Switching power supply dead zone automatic adjustment synchronous rectification circuit and method

Abstract

According to the switching power supply dead zone automatic adjustment synchronous rectification circuit and method, the input end of an output current detection circuit is connected between a filter circuit and a load, the output end of the output current detection circuit is connected with the input end of a dead zone control circuit, and the output current detection circuit is used for converting output current into voltage signals representing the size of the load; the output end of the dead-zone control circuit is connected with the input end of the driving circuit, and the dead-zone control circuit is used for controlling the driving circuit to carry out dead-zone adjustment or not according to the voltage signal related to the size of the load, and transmitting the voltage signal representing the size of the load to the driving circuit if the dead-zone adjustment is carried out; the output end of the driving circuit is connected with the rectifying tube of the rectifying circuit and used for generating a driving signal to drive the rectifying tube of the rectifying circuit to be switched on or switched off. According to the invention, dead zone adjustment of load self-adaption is completed; the problem of overlarge dead zone or direct connection is avoided; the method is not limited to a synchronous rectification driving mode, and dead zone automatic adjustment can be realized by a self-driven synchronous rectification circuit and a synchronous rectification circuit driven by a driving chip.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supply circuits, and more specifically, relates to a synchronous rectification circuit and method for automatically adjusting the dead zone of a switching power supply. Background Art

[0002] The basic principle of synchronous rectification technology is to use power MOSFET with extremely low on-resistance to replace the rectifier diode, thereby reducing the rectification loss. In the field of power conversion, especially when the output DC voltage is low, synchronous rectification can greatly reduce the loss and improve the efficiency, so it is widely used.

[0003] The diode is a passive rectifying device. Whether it is conducting or not is only related to the voltage across the diode. After using the switching MOS tube, a suitable driving voltage is required to control the opening and closing of the MOS tube. Therefore, the core technology of the synchronous rectification application in the switching power supply is the generation of the driving signal of the synchronous rectification MOS tube. If it is not properly controlled, it is easy to cause abnormal operation of the circuit or even damage the entire power supply.

[0004] The commonly used synchronous rectification driving methods are:

[0005] 1. Transformer winding voltage self-drive: This driving method generally uses a driving signal directly from the transformer winding or auxiliary winding. This driving method is simple to control and low in cost. It requires that the conduction of the secondary side be consistent with the logic of the winding voltage, which has certain limitations. Backflow problems may occur under certain load conditions, and external control logic is required; 2. The driving method using a current transformer to detect current: The MOS current is detected using a current transformer CT. The MOS is turned on when there is current and turned off when there is no current. This driving method based on current changes is complex to control and may not shut down the rectifier tube in time; 3. An external driving method using a driver chip with a dead zone adjustment function: This method generally detects the DS voltage of the secondary side MOS to control the on and off of the MOS. The circuit has high integration and is simple to use, but it has high requirements for circuit layout and is prone to early or delayed shutdown.

[0006] The patent with authorization announcement number CN213879629U proposes a synchronous rectification self-driven winding drive circuit and power supply of an active clamp forward circuit, including a rectifier tube drive circuit; a freewheeling tube drive circuit; an ON / OFF control circuit; by adding a no-load circuit to timely shut down the freewheeling tube drive, the risk of short circuit discharge on the output capacitor is avoided; but it has the disadvantages of complex circuit, driving voltage fluctuation, and unadjustable dead zone.

[0007] The patent with publication number CN109525116A proposes a synchronous rectification drive circuit with a maximum duty cycle limit, including a synchronous rectification circuit; a limiting circuit; a differential circuit; and a comparison circuit. By adjusting the maximum duty cycle, the damage caused by long-term conduction of the synchronous rectifier tube is limited, thereby reducing costs. However, its maximum duty cycle cannot automatically adapt to load changes.

[0008] The invention patent with the publication number CN113131754A proposes a CCM flyback converter synchronous rectification drive dead zone control method, including a drive circuit; a signal isolation circuit; a feedback circuit; and an external resistor to control the dead time to solve the problem of uncertainty in MOS turn-off time in continuous current mode, which affects reliability and efficiency. After the dead time is set, it cannot adapt to load changes.

