TWI798702B - Synchronous Rectification Controller - Google Patents

Abstract

The present invention proposes a synchronous rectification controller suitable for power conversion circuits. The synchronous rectification controller includes: a first terminal, a second terminal and a coil signal processing unit. The first terminal is used for coupling to the auxiliary winding of the power conversion circuit. The second terminal is used for coupling to the secondary side of the power conversion circuit. The coil signal processing unit is connected to the first end and is used to detect the excitation state of the magnetic core of the power conversion circuit through the auxiliary winding; wherein, when the coil signal processing unit detects the trigger signal of the auxiliary winding, it drives the second end to send synchronization signal to control the secondary side of the power conversion circuit.

Description

Synchronous Rectification Controller

The present invention relates to a power conversion circuit technology, more particularly to a synchronous rectification controller used in a power conversion circuit.

In a conventional power conversion circuit, such as a DC-to-DC switching power conversion circuit, an analog signal is usually fed back from the secondary side of the power conversion circuit to the primary side of the power conversion circuit as a basis for adjustment. However, the method of feeding back analog signals from the secondary side of the power conversion circuit and the circuit structure make it difficult to directly synchronize the primary side and the secondary side of the power conversion circuit, so it is also difficult to achieve synchronous rectification on the secondary side of the power conversion circuit. to precise control.

Therefore, the conventional synchronous rectification control technology of the power conversion circuit still needs to be improved.

One object of the present invention is to provide a synchronous rectification controller for a power conversion circuit. The synchronous rectification controller can detect the trigger signal of the primary side or the secondary side of the power conversion circuit, and send a synchronous control signal to the power conversion circuit accordingly. The secondary side of the circuit, so that the primary side and secondary side of the power conversion circuit are directly synchronized and precisely controlled.

To achieve at least the above objectives, the present invention provides a synchronous rectification controller suitable for power conversion circuits, the synchronous rectification controller includes: a first terminal, a second terminal and a coil signal processing unit. The first end is coupled to an auxiliary winding of the power conversion circuit. The second end is used to couple to the secondary side of the power conversion circuit. The coil signal processing unit is connected to the first end and is used to detect the magnetic excitation state of the magnetic core of the power conversion circuit through the auxiliary winding; wherein, when the coil signal processing unit detects a trigger signal of the auxiliary winding, Then drive the second end to send a synchronous signal, so as to control the secondary side of the power conversion circuit.

In some embodiments, the synchronous rectification controller further includes: a switch detection unit and a first logic unit. The switch detection unit is used for detecting the switching of the primary side of the power conversion circuit. The two input ends of the first logic unit are respectively coupled to the coil signal processing unit and the switch detection unit, and the output end of the first logic unit is coupled to the second end.

In some embodiments, the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the second terminal through the coupling unit, wherein the coupling unit is an optical coupling unit, a magnetic One of a coupling unit and a capacitive coupling unit.

In some embodiments, the synchronous rectification controller further includes: a voltage detection unit and a second logic unit. The voltage detection unit is used for detecting a detection signal of the secondary side of the power conversion circuit. The two input terminals of the second logic unit are respectively coupled to the output terminal of the first logic unit and the voltage detection unit, the output terminal of the second logic unit is coupled to the second terminal, and the second logic unit is used for to generate the synchronization signal.

In some embodiments, the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the second logic unit through the coupling unit, wherein the coupling unit is an optical coupling unit, One of a magnetic coupling unit and a capacitive coupling unit.

In some embodiments, the synchronous rectification controller further includes: a first logic unit and a comparison unit. The first logic unit is coupled to the coil signal processing unit. The two input terminals of the comparison unit are respectively used to receive a reference signal and a detection signal of the secondary side of the power conversion circuit. The one enable terminal of the comparison unit is coupled to the output terminal of the first logic unit, the output terminal of the comparison unit is coupled to the second terminal, and the comparison unit is used to compare the reference signal and the detection signal to generate the synchronization signal.

In some embodiments, the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the comparison unit through the coupling unit, wherein the coupling unit is an optical coupling unit, a magnetic coupling unit One of the unit and the capacitive coupling unit.

