Synchronous rectification method and chip for self-adaptive grid voltage regulation and control based on feedback

Abstract

The invention relates to a feedback-based self-adaptive grid voltage regulation synchronous rectification method and a chip, which are executed in a synchronous rectification chip of a power supply circuit. A voltage signal VKA between the drain electrode and the source electrode of the synchronous rectification MOS tube is detected, a feedback signal V 'KA is formed through adaptive filtering, and the driving module dynamically adjusts the grid voltage Vgs according to the V' KA. When the V 'KA is lower than a conduction detection threshold VON, the MOS tube is completely conducted; when the V 'KA rises to be close to a pre-turn-off trigger threshold value VREADY-OFF, the Vgs is dynamically reduced to increase the on resistance, so that the MOS tube is kept in an incomplete conduction state; in the state, the V 'KA is continuously monitored, when the V' KA is lower than the VON again, complete conduction is recovered, only when the V 'KA continuously rises and reaches a turn-off threshold VOFF, the MOS tube is completely turned off, and if the above conditions are not met, the MOS tube is maintained in an incomplete conduction state. According to the adaptive closed-loop adjustment method, the conduction loss and the grid driving loss can be effectively reduced, and the power supply conversion efficiency and the system reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power supply circuit, in particular to a synchronous rectification method and chip based on adaptive gate voltage regulation of feedback. BACKGROUND

[0002] In a power supply system, the energy conversion efficiency not only depends on the switching loss, conduction loss and static power consumption of the control circuit, but also is closely related to the synchronous rectification control strategy. The traditional synchronous rectification control scheme generally relies on detecting the voltage (Vds) across the secondary rectifier tube to determine the turn-on and turn-off timing. Especially at low current or power, the premature turn-off problem is prone to occur due to the fluctuation of the drain-source voltage Vds. This premature turn-off is often triggered by oscillation or waveform transient error caused by circuit parasitic parameters, resulting in the synchronous rectification MOSFET shortening the conduction time and causing additional loss.

[0003] More seriously, if the synchronous rectifier device cannot recover to the normal conduction state in time and accurately, repeated switching actions will occur, further exacerbating energy loss and efficiency decline. Therefore, how to avoid premature turn-off under voltage fluctuation conditions, ensure accurate triggering of turn-off action, and quickly identify the error when it occurs and quickly recover to the correct conduction state, is a key technical challenge to improve the reliability and system efficiency of synchronous rectification. SUMMARY

[0004] The purpose of the present application is to solve the defects existing in the prior art, and to provide a synchronous rectification method and chip based on adaptive gate voltage regulation of feedback. By introducing a dynamic gate voltage adaptive adjustment mechanism in the synchronous rectification chip, the implementation feedback based on the sampling voltage can maintain the rectifier tube in a semi-conduction state when a possible turn-off is predicted, stabilize Vds in the preset negative voltage interval, and further determine whether to trigger turn-off, thereby avoiding false turn-off triggered by ringing and improving system stability.

[0005] To achieve the above purpose, in a first aspect, the present application provides a synchronous rectification method based on adaptive gate voltage regulation of feedback, which is executed in a synchronous rectification chip of a power supply circuit, and the method comprises:

[0006] A detection module detects the voltage signal VKA between the K terminal connected to the drain of the synchronous rectification MOS tube and the A terminal connected to the source, and sends the real-time voltage signal VKA to a filtering module;

[0007] When it is detected that the VKA is lower than the turn-on detection threshold V ONWhen the detection module sends a turn-on control signal, the drive module pulls the gate voltage Vgs of the synchronous rectifier MOSFET to the set maximum drive level according to the turn-on control signal, so that the synchronous rectifier MOSFET is fully turned on.

[0008] During the period when the synchronous rectifier MOSFET is fully turned on, the filtering module adaptively filters the real-time voltage signal VKA and outputs the filtered real-time voltage signal as the feedback voltage signal V'KA of the driving module, which is used to adjust the gate drive voltage Vgs of the synchronous rectifier MOSFET.

[0009] The detection module continuously monitors the feedback voltage signal V'KA. When the feedback voltage signal V'KA rises to the pre-shutdown trigger threshold V... READY-OFF At that time, the detection module sends a pre-shutdown processing control signal to the drive module;

[0010] The driving module reduces Vgs according to the pre-shutdown processing control signal to increase the on-resistance Rds(on) of the synchronous rectifier MOSFET, so as to stabilize the feedback voltage signal V'KA within a certain range near the pre-shutdown trigger threshold.

