Driving circuit used in switching power supply system and power supply control system

Abstract

The invention discloses a driving circuit used in a switching power supply system and a power supply control system. The switching power supply system comprises a half-bridge structure, and the driving circuit is connected with a high-side power tube of the half-bridge structure and comprises a detection module which is configured to generate an action signal used for controlling on-off of the high-side power tube based on a control signal and generate a detection signal indicating whether the control signal is abnormal or not, the control signal is obtained based on the state of the high-side power tube; and the driving module is configured to determine a logic level of a driving signal used for driving the high-side power tube based on the action signal, and control the voltage rising speed of the driving signal based on the logic level of the driving signal and the detection signal.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to a drive circuit and a power supply control system used in a switching power supply system. Background Art

[0002] A power control system typically generates a drive signal based on a status signal from the switching power system (e.g., a zero-voltage signal associated with turning a power transistor on or off). This drive signal is used to turn the high-side power transistor of the switching power system on or off. During operation, the switching power system may experience signal errors, causing the power control system to output an erroneous drive signal. This in turn can cause a voltage spike between the gate and source of the high-side power transistor, potentially impacting the safety of the high-side power transistor and the entire switching power system. Summary of the Invention

[0003] According to an embodiment of the present invention, a driving circuit used in a switching power supply system includes a half-bridge structure, and the driving circuit is connected to the high-side power tube of the half-bridge structure and includes: a detection module, configured to generate an action signal for controlling the on and off of the high-side power tube based on a control signal, and generate a detection signal indicating whether the control signal is abnormal, wherein the control signal is obtained based on the state of the high-side power tube; a driving module, configured to determine the logic level of the driving signal for driving the high-side power tube based on the action signal, and control the voltage rise speed of the driving signal based on the logic level of the driving signal and the detection signal.

[0004] A power control system used in a switching power supply system according to an embodiment of the present invention includes the driving circuit as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The present invention can be better understood from the following description of specific embodiments of the present invention in conjunction with the accompanying drawings, in which:

[0006] Figure 1 An example circuit diagram of a conventional switching power supply system is shown.

[0007] Figure 2 Shown in Figure 1 An example circuit diagram of a power control system in a switching power supply system is shown.

[0008] Figure 3 A circuit logic diagram of a driving circuit used in a switching power supply system according to an embodiment of the present invention is shown.

[0009] Figure 4 Shown Figure 3 An example circuit diagram of the detection module and the boost module is shown.

[0010] Figure 5 Shown Figure 3 An example circuit diagram of the driver module is shown.

[0011] Figure 6 Shown Figure 4 and Figure 5 Schematic diagram of the waveform of the relevant signals. DETAILED DESCRIPTION

[0012] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is by no means limited to any specific configuration and algorithm proposed below, but covers any modification, replacement, and improvement of elements, components, and algorithms without departing from the spirit of the present invention. In the accompanying drawings and the following description, known structures and techniques are not shown to avoid causing unnecessary ambiguity to the present invention.

[0013] Figure 1 FIG. 1 shows an example circuit diagram of a conventional switching power supply system. Figure 1 As shown, the switching power supply system 100 can be a flyback architecture. The switching power supply system 100 includes a power factor correction (PFC) chip, an asymmetric half-bridge (AHB) chip, a synchronous rectification (SR) chip, an asymmetric half-bridge structure, and several basic circuit components. Among them, the PFC chip is located on the input side and can change the input current waveform, greatly improving the power factor. The AC power supply is power factor corrected through the PFC chip to output a stable high-voltage current; the AHB chip uses zero voltage switching (ZVS) to reduce switching losses, and the high-voltage DC is converted into a high-frequency current through the AHB chip; the SR chip uses MOSFET instead of diode rectification to reduce output losses and achieve efficient rectification output.