In some embodiments, the synchronous rectification controller further includes: a switch detection unit, a first logic unit and a comparison unit. The switch detection unit is used for detecting the switching of the primary side of the power conversion circuit. The two input terminals of the first logic unit are respectively coupled to the coil signal processing unit and the switch detection unit. The two input terminals of the comparison unit are respectively used to receive a reference signal and a detection signal of the secondary side of the power conversion circuit, an enable terminal of the comparison unit is coupled to the output terminal of the first logic unit, and the comparison unit is connected to an output terminal of the first logic unit. The output end of the unit is coupled to the second end, and the comparison unit is used for comparing the reference signal and the detection signal to generate the synchronous signal.

In some embodiments, the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the comparison unit through the coupling unit, wherein the coupling unit is an optical coupling unit, a magnetic coupling unit One of the unit and the capacitive coupling unit.

In some embodiments, the synchronous rectification controller further includes: a coupling unit, wherein the coil signal processing unit is coupled to the second end through the coupling unit, wherein the coupling unit is an optical coupling unit, a magnetic coupling unit, and a capacitor One of the coupling units.

In some embodiments, the auxiliary winding of the power conversion circuit is disposed on the primary side or the secondary side of the power conversion circuit.

In some embodiments, the synchronous rectification controller is an integrated circuit.

Multiple embodiments of a synchronous rectification controller for a power conversion circuit are proposed above. In this way, the synchronous rectification controller can be implemented to detect the trigger signal of the primary side or the secondary side of the power conversion circuit, and accordingly send the synchronous control signal to the secondary side of the power conversion circuit, so that the primary side of the power conversion circuit and the secondary side are directly synchronized and achieve precise control.

1. 1A-1F: synchronous rectification controller

11, 11A, 11B, 11C, 11D: first end

12, 12A, 12B, 12C, 12D: second terminal

9, 9A, 9B: power conversion circuit

91: Primary side of power conversion circuit

92: Secondary side of the power conversion circuit

93, 93A, 93B: auxiliary winding

110: Coil signal processing unit

120: Coupling unit

130: switch detection unit

140: The first logic unit

150: Voltage detection unit

160: second logic unit

170: Comparison unit

V _IN : input voltage

V _OUT : output voltage

FIG. 1 is a schematic block diagram of an architecture of an embodiment of a synchronous rectification controller.

FIG. 2 is a schematic block diagram of an embodiment of the synchronous rectification controller based on FIG. 1 .

FIG. 3 is a schematic block diagram of another embodiment of the synchronous rectification controller based on FIG. 1 .

FIG. 4 is a schematic block diagram of another embodiment of the synchronous rectification controller based on FIG. 1 .

FIG. 5 is a schematic block diagram of another embodiment of the synchronous rectification controller based on FIG. 1 .

FIG. 6A is a schematic block diagram of an embodiment based on the synchronous rectification controller of FIG. 1 applied to a power conversion circuit.

FIG. 6B is a schematic block diagram of another embodiment of applying the synchronous rectification controller in FIG. 1 to a power conversion circuit.

FIG. 7 is a schematic block diagram of an embodiment in which the coil signal processing unit detects a trigger signal.

FIG. 8 is a schematic block diagram of an embodiment of a coil signal processing unit.

In order to fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments and accompanying drawings, as follows:

Please refer to FIG. 1 , which is a schematic block diagram of an architecture of an embodiment of a synchronous rectification controller 1 . As shown in FIG. 1 , the synchronous rectification controller 1 is suitable for the power conversion circuit 9 , and the synchronous rectification controller 1 includes: a first terminal 11 , a second terminal 12 and a coil signal processing unit 110 . The first terminal 11 is coupled to an auxiliary winding 93 of the power conversion circuit 9 . The second terminal 12 is used for coupling to the secondary side 92 of the power conversion circuit 9 . The coil signal processing unit 110 is connected to the first end 11 and is used to detect the magnetic excitation state of the magnetic core of the power conversion circuit 9 through the auxiliary winding 93; wherein, when the coil signal processing unit 110 detects the auxiliary winding A trigger signal drives the second terminal 12 to send a synchronous signal S _SYNC , thereby controlling the secondary side 92 of the power conversion circuit 9 . In addition, the magnetic excitation state of the magnetic core includes the process of excitation and demagnetization of the magnetic core. The coil signal processing unit 110 detects the induced voltage of the auxiliary winding 93 to accurately obtain information on the change of the magnetic excitation state.

