TWI699082B - Power supply device - Google Patents

Abstract

A power supply device includes a bridge rectifier, a soft-start circuit, a transformer, a power switch element, a main output stage circuit, an auxiliary output stage circuit, and a controller. The bridge rectifier generates a rectifying voltage according to a first input voltage and a second input voltage. The soft-start circuit includes at least two charging paths. The soft-start circuit generates a start voltage according to the rectifying voltage and a compound control voltage. The transformer generates a first induction voltage and a second induction voltage according to the start voltage. The main output stage circuit generates an output voltage according to the first induction voltage. The auxiliary output stage circuit generates a feedback voltage according to the second induction voltage. The controller determines the compound control voltage and a clock voltage according to the feedback voltage.

Description

Power Supplier

The present invention relates to a power supply device, and particularly relates to a power supply device with a soft start function.

General electronic devices, such as desktop computers or notebook computers, usually have a large input capacitance to match various peripheral devices. However, when the power supply to which the electronic device is coupled is turned on, due to its capacitive load characteristics, a large inrush current is often generated, causing damage to the internal circuit of the power supply . In view of this, it is necessary to propose a brand-new solution to overcome the problems faced by the prior art.

In a preferred embodiment, the present invention provides a power supply including: a bridge rectifier that generates a rectified potential based on a first input potential and a second input potential; a soft start circuit including at least two charging paths, The soft start circuit generates a start potential based on the rectified potential and a composite control potential; a transformer includes a main coil, a secondary coil, and an auxiliary coil, wherein the main coil is used to receive the start potential, The auxiliary coil is used to generate a first induced potential, and the auxiliary coil is used to generate a second induced potential; a power switch, wherein the main coil is coupled to a ground potential through the power switch, and The power switch performs switching operations based on a clock potential; a main output stage circuit generates an output potential based on the first induced potential; an auxiliary output stage circuit generates a feedback potential based on the second induced potential And a controller for detecting the feedback potential, wherein the controller determines the composite control potential and the clock potential according to the feedback potential; wherein when the feedback potential is greater than or equal to a reference potential, the The controller discharges the charging paths and then bypasses the soft start circuit.

In order to make the purpose, features and advantages of the present invention more comprehensible, specific embodiments of the present invention are listed below in conjunction with the accompanying drawings, which are described in detail as follows.

Certain words are used in the specification and the scope of patent applications to refer to specific elements. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and the scope of patent application do not use differences in names as a way to distinguish elements, but use differences in functions of elements as a criterion for distinguishing. The terms "include" and "include" mentioned in the entire specification and the scope of the patent application are open-ended terms and should be interpreted as "including but not limited to". The term "approximately" 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 term "coupling" includes any direct and indirect electrical connection means in this specification. Therefore, if it is described in the text that 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 through other devices or connection means. Two devices.

FIG. 1 is a schematic diagram of a power supply 100 according to an embodiment of the invention. For example, the power supply 100 can be applied to a desktop computer, a notebook computer, or an integrated computer. As shown in Figure 1, the power supply 100 includes: a bridge rectifier 110, a soft start circuit 120, a transformer 130, a power switch 140, a main output stage circuit 150, an auxiliary output stage circuit 160, and a Controller 170. It should be noted that, although not shown in Figure 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 generates a rectified potential VR according to a first input potential VIN1 and a second input potential VIN2. Both the first input potential VIN1 and the second input potential VIN2 can come from an external power source, and an AC voltage with any frequency and any amplitude can be formed between the first input potential VIN1 and the second input potential VIN2. For example, the frequency of the AC voltage may be about 60 Hz, and the root mean square value of the AC voltage may be about 110V or 220V, but it is not limited to this. The soft-start circuit 120 includes at least two charging paths 121, 122, wherein each of the aforementioned charging paths 121, 122 may each include a capacitor to store charges. The soft start circuit 120 generates a start potential VE according to the rectified potential VR and a composite control potential VC. The transformer 130 includes a main coil 131, a secondary coil 132, and an auxiliary coil 133. The main coil 131 and the auxiliary coil 133 can be located on the same side of the transformer 130, and the secondary coil 132 can be located on the opposite side of the transformer 130. . The main coil 131 is used to receive the starting potential VE, and in response to the starting potential VE, the auxiliary coil 132 can be used to generate a first induced potential VS1, and the auxiliary coil 133 can be used to generate a second induced potential VS2. In addition, the main coil 131 is coupled to a ground potential VSS (for example, 0V) via the power switch 140, wherein the power switch 140 performs switching operations according to a clock potential VA. The main output stage circuit 150 generates an output potential VOUT according to the first induced potential VS1. The auxiliary output stage circuit 160 generates a feedback potential VF according to the second induced potential VS2. The controller 170 may be a pulse width modulation integrated circuit. In some embodiments, the controller 170 includes a detection circuit, a comparison circuit, and a processing circuit (not shown). The controller 170 can detect the feedback potential VF and compare it with a reference potential VM. The controller 170 determines the composite control potential VC and the clock potential VA according to the feedback potential VF. Generally speaking, when the feedback potential VF is greater than or equal to the reference potential VM, the controller 170 discharges the aforementioned charging paths 121 and 122 and then bypasses the soft start circuit 120, so that the power supply 100 enters a normal state. Operation mode. According to the actual measurement result, this circuit design method can prevent the power supply 100 from being damaged due to the initial inrush current (Inrush Current), thereby improving the reliability of the power supply 100.