[0011] The detection module continues to monitor the feedback voltage signal V'KA;

[0012] When the feedback voltage signal V'KA is at the pre-shutdown trigger threshold V READY-OFF When within a certain range, the detection module continues to send a pre-shutdown processing control signal to the drive module, so that the drive module can dynamically adjust Vgs according to real-time feedback, so that the synchronous rectifier MOS tube is kept in a partially on state;

[0013] When the feedback voltage signal V'KA is lower than the conduction detection threshold V ON When the detection module sends a turn-on control signal, the driving module restores the gate voltage Vgs of the synchronous rectifier MOSFET to the set maximum driving level according to the turn-on control signal, so that the synchronous rectifier MOSFET is fully turned on again.

[0014] When the feedback voltage signal V'KA continues to rise and reaches the turn-off threshold V OFF When the detection module sends a shutdown control signal, the drive module completely turns off the synchronous rectifier MOS transistor according to the shutdown control signal.

[0015] Wherein, the conduction detection threshold V ON Less than the pre-shutdown trigger threshold V READY-OFF Less than the turn-off threshold V OFF .

[0016] Preferably, the pre-shutdown trigger threshold V READY-OFF Within a certain range, this refers to the pre-shutdown trigger threshold V. READY-OFF The pre-shutdown trigger threshold V is set to fluctuate around the center value. READY-OFF 5% to 15%.

[0017] Preferably, the driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including:

[0018] The driving module controls and adjusts the adjustable resistor connected in series between the output terminal of the driving module and the gate of the synchronous rectifier MOS transistor according to the shutdown processing control signal. By increasing the resistance value of the adjustable resistor, the charging speed and charging amplitude of the gate of the synchronous rectifier MOS transistor are limited, thereby reducing the gate voltage Vgs.

[0019] Preferably, the driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including:

[0020] The driving module has multiple sets of resistors controlled by a switch array built into the driving current path. The conduction state of the switch array is switched according to the pre-shutdown processing control signal to change the equivalent driving impedance of the driving current path, thereby limiting the charging speed and amplitude of the gate of the synchronous rectifier MOS transistor and reducing the gate voltage Vgs.

[0021] Preferably, the driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including:

[0022] The drive module has multiple built-in preset output levels;

[0023] The driving module selects the corresponding output level according to the pre-shutdown processing control signal to reduce the gate voltage Vgs.

[0024] Preferably, the driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including:

[0025] The driver module has a clamping circuit inside;

[0026] The driving module adjusts the voltage clamping circuit according to the pre-shutdown processing control signal to limit the gate voltage of the synchronous rectifier MOS transistor to a steady-state value lower than the maximum driving level, so as to reduce the gate voltage Vgs.

[0027] Preferably, the driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including:

[0028] The drive module adjusts the controllable current source inside the drive module according to the pre-shutdown processing control signal to reduce the output current, thereby limiting the charging speed and amplitude of the gate of the synchronous rectifier MOS transistor, so as to reduce the gate voltage Vgs.

[0029] Preferably, the synchronous rectification chip further includes a self-powered module and an energy storage capacitor C1;

[0030] When the self-powered module charges the energy storage capacitor C1 during the secondary conduction of the power circuit and makes the voltage across the energy storage capacitor C1 higher than the set start-up threshold Vcc_on, the detection module, filtering module and driving module enter the working state.

[0031] Preferably, the adaptive filtering specifically involves automatically adjusting the filtering time constant based on the operating frequency of the synchronous rectifier circuit or the waveform characteristics of the voltage signal VKA.

[0032] Secondly, embodiments of the present invention provide a synchronous rectification chip, which is applied in a power supply circuit to perform the synchronous rectification method based on feedback adaptive gate voltage regulation described in the first aspect.