For example, as shown in FIG. 1 , the power conversion circuit 9 includes a primary side 91 and a secondary side 92. The power conversion circuit 9 receives an input voltage V _IN through the primary side 91 and outputs a power converted output through the secondary side 92. voltage V _OUT . For example, the power conversion circuit 9 is a DC-to-DC switching power conversion circuit. The primary side 91 and the secondary side 92 are respectively switched by switches implemented by transistors controlled by signals to perform power conversion. In addition, in the overall circuit of the power conversion circuit 9, there is a main transformer, and the transformer has a magnetic core (magnetic core), on which there are primary side windings (represented by 91 in Figure 1), secondary side windings (such as 1 represented by 92) and at least one auxiliary winding 93. The auxiliary winding 93 can be disposed on the primary side 91 (as shown in FIG. 1 and FIG. 6A ); in another example, the auxiliary winding 93 can also be disposed on the secondary side 92 (please refer to FIG. 6B ). In order to achieve real-time and precise control of the primary side 91 and the secondary side 92 of the power conversion circuit 9 , outside the power conversion circuit 9 , the synchronous rectification controller 1 is used to control the synchronous rectification. For example, the synchronous rectification controller 1 can be implemented as an integrated circuit for ease of use. In this way, the synchronous rectification controller 1 can be provided with a plurality of connection terminals with different functions, as shown in the embodiments of the synchronous rectification controller 1 in FIGS. Configured synchronous rectification controller for use in circuit design and implementation.

The internal circuit of the synchronous rectification controller 1 has a coil signal processing unit 110. The coil signal processing unit 110 can be implemented as a circuit using a comparator (as shown in FIG. 8 ) and is electrically coupled to the primary side of the power conversion circuit 9 91 Magnetically coupled auxiliary winding 93 to detect a trigger signal. The trigger signal is, for example, the voltage dip waveform shown in FIG. 7 . When the trigger signal is detected by the coil signal processing unit 110, the coil signal processing unit 110 drives the second terminal 12 to send a synchronization signal S _SYNC , thereby controlling the secondary side 92 of the power conversion circuit 9 for synchronization operation.

In some embodiments, the synchronous rectification controller 1 can generate the synchronous signal S _SYNC in various manners, such as directly or indirectly based on the trigger signal, or further combined with other conditions. Other conditions, for example, the signal of the primary side 91 of the power conversion circuit 9, such as the control signal of the control switch (such as a transistor) of the primary side 91 of the power conversion circuit 9; and/or the secondary side of the power conversion circuit 9 The signal on the side 92, such as the detection signal of the secondary side 92 of the power conversion circuit 9, such as the signal (such as the voltage of the source or drain) of the non-control end of the switch (such as a transistor). Therefore, various embodiments under the architecture of the synchronous rectification controller 1 are illustrated below.

Please refer to FIG. 2 , which is a schematic block diagram of an embodiment of the synchronous rectification controller based on FIG. 1 . As shown in FIG. 2 , the synchronous rectification controller 1A is an embodiment based on the synchronous rectification controller 1 , and has a first terminal 11A, a second terminal 12A, and a coil signal processing unit 110 . Compared with the synchronous rectification controller 1, the synchronous rectification controller 1A further includes: a coupling unit 120, which has a coupling input end and a coupling output end, wherein the coupling input end is coupled to the coil signal processing unit 110, and The coupled output end is electrically coupled to the second end 12A.

The synchronous rectification controller 1A in FIG. 2 can obtain electrical isolation between the coupling input terminal and the coupling output terminal by using the coupling unit 120 (as shown in FIG. 2, the dotted line represents isolation), thereby reducing the signal interference of the primary side and the secondary side. the benefits of.