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 used to limit the scope of the present invention.

FIG. 2 is a schematic diagram of the power supply 200 according to an embodiment of the invention. In the embodiment of Figure 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 soft start circuit 220, and a transformer 230 , A power switch 240, a main output stage circuit 250, an auxiliary output stage circuit 260, and a controller 270. The first input node NIN1 and the second input node NIN2 of the power supply 200 can receive a first input potential VIN1 and a second input potential VIN2 from an external power supply, respectively, and the output node NOUT of the power supply 200 can be used to output a The potential VOUT is output to an electronic device (for example: a notebook computer).

The bridge rectifier 210 includes a first diode (Diode) D1, a second diode D2, a third diode D3, and a fourth diode D4. The first diode D1 has an anode (Anode) and a cathode (Cathode). 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 a rectified potential VR. The second diode D2 has an anode and a cathode. The anode of the second diode D2 is coupled to the first input node NIN1, and the cathode of the second diode D2 is coupled to a ground potential VSS. The third diode D3 has an anode and a cathode. The anode of the third diode D3 is coupled to the first node N1, and the cathode of the third diode D3 is coupled to the second input node NIN2. The fourth diode D4 has an anode and a cathode. 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 soft-start circuit 220 includes a fifth diode D5, a sixth diode D6, a seventh diode D7, a resistor R1, a first capacitor C1, a second capacitor C2, and a first capacitor. Crystal M1, a second transistor M2, and a third transistor M3. For example, each of the first transistor M1, the second transistor M2, and the third transistor M3 can each be an N-type MOSFET. The fifth diode D5 has an anode and a cathode. The anode of the fifth diode D5 is coupled to the first node N1 to receive the rectified potential VR, and the cathode of the fifth diode D5 is coupled to a The second node N2. The resistor R1 has a first end and a second end. The first end of the resistor R1 is coupled to the second node N2, and the second end of the resistor R1 is coupled to a third node N3 for output A start potential VE. The sixth diode D6 has an anode and a cathode. The anode of the sixth diode D6 is coupled to the first node N1, and the cathode of the sixth diode D6 is coupled to a fourth node N4. The first capacitor C1 has a first terminal and a second terminal, wherein the first terminal of the first capacitor C1 is coupled to the fourth node N4, and the second terminal of the first capacitor C1 is coupled to the third node N3 . The seventh diode D7 has an anode and a cathode. The anode of the seventh diode D7 is coupled to the first node N1, and the cathode of the seventh diode D7 is coupled to a fifth node N5. 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 fifth node N5, and the second terminal of the second capacitor C2 is coupled to the third node N3 . It must be noted that the sixth diode D6 and the first capacitor C1 may form one of the first charging paths 221 of the soft-start circuit 220, and the seventh diode D7 and the second capacitor C2 may form one of the soft-start circuits 220 The second charging path 222.