[0033] The synchronous rectification method based on feedback adaptive gate voltage regulation provided in this invention utilizes the coordinated action of the chip's internal detection, filtering, and control unit. When VKA is detected to be close to zero, instead of directly turning off the rectifier, the drive module is controlled to reduce the gate voltage Vgs, increasing the on-resistance Rds(on) of the synchronous rectifier MOSFET. This maintains VKA within a preset negative voltage range even under low current conditions. This prevents premature turn-off caused by voltage ringing or noise pushing VKA above zero, while simultaneously rapidly raising Vgs when the load current recovers, allowing the rectifier to fully conduct again. This approach effectively avoids misjudgments and efficiency losses, maintaining low conduction losses even under heavy loads, and overall improving the accuracy of turn-off criteria and system stability. Attached Figure Description

[0034] Figure 1 A flowchart of a synchronous rectification method based on feedback adaptive gate voltage regulation provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the internal structure of the synchronous rectifier chip provided in an embodiment of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0037] This invention provides a synchronous rectification method based on feedback-driven adaptive gate voltage regulation. Figure 1 This is a flowchart of a synchronous rectification method based on feedback-driven adaptive gate voltage regulation provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the internal structure of the synchronous rectification chip provided in an embodiment of the present invention. The following is in conjunction with... Figure 1 , Figure 2 The technical solution of the present invention will be described below.

[0038] First, such as Figure 2 As shown, the internal structure of the synchronous rectification chip used to implement the feedback-based adaptive gate voltage regulation synchronous rectification method of the present invention includes: a detection module 1, a filtering module 2, a driving module 3, a synchronous rectification MOSFET Q1 (NMOS in this example), an energy storage capacitor C1, and a self-powered module 4. The connection relationships of each module and component are as follows: Figure 2 As shown in the diagram, the synchronous rectification chip has two pins, A and K. Pin K is connected to the drain of the synchronous rectification MOSFET, and pin A is connected to the source of the synchronous rectification MOSFET.

[0039] Among them, the self-powered module 4 is used to charge the energy storage capacitor C1 during the secondary conduction of the power supply circuit and make the voltage across the energy storage capacitor C1 higher than the set start-up threshold Vcc_on. When this occurs, the detection module 1, the filtering module 2 and the driving module 3 enter the working state.

[0040] The feedback-based adaptive gate voltage regulation synchronous rectification method of the present invention is implemented in the aforementioned synchronous rectification chip, which is used in a power supply circuit. After each functional module in the synchronous rectification chip of the present invention enters its working state, the main execution steps of the present invention are as follows: Figure 1 As shown, it includes:

[0041] Step 110: The detection module detects the voltage signal VKA between the drain terminal K and the source terminal A of the synchronous rectifier MOSFET, and sends the real-time voltage signal VKA to the filtering module.

[0042] Step 120, when VKA is detected to be lower than the conduction detection threshold V ON When the detection module sends a turn-on control signal, the drive module pulls the gate voltage Vgs of the synchronous rectifier MOSFET up to the set maximum drive level according to the turn-on control signal, so that the synchronous rectifier MOSFET is fully turned on.

[0043] Specifically, during secondary conduction, the detection module continuously samples the VKA voltage. When the sampled value is lower than the preset conduction detection threshold V... ON (In a specific circuit, V) ON The value is set to -200mV) which is more negative (i.e., VKA < V).ON When the detection module determines that there is a large rectified current, it sends a command to the drive module to turn on the synchronous rectifier MOSFET Q1. The drive module then pulls the gate voltage Vgs of the synchronous rectifier MOSFET Q1 to the maximum drive voltage for full conduction, so as to minimize Rds(on) and reduce conduction loss.

[0044] For an N-channel MOSFET, the on-resistance Rds(on) decreases as the gate-source voltage Vgs increases and increases as Vgs decreases. A typical relationship can be approximated by the empirical formula: Rds(on) ∝ 1 / (Vgs - Vth); where Vth is the MOSFET threshold voltage. When Vgs approaches the threshold voltage Vth, Rds(on) increases by several tens of times, resulting in weak MOSFET conduction; when Vgs is sufficiently high (e.g., 5V to 10V above the threshold voltage Vth, depending on the device), Rds(on) reaches its minimum value. Therefore, this characteristic can be used to stabilize the VKA voltage by precisely adjusting Vgs, preventing premature turn-off of the synchronous rectifier MOSFET.

[0045] Step 130: During the period when the synchronous rectifier MOSFET is fully turned on, the filtering module adaptively filters the real-time voltage signal VKA and outputs the filtered real-time voltage signal as the feedback voltage signal V'KA of the drive module, which is used to adjust the gate drive voltage Vgs of the synchronous rectifier MOSFET.