For example, the synchronous rectification controller 1A can be implemented as an integrated circuit for convenience. The synchronous rectification controller 1A can be provided with multiple connection terminals with different functions, such as AuxIN (for example, representing the auxiliary winding signal input terminal; such as the first terminal 11A), SYNC (for example, representing the synchronous signal output terminal; such as the second terminal 12A). Connect the primary side 91 and the secondary side 92 of the power conversion circuit 9 to detect the trigger signal and output the synchronous signal S _SYNC ; such as Vccp and Vccs are respectively used to connect the primary side 91 and the secondary side 92 of the power conversion circuit 9 The power supply is used for the internal circuit of the synchronous rectification controller 1A; such as GNDP and GNDS are respectively used to connect the ground terminals of the primary side 91 and the secondary side 92 of the power conversion circuit 9 for the internal use of the synchronous rectification controller 1A. circuit use. Also, the same symbols in the embodiments shown in FIG. 3 to FIG. 5 represent the same connection ends, so details are not repeated here.

In some embodiments, the coupling unit 120 can be realized by an optical coupling unit. In some other embodiments, the coupling unit 120 can also be implemented as a magnetic coupling unit. In some other embodiments, the coupling unit 120 can also be implemented as a capacitive coupling unit.

Please refer to FIG. 3 , which is a schematic block diagram of another embodiment of the synchronous rectification controller based on FIG. 1 . As shown in FIG. 3 , the synchronous rectification controller 1B is an embodiment based on the synchronous rectification controller 1 , and has a first terminal 11B, a second terminal 12B, and a coil signal processing unit 110 . Compared with the synchronous rectification controller 1A, the synchronous rectification controller 1B further includes: a switch detection unit 130 and a first logic unit 140 . The switch detection unit 130 is used for detecting the switching of the primary side 91 of the power conversion circuit 9 , for example, receiving a control signal of a switching switch (such as a transistor) of the primary side 91 of the power conversion circuit 9 . The two of the first logic unit 140 The input ends are respectively coupled to the coil signal processing unit 110 and the switch detection unit 130 , and the output end of the first logic unit 140 is coupled to the coupling input end of the coupling unit 120 .

For example, the first logic unit 140 performs a logical sum (AND) operation. Through the coil signal processing unit 110, the switch detection unit 130, and the first logic unit 140, the synchronous rectification controller 1B can further use more complex conditions as the basis for synchronous rectification controller to generate the synchronous signal S _SYNC , thereby contributing to more For direct, instant and precise synchronous control. For example, the synchronous rectification controllers in Fig. 3, Fig. 4, and Fig. 5 adopt the same architecture for the first-end circuits, and the corresponding second-end circuits can be implemented with different architectures for customization. Or meet the needs of the synchronous control of the power conversion circuit to be applied in the individual design of the synchronous rectification controller.

Please refer to FIG. 3 again. In one embodiment, the synchronous rectification controller 1B further includes: a voltage detection unit 150 and a second logic unit 160 . The voltage detection unit 150 is used for detecting a detection signal of the secondary side 92 of the power conversion circuit 9 . The two input terminals of the second logic unit 160 are coupled to the coupling output terminal and the voltage detection unit 150, the output terminals of the second logic unit 160 are coupled to the second terminal 12B, and the second logic unit 160 is used for Generate the synchronization signal S _SYNC .

In addition, general synchronous rectification refers to replacing the diode with a switching element in the charging circuit of the secondary side of the power conversion circuit. The switching element is, for example, a field effect transistor (FET), and the switching element still has a slight impedance (for example, 200 milliohm mOhm, depending on the operating current) in the conduction state. The aforementioned voltage detection unit is, for example, by detecting the voltage caused by the reaction current of the secondary side of the power conversion circuit passing through the switching element, so as to detect when the current drops to almost zero (the reaction current of the flyback type is about linearly down to zero).

For example, the second logic unit 160 performs a logical sum (AND) operation. Further through the voltage detection unit 150 and a second logic unit 160, the synchronous rectification controller 1B can further use more complex and precise conditions as the basis for the synchronous rectification controller to generate the synchronous signal S _SYNC , thus contributing to a more direct , Instant and precise synchronous control. For example, the detection signal is the detection signal from the secondary side 92 of the power conversion circuit 9, such as the signal (such as the voltage of the source or drain) of the non-control end of the switch (such as a transistor), as shown in Figure 6A or S _FB in Figure 6B.

