Synchronous rectifier controller

Abstract

This invention proposes a synchronous rectification controller suitable for power conversion circuits. The synchronous rectification controller includes a first terminal, a second terminal, and a switch detection unit. The first terminal is coupled to the primary side of the power conversion circuit. The second terminal is coupled to the secondary side of the power conversion circuit. The switch detection unit, coupled to the first terminal, detects the switching of the primary side of the power conversion circuit. When the switch detection unit detects a trigger signal, it drives the second terminal to send a synchronization signal, thereby controlling the secondary side of the power conversion circuit.

Description

Technical Field

[0001] This invention relates to a power conversion circuit technology, and more particularly to a synchronous rectifier controller for a power conversion circuit. Background Technology

[0002] In existing power conversion circuits, such as DC-DC switching power conversion circuits, analog signals are typically fed back from the secondary side of the power conversion circuit to the primary side as a basis for adjustment. However, this method of feeding back analog signals from the secondary side of the power conversion circuit and the circuit architecture make it difficult to directly synchronize the primary and secondary sides of the power conversion circuit, thus making it difficult to achieve precise control over the synchronous rectification operation of the secondary side of the power conversion circuit.

[0003] Therefore, the synchronous rectification control technology of existing power conversion circuits still needs improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a synchronous rectifier controller for a power conversion circuit. The synchronous rectifier controller can detect the trigger signal on the primary or secondary side of the power conversion circuit and send a synchronous control signal to the secondary side of the power conversion circuit accordingly, so that the primary and secondary sides of the power conversion circuit are directly synchronized and precise control is achieved.

[0005] To achieve at least the above-mentioned objectives, 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 switch detection unit. The first terminal is coupled to the primary side of the power conversion circuit. The second terminal is coupled to the secondary side of the power conversion circuit. The switch detection unit, coupled to the first terminal, detects the switching of the primary side of the power conversion circuit. When the switch detection unit detects a trigger signal, it drives the second terminal to send a synchronization signal, thereby controlling the secondary side of the power conversion circuit.

[0006] In some embodiments, the synchronous rectification controller further includes a voltage detection unit and a logic unit. The voltage detection unit is used to detect a detection signal on the secondary side of the power conversion circuit. The two input terminals of the logic unit are respectively coupled to the output terminal of the switch detection unit and the voltage detection unit, and the output terminal of the logic unit is coupled to the second terminal. The logic unit is used to generate the synchronization signal.

[0007] In some embodiments, the synchronous rectification controller further includes a coupling unit, wherein the output terminal of the switch detection unit is coupled to the logic unit through the coupling unit, wherein the coupling unit is one of an optical coupling unit, a magnetic coupling unit, and a capacitive coupling unit.

[0008] In some embodiments, the synchronous rectification controller further includes: a comparison unit, wherein two input terminals of the comparison unit are respectively used to receive a reference signal and a detection signal from the secondary side of the power conversion circuit, the enable terminal of the comparison unit is coupled to the output terminal of the switch detection unit, and 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.

[0009] In some embodiments, the synchronous rectification controller further includes a coupling unit, wherein the output terminal of the switch detection unit is coupled to the comparison unit through the coupling unit, wherein the coupling unit is one of an optical coupling unit, a magnetic coupling unit, and a capacitive coupling unit.

[0010] 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.

[0011] In some embodiments, the synchronous rectification controller is an integrated circuit.

[0012] The above presents several embodiments of a synchronous rectifier controller for a power conversion circuit. Thereby, the synchronous rectifier controller can detect trigger signals on the primary or secondary side of the power conversion circuit and send synchronous control signals to the secondary side of the power conversion circuit accordingly, thereby directly synchronizing the primary and secondary sides of the power conversion circuit and achieving precise control. Attached Figure Description

[0013] Figure 1 A schematic block diagram of the architecture of one implementation of a synchronous rectifier controller;

[0014] Figure 2 For based on Figure 1 A schematic block diagram of one embodiment of a synchronous rectifier controller;

[0015] Figure 3 For based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectification controller;

[0016] Figure 4 For based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectifier controller;

[0017] Figure 5 For based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectifier controller;

[0018] Figure 6A For based on Figure 1 A schematic block diagram of an embodiment of a synchronous rectifier controller applied to a power conversion circuit;

[0019] Figure 6B For based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectification controller applied to a power conversion circuit;

[0020] Figure 7 A schematic block diagram of an embodiment of a switch detection unit detecting a trigger signal; and

[0021] Figure 8 This is a schematic block diagram of one embodiment of a switch detection unit.

