Power supply with high output stability

Abstract

A power supply with high output stability comprises a bridge rectifier, a boost inductor, a power switcher, a first output stage circuit, a switching circuit, a transformer, a resonant capacitor, a second output stage circuit and a detection and control circuit, and an inductive current can flow through the boost inductor. When the inductive current reaches a relative maximum value, the detection and control circuit can additionally maintain the conduction state of the power switcher in a prolonged time. When the inductive current reaches a relative minimum value, the detection and control circuit can additionally maintain the off state of the power switcher in a prolonged time.

Description

Technical Field

[0001] The invention relates to a power supply, and in particular to a power supply with high output stability. Background Art

[0002] Power supplies are indispensable components in the field of notebook computers. However, if the output stability of the power supply is insufficient, it is easy to cause the overall operating performance of the related notebook computer to decline. In view of this, it is necessary to propose a new solution to overcome the difficulties faced by the previous technology. Summary of the invention

[0003] In a preferred embodiment, the present invention provides a power supply with high output stability, comprising: a bridge rectifier, generating a rectified potential according to a first input potential and a second input potential; a boost inductor, receiving the rectified potential, wherein an inductor current flows through the boost inductor; a power switch, selectively coupling the boost inductor to a ground potential according to a first drive potential; a first output stage circuit, coupled to the boost inductor, and generating an intermediate potential; a switching circuit, generating a switching potential according to the intermediate potential, a second drive potential, and a third drive potential; a transformer, comprising 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. inductor, and the main coil receives the switching potential via the leakage inductor; a resonant capacitor coupled to the excitation inductor and providing a capacitance potential; a second 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 monitoring the inductor current and generating the first drive potential, the second drive potential, and the third drive potential according to the inductor current and the capacitance potential; wherein when the inductor current reaches a relative maximum value, the detection and control circuit will additionally maintain the on state of the power switch for an extended time; wherein when the inductor current reaches a relative minimum value, the detection and control circuit will additionally maintain the off state of the power switch for the extended time.

[0004] In some embodiments, 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 cathode of the first diode 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 cathode of the second diode is coupled to the first node; a third diode having an anode and a cathode. 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; wherein the boost inductor has a first end and a second end, the first end of the boost inductor is coupled to the first node to receive the rectified potential, and the second end of the boost inductor is coupled to a second node.

[0005] In some embodiments, the detection and control circuit includes: a sensing resistor having a first end and a second end, wherein the first end of the sensing resistor is coupled to the second node, the second end of the sensing resistor is coupled to a third node, and the inductor current further flows through the sensing resistor; and a current sensor coupled to the sensing resistor, wherein the current sensor further analyzes the inductor current to obtain the relative maximum value and the relative minimum value and generate a detection potential.

[0006] In some embodiments, the power switch 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 the ground potential, and the second end of the first transistor is coupled to the third node.

[0007] In some embodiments, the first 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 a fourth node to output the intermediate potential; and a first capacitor having a first end and a second end, wherein the first end of the first capacitor is coupled to the fourth node, and the second end of the first capacitor is coupled to the ground potential.

[0008] In some embodiments, the switching circuit includes: 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 a fifth node to output the switching potential, and the second end of the second transistor is coupled to the fourth node to receive the intermediate potential; and a third transistor having a control end, a first end, and a second end, wherein the control end of the third transistor is used to receive the third driving potential, the first end of the third transistor is coupled to the ground potential, and the second end of the third transistor is coupled to the fifth node.

[0009] 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 fifth node to receive the switching potential, the second end of the leakage inductor is coupled to a sixth node, the main coil has a first end and a second end, the first end of the main coil is coupled to the sixth node, the second end of the main coil is coupled to a seventh node, the excitation inductor has a first end and a second end, the first end of the excitation inductor is coupled to the sixth node, the second end of the excitation inductor is coupled to the seventh node, and the The resonant capacitor has a first end and a second end, the first end of the resonant capacitor is coupled to the seventh node to output the capacitance potential, the second end of the resonant 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 an eighth 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 ninth node.

[0010] In some embodiments, the second output stage circuit includes: a sixth diode having an anode and a cathode, wherein the anode of the sixth diode is coupled to the eighth node, and the cathode of the sixth diode is coupled to an output node to output the output potential; a seventh diode having an anode and a cathode, wherein the anode of the seventh diode is coupled to the ninth node, and the cathode of the seventh diode is coupled to the output node; and 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 the common node.