In detail, the controller 270 can detect a feedback potential VF, and then generate a composite control potential VC and a clock potential VA by comparing the feedback potential VF with a reference potential VM, where the composite control potential VC includes a first A control potential VC1, a second control potential VC2, and a third control potential VC3. The first transistor M1 has a control terminal (or a gate), a first terminal (or a source), and a second terminal (or a drain). The control terminal of the first transistor M1 is used Upon receiving the first control potential VC1, the first end of the first transistor M1 is coupled to the fourth node N4, and the second end of the first transistor M1 is coupled to the second node N2. The second transistor M2 has a control terminal, a first terminal, and a second terminal. The control terminal of the second transistor M2 is used to receive the second control potential VC2, and the first terminal of the second transistor M2 is It is coupled to the fifth node N5, and the second terminal of the second transistor M2 is coupled to the second node N2. The third transistor M3 has a control terminal, a first terminal, and a second terminal. The control terminal of the third transistor M3 is used to receive the third control potential VC3, and the first terminal of the third transistor M3 is It is coupled to the third node N3, and the second terminal of the third transistor M3 is coupled to the first node N1.

The transformer 230 includes a main winding 231, a secondary winding 232, and an auxiliary winding 233. The primary winding 231 and the auxiliary winding 233 can be located on the same side of the transformer 230, and the secondary winding 232 can be located on the opposite side of the transformer 230. . The main coil 231 has a first end and a second end. The first end of the main coil 231 is coupled to the third node N3 to receive the activation potential VE, and the second end of the main coil 231 is coupled to a Six nodes N6. The auxiliary coil 232 has a first end and a second end. The first end of the auxiliary coil 231 is coupled to a seventh node N7 to output a first induced potential VS1, and the second end of the auxiliary coil 232 is coupled Connect to the ground potential VSS. The auxiliary coil 233 has a first end and a second end. The first end of the auxiliary coil 233 is coupled to an eighth node N8 to output a second induced potential VS2, and the second end of the auxiliary coil 233 is coupled Connect to the ground potential VSS.

The power switch 240 includes a fourth transistor M4. For example, the fourth transistor M4 can be an N-type metal oxide half field effect transistor. The fourth transistor M4 has a control terminal, a first terminal, and a second terminal. The control terminal of the fourth transistor M4 is used to receive the clock potential VA, and the first terminal of the fourth transistor M4 is coupled It is connected to the ground potential VSS, and the second terminal of the fourth transistor M4 is coupled to the sixth node N6.

The main output stage circuit 250 includes an eighth diode D8 and a third capacitor C3. The eighth diode D8 has an anode and a cathode. The anode of the eighth diode D8 is coupled to the seventh node N7 to receive the first sensing signal VS1, and the cathode of the eighth diode D8 is coupled To the output node NOUT. The third capacitor C3 has a first terminal and a second terminal. The first terminal of the third capacitor C3 is coupled to the output node NOUT, and the second terminal of the third capacitor C3 is coupled to the ground potential VSS.

The auxiliary output stage circuit 260 includes a ninth diode D9 and a fourth capacitor C4. The ninth diode D9 has an anode and a cathode. The anode of the ninth diode D9 is coupled to the eighth node N8 to receive the second sensing signal VS2, and the cathode of the ninth diode D9 is coupled To a ninth node N9 to output the feedback potential VF. The fourth capacitor C4 has a first terminal and a second terminal. The first terminal of the fourth capacitor C4 is coupled to the ninth node N9, and the second terminal of the fourth capacitor C4 is coupled to the ground potential VSS.

The operating principle of the power supply 200 can be as follows. Initially, the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are all turned off (turned off, or non-conductive). Then, the power supply 200 can sequentially operate in a first mode, a second mode, a third mode, and a fourth mode, and then enter a normal operation mode to provide a stable output potential VOUT to an electronic device . The aforementioned first mode, second mode, third mode, and fourth mode can all be regarded as a pre-calibration procedure of the power supply 200.

First, in the first mode, the first transistor M1, the second transistor M2, the third transistor M3, and the fourth transistor M4 are still maintained in the off state. The bridge rectifier 210 starts to receive the first input potential VIN1 and the second input potential VIN2 from the external power supply, so that the first capacitor C1 and the second capacitor C2 in the soft start circuit 220 are gradually charged to their maximum storage voltage. At this time, the first capacitor C1 and the second capacitor C2 can be regarded as a parallel capacitor combination, which is then coupled in series with an input capacitor of the electronic device. Since the equivalent input capacitance of the electronic device decreases, this design can effectively suppress an inrush current (Inrush Current) entering the power supply 200 and achieve the expected soft-start effect.

In the second mode, the fourth transistor M4 of the power switch 240 starts to perform high-frequency switching operations (that is, alternately turned on and off) according to the clock potential VA. At this time, the transformer 230 can transfer the input energy to the main output stage circuit 250 to form the output potential VOUT and charge the third capacitor C3; in addition, the transformer 230 can further transfer the input energy to the auxiliary output stage circuit 260 to form a feedback The potential VF charges the fourth capacitor C4.

