first input potential VIN1 and a second input potential VIN2, wherein one of the first input potential VIN1 and the second input potential VIN2 can have any frequency and any amplitude. AC voltage. For example, the frequency of the AC voltage can be about 50Hz or 60Hz, and the root mean square value of the AC voltage can be about 90V to 264V, but it is not limited thereto. The first transformer 120 includes a first main coil 121 and a first auxiliary coil 122 . The first transformer 120 may further have a built-in first exciting inductor LM1, in which the first main coil 121 and the first exciting inductor LM1 may be located on the same side of the first transformer 120, and the first secondary coil 122 may be located on the same side of the first transformer 120. The opposite side of a transformer 120 . The first main coil 121 can receive the rectified potential VR, and the first secondary coil 122 can operate in response to the rectified potential VR. The first power switch 130 can selectively couple the first main coil 121 to a ground potential VSS (eg, 0V) according to a pulse width modulation potential VM. For example, if the pulse width modulation potential VM is a high logic level, the first power switch 130 can couple the first main coil 121 to the ground potential VSS (that is, the first power switch 130 can be approximately a short-circuit path); on the contrary, if the pulse width modulation potential VM is a low logic level, the first power switch 130 will not couple the first main coil 121 to the ground potential VSS (that is, the first power Switch 130 may be approximated as a disconnect path). Similarly, the second transformer 140 includes a second main coil 141 and a second auxiliary coil 142 . The second transformer 140 may further have a second exciting inductor LM2 built-in, in which the second main coil 141 and the second exciting inductor LM2 may be located on the same side of the second transformer 140, and the second secondary coil 142 may be located on the same side of the second transformer 140. The opposite side of the two transformers 140 . The second main coil 141 can receive the rectified potential VR, and the second secondary coil 142 can operate in response to the rectified potential VR. The second power switch 150 can selectively couple the second main coil 141 to the ground potential VSS according to the pulse width modulation potential VM. For example, if the pulse width modulation potential VM is a high logic level, the second power switch 150 can couple the second main coil 141 to the ground potential VSS (that is, the second power switch 150 can be approximately a short-circuit path); on the contrary, if the pulse width modulation potential VM is a low logic level, the second power switch 150 will not couple the second main coil 141 to the ground potential VSS (that is, the second power Switch 150 may be approximated as a disconnect path). The output stage circuit 160 is coupled to the first secondary coil 122 and the second secondary coil 142 and can be used to generate an output potential VOUT. For example, the output potential VOUT can be a direct current potential, and its potential level can be between 18V and 20V. between, but not limited to that. The detection and control circuit 170 can generate the aforementioned pulse width modulation potential VM, and can detect a temperature parameter TP related to the first transformer 120 . For example, the temperature parameter TP can be a potential, a current, or any kind of signal, which is correlated with the operating temperature of the first transformer 120 . The detection and control circuit 170 can further selectively enable or disable the second transformer 140 and the second power switch 150 according to the temperature parameter TP. Under this design, even if the operating temperature of the first transformer 120 changes, the detection and control circuit 170 can still appropriately adjust the load of the first transformer 120 by selectively using the second transformer 140 . In other words, the second transformer 140 can be regarded as an auxiliary transformer, which can be used to share part of the workload of the first transformer 120 (especially when the operating temperature of the first transformer 120 is relatively high). According to actual measurement results, the design of the present invention helps prevent the first exciting inductor LM1 of the first transformer 120 from accidentally entering a magnetic saturation state, so the overall safety and reliability of the power supply 100 can be greatly improved.

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 invention.

Figure 2 is a circuit diagram of a power supply 200 according to an embodiment of the present invention. In the embodiment of FIG. 2, in the embodiment of FIG. 2, the power supply 200 has a first input node NIN1, a second input node NIN2, and an output node NOUT, and includes: a bridge rectifier 210 , a first transformer 220, a first power switch 230, a second transformer 240, a second power switch 250, an output stage circuit 260, and a detection and control circuit 270. The first input node NIN1 and the second output node NIN2 of the power supply 200 can respectively receive a first input potential VIN1 and a second input potential VIN2 from an external input power source, and the output node NOUT of the power supply 200 can be An output potential VOUT is output to an electronic device (not shown).