[0046] Specifically, after the synchronous rectifier MOSFET Q1 is turned on, the product of the rectified current Is and the internal Rds(on) is VKA≈-Is×Rds(on). This is because when the synchronous rectifier MOSFET Q1 is turned on, the current Is flows from K to A. Since the on-resistance of the synchronous rectifier MOSFET is Rds(on), a voltage drop will occur between its drain and source (i.e., K–A). The voltage direction is that the voltage at K is lower than that at A, therefore VKA≈-Is×Rds(on).

[0047] The detection module continuously samples the VKA voltage signal at high speed and sends the raw waveform to the filtering module. The filtering module is used to suppress high-frequency resonant components (such as short-time spikes and ringing) or noise generated by secondary leakage inductance, while retaining low-frequency components to form the feedback voltage signal V'KA.

[0048] The filtering module here preferably performs adaptive filtering, which automatically adjusts the filtering time constant according to the operating frequency of the synchronous rectifier circuit or the waveform characteristics of the voltage signal VKA. That is, the duration of the filtering window is dynamically adjusted according to the switching frequency and / or the waveform characteristics of the voltage signal VKA (related to the duty cycle of the MOSFET). It is shortened at high frequencies to improve the turn-off speed and extended at low frequencies to ensure anti-interference capability. The maximum and minimum values ​​can also be set within a corresponding range (e.g., 0.8μs to 1.6μs).

[0049] Filtering in the filtering module can be implemented using an ADC circuit and / or a comparator. The specific circuits used to implement filtering are well-known to those skilled in the art and will not be elaborated further.

[0050] Step 140: The detection module continuously monitors the feedback voltage signal V'KA. When the feedback voltage signal V'KA rises to the pre-shutdown trigger threshold V... READY-OFF At that time, the detection module sends a pre-shutdown processing control signal to the drive module.

[0051] Specifically, when the filtered feedback V'KA increases (the value moves towards 0V) and reaches the pre-shutdown trigger threshold V... READY-OFF (In a specific circuit, V) READY-OFF When the value is set to -40mV, the current is considered to be very small and close to the possible zero current point, but not yet truly 0V. At this time, the pre-shutdown and dynamic Vgs adjustment strategy is triggered, instead of immediately disconnecting the step rectifier MOSFET Q1.

[0052] Step 150: The drive module reduces Vgs according to the pre-shutdown processing control signal to increase the on-resistance Rds(on) of the synchronous rectifier MOSFET, so as to stabilize the feedback voltage signal V'KA within a certain range near the pre-shutdown trigger threshold.

[0053] Specifically, after receiving the pre-shutdown control signal, the drive module does not directly cut off the synchronous rectifier MOSFET Q1. Instead, it reduces the gate drive voltage Vgs of Q1 in a controlled manner. By changing the conduction level of Q1 (increasing Rds(on)), the system is maintained in a stable negative voltage range (e.g., maintaining VKA around -40mV). This prevents instantaneous positive oscillations caused by noise from pushing VKA to 0V, thus avoiding triggering shutdown. Pre-shutdown processing avoids the situation of "ringing → instantaneous zero crossing → false shutdown".

[0054] There are several control methods for the drive module to reduce Vgs based on the pre-shutdown processing control signal. These methods may include reducing the drive output level, limiting the gate charging and discharging current to make the gate voltage decrease at a controllable rate, and inserting a switchable resistor in series to make the equivalent drive impedance increase instantaneously. These specific implementation methods will be explained after introducing all the steps of this process.

[0055] Step 160: The detection module continues to monitor the feedback voltage signal V'KA.

[0056] After the drive reduces Vgs, the detection module continuously reads back the feedback voltage signal V'KA and executes steps 170, 180, or 190 according to the corresponding conditions.

[0057] Step 170, when the feedback voltage signal V'KA reaches the pre-shutdown trigger threshold V READY-OFF When the signal is within a certain range, the detection module continues to send a pre-shutdown control signal to the drive module, so that the drive module can dynamically adjust Vgs according to real-time feedback, keeping the synchronous rectifier MOSFET in a partially on state.