For example, the synchronous rectification controller 1B can be implemented as an integrated circuit for ease of use. The synchronous rectification controller 1B can be provided with a plurality of connection terminals with different functions. In addition to the above-mentioned connection terminals, SWIN and Vdrain are respectively used to connect to the control switching switch of the primary side 91 of the power conversion circuit 9 (such as The control signal of the transistor) and the signal of the secondary side 92 (such as the voltage of the drain) are used by the internal circuit of the synchronous rectification controller 1B. Please also refer to FIG. 6A or FIG. 6B. Also, the same symbols in the embodiments shown in FIG. 4 to FIG. 5 represent the same connection ends, so details are not repeated here.

Please refer to FIG. 4 , which is a schematic block diagram of another embodiment of the synchronous rectification controller based on FIG. 1 . As shown in FIG. 4 , the synchronous rectification controller 1C is an embodiment based on the synchronous rectification controller 1 , and has a first terminal 11C, a second terminal 12C, and a coil signal processing unit 110 . Compared with the synchronous rectification controller 1B, the synchronous rectification controller 1C further includes: a switch detection unit 130 and a first logic unit 140 . In some embodiments, the synchronous rectification controller 1C further includes: a comparing unit 170 . The two input terminals of the comparison unit 170 are respectively used to receive a reference signal (such as Vref) and a detection signal (such as the aforementioned S _FB ) of the secondary side 92 of the power conversion circuit 9 ; an enabling terminal of the comparison unit 170 EN is coupled to the coupled output terminal; the output terminal of the comparison unit 170 is coupled to the second terminal 12C. The comparison unit 170 is used to compare the reference signal (such as Vref) and the detection signal (such as the aforementioned S _FB ) to generate the synchronization signal S _SYNC , wherein the comparison unit 170 determines whether to pass the The output terminal of the comparison unit 170 outputs the synchronization signal S _SYNC . The first logic unit 140 controls whether the comparison unit 170 is allowed to output the synchronization signal S _SYNC through the coupling output terminal and the enable terminal EN.

Please refer to FIG. 5 , which is a schematic block diagram of another embodiment of the synchronous rectification controller based on FIG. 1 . As shown in FIG. 5 , the synchronous rectification controller 1D is an embodiment based on the synchronous rectification controller 1 , and has a first terminal 11D, a second terminal 12D, and a coil signal processing unit 110 . Compared with the synchronous rectification controller 1 , the synchronous rectification controller 1D further includes: a switch detection unit 130 , a first logic unit 140 and a comparison unit 170 . The switch detection unit 130 is used for detecting the switching of the first terminal 11 of the power conversion circuit 9 . Two input terminals of the first logic unit 140 are respectively coupled to the coil signal processing unit 110 and the switch detection unit 130 . The two input terminals of the comparison unit 170 are respectively used to receive a reference signal (such as Vref) and a detection signal (such as the aforementioned S _FB ) of the secondary side 9 of the power conversion circuit 9; an enabling terminal of the comparison unit 170 EN is coupled to the output terminal of the first logic unit 140; the output terminal of the comparison unit 170 is coupled to the second terminal 12C. The comparison unit 170 is used to compare the reference signal (such as Vref) and the detection signal (such as the aforementioned S _FB ) to generate the synchronization signal S _SYNC , wherein the comparison unit 170 determines whether to pass the The output terminal of the comparison unit 170 outputs the synchronization signal S _SYNC . The first logic unit 140 controls whether the comparison unit 170 is allowed to output the synchronization signal S _SYNC through the enable terminal EN. In FIG. 5 , the synchronous rectification controller 1D does not use the coupling unit 120 , which can be regarded as a simplified implementation of the synchronous rectification controller 1C.

Please refer to FIG. 6A, which is a schematic block diagram of an embodiment based on the synchronous rectification controller 1E of FIG. 1 applied to a power conversion circuit 9A, wherein the auxiliary winding 93A of the power conversion circuit 9A is arranged on the primary side of the power conversion circuit 9A . Please refer to FIG. 6B, which is a schematic block diagram of another embodiment based on the synchronous rectification controller 1F of FIG. Secondary side. As shown in FIG. 6A or FIG. 6B , the synchronous rectification controller 1E or 1F schematically represents the embodiment of the aforementioned synchronous rectification controller in FIGS. 2 to 5 . For example, the power conversion circuit 9A or 9B is a flyback power converter; the switches on the primary side and the secondary side of the power conversion circuit are implemented by transistors Q1 and Q2 respectively, and the control signal of transistor Q1 is PGate, and the synchronous signal of transistor Q2 is S _SYNC , wherein PGND and SGND represent the ground terminals of the primary side and the secondary side respectively. In other embodiments, the embodiments of the synchronous rectification controller can also be applied to other suitable power converters through appropriate changes, and thus are not limited by the above examples.