[0009] In summary, the existing technology has a wide input voltage variation range of the power converter, the load is not fixed, and the synchronous rectification drive dead time is large, which will reduce the power efficiency. A small dead time is likely to cause shoot-through damage, and it is difficult to accurately perform load adaptive adjustment of the dead time. Summary of the invention

[0010] In order to solve the deficiencies of the prior art, the present invention proposes a switching power supply dead zone automatic adjustment synchronous rectification circuit and method. Under the premise of ensuring reliability, the dead zone time load adaptive adjustment is achieved, the synchronous rectification dead zone time is reduced to the greatest extent, the efficiency is improved, and the loss is reduced.

[0011] The present invention adopts the following technical solution.

[0012] The first aspect of the present invention proposes a synchronous rectifier circuit for automatically adjusting the dead zone of a switching power supply. The rectifier circuit adopts two driving modes: self-driving and driving by a driving chip with a dead zone adjustment function; the rectifier circuit is composed of a rectifier module, a filter circuit, an output current detection circuit, a dead zone control circuit, and a driving circuit, specifically:

[0013] The input end of the output current detection circuit is connected between the output filter circuit and the load, and the output end is connected to the input end of the dead zone control circuit, so as to convert the output current into a voltage signal representing the load size;

[0014] The output end of the dead zone control circuit is connected to the input end of the driving circuit, and is used to control whether the driving circuit performs dead zone adjustment according to a voltage signal related to the load size. If the dead zone adjustment is performed, the voltage signal is transmitted to the driving circuit;

[0015] The rectifier module uses a rectifier tube for rectification, and the output end of the drive circuit is connected to the rectifier tube of the rectifier module to generate a drive signal to drive the rectifier tube of the rectifier circuit to turn on or off.

[0016] Preferably, the output current detection circuit is composed of an output detection resistor and a current detection chip; one end of the output detection resistor is connected to the output end of the filter circuit, and the other end of the output detection resistor is connected to the load. The two input ends of the current detection chip are respectively connected to the two ends of the current detection resistor, and the output reflects the change in the load size. The calculation formula of the signal is:

[0017] V io =ki o R s

[0018] Among them, i o is the output current of the rectifier circuit, V io is the voltage signal detected by the output current circuit, R s is the output detection resistance value, and k is the amplification factor of the current detection chip.

[0019] Preferably, the dead zone control circuit includes a voltage follower, a first comparator, a dead zone adjustment enable tube and a synchronous rectification enable module; the input end of the voltage follower is the input end of the dead zone control circuit, and the input voltage signal V representing the load size is io The output end of the voltage follower, the drain of the dead zone adjustment enable tube and the positive input end of the first comparator are connected, and the output end of the voltage follower outputs a voltage signal V that represents the load size. io Equal current sense voltage V ios The negative input terminal of the first comparator inputs the set voltage threshold V ref The output end of the first comparator is connected to the gate of the dead zone adjustment enabling tube, the control end of the synchronous rectification enabling module is connected to the output end of the first comparator, and the signal output by the output end of the first comparator is the enabling signal SR-en.

[0020] Preferably, when the rectifier circuit is driven in a self-driving manner, the rectifier module comprises a primary MOS tube, a first MOS tube Q1 for rectification, and a second MOS tube Q2 for freewheeling; when the primary MOS tube driving signal performs a rising edge, the second MOS tube driving signal performs a falling edge, and the first MOS tube driving signal performs a rising edge after a fixed dead time tdead;

[0021] When the rectifier circuit is driven in a self-driving manner, the output end of the synchronous rectification enabling module is connected to the control end of the first MOS tube and the second MOS tube. If the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enabling module controls the first MOS tube and the second MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enabling module does not control the first MOS tube and the second MOS tube.

[0022] Preferably, when the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the rectifier module includes an SR-MOS tube;

[0023] When the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the output end of the synchronous rectification enable module is connected to the control end of the SR-MOS tube; if the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the SR-MOS tube to turn off; if it reaches the set threshold, the synchronous rectification enable module does not control the SR-MOS tube.

