Power supply device with standby low power consumption function and standby low power consumption operation method thereof

Abstract

A power supply device with low standby power consumption can supply power to a load, and the power supply device includes a primary side circuit and a secondary side circuit. If the load is not coupled to the power supply device, the secondary side circuit adjusts the feedback signal provided to the primary side circuit to a specific state, and maintains the specific state for a period of time greater than or equal to a first time period, causing the primary side circuit to enter a shutdown mode. Then, after a period of time, the primary side circuit restarts to detect again whether the load is coupled to the power output port.

Description

Technical Field

[0001] This application relates to a power supply device and its operating method, and more particularly to a power supply device with standby low power consumption function and its standby low power consumption operating method. Background Technology

[0002] In the current power sector, power supply devices increasingly emphasize low power consumption, especially during standby mode, to minimize power consumption and avoid energy waste. To further reduce power consumption, current mobile phone and laptop manufacturers require standby power consumption to be less than or equal to 30mW. However, most existing chargers and adapters now use Type-C connectors, and to improve efficiency, the secondary side of these power supply products requires a controller with Power Delivery (PD) protocol and a synchronous rectification controller, making it even more difficult to achieve the 30mW minimum standby power consumption requirement.

[0003] Currently, the EU COC V5 Tier 2 standard is quite stringent. For applications with an output power of 45W or less, there are three existing technologies to reduce standby power consumption:

[0004] 1. The low-voltage start-up primary-side controller is equipped with an extremely low start-up current to increase the start-up resistance and reduce start-up resistance loss. In conjunction with the primary-side controller and the power transmission protocol controller, the controller's operating current is reduced as much as possible when there is no load, but only the standby power consumption requirement of less than or equal to 75mW can be achieved.

[0005] 2. A primary-side controller with X-capacitor discharge function is used, but it can only achieve a standby power consumption of less than or equal to 30mW.

[0006] 3. Use a primary-side controller with X-capacitor discharge function and primary-side feedback control. Although this approach can achieve a standby power consumption of less than or equal to 20mW, it cannot be applied to controllers with power delivery protocols, or requires additional control circuitry to achieve the primary-side feedback control function.

[0007] Therefore, in the prior art, if the power supply device is to meet the requirement of standby power consumption of less than or equal to 20mW, it is not compatible with the application of controllers with power transmission protocols, or it is necessary to increase the circuit cost of the control circuit, or the power supply device can only be made to consume more than 20mW in standby mode.

[0008] Therefore, how to design a power supply device with low standby power consumption function and its low standby power consumption operation method, so that the power supply device can achieve the goal of extremely low power consumption by being in a long-term shutdown and short-term power-on state, is a major research topic of this invention. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides a power supply device with low standby power consumption, overcoming the limitations of existing technologies. Therefore, the power supply device of this invention can supply power to a load, and includes a primary side circuit and a secondary side circuit. The primary side circuit includes a power switch, an energy storage capacitor, and a primary side controller, and the primary side controller includes a high-voltage start-up terminal, an operating power supply terminal, and a first feedback terminal. The primary side circuit is coupled to the high-voltage start-up terminal, and the energy storage capacitor is coupled to the operating power supply terminal. The secondary side circuit includes a secondary side controller, which provides a feedback signal to the first feedback terminal, and the secondary side controller can detect whether the load is coupled to the secondary side circuit. Specifically, when the secondary side controller determines that the load is not coupled to the secondary side circuit, the secondary side controller adjusts the feedback signal to a specific state for a duration greater than or equal to a first time period. When the primary side controller detects that the feedback signal is in a specific state for a duration greater than or equal to the first time period, the primary side controller keeps the power switch off. When the voltage of the energy storage capacitor drops to a shutdown voltage threshold, the primary side controller connects the power supply path from the high-voltage start-up terminal to the operating power supply terminal to charge the energy storage capacitor. When the capacitor voltage rises to the startup voltage threshold, the primary-side controller controls the power switch to alternately turn on and off to supply power to the secondary-side circuit, allowing the secondary-side controller to detect again whether the load is coupled to the secondary-side circuit.

[0010] The primary-side controller has a power supply path coupled from the high-voltage start-up terminal to the operating power supply terminal, and this power supply path may optionally include a current-limiting element. When the primary-side controller is notified that the load is not coupled to the secondary-side circuit, the primary-side controller turns off the power switch. The energy storage capacitor can no longer draw power from the auxiliary winding, causing the capacitor voltage of the energy storage capacitor to drop to the primary-side controller's shutdown voltage threshold, thereby triggering the primary-side controller to turn on the power supply path. The current-limiting element provides a small current to adjust the rise rate of the capacitor voltage, thereby adjusting the time it takes for the capacitor voltage to rise to the primary-side controller's start-up voltage threshold, thus determining the time interval between two consecutive starts by the primary-side controller, and also determining the detection time interval between two consecutive checks by the secondary-side controller to determine whether the load is coupled to the secondary-side circuit.

[0011] To address the aforementioned problems, this invention provides a standby low-power operation method for a power supply device, overcoming the limitations of existing technologies. Therefore, the power supply device of this invention can supply power to a load, and the power supply device includes a primary-side circuit, a primary-side controller, a secondary-side circuit, and a secondary-side controller. The standby low-power operation method includes the following steps: (I) The primary-side controller conducts the power supply path from the high-voltage start-up terminal of the primary-side controller to the operating power supply terminal of the primary-side controller, using the high-voltage start-up terminal's electrical energy to charge the energy storage capacitor coupled to the operating power supply terminal. (II) When the capacitor voltage of the energy storage capacitor rises to the start-up voltage threshold, the primary-side controller is activated to control the power switch of the primary-side circuit to alternately turn on and off, so as to supply power to the secondary-side circuit through the secondary-side winding, enabling the secondary-side controller to detect whether the load is coupled to the secondary-side circuit, and selectively supply power to the energy storage capacitor through the auxiliary winding to maintain the capacitor voltage of the energy storage capacitor. (III) When the secondary-side controller determines that the load is not coupled to the power supply device, the secondary-side controller adjusts the feedback signal to a specific state. (IV) When the primary-side controller detects a feedback signal in a specific state for a duration greater than or equal to the first time period, the following steps are performed: (a) The power switch remains off, causing the capacitor voltage of the energy storage capacitor to drop. (b) When the capacitor voltage of the energy storage capacitor drops to the shutdown voltage threshold, the primary-side controller turns on the power supply path from the high-voltage start-up terminal to the operating power supply terminal to charge the energy storage capacitor. (c) When the capacitor voltage rises again to the start-up voltage threshold, the primary-side controller is restarted to control the power switch to alternately turn on and off, so as to supply power to the secondary-side circuit through the secondary-side winding again. (d) The secondary-side controller may again detect whether the load is coupled to the secondary-side circuit.