The bridge rectifier 210 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The first diode D1 has an anode and a cathode, wherein the anode of the first diode D1 is coupled to the first input node NIN1, and the cathode of the first diode D1 is coupled to a first node N1 To output the rectified potential VR. The second diode D2 has an anode and a cathode, wherein the anode of the second diode D2 is coupled to the second input node NIN2, and the cathode of the second diode D2 is coupled to the first node N1. The third diode D3 has an anode and a cathode, wherein the anode of the third diode D3 is coupled to a ground potential VSS (for example: 0V), and the cathode of the third diode D3 is coupled to the ground potential VSS (for example: 0V). One input node NIN1. The fourth diode D4 has an anode and a cathode, wherein the anode of the fourth diode D4 is coupled to the ground potential VSS, and the cathode of the fourth diode D4 is coupled to the second input node NIN2.

The first transformer 220 includes a first main coil 221 and a first auxiliary coil 222, wherein the first transformer 220 further has a built-in first exciting inductor LM1. The first exciting inductor LM1 may be an inherent component produced when the first transformer 220 is manufactured, and is not an external independent component. The first main coil 221 and the first exciting inductor LM1 can both be located on the same side of the first transformer 220 (for example, the primary side), while the first auxiliary coil 222 can be located on the opposite side of the first transformer 220 (for example: secondary side, which can be isolated from the primary side). The first main coil 221 has a first end and a second end, wherein the first end of the first main coil 221 is coupled to the first node N1 to receive the rectified potential VR, and the second end of the first main coil 221 is coupled to a second node N2. The first exciting inductor LM1 has a first terminal and a second terminal. The first terminal of the first exciting inductor LM1 is coupled to the first node N1, and the second terminal of the first exciting inductor LM1 is coupled to the first node N1. Connected to the second node N2. The first secondary coil 222 has a first end and a second end, wherein the first end of the first secondary coil 222 is coupled to a third node N3, and the second end of the first secondary coil 222 is coupled to A common node NCM. For example, the common node NCM can be regarded as another ground potential, which can be the same as or different from the aforementioned ground potential VSS.

The first power switch 230 includes a first transistor M1. For example, the first transistor M1 may be an N-type Metal-Oxide-Semiconductor Field-Effect Transistor (NMOSFET). The first transistor M1 has a control terminal (for example: a gate), a first terminal (for example: a source), and a second terminal (for example: a drain), wherein the control terminal of the first transistor M1 The terminal is used to receive a pulse width modulation potential VM. The first terminal of the first transistor M1 is coupled to the ground potential VSS, and the second terminal of the first transistor M1 is coupled to the second node N2. .

The second transformer 240 includes a second main coil 241 and a second auxiliary coil 242, wherein the second transformer 240 further has a built-in second exciting inductor LM2. The second exciting inductor LM2 may be an inherent component produced when the second transformer 240 is manufactured, and is not an external independent component. The second main coil 241 and the second exciting inductor LM2 can both be located on the same side of the second transformer 240 (for example: the primary side), while the second secondary coil 242 can be located on the opposite side of the second transformer 240 (for example: secondary side). The second main coil 241 has a first end and a second end, wherein the first end of the second main coil 241 is coupled to the first node N1 to receive the rectified potential VR, and the second end of the second main coil 241 is coupled to a fourth node N4. The second exciting inductor LM2 has a first terminal and a second terminal, wherein the first terminal of the second exciting inductor LM2 is coupled to the first node N1, and the second terminal of the second exciting inductor LM2 is coupled to Connected to the fourth node N4. The second secondary coil 242 has a first end and a second end, wherein the first end of the second secondary coil 242 is coupled to a fifth node N5, and the second end of the second secondary coil 242 is coupled to Common node NCM.

The second power switch 250 includes a second transistor M2. For example, the second transistor M2 may be an N-type MOSFET. The second transistor M2 has a control terminal (for example, a gate), a first terminal (for example, a source), and a second terminal (for example, a drain), wherein the control terminal of the second transistor M2 The terminal is used to receive the pulse width modulation potential VM. The first terminal of the second transistor M2 is coupled to a sixth node N6, and the second terminal of the second transistor M2 is coupled to the fourth node. N4.