[0022] Figure Labels

[0023] 1. 1A-1F Synchronous Rectifier Controller

[0024] 11, 11A, 11B, 11C, 11D First end

[0025] 12, 12A, 12B, 12C, 12D Second End

[0026] 9. 9A, 9B Power Conversion Circuits

[0027] 91. Primary side

[0028] 92 Secondary side

[0029] 93A and 93B auxiliary windings

[0030] 120 coupling units

[0031] 130 Switch Detection Unit

[0032] 150 Voltage Detection Unit

[0033] 160 logic units

[0034] 170 Comparison Units

[0035] V IN Input voltage

[0036] V OUT Output voltage

[0037] S SYNC Synchronization signal Detailed Implementation

[0038] To fully understand the purpose, features, and effects of the present invention, the present invention will now be described in detail with reference to the following specific embodiments and accompanying drawings:

[0039] Please refer to Figure 1 This is a schematic block diagram of the architecture of one embodiment of the synchronous rectifier controller 1. Figure 1 As shown, a synchronous rectification controller 1 is used in a power conversion circuit 9. The synchronous rectification controller 1 includes a first terminal 11, a second terminal 12, and a switch detection unit 130. The first terminal 11 is coupled to the primary side 91 of the power conversion circuit 9. The second terminal 12 is coupled to the secondary side 92 of the power conversion circuit 9. The switch detection unit 130 is coupled to the first terminal 11 and is used to detect the switching of the primary side 91 of the power conversion circuit 9. When the switch detection unit 130 detects a trigger signal, it drives the second terminal 12 to send a synchronization signal S. SYNC This controls the secondary side 92 of the power conversion circuit 9.

[0040] For example, such as Figure 1 As shown, the power conversion circuit 9 includes a primary side 91 and a secondary side 92. The power conversion circuit 9 receives the input voltage V through the primary side 91. IN And through the secondary side 92, the output voltage V after power conversion is output. OUT For example, power conversion circuit 9 is a DC-to-DC switching power conversion circuit, where the primary side 91 and secondary side 92 are switched using switches implemented by signal-controlled transistors to perform power conversion. Furthermore, the overall circuit of power conversion circuit 9 includes a main transformer with a magnetic core on which a primary winding (such as...) is located. Figure 1 (represented by 91), secondary winding (such as...) Figure 1 (represented by 92) and at least one auxiliary winding. The auxiliary winding may be located on the primary side 91 (e.g., Figure 1 , Figure 6A In another example, the auxiliary winding can also be located on the secondary side 92 (see reference). Figure 6B To enable real-time and precise control of the primary side 91 and secondary side 92 of the power conversion circuit 9, a synchronous rectification controller 1 is used for synchronous rectification control outside the power conversion circuit 9. For example, the synchronous rectification controller 1 can be implemented as an integrated circuit for ease of use. Thus, the synchronous rectification controller 1 can be configured with multiple connection terminals with different functions, as shown below. Figures 2-5 The embodiment of the synchronous rectifier controller 1 is shown so that the synchronous rectifier controller with different circuit configurations can be realized according to the type and needs of the power conversion circuit 9, so as to facilitate the use in circuit design and implementation.

[0041] The internal circuit of the synchronous rectifier controller 1 includes a switch detection unit 130, which can be implemented, for example, using a comparator circuit (such as...). Figure 8 (Example) and electrically coupled to the primary side 91 of the power conversion circuit 9 to detect a trigger signal. The trigger signal is, for example,... Figure 7 The waveform shown is a voltage drop. When the switch detection unit 130 detects a trigger signal, it drives the second terminal 12 to send a synchronization signal S. SYNC This controls the secondary side 92 of the power conversion circuit 9 to operate synchronously.

[0042] In some embodiments, the synchronous rectifier controller 1 generates a synchronization signal S. SYNC There are various ways to implement this, such as generating it directly based on or indirectly based on a trigger signal, or generating it in conjunction with other conditions. Other conditions include, for example, signals from the primary side 91 of the power conversion circuit 9, such as control signals from the control switches (e.g., transistors) of the primary side 91 of the power conversion circuit 9; and / or signals from the secondary side 92 of the power conversion circuit 9, such as detection signals from the secondary side 92 of the power conversion circuit 9, such as signals from the non-control terminals of the switches (e.g., transistors) (e.g., the magnitude of the source or drain voltage). Therefore, the following examples illustrate various embodiments of the architecture of the synchronous rectifier controller 1.