[0012] The main objective and advantage of this invention is that the power supply device can detect whether the load is coupled to the power output port of the secondary circuit. If the load is not coupled to the power output port, the power feedback circuit notifies the primary controller to enter a shutdown mode. Then, after a period of time, the primary controller restarts to allow the power supply device to detect whether the load is coupled to the power output port again. If the load is still not coupled to the power output port, the primary controller enters the shutdown mode again. During the shutdown mode, because the primary controller is in shutdown mode, the power switch remains off, and the energy loss of all circuit components that originally needed to obtain power from the secondary winding and auxiliary winding is almost zero; therefore, there is only energy loss during the period when the power supply device detects whether the load is coupled to the power output port of the secondary circuit after the primary controller restarts. Therefore, there is no need to add additional signal feedback circuits or optocouplers for control, and this invention allows the power supply device to be in a state of long-term shutdown and short-term startup, achieving the goal of extremely low power consumption.

[0013] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Attached Figure Description

[0014] Figure 1 This is a circuit block diagram of the power supply device with low standby power consumption function of the present invention;

[0015] Figure 2 This is a waveform diagram of the power supply device with standby low power consumption function of the present invention;

[0016] Figure 3A This is a flowchart of the secondary-side operation method of the standby low-power operation method of the power supply device of the present invention; and

[0017] Figure 3B This is a flowchart of the primary side operation method of the standby low power consumption operation method of the power supply device of the present invention.

[0018] In the attached figures, the following labels are used:

[0019] 100… power supply device

[0020] IN…Power input terminal

[0021] OUT…Power output port

[0022] 1… Primary side circuit

[0023] SW1…Power Switch

[0024] C1… Energy storage capacitor

[0025] 12… Primary Side Controller

[0026] HV…High-voltage start-up terminal

[0027] VDD1…operating power supply terminal

[0028] GAT…signal output terminal

[0029] FB1…First Feedback Terminal

[0030] SW2…Controllable switch

[0031] Ls…Power supply path

[0032] 122…Current limiting element

[0033] 2…Transformer

[0034] 22… Primary winding

[0035] 24… Secondary winding

[0036] 3…Secondary side circuit

[0037] 32… Rectifier circuit

[0038] 34…Feedback Circuit

[0039] (OCA, OCB)... Optical Coupler

[0040] Co…output capacitor

[0041] 36…Secondary side controller

[0042] FB…Voltage Feedback Terminal

[0043] FB2…Second Feedback End

[0044] VDD2…Power supply terminals (CC1, CC2, D+, D-)…Communication port

[0045] VBUS…Power Output Terminal

[0046] GND…Ground terminal

[0047] SW3… switch

[0048] 4…Auxiliary Circuit

[0049] 42… Auxiliary winding

[0050] D…diode

[0051] 200…load

[0052] Vin…Input Voltage

[0053] Vdc…DC voltage

[0054] Vc…capacitor voltage

[0055] Vfb…feedback voltage

[0056] V1…Voltage threshold

[0057] Vo, Vo'… Output voltage

[0058] Sfb…feedback signal

[0059] Gate1…Pulse Width Modulation Signal

[0060] Gate2, Gate3... control signals

[0061] Sc...communication signal

[0062] Sd… Handshake signal

[0063] PWM_off… Turn-off voltage threshold

[0064] PWM_on…Startup voltage threshold

[0065] T1…First Period

[0066] T2…Second period

[0067] t1~t9…time (S100)~(S440)…steps Detailed Implementation

[0068] The structural and working principles of the present invention will be described in detail below with reference to the accompanying drawings:

[0069] Please see Figure 1 This is a circuit block diagram of a power supply device with low standby power consumption according to the present invention. The power supply device 100 receives an input voltage Vin through the power input terminal IN and can be coupled to a load 200 through the power output port OUT to convert the input voltage Vin to power the load 200. Here, the power output port OUT is, for example, a USB interface that can receive the handshake signal of the Power Delivery (PD) protocol. It can communicate with the load through four signals (CC1, CC2, D+, D-) to obtain the power information required by the load, and then output voltage through the power output terminal VBUS and the ground terminal GND to provide power to the external load. Therefore, the power output port OUT can integrate the power output terminal VBUS, the ground terminal GND, and the communication port, and the line that needs to be coupled to the load 200 is connected to the connection port of the load 200 (not shown). The power supply device 100 can be, for example but not limited to, an isolated converter, and the power supply device 100 includes a primary side circuit 1, a transformer 2, and a secondary side circuit 3. The primary side circuit 1 is coupled between the power input terminal IN and the primary winding 22 of the transformer 2, and the secondary side circuit 3 is coupled between the secondary winding 24 of the transformer 2 and the power output port OUT.

[0070] The primary side circuit 1 includes a power switch SW1, an energy storage capacitor C1, and a primary side controller 12. The primary side controller 12 includes a high-voltage start-up terminal HV, an operating power supply terminal VDD1, a signal output terminal GAT, and a first feedback terminal FB1. The secondary side circuit 3 includes a rectifier circuit 32, a feedback circuit 34, an output capacitor Co, and a secondary side controller 36. The secondary side controller 36 includes a voltage feedback terminal FB, a second feedback terminal FB2, a power supply terminal VDD2, and communication ports (CC1, CC2, D+, D-). The rectifier circuit 32 is coupled to the secondary side winding 24, the output capacitor Co, and the power output port OUT via the power output terminal VBUS. The voltage feedback terminal FB of the secondary side controller 36 receives a feedback voltage Vfb, which can be obtained by, for example, but not limited to, a voltage divider circuit (not shown) dividing the power stored in the output capacitor Co.

[0071] The power supply terminal VDD2 can be coupled to the power output terminal VBUS to draw power from the power output terminal VBUS to maintain the operation of the secondary controller 36. Similarly, components such as, but not limited to, energy storage capacitors (not shown) can also be included between the power output terminal VBUS and the power supply terminal VDD2 to provide the power required to maintain the operation of the secondary controller 36.

[0072] Feedback circuit 34 can be coupled to power output terminal VBUS via voltage feedback terminal FB to obtain feedback voltage Vfb, and modulate the voltage difference between the two terminals of optocoupler (OCA) in response to changes in feedback voltage Vfb (e.g., the cathode of light-emitting diode is coupled to the second feedback terminal FB2), thereby modulating the luminous intensity of optocoupler (OCA). The second feedback terminal FB2 can be coupled to the first feedback terminal FB1 via optocoupler (OCA, OCB), and by modulating the luminous intensity of optocoupler (OCA), the feedback signal Sfb (i.e., the current flowing through optocoupler (OCA)) detected by secondary-side controller 36 is provided to primary-side controller 12. It is worth noting that in one embodiment, in the actual application of secondary-side controller 36, different circuit coupling methods are used depending on the internal circuit type of various secondary-side controllers 36. For example, but not limited to, voltage feedback terminal FB and power supply terminal VDD2 can be integrated into the same pin to form a shared pin structure, and optocoupler (OCA) can be implemented using external circuitry instead of... Figure 1 It is formed inside the secondary-side controller 36. Therefore, the circuit coupling structure of the secondary-side controller 36 is not based on... Figure 1 For restrictions.