In some other embodiments, the switch on the primary side of the power conversion circuit is directly controlled by the secondary side of the power conversion circuit. At this time, the switch detection unit can be configured to be coupled to the secondary side of the power conversion circuit for detection . In addition, in some embodiments, an auxiliary winding is provided on the secondary side of the power conversion circuit (as shown in FIG. 6B ), so the coil signal processing unit can also be configured to be coupled to the auxiliary winding on the secondary side of the power conversion circuit to for detection. In the application scenario where the auxiliary coil in FIG. 6B is placed on the secondary side of the power conversion circuit, for example, the architecture of FIG. 5 is used to implement a synchronous rectification controller; On the secondary side, the switch control is placed on the primary side of the power conversion circuit. If isolation requires a coupler, the coupler can be placed between the switch detection unit 130 and the first logic unit 140 .

In addition, in the above-mentioned embodiments of FIG. 2 to FIG. 4, the coupling unit 120 is optional, and it can be selected whether it needs to be included in the synchronous rectification controller according to, for example, the auxiliary coil is placed on the primary side or the secondary side of the power conversion circuit. Use a coupling unit.

Some examples of applicable conditions for judging the synchronous control are listed below, such as being properly adjusted to implement the embodiments shown in FIGS. 2 to 5 .

In some examples, the switching switch (such as the transistor Q2) on the secondary side of the power conversion circuit (such as 9A or 9B) controlled by the synchronous rectification controller, the necessary condition (such as logic and (AND) to start (maintain) conduction ) to calculate the condition) is: (1) When the main switch (such as transistor Q1) of the primary side is closed (OFF), one of the primary side is closed, and the signal is sent to the secondary side, for example, the output terminal of the optical coupling is used to send the signal and (2) coils The positive voltage detected by the signal processing unit is the electromotive force (emf) generated by the energy of the magnetic core, and the electromotive force corresponding to the release of the magnetic field energy can also be used to enable the synchronous rectification switch. In addition, conditions can be further added, such as (3) the drain of the transistor on the secondary side detects a negative voltage, wherein the secondary side detects a negative voltage (such as using the voltage detection unit 150), and the amplifier ( Such as the comparison unit 170) to respond to output a synchronization signal.

In some examples, the switching switch (such as transistor Q2) on the secondary side of the power conversion circuit (such as 9A or 9B) controlled by the synchronous rectification controller is turned off to turn off the sufficient condition (such as logic or (OR) to Conditions for operation) are: (1) The main switch on the primary side is ON (for example, the power conversion circuit is a flyback type (flyback)), and when the first test is about to be turned on, the signal is sent first, such as using an optical coupling unit Forced output of low-level signals; (2) The coil signal processing unit detects a sudden drop in voltage, and when the energy of the magnetic core is about to be exhausted, the electromotive force (emf) drops significantly, and immediately sends a signal; (3) The transistor on the secondary side The drain cannot maintain a negative voltage. For example, if the setting is maintained at -40mV, the gate voltage will drop as the current drops, or once the secondary side turns from negative voltage to positive voltage (20mV) after it is turned on, the logic lock will be closed. (4) The secondary side is locked. In the locked state, the drain voltage turns negative and cannot be restarted to avoid noise or vibration. The unlocking of the lock needs to wait for the primary side (such as the light-emitting diode (LED) of the optical coupling unit The change from turning off (off) to conducting (on)).