[0043] Please refer to Figure 2 It is based on Figure 1 A schematic block diagram of an embodiment of a synchronous rectification controller. (See diagram below.) Figure 2 As shown, the synchronous rectifier controller 1A is an embodiment based on the synchronous rectifier controller 1, and has a first terminal 11A, a second terminal 12A, and a switch detection unit 130. Compared to the synchronous rectifier controller 1, the synchronous rectifier controller 1A further includes a coupling unit 120, which has a coupling input terminal and a coupling output terminal, wherein the coupling input terminal is coupled to the switch detection unit 130, and the coupling output terminal is electrically coupled to the second terminal 12A.

[0044] Figure 2 The synchronous rectifier controller 1A, by utilizing the coupling unit 120, can achieve electrical isolation between the coupling input and coupling output terminals (e.g., Figure 2 The dashed line in the middle represents isolation, which reduces the benefits of primary and secondary signal interference.

[0045] For example, the synchronous rectifier controller 1A can be implemented as an integrated circuit for ease of use. The synchronous rectifier controller 1A can be configured with multiple connection terminals with different functions, such as SWIN (representing a switching signal input terminal; e.g., the first terminal 11A) and SYNC (representing a synchronization signal output terminal; e.g., the second terminal 12A), which are respectively used to connect to the primary side 91 and the secondary side 92 of the power conversion circuit 9 to detect trigger signals and output synchronization signals S. SYNCFor example, Vccp and Vccs are used to connect the power supplies (such as Vcc) of the primary side 91 and secondary side 92 of the power conversion circuit 9, respectively, for use by the internal circuitry of the synchronous rectifier controller 1A; GNDP and GNDS are used to connect the ground terminals of the primary side 91 and secondary side 92 of the power conversion circuit 9, respectively, for use by the internal circuitry of the synchronous rectifier controller 1A. The following... Figures 3-5 In the embodiments, the same symbols represent the same connection ends, so they will not be described again.

[0046] In some embodiments, the coupling unit 120 may be implemented using an optical coupling unit. In other embodiments, the coupling unit 120 may also be implemented using a magnetic coupling unit. In still other embodiments, the coupling unit 120 may also be implemented using a capacitive coupling unit.

[0047] Please refer to Figure 3 It is based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectification controller. (See diagram below.) Figure 3 As shown, the synchronous rectification controller 1B is an embodiment based on the synchronous rectification controller 1, having a first terminal 11B, a second terminal 12B, and a switch detection unit 130. The switch detection unit 130 is used to detect the switching of the primary side 91 of the power conversion circuit 9, for example, receiving the control signal of the switching switch (such as a transistor) of the primary side 91 of the power conversion circuit 9. The synchronous rectification controller 1B also includes a voltage detection unit 150 and a logic unit 160. The voltage detection unit 150 is used to detect the detection signal of the secondary side 92 of the power conversion circuit 9. The two input terminals of the logic unit 160 are respectively coupled to the switch detection unit 130 and coupled to the voltage detection unit 150, and the output terminal of the logic unit 160 is coupled to the second terminal 12B. The logic unit 160 is used to generate the synchronization signal S. SYNC .exist Figure 3 In one embodiment, the switch detection unit 130 is coupled to the logic unit 160 via the coupling unit 120.

[0048] Furthermore, typical synchronous rectification refers to replacing the diode with a switching element in the charging circuit on the secondary side of the power conversion circuit. This switching element is, for example, a field-effect transistor (FET), which still exhibits some impedance in the on-state (e.g., 200 milliohms, depending on the operating current). The aforementioned voltage detection unit detects when the current drops to almost zero (the flyback current drops to zero approximately linearly) by detecting the voltage caused by the reactive current on the secondary side of the power conversion circuit passing through the switching element.

[0049] For example, logic unit 160 performs a logical AND operation. Further via voltage detection unit 150 and logic unit 160, synchronous rectifier controller 1B can utilize more complex and precise conditions to generate a synchronization signal S. SYNC This provides a foundation for more direct, immediate, and precise synchronous control. For example, the detection signal is a signal from the secondary side 92 of the power conversion circuit 9, such as a signal from the non-control terminal of a switching switch (e.g., a transistor) (e.g., the magnitude of the source or drain voltage), such as... Figure 6A or Figure 6B S in FB .

[0050] 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 multiple connection terminals with different functions. In addition to the connection terminals mentioned above, it also includes Vdrain (or denoted as VD) for connecting signals (such as the drain voltage magnitude) to the secondary side 92 of the power conversion circuit 9, for use by the internal circuitry of the synchronous rectification controller 1B. See also... Figure 6A or Figure 6B . the following Figures 4-5 In the embodiments, the same symbols represent the same connection ends, so they will not be described again.