[0073] The primary side circuit 1 is coupled to the high-voltage starting terminal HV, and the energy storage capacitor C1 is coupled to the operating power supply terminal VDD1. The power supply device 100 may also include an auxiliary circuit 4, and the auxiliary circuit 4 includes an auxiliary winding 42. The auxiliary winding 42 is coupled to the transformer 2, and the energy storage capacitor C1 is coupled to the auxiliary winding 42. A controllable switch SW2 is also included between the high-voltage starting terminal HV and the operating power supply terminal VDD1. The controllable switch SW2 is used to receive the control signal Gate2 provided by the primary side controller 12 and turn it on / off, thereby establishing / disconnecting the power supply path Ls. When the auxiliary winding 42 does not charge the energy storage capacitor C1, causing the capacitor voltage Vc to be too low and unable to provide sufficient power to the operating power supply terminal VDD1 to maintain the operation of the primary side controller 12, the controllable switch SW2 is turned on to establish the power supply path Ls. For example, when the power supply device 100 transitions from a non-started / off inactive state to receiving an input voltage Vin (e.g., but not limited to, 90Vac to 264Vac), the primary-side circuit 1 provides a DC voltage Vdc to the high-voltage start-up terminal HV based on the input voltage Vin. The DC voltage Vdc charges the energy storage capacitor C1 through the power supply path Ls from the high-voltage start-up terminal HV of the primary-side controller 12 to the operating power supply terminal VDD1, thereby establishing a capacitor voltage Vc in the energy storage capacitor C1. When the capacitor voltage Vc of the energy storage capacitor C1 rises to the start-up voltage threshold of the primary-side controller 12, the primary-side controller 12 completes its startup and begins to control the power switch SW1 to alternately turn on and off by providing a pulse width modulation signal Gate1 through the signal output terminal GAT. This causes the transformer 2 to begin energy storage / release operations, thereby causing the auxiliary winding 42 to also begin charging the energy storage capacitor C1 to maintain the capacitor voltage Vc. Once the operating power supply terminal VDD1 can receive enough electrical energy from the auxiliary winding 42 to maintain the operation of the primary side controller 12, the primary side controller 12 can turn off the controllable switch SW2 to disconnect the power supply path Ls from the high-voltage starting terminal HV with poor conversion efficiency to the operating power supply terminal VDD1.

[0074] At this time, the auxiliary winding 42 generates energy by coupling with the primary winding 22, and this energy, clamped by diode D, continuously charges the energy storage capacitor C1 to maintain the stable operation of the primary-side controller 12. Similarly, the secondary winding 24 generates energy by coupling with the primary winding 22, and this energy, after being rectified by the rectifier circuit 32, charges the output capacitor Co to provide the output voltage (Vo, Vo') at the power output terminal VBUS. The output voltage (Vo, Vo') is also provided by the power output terminal VBUS to the power supply terminal VDD2 to power the secondary-side controller 36 and maintain its operation.

[0075] The secondary-side controller 36 can adjust the strength of the feedback signal Sfb by modulating the electrical signal at the second feedback terminal FB2. For example, the feedback circuit 34 also includes optocouplers (OCA, OCB). The two bias input terminals of the optocoupler (OCA) can be selectively coupled to the second feedback terminal FB2 and the power output terminal VBUS (through the internal circuit of the secondary-side controller 36), respectively. For example, when the secondary-side controller 36 pulls down the voltage of the second feedback terminal FB2, increasing the voltage difference between the output voltage (Vo, Vo') of the power output terminal VBUS and the second feedback terminal FB2, the light emission intensity of the optocoupler (OCA) increases. The light receiving terminal of the optocoupler (OCB) is coupled to the first feedback terminal FB1. When the light emission intensity of the optocoupler (OCA) changes, the voltage and current signals of the first feedback terminal FB1 also change accordingly. The feedback signal Sfb is thus coupled to the first feedback terminal FB1 through the optical coupler (OCA, OCB), and the primary side controller 12 adjusts the pulse width modulation signal Gate1 based on the feedback signal Sfb to stabilize the output voltage (Vo, Vo') on the power output terminal VBUS.

[0076] On the other hand, when the input voltage Vin is removed or the primary-side controller 12 stops providing the pulse width modulation signal Gate1, the power switch SW1 stops alternately turning on and off to allow the transformer 2 to store / release energy, which causes the auxiliary winding 42 and the secondary-side winding 24 to also fail to generate sufficient energy. Therefore, the capacitor voltage Vc of the energy storage capacitor C1 and the output voltage (Vo, Vo') gradually decrease. When the capacitor voltage Vc drops below the shutdown voltage threshold of the primary-side controller 12 (also known as undervoltage lockout; UVLO), the primary-side controller 12 is turned off, keeping the already stopped pulse width modulation signal Gate1 in a stopped state, and the controllable switch SW2 is turned on to establish the power supply path Ls. Similarly, when the output voltage (Vo, Vo') at the power output terminal VBUS drops below the shutdown voltage threshold of the secondary-side controller 36, the secondary-side controller 36 is turned off and stops providing the feedback signal Sfb.

[0077] It is worth mentioning that, in one embodiment, the establishment / disconnection of the power supply path Ls is not limited to controllable switch SW2. Any circuit architecture capable of establishing / disconnecting the power supply path Ls should be included in this embodiment. Furthermore, the circuit architecture of the feedback circuit 34 presented in this embodiment is only one type of feedback circuit. Therefore, the architecture of the feedback circuit 34 can be adaptively adjusted according to the actual needs of the power supply device 100, and will not be elaborated further here. Similarly, the optocouplers (OCA, OCB) are only used for electrical isolation transmission of the feedback signal Sfb between the primary-side controller 12 and the secondary-side controller 36. Therefore, any circuit architecture that can achieve signal electrical isolation transmission should be included in this embodiment. On the other hand, the circuit architecture of the primary-side circuit 1 and the secondary-side circuit 3 can be determined according to the type of converter used by the power supply device 100 (e.g., but not limited to, resonant converters, forward converters, flyback converters, etc.), and therefore is not limited to... Figure 1 The circuit architecture is limited to this. Similarly, the circuit architecture of auxiliary circuit 4 is only one of many auxiliary circuits. Therefore, the architecture of auxiliary circuit 4 can be adapted to meet the actual needs of power supply device 100, and will not be elaborated here.