[0011] In some embodiments, the detection and control circuit further includes: a pulse width modulation integrated circuit, which generates the first driving potential according to the detection potential; and a microcontroller, which generates the second driving potential and the third driving potential and controls the pulse width modulation integrated circuit according to the capacitor potential.

[0012] In some embodiments, the microcontroller further stores a reference table, and the microcontroller further queries the reference table according to a highest level of the capacitor potential to determine the extension time. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram showing a power supply according to an embodiment of the present invention.

[0014] Figure 2 is a circuit diagram showing a power supply according to an embodiment of the present invention.

[0015] Figure 3 FIG. 4 is a signal waveform diagram showing a power supply according to an embodiment of the present invention.

[0016] Figure 4 is a waveform diagram showing a capacitor potential according to an embodiment of the present invention.

[0017] Figure 5 is a relationship diagram showing a comparison table according to an embodiment of the present invention.

[0018] Figure 6 FIG. 4 is a diagram showing a waveform of an inductor current according to an embodiment of the present invention.

[0019] Figure 7 FIG. 4 is a diagram showing a waveform of an inductor current according to an embodiment of the present invention.

[0020] The reference numerals are described as follows:

[0021] 100, 200: Power supply

[0022] 110, 210: Bridge rectifier

[0023] 120, 220: Power switch

[0024] 130, 230: First output stage circuit

[0025] 140, 240: Switching circuit

[0026] 150, 250: Transformer

[0027] 151, 251: Main coil

[0028] 152, 252: The first secondary coil

[0029] 153, 253: Second secondary coil

[0030] 160, 260: Second output stage circuit

[0031] 170, 270: Detection and control circuits

[0032] 272: Current sensor

[0033] 274: Pulse Width Modulation Integrated Circuit

[0034] 276: Microcontroller

[0035] 278: Comparison Table

[0036] C1: First capacitor

[0037] C2: Second capacitor

[0038] CR: Resonant capacitor

[0039] D1: The first diode

[0040] D2: Second diode

[0041] D3: The third diode

[0042] D4: The fourth diode

[0043] D5: The fifth diode

[0044] D6: The sixth diode

[0045] D7: The seventh diode

[0046] HL: Highest Level

[0047] IL: Inductor current

[0048] LM: Magnetizing Inductor

[0049] LR: Leakage Inductor

[0050] LU: Boost Inductor

[0051] M1: First transistor

[0052] M2: Second transistor

[0053] M3: The third transistor

[0054] MAX: relative maximum value

[0055] MIN: relative minimum value

[0056] N1: First node

[0057] N2: Second node

[0058] N3: The third node

[0059] N4: The fourth node

[0060] N5: The fifth node

[0061] N6: The sixth node

[0062] N7: Seventh node

[0063] N8: Node 8

[0064] N9: Ninth Node

[0065] NCM: Common Node

[0066] NIN1: First input node

[0067] NIN2: Second input node

[0068] NOUT: Output node

[0069] RS: Sense resistor

[0070] T1: First time point

[0071] T2: Second time point

[0072] TG: Extended time

[0073] TGM: Relative maximum extension time

[0074] TGS: Relative shortest extension time

[0075] VE: Middle potential

[0076] VG1: First driving potential

[0077] VG2: Second driving potential

[0078] VG3: The third driving potential

[0079] VIN1: First input potential

[0080] VIN2: Second input potential

[0081] VOUT: output potential

[0082] VP: Capacitor potential

[0083] VR: Rectification potential

[0084] VSS: Ground potential

[0085] VW: Switching potential

[0086] ΔV: Potential difference DETAILED DESCRIPTION

[0087] In order to make the purpose, features and advantages of the present invention more clearly understood, specific embodiments of the present invention are given below and described in detail with reference to the accompanying drawings.

[0088] Certain words are used in the specification and claims to refer to specific components. It should be understood by those skilled in the art that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. The words "including" and "comprising" mentioned throughout the specification and claims are open-ended 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 the text describes a first device 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 connection means.

[0089] Figure 1 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 notebook computer, or an all-in-one computer. Figure 1 As shown, the power supply 100 includes: a bridge rectifier 110, a boost inductor LU, a power switch 120, a first output stage circuit 130, a switching circuit 140, a transformer 150, a resonant capacitor CR, a second output stage circuit 160, and a detection and control circuit 170. It should be noted that although not shown in Figure 1 However, the power supply 100 may further include other components, such as: a regulator and / or a negative feedback circuit.