[0024] Preferably, when the rectifier circuit is driven in a self-driving mode, the driving circuit includes a second comparator, an OR gate, a NOT gate, a first resistor Rd, a first capacitor Cd, and a first diode. The positive input end of the second comparator serves as the input end of the driving circuit, and the current detection signal V ios , the negative phase input end of the second comparator, one end of the first resistor, one end of the first diode and one end of the first capacitor are connected, the other end of the first capacitor is connected to the ground, the other end of the first resistor, the other end of the first diode, the gate of the first MOS tube and the input end of the NOT gate are connected; the output end of the second comparator is connected to the first input end of the OR gate, the output end of the NOT gate is connected to the second input end of the OR gate, and the output end of the OR gate is connected to the gate of the second MOS tube;

[0025] The driving circuit makes the primary MOS tube driving signal of the rectifier module rise, and the falling edge of the second MOS tube driving signal is delayed by a time Δt related to the load:

[0026]

[0027] Among them, V c The first resistor Rd and the first capacitor Cd are charged with a delay voltage; d is the resistance value of the first resistor Rd; V gd It is the primary MOS tube driving signal.

[0028] Preferably, Δt sets a maximum delay time tdmax, tdmax is equal to the fixed dead time tdead between the falling edge of the second MOS tube drive signal and the rising edge of the first MOS tube drive signal due to self-drive, when the delay Δt of the second MOS tube exceeds tdmax, the second MOS tube is turned off.

[0029] Preferably, when the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the driver circuit includes a driver chip with a dead zone adjustment function and a control module, and the input end of the control module inputs a current detection signal V ios , the control module amplifies the current detection signal and outputs the feedback voltage V z :

[0030] V z =k'×V ios

[0031] Where, k′ is the magnification of the control module;

[0032] The feedback voltage V z The first input terminal of the driver chip with the function of adjusting the dead zone is connected to the source of the SR-MOS tube for feedback. The second input terminal of the driver chip with the function of adjusting the dead zone is connected to the drain of the SR-MOS tube. The driver circuit automatically adjusts the dead zone time of the SR-MOS tube according to the input of the first and second input terminals. The dead zone time adjusted by the driver chip with the function of adjusting the dead zone is proportional to V z Positive correlation.

[0033] Preferably, when the driving chip with the dead zone adjustment function is a driving chip that needs to inject current, the driving circuit includes a second resistor to adjust the current detection voltage V ios The second resistor is connected in series and then connected to the current injection terminal of the driving chip.

[0034] The second aspect of the present invention provides a method for automatically adjusting synchronous rectification in the dead zone of a switching power supply using the rectification circuit described in the first aspect of the present invention, comprising the following contents:

[0035] Collect the output current and convert it into a voltage signal V that represents the load size io ; The voltage signal is output as a current sensing voltage V of the same magnitude through a voltage follower. ios ;

[0036] Then the current sensing voltage V ios The first comparator is connected to the set voltage threshold V ref Value comparison, if greater than the threshold V ref , the output of the first comparator is high level, controlling the dead zone adjustment enable tube to turn on, and V ios Sent to the driving circuit;

[0037] At the same time, the output end of the first comparator outputs the enable signal SR-en of the synchronous rectification module to determine the driving mode of the rectification circuit. If the rectification circuit is self-driven and the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the first MOS tube and the second MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enable module does not control the first MOS tube and the second MOS tube; if the rectification circuit is driven by a driver chip with a dead zone adjustment function and the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the SR-MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enable module does not control the SR-MOS tube;

[0038] If the rectifier circuit is self-driven, the control signal V gd The first capacitor Cd is charged through the first resistor Rd, and the output capacitor voltage V c , the capacitor voltage V c With the current sense voltage V ios When the capacitor voltage V c Less than V ios When the output signal of the second comparator V gQ2d is high level, when the capacitor voltage V c Greater than or equal to the current sensing voltage V ios When V gQ2d is low level; capacitor voltage V c The output V is inverted by the NOT gate gQ2 The first input and the second output of the OR gate are input with V gQ2d With V gQ2 signal, output delayed driving signal V gQ2 ', so that the delay will be automatically adjusted with the load size, when the control signal V gd When it becomes low, the first capacitor Cd is automatically discharged;