[0078] See also Figure 1 The main objective and effect of this invention is that the power supply device 100 can detect whether the load 200 is coupled to the power output port OUT. If the load 200 is not coupled to the power output port OUT, the primary-side controller 12 is notified to enter the shutdown mode via the power feedback circuit (i.e., feedback circuit 34). Then, after a period of time, the primary-side controller 12 will restart to make the power supply device 100 detect whether the load 200 is coupled to the power output port OUT again. If the load 200 is still not coupled, the primary-side controller 12 will enter the shutdown mode again; if the load 200 is coupled, it will enter the standard startup mode.

[0079] During the shutdown mode, because the primary-side controller 12 is off, the power consumption of all circuit components that would normally draw power from the secondary-side winding 24 and auxiliary winding 42 approaches zero. Therefore, significant power consumption only occurs when the power supply device 100 detects whether the power output port OUT is coupled to the load 200 after the primary-side controller 12 restarts. Thus, no additional signal feedback circuits or optocouplers are needed for this energy-saving operation control. Furthermore, this invention allows the power supply device 100 to be in a state of prolonged shutdown and brief startup when not coupled to the load 200, achieving extremely low power consumption.

[0080] Specifically, the communication ports (CC1, CC2, D+, D-) of the secondary-side controller 36 are coupled to the power output port OUT, and the secondary-side controller 36 can determine whether the load 200 is coupled to the secondary-side circuit 3 through the communication signals Sc received by the communication ports (CC1, CC2, D+, D-). The communication ports (CC1, CC2) and (D+, D-) can receive different types of communication signals Sc. The communication ports (CC1, CC2) typically receive a handshake signal Sd with a Power Delivery (PD) protocol (meaning the communication signal Sc is a handshake signal Sd, and both the secondary-side circuit 3 and the load 200 have a Power Delivery protocol). The secondary-side controller 36 communicates with the load 200 through the communication ports (CC1, CC2) to determine whether the load 200 is coupled to the secondary-side circuit 36 ​​based on the communication results. The communication ports (D+, D-) are communication signals Sc that can be used with general powerless transmission protocols. Therefore, the secondary controller 36 can select one of the communication ports (CC1, CC2, D+, D-) or both, depending on actual needs.

[0081] Please see Figure 2 The waveform diagram is shown below for the power supply device with low standby power consumption function of the present invention. See also the attached diagram. Figure 1 .

[0082] At time t1, load 200 is removed from the power output port OUT of the secondary side circuit 3.

[0083] Between time points t1 and t2, the secondary-side controller 36 detects whether the load 200 is coupled to the secondary-side circuit 3 via the communication signal Sc. The required time period between time points t1 and t2 is determined by the required time length determined by the communication signal Sc.

[0084] At time t2, when the secondary controller 36 determines that the load 200 is not coupled to the secondary circuit 3, the secondary controller 36 adjusts the feedback signal Sfb to a specific state (time t2) and it will continue for more than the first time period T1. For example, the secondary controller 36 pulls down the voltage of the second feedback terminal FB2, so that the optical coupler (OCA) has a brighter light intensity, and thus the voltage Vfb1 of the first feedback terminal FB1 is pulled down synchronously and continues for more than the first time period T1. On the primary side, when the voltage Vfb1 of the first feedback terminal FB1 is pulled down, the primary controller 12 is triggered to perform two operations: (1) interrupt the pulse width modulation signal Gate1 of the signal output terminal GAT, so that the power switch SW1 remains off, and (2) start counting the duration of the feedback signal Sfb in the specific state.

[0085] Between time points t2 and t3, because power switch SW1 remains off:

[0086] (1) If the energy storage capacitor C1 stores a large amount of electricity, then between time points t2 and t3, the capacitor voltage Vc will not drop to near the controller 12's shut-off voltage threshold (e.g., Figure 2 (As shown); therefore, the energy storage capacitor C1 can provide power to maintain the operation of the primary side controller 12 between time points t2 and t3, so as to complete the judgment of whether the load 200 has been removed; similar operations can also be performed at later time points t5 and t6.

[0087] (2) If the energy storage capacitor C1 stores a small amount of energy, between time points t2 and t3, because the power switch SW1 remains off, the capacitor voltage Vc may drop to near the off voltage threshold of the controller 12 (not shown), which may cause the primary-side controller 12 to fail to maintain its initial operation. In this case, the power switch SW1 can provide the pulse width modulation signal Gate1 again, so that the power switch SW1 alternately turns on and off to allow the transformer 2 to store / release energy, so that the auxiliary winding 42 and the secondary winding 24 generate power to maintain the operation of the primary controller 12 and the secondary-side controller 36, and maintain the operation of the primary-side controller 12 between time points t2 and t3 to complete the determination of whether the load 200 has been removed; a similar operation can also be performed at later time points t5 and t6.

[0088] (3) During time points t2 to t3, since the duration is shorter than the first time period T1, the primary side controller 12 does not enter the shutdown mode and is still operating, thus consuming more electrical energy. Therefore, the capacitor voltage Vc during time points t2 to t3 will decrease with, for example but not limited to, the first slope.

[0089] At time t3, when the feedback signal Sfb is in a specific state, and the duration of the voltage Vfb1 at the first feedback terminal FB1 being low is greater than or equal to the first time period T1 (the time period from real time t2 to t3), the primary-side controller 12 is triggered to determine that the load 200 is not actually coupled to the power output port OUT or the secondary-side controller 36 may enter a protection mode (e.g., but not limited to, output overvoltage protection (OVP), output overcurrent protection (OCP), output short circuit protection (SCP), output overtemperature protection (OTP), etc.). The primary-side controller 12 enters the shutdown mode, keeping the power switch SW1 off, causing the capacitor voltage Vc of the energy storage capacitor C1 to drop, and the output voltage (Vo, Vo') provided at the power output terminal VBUS also drops accordingly.

[0090] At time t3, since the primary-side controller 12 enters the shutdown mode, it consumes less power, or even no power at all. Therefore, at time t3, most of the capacitor voltage Vc is consumed by line impedance such as line resistance and internal resistance, causing the capacitor voltage Vc to decrease with, for example but not limited to, a second slope, and the second slope is gentler than the first slope. That is, the second slope (for example but not limited to -2) is less than the first slope (for example but not limited to -1).