In the third mode, when it is detected that the feedback potential VF has risen to reach the reference potential VM, the controller 270 outputs the first control potential VC1 and the second control potential VC2 with high logic levels to the soft start circuit 220. At this time, both the first transistor M1 and the second transistor M2 are turned on (turned on), so that both the first capacitor C1 and the second capacitor C2 can be discharged through the resistor R1. When the first capacitor C1 and the second capacitor C2 have no stored charge (that is, the fully discharged state), the controller 270 then outputs the first control potential VC1 and the second control potential VC2 with low logic levels to restore Turn off the first transistor M1 and the second transistor M2.

Finally, in the fourth mode, after both the first capacitor C1 and the second capacitor C2 have been completely discharged, the controller 270 then outputs the third control potential VC3 with a high logic level to the soft start circuit 220. At this time, the third transistor M3 is activated and forms a bypass path similar to a short circuit, which can completely disable the soft start circuit 220 as a whole. Under this design, the soft start circuit 220 no longer consumes additional power, which can ensure that the power supply 200 will not be negatively affected by the soft start circuit 220 during the normal operation mode. In other words, the power supply 200 can provide a preset output specification to the electronic device in the normal operation mode, and it has no correlation with the soft start circuit 220.

In some embodiments, the component parameters of the power supply 200 may be as described below. The resistance of the resistor R1 can be between 9kΩ and 11kΩ, preferably 10kΩ. The capacitance of the first capacitor C1 can be between 17.6 μF and 26.4 μF, preferably 22 μF. The capacitance value of the second capacitor C2 can be between 37.6 μF and 56.4 μF, preferably 47 μF. The capacitance of the third capacitor C3 can be between 544 μF and 816 μF, preferably 680 μF. The capacitance value of the fourth capacitor C4 can be between 37.6 μF and 56.4 μF, preferably 47 μF. The ratio of the number of turns of the primary coil 231 to the secondary coil 232 can be between 1 and 10, preferably 5. The ratio of the number of turns of the auxiliary coil 232 to the auxiliary coil 233 may be between 1 and 20, preferably 10. The above parameter range is based on the results of many experiments, which helps to optimize the conversion efficiency and soft start effect of the power supply 200.

FIG. 3 is a schematic diagram of a power supply 300 according to another embodiment of the invention. Figure 3 is similar to Figure 2. In the embodiment of FIG. 3, the composite control potential VC further includes a fourth control potential VC4, and a soft start circuit 320 of the power supply 300 further includes a twelfth pole body D10, a fifth capacitor C5, and A fifth transistor M5. The twelfth polar body D10 has an anode and a cathode. The anode of the twelfth polar body D10 is coupled to the first node N1, and the cathode of the twelfth polar body D10 is coupled to a tenth node N10. The fifth capacitor C5 has a first terminal and a second terminal, wherein the first terminal of the fifth capacitor C5 is coupled to the tenth node N10, and the second terminal of the fifth capacitor C5 is coupled to the third node N3 . For example, the capacitance value of the fifth capacitor C5 may be between 54.4 μF and 81.6 μF, preferably 68 μF. It must be noted that the twelfth polar body D10 and the fifth capacitor C5 may form a third charging path 223 of the soft start circuit 320. For example, the fifth transistor M5 can be an N-type MOSFET. The fifth transistor M5 has a control terminal, a first terminal, and a second terminal. The control terminal of the fifth transistor M5 is used to receive the fourth control potential VC4, and the first terminal of the fifth transistor M5 is It is coupled to the tenth node N10, and the second terminal of the fifth transistor M5 is coupled to the second node N2. Similarly, in the aforementioned third mode, when it is detected that the feedback potential VF has reached the reference potential VM, the controller 270 further outputs the fourth control potential VC4 with a high logic level to activate the fifth transistor M5. The fifth capacitor C5 can be discharged through the resistor R1. After the fifth capacitor C5 is completely discharged, the controller 270 outputs a fourth control potential VC4 with a low logic level to turn off the fifth transistor M5 again. According to actual measurement results, the addition of the third charging path 223 can further reduce the equivalent input capacitance value of the electronic device and at the same time enhance the soft-start function of the power supply 300. The remaining features of the power supply 300 in FIG. 3 are similar to those of the power supply 200 in FIG. 2. Therefore, both embodiments can achieve similar operating effects.