[0039] If the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the current detection signal V ios Amplify the feedback voltage V z , connect it to the source of the SR-MOS tube for feedback. The driver chip with the dead zone adjustment function automatically adjusts the dead zone time of the SR-MOS tube by detecting the source and drain voltage of the SR-MOS tube. After feedback, the dead zone time adjusted by the driver chip with the dead zone adjustment function is the same as V z Positive correlation.

[0040] The third aspect of the present invention proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when loaded into the processor, implements the method for automatically adjusting the dead zone of a switching power supply according to the second aspect of the present invention.

[0041] The fourth aspect of the present invention proposes a computer-readable storage medium, which stores a computer program, and is characterized in that when the computer program is executed by a processor, it implements the method for automatically adjusting the dead zone of the switching power supply according to the second aspect of the present invention.

[0042] The beneficial effect of the present invention is that, compared with the prior art,

[0043] 1. The dead zone automatic adjustment synchronous rectification circuit proposed in the present invention uses an output current detection circuit to detect a voltage signal representing the load size; uses a dead zone control circuit to control whether a drive circuit performs dead zone adjustment according to a voltage signal related to the load size; transmits the voltage signal representing the load size to the drive circuit to complete load adaptive dead zone adjustment; and avoids the problem of excessive dead zone or direct pass.

[0044] 2. The dead zone automatic adjustment synchronous rectification circuit proposed in the present invention selects a delay control driving circuit when self-driven, and selects to amplify the voltage signal representing the load size and then feed it back to the driving chip when chip driven. Therefore, it is not limited to the synchronous rectification driving mode and can realize automatic dead zone adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The framework diagram of the synchronous rectification circuit for automatically adjusting the dead zone of the switching power supply;

[0046] Figure 2 The schematic diagram of the synchronous rectification circuit for automatically adjusting the dead zone of the switching power supply;

[0047] Figure 3 This is the schematic diagram of the output current detection circuit;

[0048] Figure 4 This is the input and output diagram of the dead zone control circuit;

[0049] Figure 5 A schematic diagram of automatic dead zone adjustment of a synchronous rectification circuit driven by a driving circuit;

[0050] Figure 6 It is the schematic diagram of the self-driven synchronous rectification circuit;

[0051] Figure 7 A timing diagram for automatic dead-zone adjustment control of a self-driven synchronous rectification circuit;

[0052] Figure 8 This is a schematic diagram of self-driven dead zone delay control.

[0053] Fig. 9 This is the timing diagram of self-driven dead zone delay control. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0055] The output of the high-frequency conversion circuit needs to be synchronously rectified, and the high-frequency conversion circuit can be a flyback, forward, or LLC circuit;

[0056] like Figure 1 As shown, Embodiment 1 of the present invention proposes a synchronous rectification circuit for automatically adjusting the dead zone of a switching power supply. The rectification circuit adopts two driving modes: self-driving and driving by a driving chip with a dead zone adjustment function. The rectification circuit is composed of a rectification module, a filtering circuit, an output current detection circuit, a dead zone control circuit, and a driving circuit, specifically:

[0057] The input end of the output current detection circuit is connected between the output filter circuit and the load, and the output end is connected to the input end of the dead zone control circuit, so as to convert the output current into a voltage signal representing the load size;

[0058] The output end of the dead zone control circuit is connected to the input end of the driving circuit, and is used to control whether the driving circuit performs dead zone adjustment according to a voltage signal related to the load size. If the dead zone adjustment is performed, the voltage signal is transmitted to the driving circuit;

[0059] The rectifier module uses a rectifier tube for rectification, and the output end of the drive circuit is connected to the rectifier tube of the rectifier module to generate a drive signal to drive the rectifier tube of the rectifier circuit to turn on or off.