[0058] Among them, the pre-shutdown trigger threshold V READY-OFF Within a certain range, this refers to the pre-shutdown trigger threshold V. READY-OFF The value fluctuates around the center value by ΔV, and ΔV is preferably the pre-shutdown trigger threshold V. READY-OFF 5% to 15%.

[0059] In one alternative implementation, when the feedback voltage signal V'KA exceeds the pre-shutdown trigger threshold V READY-OFF Nearby tolerance range (V) READY-OFF When V'KA is ±ΔV, if the incomplete conduction sustaining condition is not met, the drive module will not be able to continue adjusting the gate drive voltage Vgs according to the preset logic. In this case, the synchronous rectifier MOSFET will remain in its current conduction state, neither triggering full conduction nor triggering a turn-off operation, thus ensuring that V'KA remains at the conduction detection threshold Vgs. ON With the turn-off threshold V OFF The circuit maintains continuous operation within the specified interval. This scheme has a simple structure, clear control logic, and is suitable for circuit environments with small feedback fluctuations and controllable parasitic ringing and noise effects.

[0060] In another alternative implementation, when the feedback voltage signal V'KA exceeds the preset tolerance range V READY-OFF ±ΔV, but still within the conduction detection threshold V. ON With the turn-off threshold V OFF During this period, the drive module can employ additional dynamic adjustment logic to slightly adjust the gate drive voltage Vgs, maintaining the synchronous rectifier MOSFET in a nearly stable on-state. In this way, even if V'KA fluctuates beyond the tolerance range, closed-loop control can still reduce the instability of the on-state, preventing excessive changes in the on-resistance Rds(on), and further optimizing power efficiency. This solution is suitable for applications with large feedback signal fluctuations or significant parasitic ringing. The maximum allowable adjustment range can be set by those skilled in the art based on the actual circuit application environment.

[0061] Step 180, when the feedback voltage signal V'KA is lower than the conduction detection threshold V ONWhen the detection module sends a turn-on control signal, the drive module restores the gate voltage Vgs of the synchronous rectifier MOSFET to the set maximum drive level according to the turn-on control signal, so that the synchronous rectifier MOSFET is fully turned on again.

[0062] Step 190, when the feedback voltage signal V'KA continues to rise and reaches the turn-off threshold V OFF At that time, the detection module sends a shutdown control signal, and the drive module completely turns off the synchronous rectifier MOSFET according to the shutdown control signal.

[0063] The above-mentioned conduction detection threshold V ON Less than the pre-shutdown trigger threshold V READY-OFF Less than the turn-off threshold V OFF .

[0064] The control method for the drive module to reduce Vgs based on the pre-shutdown processing control signal in step 150 above can specifically include, but is not limited to, the following methods:

[0065] The first method involves the drive module adjusting the adjustable resistor connected in series between the output terminal of the drive module and the gate of the synchronous rectifier MOSFET according to the shutdown processing control signal. By increasing the resistance value of the adjustable resistor, the charging speed and charging amplitude of the gate of the synchronous rectifier MOSFET are limited, thereby reducing the gate voltage Vgs.

[0066] The second type of drive module has multiple sets of resistors controlled by a switch array built into the drive current path. The conduction state of the switch array is switched according to the pre-shutdown processing control signal to change the equivalent drive impedance of the drive current path, thereby limiting the charging speed and amplitude of the gate of the synchronous rectifier MOSFET and reducing the gate voltage Vgs.

[0067] The third type is a driver module with multiple preset output levels, that is, multiple preset voltage levels (e.g., 8V fully open, 5V half open, and 3V weakly open). The driver module selects the corresponding output level according to the pre-shutdown processing control signal to reduce the gate voltage Vgs.

[0068] The fourth type is to set up a clamping circuit inside the drive module (such as a Zener diode, a voltage divider + D / A, and a linear clamping amplifier). The drive module adjusts the voltage clamping circuit according to the pre-shutdown processing control signal to limit the gate voltage of the synchronous rectifier MOSFET to a steady-state value lower than the maximum drive level, so as to reduce the gate voltage Vgs.

[0069] The fifth method involves the drive module adjusting the controllable current source inside the drive module according to the pre-shutdown processing control signal to reduce the output current, thereby limiting the charging speed and amplitude of the gate of the synchronous rectifier MOSFET and reducing the gate voltage Vgs.

[0070] When implementing this solution, those skilled in the art can select any one of the five methods mentioned above to control the reduction of the gate voltage Vgs.