The present invention provides a novel power supply, which includes a soft start circuit. According to the actual measurement results, the power supply using the aforementioned soft-start circuit can have higher reliability to comply with the International Electro Technical Commission (IEC) specifications. Generally speaking, the power supply of the present invention is not susceptible to the negative effects of the initial surge current, so it is very suitable for application in various electronic devices.

It is worth noting that the above-mentioned potential, current, resistance value, inductance value, capacitance value, and other component parameters are not limitations of the present invention. The designer can adjust these settings according to different needs. The power supply of the present invention is not limited to the state shown in Figures 1-3. The present invention may only include any one or more of the features of any one or more of the embodiments in FIGS. 1-3. In other words, not all the features shown in the figures need to be implemented in the power supply of the present invention. Although the embodiment of the present invention uses metal oxide half field effect transistors as an example, the present invention is not limited to this. Those skilled in the art can use other types of transistors, such as junction field effect transistors or fins. Type field effect transistors, 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., do not have a sequential relationship with each other, and they are only used to distinguish between two having the same Different components of the name.

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

100, 200, 300: power supply 110, 210: Bridge rectifier 120, 220, 320: soft start circuit 121, 122: charging path 130, 230: Transformer 131, 231: main coil 132, 232: secondary coil 133, 233: auxiliary coil 140, 240: power switch 150, 250: main output stage circuit 160, 260: auxiliary output stage circuit 170, 270: Controller 221: first charging path 222: Second charging path 223: Third charging path C1: The first capacitor C2: second capacitor C3: third capacitor C4: Fourth capacitor C5: fifth capacitor D1: The first diode D2: The second diode D3: The third diode D4: The fourth diode D5: Fifth diode D6: The sixth diode D7: seventh diode D8: Eighth diode D9: Ninth Diode D10: Twelfth polar body M1: The first transistor M2: second transistor M3: third transistor M4: The fourth transistor M5: fifth transistor N1: the first node N2: second node N3: third node N4: Fourth node N5: fifth node N6: sixth node N7: seventh node N8: Eighth node N9: Ninth node N10: Tenth node NIN1: the first input node NIN2: second input node NOUT: output node R1: resistor VA: clock potential VC: compound control potential VC1: The first control potential VC2: second control potential VC3: third control potential VC4: Fourth control potential VE: Starting potential VF: feedback potential VIN1: first input potential VIN2: second input potential VM: Reference potential VOUT: output potential VR: Rectified potential VS1: First induction potential VS2: second induction potential VSS: Ground potential

Fig. 1 is a schematic diagram of a power supply according to an embodiment of the invention. FIG. 2 is a schematic diagram of the power supply according to an embodiment of the invention. Fig. 3 is a schematic diagram of a power supply according to another embodiment of the invention.

100: power supply

110: Bridge rectifier

120: soft start circuit

121, 122: charging path

130: Transformer

131: main coil

132: Secondary coil

133: auxiliary coil

140: power switch

150: Main output stage circuit

160: auxiliary output stage circuit

170: Controller

VA: clock potential

VC: compound control potential

VE: Starting potential

VF: feedback potential

VIN1: first input potential

VIN2: second input potential

VM: Reference potential

VOUT: output potential

VR: Rectified potential

VS1: First induction potential

VS2: second induction potential

VSS: Ground potential

Claims (10)