[0060] Preferably, if Figure 3 As shown, the output current detection circuit is composed of an output detection resistor and a current detection chip; one end of the output detection resistor is connected to the output end of the filter circuit, and the other end of the output detection resistor is connected to the load. The two input ends of the current detection chip are respectively connected to the two ends of the current detection resistor, and the output reflects the change in the load size. The calculation formula of the signal is:

[0061] V io =ki o R s

[0062] Among them, i o is the output current of the rectifier circuit, V io is the voltage signal detected by the output current circuit, R s is the output detection resistance value, and k is the amplification factor of the current detection chip.

[0063] Specifically, the amplification factor k of the current detection chip in this embodiment is 50.

[0064] Preferably, the dead zone control circuit includes a voltage follower, a first comparator, a dead zone adjustment enable tube and a synchronous rectification enable module; the input end of the voltage follower is the input end of the dead zone control circuit, and the input voltage signal V representing the load size is ioThe output end of the voltage follower, the drain of the dead zone adjustment enable tube and the positive input end of the first comparator are connected, and the output end of the voltage follower outputs a voltage signal V that represents the load size. io Equal current sense voltage V ios The negative input terminal of the first comparator inputs the set voltage threshold V ref , the output terminal of the first comparator is connected to the gate of the dead zone adjustment enabling tube, such as Figure 4 As shown, the control end of the synchronous rectification enabling module is connected to the output end of the first comparator, and the signal output by the output end of the first comparator is the enabling signal SR-en.

[0065] Preferably, if Figure 6 As shown, when the rectifier circuit is driven in a self-driving manner, the rectifier module includes a primary MOS tube, a first MOS tube Q1 for rectification, and a second MOS tube Q2 for freewheeling; when the primary MOS tube driving signal is on a rising edge, the second MOS tube driving signal is on a falling edge, and the first MOS tube driving signal is on a rising edge after a fixed dead time tdead;

[0066] When the rectifier circuit is driven in a self-driving manner, the output end of the synchronous rectification enabling module is connected to the control end of the first MOS tube and the second MOS tube. If the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enabling module controls the first MOS tube and the second MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enabling module does not control the first MOS tube and the second MOS tube.

[0067] Preferably, when the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the rectifier module includes an SR-MOS tube;

[0068] When the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the output end of the synchronous rectification enable module is connected to the control end of the SR-MOS tube; if the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the SR-MOS tube to turn off; if it reaches the set threshold, the synchronous rectification enable module does not control the SR-MOS tube.

[0069] Specifically, the enabling threshold set in this embodiment is 2A.

[0070] Preferably, if Figure 2 As shown, when the rectifier circuit is driven in a self-driving mode, the driving circuit includes a second comparator, an OR gate, a NOT gate, a first resistor Rd, a first capacitor Cd, and a first diode. The positive input end of the second comparator is used as the input end of the driving circuit, and the current detection signal V is input. ios, the negative phase input end of the second comparator, one end of the first resistor, one end of the first diode and one end of the first capacitor are connected, the other end of the first capacitor is connected to the ground, the other end of the first resistor, the other end of the first diode, the gate of the first MOS tube and the input end of the NOT gate are connected; the output end of the second comparator is connected to the first input end of the OR gate, the output end of the NOT gate is connected to the second input end of the OR gate, and the output end of the OR gate is connected to the gate of the second MOS tube;

[0071] The driving circuit makes the primary MOS tube driving signal of the rectifier module rise, and the falling edge of the second MOS tube driving signal is delayed by a time Δt related to the load:

[0072] Δt= C d ×V ios ×R d

[0073] V gd

[0074] Among them, V c The first resistor Rd and the first capacitor Cd are charged with a delay voltage; d is the resistance value of the first resistor Rd; V gd It is the primary MOS tube driving signal.

[0075] Preferably, Δt sets a maximum delay time tdmax, tdmax is equal to the fixed dead time tdead between the falling edge of the second MOS tube drive signal and the rising edge of the first MOS tube drive signal due to self-drive, when the delay Δt of the second MOS tube exceeds tdmax, the second MOS tube is turned off.