[0051] In other embodiments, another logic unit can be connected after the switch detection unit 130 to perform logical operations or act as a buffer. The synchronous rectifier controller 1B can further utilize more complex conditions to generate a synchronization signal S. SYNC This provides a foundation for more direct, immediate, and precise synchronous control. For example, in... Figure 3 , Figure 4 , Figure 5 The circuits of the synchronous rectifier controller in the first terminal all adopt the same architecture, while the corresponding circuits of the second terminal can be implemented with different architectures in order to customize or to meet the synchronous control needs of the power conversion circuit to be applied in the individual design of the synchronous rectifier controller.

[0052] Please refer to Figure 4 It is based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectification controller. (See diagram below.) Figure 4 As shown, the synchronous rectifier controller 1C is an embodiment based on the synchronous rectifier controller 1, and has a first terminal 11C, a second terminal 12C, and a switch detection unit 130. Compared to the synchronous rectifier controller 1B, the synchronous rectifier controller 1C further includes a comparison 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) from the secondary side 92 of the power conversion circuit 9.FB The enable terminal EN of the comparison unit 170 is coupled to the switch detection unit 130 (e.g., via coupling unit 120); 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 (e.g., Vref) and the detection signal (e.g., the aforementioned S). FB To generate the synchronization signal S SYNC The comparison unit 170 determines whether to output the synchronization signal S through its output terminal based on the signal from the enable terminal EN. SYNC The switch detection unit 130 controls whether the comparison unit 170 allows the output of the synchronization signal S via the coupling output terminal and the enable terminal EN. SYNC .

[0053] Please refer to Figure 5 It is based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectification controller. (See diagram below.) Figure 5 As shown, the synchronous rectifier controller 1D is an embodiment of the synchronous rectifier controller 1C, and includes a first terminal 11D, a second terminal 12D, a switch detection unit 130, and a comparison unit 170. Compared to the synchronous rectifier controller 1C, the synchronous rectifier controller 1D does not use the coupling unit 120. 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) from the secondary side 9 of the power conversion circuit 9. FB The enable terminal EN of the comparison unit 170 is coupled to the output terminal of the switch detection unit 130; 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 (e.g., Vref) and the detection signal (e.g., the aforementioned S). FB To generate the synchronization signal S SYNC The comparison unit 170 determines whether to output the synchronization signal S through its output terminal based on the signal from the enable terminal EN. SYNC The switch detection unit 130 controls the comparison unit 170 to allow the output of the synchronization signal S via the enable terminal EN. SYNC .exist Figure 5 In this embodiment, the synchronous rectifier controller 1D does not use the coupling unit 120, and can be regarded as a simplified implementation of the synchronous rectifier controller 1C.

[0054] Please refer to Figure 6A It is based on Figure 1 A schematic block diagram of an embodiment of a synchronous rectifier controller 1E applied to a power conversion circuit 9A, wherein an auxiliary winding 93A of the power conversion circuit 9A is disposed on the primary side of the power conversion circuit 9A. Please refer to... Figure 6B It is based on Figure 1 A schematic block diagram of another embodiment of the synchronous rectification controller 1F applied to the power conversion circuit 9B, wherein the auxiliary winding 93B of the power conversion circuit 9B is disposed on the secondary side of the power conversion circuit 9B. Figure 6A or Figure 6B As shown, the synchronous rectifier controller 1E or 1F is schematically representing the aforementioned Figures 2-5 An embodiment of the synchronous rectification controller is provided. For example, power conversion circuit 9A or 9B is a flyback power converter; the switching on the primary and secondary sides of the power conversion circuit is implemented using transistors Q1 and Q2, respectively. The control signal (switching signal) of transistor Q1 is PGate, and the synchronization signal of transistor Q2 is S. SYNC Here, PGND and SGND represent the ground terminals on the primary and secondary sides, respectively. In other embodiments, the synchronous rectifier controller can also be appropriately modified for use with other suitable power converters, and is therefore not limited to the examples described above.

[0055] In 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. In this case, the switch detection unit can be configured to be coupled to the secondary side of the power conversion circuit for detection. Additionally, in some embodiments, an auxiliary winding (e.g., ...) is provided on the secondary side of the power conversion circuit. Figure 6B As shown), 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 for detection. Regarding... Figure 6B In applications where the auxiliary coil is placed on the secondary side of a power conversion circuit, for example, using... Figure 5 The architecture is used to implement the synchronous rectification controller.

[0056] In addition, in the above Figures 2-4 In some embodiments, the coupling unit 120 is optional, and whether the coupling unit needs to be used in the synchronous rectifier controller can be selected based on, for example, whether the auxiliary coil is placed on the primary or secondary side of the power conversion circuit.