The output stage circuit 260 includes a fifth diode D5, a sixth diode D6, and an output capacitor CO. The fifth diode D5 has an anode and a cathode, wherein the anode of the fifth diode D5 is coupled to the third node N3, and the cathode of the fifth diode D5 is coupled to the output node NOUT. The sixth diode D6 has an anode and a cathode, wherein the anode of the sixth diode D6 is coupled to the fifth node N5, and the cathode of the sixth diode D6 is coupled to the output node NOUT. The output capacitor CO has a first terminal and a second terminal, wherein the first terminal of the output capacitor CO is coupled to the output node NOUT, and the second terminal of the output capacitor CO is coupled to the common node NCM.

The detection and control circuit 270 includes a third transistor M3, a fourth transistor M4, a first resistor R1, a second resistor R2, a microcontroller unit (Microcontroller Unit, MCU) 275, and a negative Temperature coefficient (Negative Temperature Coefficient, NTC) resistor RN. The third transistor M3 and the fourth transistor M4 may each be an N-type MOSFET. The microcontroller 275 can be used to generate the aforementioned pulse width modulation potential VM. For example, the pulse width modulation potential VM can be maintained at a fixed potential when the power supply 200 is initialized, and can provide a periodic clock waveform after the power supply 200 enters the normal use stage.

The first resistor R1 has a first terminal and a second terminal, wherein the first terminal of the first resistor R1 is coupled to a first control node NC1 to receive a first control potential VC1, and the first resistor R1 The second end of R1 is coupled to a seventh node N7. The third transistor M3 has a control terminal (for example: a gate), a first terminal (for example: a source), and a second terminal (for example: a drain), wherein the control terminal of the third transistor M3 The terminal is coupled to the seventh node N7, the first terminal of the third transistor M3 is coupled to the ground potential VSS, and the second terminal of the third transistor M3 is coupled to the sixth node N6.

The second resistor R2 has a first terminal and a second terminal, wherein the first terminal of the second resistor R2 is coupled to a second control node NC2 to receive a second control potential VC2, and the second resistor R2 The second end of R2 is coupled to an eighth node N8. The fourth transistor M4 has a control terminal (for example: a gate), a first terminal (for example: a source), and a second terminal (for example: a drain), wherein the control terminal of the fourth transistor M4 The terminal is coupled to the eighth node N8, the first terminal of the fourth transistor M4 is coupled to the ground potential VSS, and the second terminal of the fourth transistor M4 is coupled to the seventh node N7.

The negative temperature coefficient resistor RN has a first terminal and a second terminal, wherein the first terminal of the negative temperature coefficient resistor RN is coupled to a detection node ND, and the second terminal of the negative temperature coefficient resistor RN is Coupled to the common node NCM. It must be noted that the negative temperature coefficient resistor RN is disposed adjacent to the first secondary coil 222 . For example, the distance between the negative temperature coefficient resistor RN and the first secondary coil 222 may be less than or equal to 5 mm, but is not limited thereto. In some embodiments, if the operating temperature of the first transformer 220 increases, the resistance value of the negative temperature coefficient resistor RN will become smaller; conversely, if the operating temperature of the first transformer 220 decreases, the resistance value of the negative temperature coefficient resistor RN will decrease. The resistance value will become larger.

The microcontroller 275 can further output a detection current ID to the detection node ND, and can further detect a feedback potential VF at the detection node ND. The microcontroller 275 can further output the feedback potential VF according to the feedback potential VF. The potential VOUT is used to generate the aforementioned first control potential VC1 and second control potential VC2. For example, the detection current ID may generally have a fixed current value. According to Ohm's law, the microcontroller 275 can estimate the resistance value of the negative temperature coefficient resistor RN and the corresponding operating temperature of the first transformer 220 by analyzing the feedback potential VF. In addition, the output potential VOUT can be used to indicate whether the power supply 200 is in a normal state. For example, if the output potential VOUT is between a potential lower limit value VL and a potential upper limit value VH, the microcontroller 275 will determine that the power supply 200 is in a normal state; otherwise, the microcontroller 275 will determine that the power supply 200 is in a normal state. The supplier 200 is in an abnormal state.