[0076] Preferably, if Figure 5 As shown, when the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the driver circuit includes a driver chip with a dead zone adjustment function and a control module, and the input end of the control module inputs a current detection signal V ios , the control module amplifies the current detection signal and outputs the feedback voltage V z :

[0077] V z =k'×V ios

[0078] Wherein, k′ is the magnification of the control module;

[0079] The feedback voltage V zThe first input terminal of the driver chip with the function of adjusting the dead zone is connected to the source of the SR-MOS tube for feedback. The second input terminal of the driver chip with the function of adjusting the dead zone is connected to the drain of the SR-MOS tube. The driver circuit automatically adjusts the dead zone time of the SR-MOS tube according to the input of the first and second input terminals. The dead zone time adjusted by the driver chip with the function of adjusting the dead zone is proportional to V z Positive correlation.

[0080] Preferably, when the driving chip with the dead zone adjustment function is a driving chip that needs to inject current, the driving circuit includes a second resistor to adjust the current detection voltage V ios The second resistor is connected in series and then connected to the current injection terminal of the driving chip.

[0081] Embodiment 2 of the present invention proposes a method for automatically adjusting synchronous rectification in the dead zone of a switching power supply using the rectification circuit described in Embodiment 1 of the present invention, comprising the following contents:

[0082] Collect the output current and convert it into a voltage signal V that represents the load size io ; The voltage signal is output as a current sensing voltage V of the same magnitude through a voltage follower. ios ;

[0083] Then the current sensing voltage V ios The first comparator is connected to the set voltage threshold V ref Value comparison, if greater than the threshold V ref , the output of the first comparator is high level, controlling the dead zone adjustment enable tube to turn on, and V ios Sent to the driving circuit;

[0084] At the same time, the output end of the first comparator outputs the enable signal SR-en of the synchronous rectification module to determine the driving mode of the rectification circuit. If the rectification circuit is self-driven and the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the first MOS tube and the second MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enable module does not control the first MOS tube and the second MOS tube; if the rectification circuit is driven by a driver chip with a dead zone adjustment function and the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the SR-MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enable module does not control the SR-MOS tube;

[0085] like Figure 8 As shown, if the rectifier circuit is self-driven, the control signal V gd The first capacitor Cd is charged through the first resistor Rd, and the output capacitor voltage V c ,like Fig. 9 As shown, the capacitor voltage Vc With the current sense voltage V ios When the capacitor voltage V c Less than V ios When the output signal of the second comparator V gQ2d is high level, when the capacitor voltage V c Greater than or equal to the current sensing voltage V ios When V gQ2d is low level; Figure 7 As shown, the capacitor voltage V c The output V is inverted by the NOT gate gQ2 The first input and the second output of the OR gate are input with V gQ2d With V gQ2 signal, output delayed driving signal V gQ2 ', so that the delay will be automatically adjusted with the load size, when the control signal V gd When it becomes low, the first capacitor Cd is automatically discharged;

[0086] If the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the current detection signal V ios Amplify the feedback voltage V z , connect it to the source of the SR-MOS tube for feedback. The driver chip with the dead zone adjustment function automatically adjusts the dead zone time of the SR-MOS tube by detecting the source and drain voltage of the SR-MOS tube. After feedback, the dead zone time adjusted by the driver chip with the dead zone adjustment function is the same as V z Positive correlation.

[0087] Embodiment 3 of the present invention proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the computer program is loaded into the processor, the method for automatically adjusting the dead zone of a switching power supply according to embodiment 2 of the present invention is implemented.

[0088] Embodiment 4 of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the method for automatically adjusting the dead zone of a switching power supply according to embodiment 2 of the present invention is implemented.