[0090] The bridge rectifier 110 can generate a rectified potential VR according to a first input potential VIN1 and a second input potential VIN2, wherein 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 can be approximately 50 Hz or 60 Hz, and the root mean square value of the AC voltage can be approximately between 90 V and 264 V, but is not limited thereto. The boost inductor LU can receive the rectified potential VR, wherein an inductor current IL can flow through the boost inductor LU. The power switch 120 can selectively couple the boost inductor LU to a ground potential VSS (e.g., 0 V) ​​according to a first drive potential VG1. For example, if the first driving potential VG1 is a high logic level (i.e., logic "1"), the power switch 120 can couple the boost inductor LU to the ground potential VSS (i.e., the power switch 120 can be similar to a short-circuit path); conversely, if the first driving potential VG1 is a low logic level (i.e., logic "0"), the power switch 120 will not couple the boost inductor LU to the ground potential VSS (i.e., the power switch 120 can be similar to a break path). The first output stage circuit 130 is coupled to the boost inductor LU and can generate an intermediate potential VE. The switching circuit 140 can generate a switching potential VW according to the intermediate potential VE, a second driving potential VG2, and a third driving potential VG3.

[0091] The transformer 150 includes a main winding 151, a first sub-winding 152, and a second sub-winding 153. The transformer 150 may further include a leakage inductor LR and a magnetizing inductor LM, wherein the leakage inductor LR, the magnetizing inductor LM, and the main winding 151 may be located on the same side of the transformer 150, and the first sub-winding 152 and the second sub-winding 153 may be located on the other side of the transformer 150. The main winding 151 may receive a switching potential VW via the leakage inductor LR, and the first sub-winding 152 and the second sub-winding 153 may operate in response to the switching potential VW. The resonant capacitor CR is coupled to the magnetizing inductor LM, wherein the resonant capacitor CR may provide a capacitance potential VP. For example, the leakage inductor LR, the magnetizing inductor LM, and the resonant capacitor CR may together form a resonant tank of the power supply 100. The second output stage circuit 160 is coupled to the first sub-coil 152 and the second sub-coil 153 and can generate an output potential VOUT. For example, the output potential VOUT can be a DC potential, and its potential level can be between 18V and 22V, but is not limited thereto.

[0092] The detection and control circuit 270 can monitor the inductor current IL and the capacitor potential VP. Then, the detection and control circuit 270 can generate a first driving potential VG1, a second driving potential VG2, and a third driving potential VG3 according to the inductor current IL and the capacitor potential VP. When the inductor current IL reaches a relative maximum value MAX, the detection and control circuit 170 can maintain the on state of the power switch 120 for an additional extended time TG. When the inductor current IL reaches a relative minimum value MIN, the detection and control circuit 170 can maintain the off state of the power switch for an additional extended time TG. Since the energy stored in the boost inductor LU will be increased, this design will avoid the problem of insufficient energy faced by the power supply 100 in response to a dynamic load. According to actual measurement results, the power supply 100 proposed by the present invention will greatly improve its own output stability.

[0093] The following embodiments will introduce the detailed structure and operation of the power supply 100. It should be understood that these drawings and descriptions are only for example and are not intended to limit the scope of the present invention.

[0094] Figure 2 FIG. 2 is a circuit diagram showing a power supply 200 according to an embodiment of the present invention. Figure 2 In the embodiment of Figure 2 In the embodiment of the present invention, 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 boost inductor LU, a power switch 220, a first output stage circuit 230, a switching circuit 240, a transformer 250, a resonant capacitor CR, a second 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 receive a first input potential VIN1 and a second input potential VIN2 from an external input power source (not shown), respectively, and the output node NOUT of the power supply 200 can be used to output an output potential VOUT to an external device, such as: a notebook computer (not shown).

[0095] 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 a 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, and the cathode of the third diode D3 is coupled to the first 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.

[0096] The boost inductor LU has a first terminal and a second terminal, wherein the first terminal of the boost inductor LU is coupled to the first node N1 to receive the rectified potential VR, and the second terminal of the boost inductor LU is coupled to a second node N2. In addition, an inductor current IL can also flow through the boost inductor LU.

[0097] The power switch 220 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 (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 the ground potential VSS, and the second terminal of the first transistor M1 is coupled to a third node N3. In some embodiments, the third node N3 may be almost equivalent to the second node N2, which will be described in detail later.

[0098] The first output stage circuit 230 includes a fifth diode D5 and a first capacitor C1. 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 a fourth node N4 to output an intermediate potential VE. 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, and the second end of the first capacitor C1 is coupled to the ground potential VSS.