[0091] At time t3', when the capacitor voltage Vc of the energy storage capacitor C1 drops to the shutdown voltage threshold PWM_off, the primary side controller 12 is triggered to turn on the controllable switch SW2 to establish a power supply path Ls from the high-voltage start-up terminal HV to the operating power supply terminal VDD1, and the power energy of the high-voltage start-up terminal HV begins to charge the energy storage capacitor C1.

[0092] Specifically, after time point t2, keeping the power switch SW1 off will cause the output voltage (Vo, Vo') to drop. When the capacitor voltage Vo' of the output capacitor Co drops to the off voltage threshold of the secondary controller 36, the secondary controller 36 will be turned off. The secondary controller 36 will remain off until the primary controller 12 is restarted.

[0093] At time t4, when the capacitor voltage Vc rises to the startup voltage threshold PWM_on, the primary side controller 12 completes the restart and provides the pulse width modulation signal Gate1 again to control the power switch SW1 to alternately turn on and off, supplying power to the secondary side circuit 3 through the secondary side winding 24, causing the secondary side controller 36 to start up again, and can detect again whether the load 200 is coupled to the secondary side circuit 3.

[0094] Between time points t4 and t5, the secondary controller 36 performs operations similar to those between time points t1 and t2. The secondary controller 36 uses the communication signal Sc to detect whether the load 200 is coupled to the secondary circuit 3.

[0095] At time t5, when the load 200 is still not coupled to the power output port OUT of the secondary circuit 3, the secondary controller 36 performs an operation similar to that at time t2, readjusting the feedback signal Sfb to a specific state, and continuing for more than the first time period T1 from time t5.

[0096] In response to the feedback signal Sfb being in a specific state again, the primary side controller 12 also performs two operations similar to time point t2: (1) interrupts the pulse width modulation signal Gate1 of the signal output terminal GAT to keep the power switch SW1 off, and (2) starts counting the duration of the feedback signal Sfb being in a specific state.

[0097] At time points t6, t6', and t7, the primary-side controller 12 and the secondary-side controller 36 also perform operations similar to those at time points t3, t3', and t4, which will not be described in detail here.

[0098] At time t8, when the load 200 is recoupled to the power output port OUT of the secondary circuit 3, the secondary controller 36 determines that the load 200 is recoupled to the secondary circuit 3 through the communication signal Sc (i.e., the secondary controller 36 receives the communication signal Sc). The secondary controller 36 will avoid adjusting the feedback signal Sfb to a specific state and continuing for more than the first time period T1. In this way, the primary controller 12 will not be triggered to enter the shutdown mode.

[0099] After time point t8, the secondary-side controller 36 turns on switch SW3, and the power supply device 100 provides output voltages (Vo, Vo'). The secondary-side controller 36 modulates the feedback signal Sfb according to the magnitude of the output current drawn by the load 200, causing the primary-side controller 12 to modulate the pulse width modulation signal Gate1 based on the adjustment of the feedback signal Sfb. For example, assuming the output current Po drawn by the load 200 changes from 5V, 3A to 5V, 1A, then the energy transferred to the secondary side by transformer 2 is excessive, and the voltage at the second feedback terminal FB2 needs to be lowered. This allows the optocoupler (OCA) to emit more light, causing the voltage Vfb1 received at the first feedback terminal FB1 to be lowered, thus notifying the primary-side controller 12 to reduce the energy transferred to the secondary side. Conversely, when the output current Po drawn by the load 200 changes from 5V, 1A to 5V, 3A, the energy transferred to the secondary side by transformer 2 is insufficient, and the voltage at the second feedback terminal FB2 needs to be increased. In this way, the weaker the light emitted by the optical coupler (OCA), the higher the voltage Vfb1 received by the first feedback terminal FB1 is, which in turn notifies the primary-side controller 12 to increase the energy transferred to the secondary side.

[0100] Therefore, the specific state typically refers to the voltage at the second feedback terminal FB2 being pulled to its lowest level, causing the optocoupler (OCA) to emit the strongest light to notify the primary-side controller 12, thus pulling the voltage received by the first feedback terminal FB1 below the voltage threshold V1. However, when the load 200 is coupled to the secondary-side circuit 3, it is possible that, for example, but not limited to, the output current drawn by the load 200 suddenly changes from full load to no load (i.e., the load 200 changes drastically). This could cause the voltage at the second feedback terminal FB2 to drop below the first time period T1, and the voltage received by the first feedback terminal FB1 to be pulled below the voltage threshold V1, exceeding the first time period T1. Therefore, when the load 200 is coupled to the power output port OUT, the secondary-side controller 36 will ensure that the longest duration for which the feedback signal Sfb is continuously maintained in the specific state is shorter than the first time period T1, to avoid situations where the output current drawn by the load 200 continuously decreases or the load 200 changes drastically, which could be mistakenly interpreted as the load 200 not being coupled to the power output port OUT, leading to erroneous operations.

[0101] For reference, see the following: Figure 1During the time intervals t2 to t4 and t5 to t7 (i.e., the sum of the first time period T1 and the second time period T2), the primary side controller 12 stops providing the pulse width modulation signal Gate1. The longer this period of stopping the provision of the pulse width modulation signal Gate1 is, the more energy is consumed by the power supply device 100 during standby.

[0102] As described in the previous paragraphs, at time points t3 and t6, the primary-side controller 12 has determined that the load 200 is not actually coupled to the power output port OUT or the secondary-side controller 36 may enter the protection mode, thereby triggering the primary-side controller 12 to enter the shutdown mode. In addition to the sub-circuit required by the PWM_off mechanism to determine whether the capacitor voltage Vc has dropped to the shutdown voltage threshold, other sub-circuits inside the primary-side controller 12 (e.g., feedback circuit, protection circuit, etc.) will be shut down as much as possible to reduce power loss (e.g., the capacitor voltage Vc drops more rapidly during time points t2 to t3 and t5 to t6, while the capacitor voltage Vc drops more gently during time points t3 to t3' and t6 to t6'), thereby extending the time interval between time points t3 to t3' and t6 to t6', and extending the first half of the second time period T2.

[0103] On the other hand, in order to extend the time intervals t3'~t4 and t6'~t7, a current-limiting element 122 may be selectively included in the power supply path Ls from the high-voltage start-up terminal HV to the operating power supply terminal VDD1. The current-limiting element 122 is mainly used to adjust the rise rate (also called the required time) of the capacitor voltage Vc from the off-voltage threshold PWM_off to the start-up voltage threshold PWM_on when the power supply path Ls is turned on, by controlling the magnitude of the charging current to the energy storage capacitor C1. This rise rate (required time) can adjust the time when the primary-side controller 12 is turned off (the time intervals t3'~t4 and t6'~t7), thereby adjusting the time when the power supply device 100 is off. Therefore, the current-limiting element 122 can be a resistor, a constant current source, or other components with controllable current magnitude.