[0089] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0090] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0091] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0092] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A synchronous rectifier circuit for automatically adjusting the dead zone of a switching power supply, wherein the rectifier circuit adopts two driving modes: self-driving and driving by a driver chip with a dead zone adjustment function; the rectifier circuit is composed of a rectifier module, a filter circuit, an output current detection circuit, a dead zone control circuit, and a drive circuit, and is characterized in that: The input end of the output current detection circuit is connected between the output filter circuit and the load, and the output end is connected to the input end of the dead zone control circuit, so as to convert the output current into a voltage signal representing the load size; The output end of the dead zone control circuit is connected to the input end of the driving circuit, and is used to control whether the driving circuit performs dead zone adjustment according to a voltage signal related to the load size. If the dead zone adjustment is performed, the voltage signal is transmitted to the driving circuit; The rectifier module uses a rectifier tube for rectification, and the output end of the drive circuit is connected to the rectifier tube of the rectifier module to generate a drive signal to drive the rectifier tube of the rectifier circuit to turn on or off.

2. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 1, characterized in that: The output current detection circuit is composed of an output detection resistor and a current detection chip; one end of the output detection resistor is connected to the output end of the filter circuit, and the other end of the output detection resistor is connected to the load. The two input ends of the current detection chip are respectively connected to the two ends of the current detection resistor, and the output reflects the change in the load size. The calculation formula of the signal is: V io =ki o R s Among them, i o is the output current of the rectifier circuit, V io is the voltage signal detected by the output current circuit, R s is the output detection resistance value, and k is the amplification factor of the current detection chip.

3. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 1, characterized in that: The dead zone control circuit includes a voltage follower, a first comparator, a dead zone adjustment enable tube and a synchronous rectification enable module; the input end of the voltage follower is the input end of the dead zone control circuit, and the input voltage signal V representing the load size is io The output end of the voltage follower, the drain of the dead zone adjustment enable tube and the positive input end of the first comparator are connected, and the output end of the voltage follower outputs a voltage signal V that represents the load size. io Equal current sense voltage V ios The negative input terminal of the first comparator inputs the set voltage threshold V ref The output end of the first comparator is connected to the gate of the dead zone adjustment enabling tube, the control end of the synchronous rectification enabling module is connected to the output end of the first comparator, and the signal output by the output end of the first comparator is the enabling signal SR-en.

4. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 3, characterized in that: When the rectifier circuit is driven in a self-driving manner, the rectifier module includes a primary MOS tube, a first MOS tube Q1 for rectification, and a second MOS tube Q2 for freewheeling; when the primary MOS tube driving signal is on a rising edge, the second MOS tube driving signal is on a falling edge, and the first MOS tube driving signal is on a rising edge after a fixed dead time tdead; When the rectifier circuit is driven in a self-driving manner, the output end of the synchronous rectification enabling module is connected to the control end of the first MOS tube and the second MOS tube. If the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enabling module controls the first MOS tube and the second MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enabling module does not control the first MOS tube and the second MOS tube.

5. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 3, characterized in that: When the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the rectifier module includes an SR-MOS tube; When the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the output end of the synchronous rectification enable module is connected to the control end of the SR-MOS tube; if the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the SR-MOS tube to turn off; if it reaches the set threshold, the synchronous rectification enable module does not control the SR-MOS tube.

6. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 4, characterized in that: When the rectifier circuit is driven in a self-driving mode, the driving circuit includes a second comparator, an OR gate, a NOT gate, a first resistor Rd, a first capacitor Cd, and a first diode. The positive input end of the second comparator is used as the input end of the driving circuit, and the current detection signal V is input. ios , the negative phase input end of the second comparator, one end of the first resistor, one end of the first diode and one end of the first capacitor are connected, the other end of the first capacitor is connected to the ground, the other end of the first resistor, the other end of the first diode, the gate of the first MOS tube and the input end of the NOT gate are connected; the output end of the second comparator is connected to the first input end of the OR gate, the output end of the NOT gate is connected to the second input end of the OR gate, and the output end of the OR gate is connected to the gate of the second MOS tube; The driving circuit makes the primary MOS tube driving signal of the rectifier module rise, and the falling edge of the second MOS tube driving signal is delayed by a time Δt related to the load: Among them, V c The first resistor Rd and the first capacitor Cd are charged with a delay voltage; d is the resistance value of the first resistor Rd; V gd It is the primary MOS tube driving signal.

7. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 6, characterized in that: Δt sets a maximum delay time tdmax, tdmax is equal to the fixed dead time tdead between the falling edge of the second MOS tube drive signal and the rising edge of the first MOS tube drive signal due to self-drive. When the delay Δt of the second MOS tube exceeds tdmax, the second MOS tube is turned off.

8. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 5, characterized in that: When the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the driver circuit includes a driver chip with a dead zone adjustment function and a control module. The input end of the control module inputs a current detection signal V ios , the control module amplifies the current detection signal and outputs the feedback voltage V z : V z =k'×V ios Where, k′ is the magnification of the control module; The feedback voltage V z The first input terminal of the driver chip with the function of adjusting the dead zone is connected to the source of the SR-MOS tube for feedback. The second input terminal of the driver chip with the function of adjusting the dead zone is connected to the drain of the SR-MOS tube. The driver circuit automatically adjusts the dead zone time of the SR-MOS tube according to the input of the first and second input terminals. The dead zone time adjusted by the driver chip with the function of adjusting the dead zone is proportional to V z Positive correlation.

9. The switching power supply dead zone automatic adjustment synchronous rectification circuit according to claim 8, characterized in that: When the driver chip with the dead zone adjustment function is a driver chip that needs to inject current, the driver circuit includes a second resistor to adjust the current detection voltage V ios The second resistor is connected in series and then connected to the current injection terminal of the driving chip.

10. A method for automatically adjusting synchronous rectification in dead zone of a switching power supply using the rectification circuit according to any one of claims 1 to 9, characterized in that: Includes the following: Collect the output current and convert it into a voltage signal V that represents the load size io ; The voltage signal is output as a current sensing voltage V of the same magnitude through a voltage follower. ios ; Then the current sensing voltage V ios The first comparator is connected to the set voltage threshold V ref Value comparison, if greater than the threshold V ref , the output of the first comparator is high level, controlling the dead zone adjustment enable tube to turn on, and V ios Sent to the driving circuit; At the same time, the output end of the first comparator outputs the enable signal SR-en of the synchronous rectification module to determine the driving mode of the rectification circuit. If the rectification circuit is self-driven and the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the first MOS tube and the second MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enable module does not control the first MOS tube and the second MOS tube; if the rectification circuit is driven by a driver chip with a dead zone adjustment function and the enable signal SR-en does not reach the set enable threshold, the synchronous rectification enable module controls the SR-MOS tube to be turned off. If the set threshold is reached, the synchronous rectification enable module does not control the SR-MOS tube; If the rectifier circuit is self-driven, the control signal V gd The first capacitor Cd is charged through the first resistor Rd, and the output capacitor voltage V c , the capacitor voltage V c With the current sense voltage V ios When the capacitor voltage V c Less than V ios When the output signal of the second comparator V gQ2d is high level, when the capacitor voltage V c Greater than or equal to the current sensing voltage V ios When V gQ2d is low level; capacitor voltage V c The output V is inverted by the NOT gate gQ2 The first input and the second output of the OR gate are input with V gQ2d With V gQ2 signal, output delayed driving signal V gQ2 ', so that the delay will be automatically adjusted with the load size, when the control signal V gd When it becomes low, the first capacitor Cd is automatically discharged; If the rectifier circuit is driven by a driver chip with a dead zone adjustment function, the current detection signal V ios Amplify the feedback voltage V z , connect it to the source of the SR-MOS tube for feedback. The driver chip with the dead zone adjustment function automatically adjusts the dead zone time of the SR-MOS tube by detecting the source and drain voltage of the SR-MOS tube. After feedback, the dead zone time adjusted by the driver chip with the dead zone adjustment function is the same as V z Positive correlation.

11. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into a processor, the method for automatically adjusting synchronous rectification in the dead zone of a switching power supply according to claim 10 is implemented.

12. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for automatically adjusting synchronous rectification of a switching power supply dead zone according to claim 10 is implemented.

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