[0099] The switching circuit 240 includes a second transistor M2 and a third transistor M3. For example, the second transistor M2 and the third transistor M3 may each be an N-type metal oxide semiconductor field effect transistor. 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 a fifth node N5 to output a switching potential VW, and the second terminal of the second transistor M2 is coupled to the fourth node N4 to receive the intermediate potential VE. The third transistor M3 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 third transistor M3 is used to receive a third driving potential VG3, 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 fifth node N5.

[0100] The transformer 250 includes a main winding 251, a first secondary winding 252, and a second secondary winding 253, wherein the transformer 250 further has a leakage inductor LR and an excitation inductor LM built therein. The leakage inductor LR and the excitation inductor LM may be inherent components generated when the transformer 250 is manufactured, and are not external independent components. The leakage inductor LR, the main winding 251, and the excitation inductor LM may be located on the same side (e.g., primary side) of the transformer 250, while the first secondary winding 252 and the second secondary winding 253 may be located on the other side (e.g., secondary side, which may be isolated from the primary side) of the transformer 250. 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 fifth node N5 to receive the switching potential VW, and the second end of the leakage inductor LR is coupled to a sixth node N6. The main coil 251 has a first end and a second end, wherein the first end of the main coil 251 is coupled to the sixth node N6, and the second end of the main coil 251 is coupled to a seventh node N7. 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 sixth node N6, and the second end of the excitation inductor LM is coupled to the seventh node N7. The resonant capacitor CR has a first end and a second end, wherein the first end of the resonant capacitor CR is coupled to the seventh node N7 to output a capacitance potential VP, and the second end of the resonant capacitor CR is coupled to the ground potential VSS. For example, the leakage inductor LR, the excitation inductor LM, and the resonant capacitor CR can form a resonant tank of the power supply 200 together. The first sub-coil 252 has a first end and a second end, wherein the first end of the first sub-coil 252 is coupled to an eighth node N8, and the second end of the first sub-coil 252 is coupled to a common node NCM. For example, the common node NCM can provide a common potential, which can be regarded as another ground potential and can be the same as or different from the aforementioned ground potential VSS. The second sub-coil 253 has a first end and a second end, wherein the first end of the second sub-coil 253 is coupled to the common node NCM, and the second end of the second sub-coil 253 is coupled to a ninth node N9.

[0101] The second output stage circuit 260 includes a sixth diode D6, a seventh diode D7, and a second capacitor C2. The sixth diode D6 has an anode and a cathode, wherein the anode of the sixth diode D6 is coupled to the eighth node N8, and the cathode of the sixth diode D6 is coupled to the output node NOUT. The seventh diode D7 has an anode and a cathode, wherein the anode of the seventh diode D7 is coupled to the ninth node N9, and the cathode of the seventh diode D7 is coupled to the output node NOUT. The second capacitor C2 has a first end and a second end, wherein the first end of the second capacitor C2 is coupled to the output node NOUT, and the second end of the second capacitor C2 is coupled to the common node NCM.

[0102] The detection and control circuit 270 includes a current sensor 272 , a pulse width modulation integrated circuit (PWM IC) 274 , a microcontroller unit (MCU) 276 , and a sensing resistor RS.

[0103] The sensing resistor RS has a first end and a second end, wherein the first end of the sensing resistor RS is coupled to the second node N2, and the second end of the sensing resistor RS is coupled to the third node N3. Since the sensing resistor RS is coupled in series with the boost inductor LU, the aforementioned inductor current IL can flow through the sensing resistor RS. It should be understood that since the resistance value of the sensing resistor RS is very small (e.g., less than or equal to 1Ω), it can be almost regarded as a short-circuit path, and the third node N3 will be almost equal to the second node N2.

[0104] The current sensor 272 is coupled to the first end and the second end of the sensing resistor RS, respectively, to detect a potential difference ΔV between the second node N2 and the third node N3. According to Ohm's law, the current sensor 272 can also calculate the current value of the inductor current IL by dividing the potential difference ΔV by the resistance value of the sensing resistor RS. Then, the current sensor 272 can further analyze the inductor current IL to obtain its relative maximum value MAX and relative minimum value MIN and generate a detection potential VD. In some embodiments, the detection potential VD can record various related information of the inductor current IL, such as: instantaneous current value, relative maximum value MAX, and relative minimum value MIN, but is not limited thereto.