[0057] The following are some examples of conditions applicable to determining synchronization control, which can be appropriately adjusted to achieve, for example... Figures 2-5 Examples of implementations.

[0058] In some examples, the necessary conditions (such as AND operations) for 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 rectifier controller to start (maintain) conduction are: (1) when the primary side main switch (such as transistor Q1) is closed, a signal is sent to the secondary side, for example, by sending a signal through the output terminal of an optocoupler; and (2) the coil signal processing unit detects a positive voltage, the source of which is the electromotive force (EMF) generated by the magnetic core energy, which is also an indicator of signal lag, wherein the synchronous rectifier switch can also be enabled by the EMF corresponding to the release of magnetic field energy. In addition, conditions can be further added, such as (3) a negative voltage is detected at the drain of the transistor on the secondary side, wherein the secondary side detects a negative voltage (such as by using voltage detection unit 150), and an amplifier (such as comparator unit 170) can be used to respond to and output a synchronization signal.

[0059] In some examples, the sufficient condition (e.g., using a logical OR operation) for turning off the secondary-side switching switch (e.g., transistor Q2) of the power conversion circuit (e.g., 9A or 9B) controlled by the synchronous rectifier controller is: (1) the primary-side main switch is ON (e.g., the power conversion circuit is flyback). (1) When the primary side is about to be turned on, a signal is sent first, such as using an optocoupler unit to force the output of a low-level signal; (2) The coil signal processing unit detects a sudden drop in voltage, where the electromotive force (emf) drops significantly when the magnetic core energy is about to be exhausted, and a signal is sent immediately; (3) The drain of the transistor on the secondary side cannot maintain a negative voltage, where for example, it is set to maintain at -40mV, the gate voltage drops as the current decreases, or after being turned on, once the secondary side changes from a negative voltage to a positive voltage (20mV), the logic locks the off state; (4) The secondary side is locked, where the drain voltage turns negative and cannot be restarted to avoid noise or oscillation. The unlocking of the lock depends on the change of the primary side (such as the light-emitting diode (LED) of the optocoupler unit changing from off to on).

[0060] Please refer to Figure 8 This is a schematic block diagram of one embodiment of the switch detection unit 130. As shown above, the switch detection unit 130 in the above embodiment can be implemented using comparator circuitry. Figure 8 As shown, one embodiment of the switch detection unit 130 may include a comparator, a resistor, and a capacitor, wherein the negative input terminal of the comparator is used to receive a reference signal V through a resistor. ref2The positive input of the comparator receives a signal from the primary side 91 of the power conversion circuit 9 via a circuit containing resistors and capacitors, such as through SWIN (e.g., representing the switching signal input; e.g., the first terminal 11A). The output of the comparator provides positive feedback to the positive input, which is one implementation of a Schmitt trigger.

[0061] As described above, several embodiments of a synchronous rectifier controller for a power conversion circuit are proposed. Accordingly, the synchronous rectifier controller can detect trigger signals on the primary or secondary side of the power conversion circuit and send synchronization control signals to the secondary side of the power conversion circuit, thereby directly synchronizing the primary and secondary sides of the power conversion circuit and achieving precise control.

[0062] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that the embodiments are merely illustrative and should not be construed as limiting the scope of the invention. It should be noted that all variations and substitutions equivalent to the described embodiments should be considered within the scope of the present invention. Therefore, the scope of protection of the present invention is defined by the claims.

Claims

1. A synchronous rectification controller suitable for use in a power conversion circuit, characterized by, The synchronous rectification controller includes: The first terminal is used to couple to the primary side of the power conversion circuit; The second terminal is used to couple to the secondary side of the power conversion circuit; A switch detection unit, coupled to the first terminal, is used to detect the switching of the primary side of the power conversion circuit; A voltage detection unit is used to detect the detection signal on the secondary side of the power conversion circuit; A logic unit, wherein the two input terminals of the logic unit are respectively coupled to the output terminal of the switch detection unit and the voltage detection unit, and the output terminal of the logic unit is coupled to the second terminal, the logic unit being used to generate a synchronization signal; and A coupling unit, wherein the output terminal of the switch detection unit is coupled to the logic unit through the coupling unit, wherein the coupling unit is one of an optical coupling unit, a magnetic coupling unit, and a capacitive coupling unit; When the switch detection unit detects a trigger signal, it drives the second terminal to send the synchronization signal, thereby controlling the secondary side of the power conversion circuit.

2. The synchronous rectification controller of claim 1, wherein, The auxiliary winding of the power conversion circuit is located on the primary or secondary side of the power conversion circuit.

3. The synchronous rectification controller of claim 1, wherein, The synchronous rectification controller is an integrated circuit.

Images