Please refer to FIG. 8 , which is a schematic block diagram of an embodiment of the coil signal processing unit. As shown above, the coil signal processing unit 110 in the above embodiment can be realized by using a comparator circuit. As shown in FIG. 8 , an embodiment of the coil signal processing unit can be realized by including a comparator, a resistor, a capacitor and a diode, wherein a positive input terminal of the comparator is used to receive the reference signal V _ref2 through a resistor, and the comparator’s A negative input terminal is used to receive the signal from the auxiliary winding through a circuit including a resistor, a capacitor and a diode, such as being coupled to the auxiliary winding through AuxIN (representing the auxiliary winding signal input terminal; such as the first terminal 11A) to receive the signal signal. The output of the comparator provides a small amount of positive feedback to the positive input, which is an implementation of a Schmitt trigger. In some embodiments, the coil signal processing unit can also be implemented according to another implementation manner of a Schmitt trigger.

As mentioned above, several embodiments of a synchronous rectification controller for a power conversion circuit are proposed above. In this way, the synchronous rectification controller can be implemented to detect the trigger signal of the primary side or the secondary side of the power conversion circuit, and accordingly send the synchronous control signal to the secondary side of the power conversion circuit, so that the primary side of the power conversion circuit and the secondary side are directly synchronized and achieve precise control.

The present invention has been disclosed above with preferred embodiments, but those skilled in the art should understand that the embodiments are only used to describe the present invention, and should not be construed as limiting the scope of the present invention. It should be noted that all changes and substitutions equivalent to these embodiments should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of the patent application.

1: Synchronous rectification controller

11: first end

12: Second end

9: Power conversion circuit

91: Primary side of power conversion circuit

92: Secondary side of the power conversion circuit

93: Auxiliary winding

110: Coil signal processing unit

V _IN : input voltage

V _OUT : output voltage

Claims (8)

A synchronous rectification controller suitable for a power conversion circuit, the synchronous rectification controller includes: a first terminal for coupling to an auxiliary winding of the power conversion circuit; a second terminal for coupling to the power supply the secondary side of the conversion circuit; and a coil signal processing unit connected to the first end and used to detect the magnetic excitation state of the magnetic core of the power conversion circuit through the auxiliary winding; wherein, when the coil The signal processing unit detects a trigger signal of the auxiliary winding, and then drives the second terminal to send a synchronous signal, thereby controlling the secondary side of the power conversion circuit; wherein the synchronous rectification controller further includes: a switch detection A unit for detecting the switching of the primary side of the power conversion circuit; a first logic unit, the two input ends of the first logic unit are respectively coupled to the coil signal processing unit and the switch detection unit, the first The output end of the logic unit is coupled to the second end. The synchronous rectification controller as described in claim 1, wherein the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the second terminal through the coupling unit, wherein the coupling The unit is one of an optical coupling unit, a magnetic coupling unit and a capacitive coupling unit. The synchronous rectification controller as described in claim 1, wherein the synchronous rectification controller further includes: a voltage detection unit for detecting a detection signal of the secondary side of the power conversion circuit; a second logic unit , the two input ends of the second logic unit are respectively coupled to the output end of the first logic unit and the voltage detection unit, the output end of the second logic unit is coupled to the second end, and the second logic unit used to generate the synchronization signal. The synchronous rectification controller as described in claim 3, wherein the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the second logic unit through the coupling unit, wherein the The coupling unit is one of an optical coupling unit, a magnetic coupling unit and a capacitive coupling unit. The synchronous rectification controller as described in claim 1, wherein the synchronous rectification controller further includes: a comparison unit, the two input terminals of the comparison unit are used to receive a reference signal and a secondary side of the power conversion circuit respectively A detection signal, the one enable terminal of the comparison unit is coupled to the output terminal of the first logic unit, the output terminal of the comparison unit is coupled to the second terminal, and the comparison unit is used for comparing the reference signal and the detection signal to generate the synchronization signal. The synchronous rectification controller as described in claim item 5, wherein the synchronous rectification controller further includes: a coupling unit, wherein the output terminal of the first logic unit is coupled to the comparison unit through the coupling unit, wherein the coupling unit It is one of optical coupling unit, magnetic coupling unit and capacitive coupling unit. The synchronous rectification controller according to claim 1, wherein the auxiliary winding of the power conversion circuit is arranged on the primary side or the secondary side of the power conversion circuit. The synchronous rectification controller according to claim 1, wherein the synchronous rectification controller is an integrated circuit.

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