[0105] The pulse width modulation integrated circuit 274 is coupled to the current sensor 272. The pulse width modulation integrated circuit 274 can generate a first driving potential VG1 according to the detection potential VD. For example, the first driving potential VG1 can be maintained at a fixed potential when the power supply 200 is just initialized, and can provide a periodic time pulse shape after the power supply 200 enters the normal use stage.

[0106] The microcontroller 276 is coupled between the pulse width modulation integrated circuit 274 and the resonant capacitor CR. The microcontroller 276 can generate a second driving potential VG2 and a third driving potential VG3. For example, the second driving potential VG2 and the third driving potential VG3 can have complementary logic levels. In addition, the microcontroller 276 can also control the pulse width modulation integrated circuit 274 according to the capacitor potential VP.

[0107] Figure 3 is a signal waveform diagram of a 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). Figure 3 As shown, the inductor current IL can reach its relative maximum value MAX at a first time point T1. At this time, the pulse width modulation integrated circuit 274 can fine-tune and delay the high logic interval of the first driving potential VG1. Therefore, the pulse width modulation integrated circuit 274 can maintain the on state of the power switch 220 for an additional extended time TG. After the extended time TG has expired, the first driving potential VG1 will switch from a high logic level to a low logic level to disconnect the power switch 220.

[0108] On the other hand, the inductor current IL can also reach its relative minimum value MIN at a second time point T2. At this time, the pulse width modulation integrated circuit 274 can fine-tune and delay the low logic interval of the first driving potential VG1. Therefore, the pulse width modulation integrated circuit 274 can maintain the disconnection state of the power switch 220 for an additional extended time TG. After the extended time TG has expired, the first driving potential VG1 will switch from a low logic level to a high logic level to turn on the power switch 220. It must be understood that Figure 3 Although the two extended times TG start at different time points, they both have the same duration, so they can be regarded as the same thing in this specification.

[0109] Figure 4 is a waveform diagram showing the capacitor potential VP according to an embodiment of the present invention, wherein the horizontal axis represents time (s) and the vertical axis represents the potential level (V). Figure 4 As shown, the capacitance potential VP of the resonant capacitor CR has a highest level HL. The microcontroller 276 can monitor the capacitance potential VP and obtain its highest level HL. In addition, the microcontroller 276 can also store a mapping table 278, wherein the microcontroller 276 can further query the mapping table 278 according to the highest level HL of the capacitance potential VP to determine the aforementioned extension time TG of the pulse width modulation integrated circuit 274.

[0110] Figure 5 278 according to an embodiment of the present invention, wherein the horizontal axis represents the potential level (V) and the vertical axis represents the time (s). Figure 5As shown, if an output current of the power supply 200 increases, the highest level HL of the capacitor potential VP will become higher, and the extension time TG of the pulse width modulation integrated circuit 274 will become longer. Conversely, if the output current of the power supply 200 decreases, the highest level HL of the capacitor potential VP will become lower, and the extension time TG of the pulse width modulation integrated circuit 274 will become shorter. For example, the upper limit of the extension time TG can be regarded as a relative maximum extension time TGM, and the lower limit of the extension time TG can be regarded as a relative shortest extension time TGS, but it is not limited thereto.

[0111] Figure 6 is a waveform diagram showing the inductor current IL according to an embodiment of the present invention, wherein the horizontal axis represents time (s) and the vertical axis represents the current value (A). Figure 6 In the embodiment of the present invention, the PWM integrated circuit 274 provides a relatively shortest extension time TGS to the power switch 220 so that the power supply 200 can support a light load operation.

[0112] Figure 7 is a waveform diagram showing the inductor current IL according to an embodiment of the present invention, wherein the horizontal axis represents time (s) and the vertical axis represents the current value (A). Figure 7 In the embodiment of the present invention, the PWM integrated circuit 274 provides a relatively maximum extension time TGM to the power switch 220, so that the power supply 200 can support a heavy load operation.

[0113] The present invention provides a novel power supply. According to actual measurement results, the output stability of the power supply using the above design can be greatly improved, so it is very suitable for application in various devices.

[0114] 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 setting values ​​according to different needs. The power supply of the present invention is not limited to Figure 1-Figure 7 The present invention may only include Figure 1-Figure 7 In other words, not all the features shown in the figure 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 semiconductor 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 effect of the present invention.

[0115] Ordinal numbers in this specification and claims, such as "first", "second", "third", etc., have no sequential relationship with each other and are only used to distinguish two different elements with the same name.