[0071] This invention employs a graded threshold (V) ON <<V READY-OFF <<V OFF This ensures good hysteresis between turn-on, pre-turn-off, and full turn-off, avoiding jumps during the ringing range. When approaching zero current, the synchronous rectifier MOSFET is not directly turned off; instead, VKA is stabilized at a small negative value (around -40mV) by controlling the reduction of Vgs, thus avoiding false turn-off. When the load recovers, Vgs can be quickly restored to full drive, thus balancing efficiency and dynamic response.

[0072] In this invention, the synchronous rectifier MOSFET detects the voltage signal VKA between its drain and source through signal detection points K and A, and sends the real-time signal to the filtering module to form a feedback signal V'KA, which is used to drive the module to dynamically adjust the gate drive voltage Vgs of the synchronous rectifier MOSFET. This control logic enables the synchronous rectifier MOSFET to reach the pre-turn-off trigger threshold Vgs. READY-OFF The synchronous rectifier MOSFET is kept in a partially on state within the nearby tolerance range. By keeping the synchronous rectifier MOSFET in a partially on state, the impact of on-resistance fluctuations on the voltage signal can be reduced, while ensuring the stability of the closed-loop control.

[0073] Furthermore, the combination of the filtering module and dynamic Vgs adjustment effectively suppresses parasitic ringing and noise interference with voltage feedback. This allows the drive module to continuously adjust Vgs based on the real-time feedback signal V'KA before the conditions for full conduction or complete turn-off are met, ensuring that the synchronous rectifier MOSFET is neither fully turned on nor prematurely turned off. This control method significantly reduces the MOSFET's conduction losses and gate drive losses, thereby improving power conversion efficiency.

[0074] Furthermore, in the incomplete conduction state, through feedback dynamic adjustment and continuous monitoring of V'KA, when V'KA falls below V again... ON Full conduction is restored only when V'KA continues to rise and reaches the turn-off threshold V. OFF Only when the above conditions are met will the MOSFET be completely turned off. If the above conditions are not met, it will remain in a partially on state, which effectively improves the system reliability.

[0075] This invention introduces an adaptive filtering and feedback adjustment mechanism, enabling the gate drive voltage Vgs of the synchronous rectifier MOSFET to no longer rely on fixed preset conditions for unidirectional adjustment. Instead, it uses dynamic closed-loop control based on real-time detection of the filter feedback signal V'KA. The advantages of this design are: when V'KA approaches the pre-turn-off trigger threshold, feedback adjustment can precisely lower Vgs, keeping the device in a stable, partially on state, effectively resisting false turn-off caused by parasitic parameters or waveform disturbances. Furthermore, if the feedback signal recovers below the on-threshold, the system can immediately return to a fully on state, ensuring the continuity and stability of synchronous rectification; and only when V'KA continuously rises to the turn-off threshold is the actual turn-off action executed, achieving accurate turn-off triggering. Through this adaptive feedback control method, premature turn-off and erroneous actions can be avoided under voltage fluctuation environments, and rapid recovery after false judgments is ensured. Overall, the reliability of the synchronous rectifier device is improved, unnecessary conduction and switching losses are reduced, thereby optimizing the system's energy conversion efficiency.