Figure 3 shows a signal waveform diagram of the power supply 200 according to an embodiment of the present invention, in which the horizontal axis represents time, and the vertical axis represents current value or potential level. According to the measurement results in Figure 3, the power supply 200 can operate in a first stage T1, a second stage T2, or a third stage T3, and the operating principles thereof can be described as follows.

The first stage T1 can be regarded as an initial stage of the power supply 200 . During the first stage T1, the operating temperature of the first transformer 220 is relatively low, and the feedback potential VF is relatively high. At this time, both the first control potential VC1 and the second control potential VC2 are maintained at a low logic level to disable the second transformer 240 and the second power switch 250 . That is, only the first transformer 220 and the first power switch 230 operate normally.

Then, the operating temperature of the first transformer 220 gradually increases, and the feedback potential VF gradually decreases. The microcontroller 275 continuously monitors the feedback potential VF. In some embodiments, if it is detected that the feedback potential VF is lower than or equal to a first threshold potential VTH1, the microcontroller 275 will switch the first control potential VC1 to a high logic level. In other embodiments, if it is detected that the feedback potential VF drops by a specific ratio within a unit time (for example, within 1 μs, the feedback potential VF drops by 40% or more), the microcontroller 275 The first control potential VC1 will also be switched to a high logic level. At this time, the power supply 200 will leave the first phase T1 and enter the second phase T2.

During the second phase T2, the first control potential VC1 is maintained at a high logic level, and the second control potential VC2 is maintained at a low logic level. At this time, both the second transformer 240 and the second power switch 250 are enabled, so that the inductor current IL passing through the second exciting inductor LM2 exhibits an up-and-down oscillating current waveform. Since the addition of the second transformer 240 can reduce the load of the first transformer 220, the operating temperature of the first transformer 220 will gradually decrease, which will prevent the first exciting inductor LM1 from accidentally entering a magnetic saturation state. In some embodiments, the number of winding turns of the second transformer 240 is at least 1.5 times that of the first transformer 220 , and the inductance value of the second exciting inductor LM2 is also at least that of the first exciting inductor LM1 1.5 times the inductance value.

In some embodiments, if it is detected that the feedback potential VF rises and is higher than or equal to a second critical potential VTH2, the microcontroller 275 will switch the first control potential VC1 to a low logic level and switch the second Control potential VC2 to a high logic level. At this time, the power supply 200 will leave the second stage T2 and enter the third stage T3. For example, the second critical potential VTH2 can be at least 0.5V higher than the first critical potential VTH1 to reduce the probability of misjudgment.

During the third stage T3, the turned-on fourth transistor M4 can rapidly discharge the seventh node N7, causing a potential V7 at the seventh node N7 to drop to a low logic level in a very short time. Therefore, the third transistor M3 will be turned off quickly without causing any non-ideal switching delay due to the non-ideal parasitic capacitance at its control terminal. At this time, the second transformer 240 and the second power switch 250 are disabled again, and only the first transformer 220 and the first power switch 230 operate normally.

In some embodiments, only when the output potential VOUT is between the potential lower limit value VL and the potential upper limit value VH, the microcontroller 275 will perform the aforementioned judgment and operation procedures. However, the present invention is not limited thereto.

Figure 4 is a diagram showing the operating characteristics of the first exciting inductor LM1 according to an embodiment of the present invention. The horizontal axis represents the magnetic field strength H (unit: A/m) of the first exciting inductor LM1, and the vertical axis Represents the magnetic flux density B (unit: T) of the first exciting inductor LM1. As shown in FIG. 4 , a first curve CC1 represents the characteristics of the first exciting inductor LM1 when the operating temperature of the first transformer 220 is relatively low, and a second curve CC2 represents the characteristics of the first magnetizing inductor LM1 when the operating temperature of the first transformer 220 is relatively low. Characteristics of the first exciting inductor LM1 at high times. According to the measurement results in Figure 4, even if the operating temperature of the first transformer 220 changes, the characteristics of the first exciting inductor LM1 will still be only slightly different, so it will not easily enter the magnetic saturation state.