[0116] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the scope of the present invention. Anyone skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A power supply with high output stability, comprising: a bridge rectifier, generating a rectified potential according to a first input potential and a second input potential; a boost inductor receiving the rectified potential, wherein an inductor current flows through the boost inductor; a power switch selectively coupling the boost inductor to a ground potential according to a first driving potential; a first output stage circuit coupled to the boost inductor and generating an intermediate potential; a switching circuit, generating a switching potential according to the intermediate potential, a second driving potential, and a third driving potential; A transformer, comprising a main coil, a first secondary coil, and a second secondary coil, wherein a leakage inductor and an exciting inductor are built in the transformer, and the main coil receives the switching potential via the leakage inductor; a resonant capacitor coupled to the magnetizing inductor and providing a capacitance potential; a second output stage circuit, coupled to the first secondary coil and the second secondary coil, and generating an output potential; as well as a detection and control circuit, monitoring the inductor current, and generating the first driving potential, the second driving potential, and the third driving potential according to the inductor current and the capacitor potential; When the inductor current reaches a relative maximum value, the detection and control circuit will maintain the on state of the power switch for an additional extended time; When the inductor current reaches a relatively minimum value, the detection and control circuit will additionally maintain the disconnected state of the power switch for the extended time.

2. The power supply as claimed in claim 1, wherein the bridge rectifier comprises: 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 cathode of the first diode 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 cathode of the second diode 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; as well as 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 boost inductor has a first end and a second end. The first end of the boost inductor is coupled to the first node to receive the rectified potential, and the second end of the boost inductor is coupled to a second node.

3. The power supply as claimed in claim 2, wherein the detection and control circuit comprises: a sensing resistor having a first end and a second end, wherein the first end of the sensing resistor is coupled to the second node, the second end of the sensing resistor is coupled to a third node, and the inductor current further flows through the sensing resistor; as well as A current sensor is coupled to the sensing resistor, wherein the current sensor further analyzes the inductor current to obtain the relative maximum value and the relative minimum value and generate a detection potential.

4. The power supply as claimed in claim 3, wherein the power switch comprises: A first transistor has 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 the ground potential, and the second end of the first transistor is coupled to the third node.

5. The power supply as claimed in claim 3, wherein the first output stage circuit comprises: 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 a fourth node to output the intermediate potential; as well as A first capacitor has a first end and a second end, wherein the first end of the first capacitor is coupled to the fourth node, and the second end of the first capacitor is coupled to the ground potential.

6. The power supply as claimed in claim 5, wherein the switching circuit comprises: 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 a fifth node to output the switching potential, and the second terminal of the second transistor is coupled to the fourth node to receive the intermediate potential; as well as A third transistor has a control end, a first end, and a second end, wherein the control end of the third transistor is used to receive the third driving potential, the first end of the third transistor is coupled to the ground potential, and the second end of the third transistor is coupled to the fifth node.

7. The power supply as claimed in claim 6, wherein the leakage inductor has a first end and a second end, the first end of the leakage inductor is coupled to the fifth node to receive the switching potential, the second end of the leakage inductor is coupled to a sixth node, the main coil has a first end and a second end, the first end of the main coil is coupled to the sixth node, the second end of the main coil is coupled to a seventh node, the excitation inductor has a first end and a second end, the first end of the excitation inductor is coupled to the sixth node, the second end of the excitation inductor is coupled to the seventh node The seventh node, the resonant capacitor has a first end and a second end, the first end of the resonant capacitor is coupled to the seventh node to output the capacitance potential, the second end of the resonant 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 an eighth 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 ninth node.

8. The power supply as claimed in claim 7, wherein the second output stage circuit comprises: a sixth diode having an anode and a cathode, wherein the anode of the sixth diode is coupled to the eighth node, and the cathode of the sixth diode is coupled to an output node to output the output potential; a seventh diode having an anode and a cathode, wherein the anode of the seventh diode is coupled to the ninth node, and the cathode of the seventh diode is coupled to the output node; as well as A second capacitor has 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 the common node.

9. The power supply as claimed in claim 3, wherein the detection and control circuit further comprises: a pulse width modulation integrated circuit, generating the first driving potential according to the detection potential; as well as A microcontroller generates the second driving potential and the third driving potential, and controls the pulse width modulation integrated circuit according to the capacitor potential. 10 . The power supply as claimed in claim 9 , wherein the microcontroller further stores a reference table, and the microcontroller further searches the reference table according to a highest level of the capacitor potential to determine the extension time.

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