[0076] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0077] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented in hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A synchronous rectification method based on feedback-driven adaptive gate voltage regulation, characterized in that, The method is executed in a synchronous rectification chip of a power supply circuit, and the method includes: The detection module detects the voltage signal VKA between the drain terminal K and the source terminal A of the synchronous rectifier MOSFET, and sends the real-time voltage signal VKA to the filtering module. When the detected VKA is lower than the conduction detection threshold V ON When the detection module sends a turn-on control signal, the drive module pulls the gate voltage Vgs of the synchronous rectifier MOSFET to the set maximum drive level according to the turn-on control signal, so that the synchronous rectifier MOSFET is fully turned on. During the period when the synchronous rectifier MOSFET is fully turned on, the filtering module adaptively filters the real-time voltage signal VKA and outputs the filtered real-time voltage signal as the feedback voltage signal V'KA of the driving module, which is used to adjust the gate drive voltage Vgs of the synchronous rectifier MOSFET. The detection module continuously monitors the feedback voltage signal V'KA. When the feedback voltage signal V'KA rises to the pre-shutdown trigger threshold V... READY-OFF At that time, the detection module sends a pre-shutdown processing control signal to the drive module; The driving module reduces Vgs according to the pre-shutdown processing control signal to increase the on-resistance Rds(on) of the synchronous rectifier MOSFET, so as to stabilize the feedback voltage signal V'KA within a certain range near the pre-shutdown trigger threshold. The detection module continues to monitor the feedback voltage signal V'KA; When the feedback voltage signal V'KA is at the pre-shutdown trigger threshold V READY-OFF When within a certain range, the detection module continues to send a pre-shutdown processing control signal to the drive module, so that the drive module can dynamically adjust Vgs according to real-time feedback, so that the synchronous rectifier MOS tube is kept in a partially on state; When the feedback voltage signal V'KA is lower than the conduction detection threshold V ON When the detection module sends a turn-on control signal, the driving module restores the gate voltage Vgs of the synchronous rectifier MOSFET to the set maximum driving level according to the turn-on control signal, so that the synchronous rectifier MOSFET is fully turned on again. When the feedback voltage signal V'KA continues to rise and reaches the turn-off threshold V OFF When the detection module sends a shutdown control signal, the drive module completely turns off the synchronous rectifier MOS transistor according to the shutdown control signal. Wherein, the conduction detection threshold V ON Less than the pre-shutdown trigger threshold V READY-OFF Less than the turn-off threshold V OFF .

2. The synchronous rectification method according to claim 1, characterized in that, The pre-shutdown trigger threshold V READY-OFF Within a certain range, this refers to the pre-shutdown trigger threshold V. READY-OFF The pre-shutdown trigger threshold V is set to fluctuate around the center value. READY-OFF The range is 5% to 15%.

3. The synchronous rectification method according to claim 1, characterized in that, The driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including: The driving module controls and adjusts the adjustable resistor connected in series between the output terminal of the driving module and the gate of the synchronous rectifier MOS transistor according to the shutdown processing control signal. By increasing the resistance value of the adjustable resistor, the charging speed and charging amplitude of the gate of the synchronous rectifier MOS transistor are limited, thereby reducing the gate voltage Vgs.

4. The synchronous rectification method according to claim 1, characterized in that, The driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including: The driving module has multiple sets of resistors controlled by a switch array built into the driving current path. The conduction state of the switch array is switched according to the pre-shutdown processing control signal to change the equivalent driving impedance of the driving current path, thereby limiting the charging speed and amplitude of the gate of the synchronous rectifier MOS transistor and reducing the gate voltage Vgs.

5. The synchronous rectification method according to claim 1, characterized in that, The driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including: The drive module has multiple built-in preset output levels; The driving module selects the corresponding output level according to the pre-shutdown processing control signal to reduce the gate voltage Vgs.

6. The synchronous rectification method according to claim 1, characterized in that, The driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including: The driver module has a clamping circuit inside; The driving module adjusts the voltage clamping circuit according to the pre-shutdown processing control signal to limit the gate voltage of the synchronous rectifier MOS transistor to a steady-state value lower than the maximum driving level, so as to reduce the gate voltage Vgs.

7. The synchronous rectification method according to claim 1, characterized in that, The driving module reduces Vgs according to the pre-shutdown processing control signal, specifically including: The drive module adjusts the controllable current source inside the drive module according to the pre-shutdown processing control signal to reduce the output current, thereby limiting the charging speed and amplitude of the gate of the synchronous rectifier MOS transistor, so as to reduce the gate voltage Vgs.

8. The synchronous rectification method according to claim 1, characterized in that, The synchronous rectification chip also includes a self-powered module and an energy storage capacitor C1; When the self-powered module charges the energy storage capacitor C1 during the secondary conduction of the power circuit and makes the voltage across the energy storage capacitor C1 higher than the set start-up threshold Vcc_on, the detection module, filtering module and driving module enter the working state.

9. The synchronous rectification method according to claim 1, characterized in that, The adaptive filtering specifically involves automatically adjusting the filtering time constant based on the operating frequency of the synchronous rectifier circuit or the waveform characteristics of the voltage signal VKA.

10. A synchronous rectification chip, characterized in that, The chip is used in a power supply circuit to perform the synchronous rectification method based on feedback adaptive gate voltage regulation as described in any one of claims 1-9.

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