The present invention proposes a novel power supply that can effectively suppress the non-ideal magnetic saturation phenomenon. According to the actual measurement results, the safety of the power supply using the above-mentioned design will be greatly improved, so it is very suitable for use in various types of devices.

It is worth noting that the above-mentioned potential, current, resistance value, inductance value, capacitance value, and other component parameters 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 state shown in Figures 1-4. The present invention may only include any one or multiple features of any one or multiple embodiments of Figures 1-4. In other words, not all features shown in the figures need to be implemented in the power supply of the present invention at the same time. Although the embodiment of the present invention uses a metal oxide semi-field effect transistor as an example, the present invention is not limited thereto. Those skilled in the art can use other types of transistors, such as junction field effect transistors or fins. type field effect transistor, etc., without affecting the effect of the present invention.

The 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. They are only used to distinguish two items with the same Different components with names.

Although the present invention is disclosed above in terms of preferred embodiments, they are not intended to limit the scope of the present invention. Anyone skilled in the art can make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

100,200:Power supply 110,210: Bridge rectifier 120,220:First transformer 121,221: first main coil 122,222: first secondary coil 130,230: First power switcher 140,240: Second transformer 141,241: Second main coil 142,242: Second secondary coil 150,250: Second power switch 160,260: Output stage circuit 170,270: Detection and control circuit 275:Microcontroller B: Magnetic flux density CC1: first curve CC2: Second curve CO: output capacitor D1: first diode D2: Second diode D3: The third diode D4: The fourth diode D5: The fifth diode D6: The sixth diode H: magnetic field strength ID: detect current IL: inductor current LM1: First exciting inductor LM2: Second exciting inductor M1: the first transistor M2: Second transistor M3: The third transistor M4: The fourth transistor N1: first node N2: second node N3: The third node N4: fourth node N5: fifth node N6: The sixth node N7: The seventh node N8: The eighth node NC1: first control node NC2: second control node NCM: common node ND: detection node NIN1: first input node NIN2: second input node NOUT: output node R1: first resistor R2: second resistor RN: Negative temperature coefficient resistor T1: first stage T2: The second stage T3: The third stage TP: temperature parameter V7:potential VC1: first control potential VC2: second control potential VF: feedback potential VH: Potential upper limit value VIN1: first input potential VIN2: second input potential VL: potential upper limit value VM: pulse width modulation potential VOUT: output potential VR: rectifier potential VSS: ground potential VTH1: first critical potential VTH2: second critical potential

Figure 1 is a schematic diagram of a power supply according to an embodiment of the present invention. Figure 2 is a circuit diagram showing a power supply according to an embodiment of the present invention. Figure 3 shows a signal waveform diagram of a power supply according to an embodiment of the present invention. FIG. 4 is a diagram showing the operating characteristics of the first exciting inductor according to an embodiment of the present invention.

100:Power supply

110: Bridge rectifier

120:First transformer

121: First main coil

122: First secondary coil

130:First power switcher

140:Second transformer

141: Second main coil

142: Second secondary coil

150: Second power switcher

160:Output stage circuit

170: Detection and control circuit

LM1: First exciting inductor

LM2: Second exciting inductor

TP: temperature parameter

VIN1: first input potential

VIN2: second input potential

VM: pulse width modulation potential

VOUT: output potential

VR: rectifier potential

VSS: ground potential

Claims (10)