A power supply including: A bridge rectifier that generates a rectified potential according to a first input potential and a second input potential; A soft start circuit including at least two charging paths, wherein the soft start circuit generates a start potential according to the rectified potential and a composite control potential; A transformer includes a main coil, a secondary coil, and an auxiliary coil, wherein the main coil is used to receive the starting potential, the secondary coil is used to generate a first induced potential, and the auxiliary coil is used to generate A second induced potential; A power switch, wherein the main coil is coupled to a ground potential via the power switch, and the power switch performs switching operations according to a clock potential; A main output stage circuit that generates an output potential according to the first induced potential; An auxiliary output stage circuit that generates a feedback potential based on the second induced potential; and A controller detecting the feedback potential, wherein the controller determines the composite control potential and the clock potential according to the feedback potential; When the feedback potential is greater than or equal to a reference potential, the controller discharges the charging paths and then bypasses the soft start circuit. The power supply described in item 1 of the scope of patent application, wherein the bridge rectifier includes: A first diode has 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 of the 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 the first input node, and the cathode of the second diode is coupled to the ground Potential A third diode having an anode and a cathode, wherein the anode of the third diode is coupled to the first node, and the cathode of the third diode is coupled to a second Input node to receive the second input potential; 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 as described in item 2 of the scope of patent application, wherein the soft start circuit includes: A fifth diode has an anode and a cathode, wherein the anode of the fifth diode is coupled to the first node to receive the rectified potential, and the cathode of the fifth diode is coupled Connected to a second node; A resistor having a first terminal and a second terminal, wherein the first terminal of the resistor is coupled to the second node, and the second terminal of the resistor is coupled to a third node To output the starting potential; A sixth diode having an anode and a cathode, wherein the anode of the sixth diode is coupled to the first node, and the cathode of the sixth diode is coupled to a fourth node; A first capacitor has a first terminal and a second terminal, wherein the first terminal of the first capacitor is coupled to the fourth node, and the second terminal of the first capacitor is coupled to the Third node A seventh diode having an anode and a cathode, wherein the anode of the seventh diode is coupled to the first node, and the cathode of the seventh diode is coupled to a fifth Node; and A second capacitor has a first terminal and a second terminal, wherein the first terminal of the second capacitor is coupled to the fifth node, and the second terminal of the second capacitor is coupled to the The third node. For the power supply described in item 3 of the scope of patent application, the composite control potential includes a first control potential, a second control potential, and a third control potential, and the soft start circuit further 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 first control potential, and the second terminal of the first transistor One end is coupled to the fourth node, and the second end of the first transistor is coupled to the second node; and 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 second control potential, and the first terminal of the second transistor One end is coupled to the fifth node, and the second end of the second transistor is coupled to the second node. For the power supply described in item 4 of the scope of patent application, the soft start circuit further includes: A third transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the third transistor is used to receive the third control potential, and the second terminal of the third transistor One end is coupled to the third node, and the second end of the third transistor is coupled to the first node. The power supply of claim 5, wherein the main coil has a first end and a second end, and the first end of the main coil is coupled to the third node to receive the start potential , The second end of the main coil is coupled to a sixth node, the auxiliary coil has a first end and a second end, and the first end of the auxiliary coil is coupled to a seventh node for output The first induced potential, the second end of the auxiliary coil is coupled to the ground potential, the auxiliary coil has a first end and a second end, and the first end of the auxiliary coil is coupled to a first end Eight nodes are used to output the second induced potential, and the second end of the auxiliary coil is coupled to the ground potential. The power supply described in item 6 of the scope of patent application, wherein the power switch includes: A fourth transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the fourth transistor is used to receive the clock potential, and the first terminal of the fourth transistor The terminal is coupled to the ground potential, and the second terminal of the fourth transistor is coupled to the sixth node. For the power supply described in item 7 of the scope of patent application, the main output stage circuit includes: An eighth diode having an anode and a cathode, wherein the anode of the eighth diode is coupled to the seventh node to receive the first sensing signal, and the cathode of the eighth diode Is coupled to an output node to output the output potential; and A third capacitor having a first terminal and a second terminal, wherein the first terminal of the third capacitor is coupled to the output node, and the second terminal of the third capacitor is coupled to the ground Potential. In the power supply described in item 8 of the scope of patent application, the auxiliary output stage circuit includes: A ninth diode having an anode and a cathode, wherein the anode of the ninth diode is coupled to the eighth node to receive the second sensing signal, and the cathode of the ninth diode Is coupled to a ninth node to output the feedback potential; and A fourth capacitor having a first terminal and a second terminal, wherein the first terminal of the fourth capacitor is coupled to the ninth node, and the second terminal of the fourth capacitor is coupled to the Ground potential. In the power supply described in item 9 of the scope of patent application, the composite control potential further includes a fourth control potential, and the soft start circuit further includes: A twelfth polar body having an anode and a cathode, wherein the anode of the twelfth polar body is coupled to the first node, and the cathode of the twelfth polar body is coupled to a tenth node; A fifth capacitor has a first terminal and a second terminal, wherein the first terminal of the fifth capacitor is coupled to the tenth node, and the second terminal of the fifth capacitor is coupled to the The third node; and A fifth transistor has a control terminal, a first terminal, and a second terminal, wherein the control terminal of the fifth transistor is used to receive the fourth control potential, and the second terminal of the fifth transistor One end is coupled to the tenth node, and the second end of the fifth transistor is coupled to the second node.

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