[0104] Taking the current-limiting element 122 as a constant current source as an example, when the power supply path Lc is turned on, the primary-side controller 12 controls the constant current source to charge the energy storage capacitor C1 with a constant current, so as to adjust and stabilize the rise rate of the capacitor voltage Vc. Therefore, by adjusting the rise rate, the time intervals t3'~t4 and t6'~t7 are extended, thereby extending the latter half of the second time period T2.

[0105] by Figure 2As shown, the primary-side controller 12 restarts and completes the detection of whether the load 200 is connected to the power output port OUT once (time points t4 to t7) as an example: (1) The duration of the pulse width modulation signal Gate1 provided by the primary-side controller 12 (time points t4 to t5) will be much shorter than (2) The duration of the pulse width modulation signal Gate1 stopped by the primary-side controller 12 (time points t5 to t7, i.e., the sum of the first time period T1 and the second time period T2); In this way, the energy loss of the power supply device 100 in the standby state can be greatly reduced, which is a better implementation method.

[0106] Furthermore, the current limiting element 122 can be selectively enabled / disabled. Specifically, when the primary-side controller 12 is first started due to the power supply device 100 receiving the input voltage Vin, the power supply path Lc is turned on. Since this startup is the normal startup procedure of the primary-side controller 12, in order to enable the primary-side controller 12 to operate as quickly as possible, the primary-side controller 12 disables the current limiting element 122, thus preventing the current limiting element 122 from operating. Because the current limiting element 122 is not operating, the power supply path Lc can provide a larger current, causing the capacitor voltage Vc to rise to the startup voltage threshold PWM_on more quickly. Conversely, when the primary-side controller 12 is notified that the load 200 is not coupled to the secondary-side circuit 3 and turns off the power switch SW1, causing the capacitor voltage Vc of the energy storage capacitor C1 to drop to the shutdown voltage threshold PWM_off, the primary-side controller 12 controls the power supply path Lc to turn on because the primary-side controller 12 shuts down to save power consumption, not as part of the normal startup procedure. Therefore, the primary-side controller 12 enables the current-limiting element 122, which restricts the power supply path Lc to provide only a smaller current (i.e., a current value less than the larger current) to adjust the rise rate (also known as the required time) of the capacitor voltage Vc to the start-up voltage threshold PWM_on. In this way, the detection time interval for the secondary-side controller 36 to detect whether the load 200 is coupled to the secondary-side circuit 3 twice consecutively (real time t1~t2, t4~t5) can be determined by adjusting the time it takes for the capacitor voltage Vc to rise to the start-up voltage threshold PWM_on.

[0107] On the other hand, the secondary circuit 3 further includes a switch SW3. Switch SW3 is coupled between the power output port OUT and the output capacitor Co. When the secondary controller 36 determines via the communication signal Sc that the load 200 is not coupled to the secondary circuit 3 (real time t2), in addition to adjusting the feedback signal Sfb to a specific state, the secondary controller 36 also provides a control signal Gate3 to control switch SW3 to turn off, thus creating an open circuit between the output capacitor Co and the load 200, preventing the power supply device 100 from providing output voltage Vo. Therefore, the output voltage at the power output terminal VBUS between the rectifier circuit 32 and switch SW3 is labeled Vo', and the output voltage from switch SW3 to the power output port OUT is labeled Vo, clearly indicating that these two voltages are different when switch SW3 is off. Conversely, when the secondary controller 36 determines via the communication signal Sc that the load 200 is coupled to the secondary circuit 3, the secondary controller 36 controls switch SW3 to turn on, creating a short circuit between the output capacitor Co and the load 200.

[0108] Please see Figure 3A This is a flowchart of the secondary-side operation method of the standby low-power operation method of the power supply device of the present invention. Figure 3B This is a flowchart of the primary side operation method of the standby low power consumption operation method of the power supply device of the present invention, which can be further referred to. Figures 1-2 The power supply device 100 of the present invention can detect whether the load 200 is coupled to the power output port OUT, and when the load 200 is not coupled to the power output port OUT, it notifies the primary-side controller 12 to enter the shutdown mode using the power feedback circuit (i.e., feedback circuit 34). Then, after a period of time, the primary-side controller 12 will restart to make the power supply device 100 detect whether the load 200 is coupled to the power output port OUT again.

[0109] Therefore, in Figures 3A-3BThe standby low-power operation method of the power supply device 100 includes the following steps: when the capacitor voltage rises to the start-up voltage threshold, the primary-side controller operates to provide a pulse width modulation signal to control the power switch to alternately turn on and off, thereby generating an output voltage in the secondary-side circuit (S100). When the power supply device 100 receives an input voltage Vin, the primary-side circuit 1 provides a DC voltage Vdc to the high-voltage start-up terminal HV according to the input voltage Vin. The DC voltage Vdc charges the energy storage capacitor C1 through the power supply path Ls from the high-voltage start-up terminal HV of the primary-side controller 12 to the operating power terminal VDD1, so that the energy storage capacitor C1 establishes a capacitor voltage Vc. When the capacitor voltage Vc of the energy storage capacitor C1 rises to the start-up voltage threshold PWM_on of the primary-side controller 12, the primary-side controller 12 starts to provide a pulse width modulation signal Gate1 to control the power switch SW1 to alternately turn on and off, so that the transformer 2 starts to store / release energy. The secondary winding 24 generates energy by coupling the primary winding 22, and this energy is rectified by the rectifier circuit 32 to charge the output capacitor Co and provide the output voltage (Vo, Vo') at the power output terminal VBUS.

[0110] exist Figure 3A In the secondary-side operation method, when the output voltage is sufficient to power the secondary-side controller, the secondary-side controller determines whether the load is coupled to the power supply device during a specific time period (S120). The output voltage (Vo, Vo') is also provided by the power output terminal VBUS to the power supply terminal VDD2 to power the secondary-side controller 36 and maintain its operation. At time point t1, when the load 200 is removed from the power output port OUT of the secondary-side circuit 3, the secondary-side controller 36 operates from time t1 to t2. Figure 2Within a specific time period, the secondary controller 36 determines whether the load 200 is coupled to the secondary circuit 3 by receiving the communication signal Sc through the communication ports (CC1, CC2, D+, D-). At time point t2, when the determination result of step (S120) is "yes", that is, when the secondary controller 36 determines that the load 200 is coupled to the power output port OUT, the secondary controller adjusts the feedback signal according to the communication signal and transmits the feedback signal to the primary controller (S140). The secondary controller 36 can adjust the strength of the feedback signal Sfb by modulating the electrical signal of the second feedback terminal FB2. The feedback signal Sfb is also coupled to the first feedback terminal FB1 through the optocouplers (OCA, OCB), and the primary controller 12 adjusts the pulse width modulation signal Gate1 based on the feedback signal Sfb to stabilize and adjust the output voltage (Vo, Vo') on the power output terminal VBUS. After step (S140), the secondary controller continues to determine whether the load is coupled (S160). The secondary controller 36 continuously determines whether the load 200 is coupled to the power supply device 100, and when the determination result is "yes", it returns to step (S140) to continuously supply power to the load 200, and continuously detects whether the load 200 is removed from the power output port OUT.