A power supply that suppresses magnetic saturation, including: A bridge rectifier generates a rectified potential based on a first input potential and a second input potential; A first transformer, including a first main coil and a first auxiliary coil, wherein the first transformer has a built-in first exciting inductor, and the first main coil is used to receive the rectified potential; a first power switch that selectively couples the first main coil to a ground potential according to a pulse width modulation potential; a second transformer, including a second main coil and a second auxiliary coil, wherein the second transformer has a built-in second exciting inductor, and the second main coil is used to receive the rectified potential; a second power switch that selectively couples the second main coil to the ground potential according to the pulse width modulation potential; An output stage circuit is coupled to the first secondary coil and the second secondary coil and generates an output potential; and A detection and control circuit generates the pulse width modulation potential and detects a temperature parameter related to the first transformer, wherein the detection and control circuit further selectively enables or disables the temperature parameter according to the temperature parameter. The second transformer and the second power switch can be used. The power supply of claim 1, wherein the bridge rectifier includes: a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to a first input node to receive the first input potential, and the first diode The cathode is coupled to a first node to output the rectified potential; a second diode having an anode and a cathode, wherein the anode of the second diode is coupled to a second input node to receive the second input potential, and the The cathode is coupled to the first node; a third diode having an anode and a cathode, wherein the anode of the third diode is coupled to the ground potential, and the cathode of the third diode is coupled to the first input node; and a fourth diode having an anode and a cathode, wherein the anode of the fourth diode is coupled to the ground potential, and the cathode of the fourth diode is coupled to the second input node. The power supply of claim 2, wherein the first main coil has a first end and a second end, and the first end of the first main coil is coupled to the first node to receive the rectified potential, The second end of the first main coil is coupled to a second node, the first exciting inductor has a first end and a second end, and the first end of the first exciting inductor is coupled to The first node, the second end of the first exciting inductor are coupled to the second node, the first secondary coil has a first end and a second end, the first end of the first secondary coil The terminal is coupled to a third node, and the second terminal of the first secondary coil is coupled to a common node. The power supply of claim 3, wherein the first power switch includes: A first transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the first transistor is used to receive the pulse width modulation potential, the first transistor The first terminal is coupled to the ground potential, and the second terminal of the first transistor is coupled to the second node. The power supply of claim 3, wherein the second main coil has a first end and a second end, and the first end of the second main coil is coupled to the first node to receive the rectified potential, The second end of the second main coil is coupled to a fourth node, the second exciting inductor has a first end and a second end, and the first end of the second exciting inductor is coupled to The first node, the second end of the second exciting inductor are coupled to the fourth node, the second secondary coil has a first end and a second end, the first end of the second secondary coil The terminal is coupled to a fifth node, and the second terminal of the second secondary coil is coupled to the common node. The power supply of claim 5, wherein the second power switch includes: A second transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the second transistor is used to receive the pulse width modulation potential, and the second transistor The first terminal of the transistor is coupled to a sixth node, and the second terminal of the second transistor is coupled to the fourth node. The power supply of claim 5, wherein the output stage circuit includes: a fifth diode having an anode and a cathode, wherein the anode of the fifth diode is coupled to the third node, and the cathode of the fifth diode is coupled to an output node to output the output potential; a sixth diode having an anode and a cathode, wherein the anode of the sixth diode is coupled to the fifth node, and the cathode of the sixth diode is coupled to the output node ;as well as An output capacitor has a first terminal and a second terminal, wherein the first terminal of the output capacitor is coupled to the output node, and the second terminal of the output capacitor is coupled to the common node. For example, the power supply of claim 6, wherein the detection and control circuit includes: a first resistor having a first end and a second end, wherein the first end of the first resistor is coupled to a first control node to receive a first control potential, and the first resistor The second end of the device is coupled to a seventh node; and A third transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the third transistor is coupled to the seventh node, and the first terminal of the third transistor A terminal is coupled to the ground potential, and the second terminal of the third transistor is coupled to the sixth node. For example, the power supply of claim 8, wherein the detection and control circuit further includes: a second resistor having a first end and a second end, wherein the first end of the second resistor is coupled to a second control node to receive a second control potential, and the second resistor The second end of the device is coupled to an eighth node; and A fourth transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the fourth transistor is coupled to the eighth node, and the first terminal of the fourth transistor A terminal is coupled to the ground potential, and the second terminal of the fourth transistor is coupled to the seventh node. For example, the power supply of claim 9, wherein the detection and control circuit further includes: A negative temperature coefficient resistor has a first terminal and a second terminal adjacent to the first secondary coil, wherein the first terminal of the negative temperature coefficient resistor is coupled to a detection node, and the The second terminal of the negative temperature coefficient resistor is coupled to the common node; and A microcontroller outputs a detection current to the detection node and detects a feedback potential at the detection node, wherein the microcontroller further generates the first feedback potential based on the feedback potential and the output potential. control potential and this second control potential.

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