[0111] When the judgment result of step (S120) or step (S160) is "no", the secondary side controller adjusts the feedback signal to a specific state, and the duration of maintaining the feedback signal in the specific state is greater than or equal to the first time period (S180). After the potential of VDD2 at the secondary side power supply terminal decreases, it returns to step (S120).

[0112] like Figure 2 At time t2, when the secondary controller 36 determines through the communication signal Sc that the load 200 is not coupled to the power output port OUT, the secondary controller 36 adjusts the feedback signal Sfb to a specific state and maintains the feedback signal Sfb in the specific state for a duration greater than or equal to the first time period T1 (the time period from real time t2 to t3). Alternatively, in addition to adjusting the feedback signal Sfb to the specific state and maintaining it greater than or equal to the first time period T1, the secondary controller 36 may also execute step (S200) to control the switch SW3 to turn off, so that the output capacitor Co and the load 200 are disconnected, and the power supply device 100 does not provide output voltage (Vo, Vo').

[0113] exist Figure 3BIn the primary-side operation method, the primary-side controller determines whether the feedback signal is in a specific state and whether the duration of the feedback signal being in the specific state is greater than or equal to the first time period T1 (S320). The second feedback terminal FB2 is coupled to the first feedback terminal FB1 through optocouplers (OCA, OCB). Therefore, when the secondary-side controller 36 adjusts the feedback signal Sfb, the adjustment of the feedback signal Sfb is transmitted to the first feedback terminal FB1 through the optocouplers (OCA, OCB), enabling the primary-side controller 12 to determine whether the feedback signal Sfb is in a specific state and whether the duration of the feedback signal Sfb being in the specific state is greater than or equal to the first time period T1. When the determination result of step (S320) is "no", the power supply device normally provides the output voltage, and the primary-side controller adjusts the pulse width modulation signal according to the feedback signal to supply power to the load (S340). When the secondary-side controller 36 adjusts the feedback signal Sfb, the adjustment of the feedback signal Sfb is transmitted to the first feedback terminal FB1 through the optocoupler (OCA, OCB), so that the primary-side controller 12 adjusts the pulse width modulation signal Gate1 through the feedback signal Sfb, thereby stabilizing and adjusting the output voltage (Vo, Vo') on the power output terminal VBUS, so that the power supply device 100 can normally supply power to the load 200. After step (S340), the primary-side controller continuously determines whether the feedback signal is in a specific state, and whether the duration of the feedback signal being in a specific state is greater than or equal to the first time period (S360). When the determination result of step (S360) is "no", it returns to step (S360) to continue the determination.

[0114] When the judgment result of step (S320) or step (S360) is "yes", the power supply device enters the shutdown mode (S380). Later, when the voltage Vc of the energy storage capacitor C1 rises to the start-up voltage threshold PWM_on, causing the primary side controller 12 to leave the shutdown mode, the process returns to step (S320).

[0115] In the power-off mode, the primary-side controller 12 executes steps (S400) to (S420), and optionally step (S440):

[0116] Step (S400): Turn off the power switch to reduce the voltage of the energy storage capacitor.

[0117] Step (S420): At time point t3', when the capacitor voltage Vc of the energy storage capacitor C1 drops to the shutdown voltage threshold PWM_off, the primary side controller 12 executes step S420, turns on the controllable switch SW2, and establishes the power supply path Ls from the high voltage start terminal HV to the operating power supply terminal VDD1, so that the energy storage capacitor C1 starts charging from the lower potential of the shutdown voltage threshold PWM_off.

[0118] Step (S440): Optionally, the energy storage capacitor is charged with a constant current. The power supply path Ls from the high-voltage start-up terminal HV to the operating power supply terminal VDD1 may optionally include a current-limiting element 122, and the current-limiting element 122 can be a constant current source. When the power supply path Lc is on, the primary-side controller 12 controls the constant current source to charge the energy storage capacitor C1 with a constant current, thereby adjusting and stabilizing the rate of rise of the capacitor voltage Vc. It is worth mentioning that, in one embodiment, Figures 3A-3B For detailed operating instructions regarding the low standby power consumption of the power supply device 100 (not detailed here), please refer to the relevant documentation. Figures 1-2 This will not be elaborated upon further here.

[0119] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A power supply device with low standby power consumption function, characterized in that, The power supply device can supply power to a load, and the power supply device includes: A primary-side circuit includes a power switch, an energy storage capacitor, and a primary-side controller. The primary-side controller includes a high-voltage start-up terminal, an operating power supply terminal, and a first feedback terminal. The primary-side circuit is coupled to the high-voltage start-up terminal, and the energy storage capacitor is coupled to the operating power supply terminal. A secondary-side circuit includes a primary-side controller, wherein the secondary-side controller provides a feedback signal to the first feedback terminal, and the secondary-side controller can detect whether the load is coupled to the secondary-side circuit. Wherein, when the secondary-side controller determines that the load is not coupled to the secondary-side circuit, the secondary-side controller adjusts the feedback signal to a specific state, and the duration is greater than or equal to a first time period; and When the primary-side controller detects that the feedback signal is in the specific state and the duration is greater than or equal to the first time period, the primary-side controller keeps the power switch off. When the voltage of the energy storage capacitor drops to a shutdown voltage threshold, the primary-side controller turns on a power supply path from the high-voltage start-up terminal to the operating power supply terminal to charge the energy storage capacitor. When the capacitor voltage rises to a start-up voltage threshold, the primary-side controller controls the power switch to alternately turn on and off to supply power to the secondary-side circuit, so that the secondary-side controller can detect again whether the load is coupled to the secondary-side circuit.

2. The power supply apparatus of claim 1, wherein When the secondary controller determines that the load is coupled to the secondary circuit, the secondary controller modulates the feedback signal according to the magnitude of the output current drawn by the load, and prevents the feedback signal from maintaining the specific state for more than the first time period.

3. The power supply apparatus of claim 1, wherein The secondary controller further includes a communication port, through which the secondary controller communicates with the load to determine whether the load is coupled to the secondary circuit based on the communication result.

4. The power supply apparatus of claim 1, wherein The power supply path includes a current limiting element, and when the power supply path is turned on, the current limiting element controls the current charging the energy storage capacitor to determine the time required for the capacitor voltage to rise from the shutdown voltage threshold to the startup voltage threshold.

5. The power supply apparatus of claim 1, wherein When the feedback signal is in the specific state and the duration is greater than or equal to the first time period, the power switch is turned off to cause the output voltage provided by the power supply device to drop to the level where the secondary controller is turned off, and the secondary controller remains in the off state until the capacitor voltage rises to the start-up voltage threshold.

6. The power supply device as described in claim 1, characterized in that, The secondary circuit includes: A switch is coupled to an output capacitor of the secondary side circuit, and when the feedback signal is in the specific state, the secondary side controller controls the switch to turn off so that the output capacitor is disconnected from the load.

7. The power supply device as described in claim 6, characterized in that, When the secondary controller determines that the load is coupled to the power supply device, the secondary controller controls the switch to turn on so that the output capacitor and the load are short-circuited.

8. The power supply device as described in claim 1, characterized in that, When the primary controller detects that the feedback signal is in the specific state, but the duration is less than the first time period, the primary controller does not enter a shutdown mode and consumes more power, and the capacitor voltage decreases at a first slope. and When the primary-side controller detects that the feedback signal is in the specific state and the duration is greater than or equal to the first time period, the primary-side controller enters the shutdown mode and consumes less power. The capacitor voltage decreases at a second slope, wherein the second slope is gentler than the first slope.

9. A power supply device with low standby power consumption function, characterized in that, The power supply device can supply power to a load, and the power supply device includes: A primary-side circuit includes a power switch, an energy storage capacitor, and a primary-side controller. The primary-side controller includes a high-voltage start-up terminal, an operating power supply terminal, and a first feedback terminal. The primary-side circuit is coupled to the high-voltage start-up terminal, and the energy storage capacitor is coupled to the operating power supply terminal. A secondary-side circuit includes a primary-side controller, wherein the secondary-side controller provides a feedback signal to the first feedback terminal, and the secondary-side controller can detect whether the load is coupled to the secondary-side circuit. The high-voltage starting terminal to the operating power supply terminal includes a power supply path, and the power supply path may selectively include a current-limiting element; and When the primary-side controller is notified that the load is not coupled to the secondary-side circuit, the primary-side controller turns off the power switch, causing the voltage of the energy storage capacitor to drop to a shutdown voltage threshold, thereby turning on the power supply path. The current limiting element provides a small current to adjust the rate at which the capacitor voltage rises to the startup voltage threshold, thereby adjusting the time it takes for the capacitor voltage to rise to the startup voltage threshold and determining the detection time interval between two consecutive checks by the secondary-side controller to determine whether the load is coupled to the secondary-side circuit.

10. The power supply device as claimed in claim 9, characterized in that, When the primary-side controller is first started, the power supply path is turned on, and the current limiting element is not activated, but a larger current is provided to make the capacitor voltage rise to the start-up voltage threshold. The larger current is greater than the smaller current.

11. A standby low-power operation method for a power supply device, characterized in that, The power supply device can supply power to a load, and the power supply device includes a primary side circuit, a primary side controller, a secondary side circuit, and a secondary side controller. The standby low power consumption operation method includes the following steps: The primary side controller connects a power supply path from a high-voltage start terminal of the primary side controller to an operating power terminal of the primary side controller, thereby charging an energy storage capacitor coupled to the operating power terminal. When the voltage of the energy storage capacitor rises to a start-up voltage threshold, the primary-side controller controls a power switch of the primary-side circuit to alternately turn on and off to supply power to the secondary-side circuit, thereby enabling the secondary-side controller to detect whether the load is coupled to the secondary-side circuit. When the secondary controller determines that the load is not coupled to the power supply device, the secondary controller adjusts the feedback signal to a specific state; and When the primary-side controller detects that the feedback signal is in the specific state and the duration is greater than or equal to a first time period, the following steps are performed: (a) Turn off the power switch, causing the voltage of one capacitor of the energy storage capacitor to drop; (b) When the voltage of one capacitor of the energy storage capacitor drops to a shutdown voltage threshold, the primary side controller turns on a power supply path from the high voltage start terminal to the operating power supply terminal to charge the energy storage capacitor. (c) When the capacitor voltage rises to a startup voltage threshold, the primary-side controller controls the power switch to alternately turn on and off to supply power to the secondary-side circuit; and (d) The secondary controller can detect again whether the load is coupled to the secondary circuit.

12. The standby low-power operation method as described in claim 11, characterized in that, It also includes the following steps: When the secondary-side controller determines that the load is coupled to the secondary-side circuit, the secondary-side controller modulates the feedback signal according to the magnitude of an output current drawn by the load, and prevents the feedback signal from maintaining the specific state for more than the first time period.

13. The standby low-power operation method as described in claim 11, characterized in that, It also includes the following steps: The secondary controller communicates with the load to determine, based on the results of the communication, whether the load is coupled to the secondary circuit.

14. The standby low-power operation method as described in claim 11, characterized in that, It also includes the following steps: When the power supply path is turned on, the rate at which the capacitor voltage rises to the start-up voltage threshold is adjusted.

15. The standby low-power operation method as described in claim 14, characterized in that, It also includes the following steps: When the power supply path is turned on, a current limiting element controls the current charging the energy storage capacitor to determine the time required for the capacitor voltage to rise from the shutdown voltage threshold to the startup voltage threshold.

16. The standby low-power operation method as described in claim 11, characterized in that, It also includes the following steps: When the feedback signal is in the specific state and the duration is greater than or equal to the first time period, the power switch is turned off until the output voltage provided by the power supply device drops to the point where the secondary-side controller is turned off; and The secondary controller maintains the off state until the capacitor voltage rises to the start-up voltage threshold.

17. The standby low-power operation method as described in claim 11, characterized in that, The power supply device includes a switch between an output capacitor coupled to the secondary side circuit and the load, and the standby low power consumption operation method further includes the following steps: When the feedback signal is in this specific state, the secondary controller controls the switch to turn off, so that there is no circuit between the output capacitor and the load; and When the secondary circuit determines that the load is coupled to the power supply device, the secondary controller controls the switch to turn on so that the output capacitor and the load are short-circuited.

18. The standby low-power operation method as described in claim 11, characterized in that, This low-power standby operation method further includes the following steps: When the primary-side controller detects that the feedback signal is in the specific state, but the duration is less than the first time period, the primary-side controller does not enter a shutdown mode and consumes more power, and the capacitor voltage decreases at a first slope. and When the primary-side controller detects that the feedback signal is in the specific state and the duration is greater than or equal to the first time period, the primary-side controller enters the shutdown mode and consumes less power. The capacitor voltage decreases at a second slope, wherein the second slope is gentler than the first slope.

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