[0014] Figure 2 Shown in Figure 1 An example circuit diagram of a power control system in a switching power supply system is shown in FIG. Figure 2 As shown, the power control system 200 may include Figure 1In the AHB chip shown, voltage adjustment and switch isolation can be achieved, switching losses can be optimized, and voltage and frequency conversion efficiency and safety can be improved. Based on the maximum delay (Td_max), zero voltage switching (ZVS), pulse width modulation (PWM) signal shutdown signal (PWM_OFF), overcurrent protection (OCP) and other signals inside the AHB chip, a drive signal GATEH is generated through a high-side delay logic circuit, RS trigger, logic control circuit, and high-side drive circuit to drive the high-side power tube. The ZVS signal is generated based on the status signal of the switching power system received by the DEM pin. The VBOOT pin provides power for the high-side power tube and is connected to the HB pin through a capacitor. The HB pin is connected to the source end of the high-side power tube as a floating ground. As shown Figure 1 and Figure 2 As shown, during the operation of the switching power supply system, the signal may be erroneous due to resonant parameter mismatch, drive timing error, parasitic parameters or unexpected conditions (for example, the ZVS signal is abnormal at non-zero voltage), causing the AHB chip to output an erroneous drive signal GATEH, and a spike voltage appears between the gate and source of the high-side power tube. Repeated spike voltages may cause the high-side power tube to be broken down, the circuit function to fail, or even burn the chip. The operation process of the general traditional functional modules in the AHB chip that are not related to this embodiment is well known in the art and will not be described in detail herein. In addition to the AHB chip, the power control system can also be included in the LLC chip or other chips for driving the high-side power tube.

[0015] In view of the above situation, a drive circuit and a power supply control system for use in a switching power supply system according to an embodiment of the present invention are proposed, wherein the drive circuit generates a detection signal indicating whether the control signal is abnormal and uses the detection signal to control the voltage rise rate of the drive signal, thereby reducing the negative impact of the abnormal control signal on the drive signal and the high-side power tube, reducing the risk of breakdown of the high-side power tube, enhancing the reliability and stability of the high-side power tube and the entire switching power supply system, and improving the durability and safety of the circuit and chip.

[0016] Figure 3 FIG. 1 shows a circuit logic diagram of a driving circuit used in a switching power supply system according to an embodiment of the present invention. Figure 3 As shown, the driving circuit 300 is connected to the high-side power tube Q of the half-bridge structure. The driving circuit 300 includes: a detection module 310, which is configured to generate an action signal for controlling the on and off of the high-side power tube based on a control signal, and generate a detection signal indicating whether the control signal is abnormal, wherein the control signal is obtained based on the state of the high-side power tube Q; a driving module 320, which is configured to determine the logic level of the driving signal for driving the high-side power tube based on the action signal, and control the voltage rising speed of the driving signal based on the logic level of the driving signal and the detection signal.

[0017] In some embodiments, the driving circuit 300 is generally located in a power control system. For example, the driving circuit 300 can be implemented Figure 2 The function of the high-side drive circuit in the power control system 200. The drive module 320 outputs a drive signal to the gate of the high-side power tube Q. The voltage change of the drive signal determines whether the voltage between the gate and source of the high-side power tube Q is a peak voltage. The control signal is a signal generated by the front circuit of the drive circuit 300 based on the state of the high-side power tube Q (for example, the zero voltage switching ZVS signal) and other signals inside the power control system for calculation and processing, and is used to control the high-side power tube to be turned on or off. During the operation of the drive circuit 300, the generated control signal may be abnormal. The drive circuit 300 generates a detection signal indicating whether the control signal is abnormal and controls the voltage rise rate of the drive signal based on the detection signal, thereby reducing the negative impact of the abnormal control signal on the drive signal. The possibility of the high-side power tube Q being broken down due to the drive signal is reduced, thereby enhancing the reliability and stability of the high-side power tube Q and the entire switching power supply system, and improving the durability and safety of the circuit and chip.

[0018] like Figure 3 As shown, the driving circuit 300 may further include a boost module 330 configured to boost the control signal to a voltage domain where the detection module 310 is located.

[0019] Figure 4 Shown Figure 3 An example circuit diagram of the detection module and the boost module is shown. Figure 6 Shown Figure 4 Schematic diagram of the waveform of the relevant signals.

[0020] like Figure 4 and Figure 6 As shown, in some embodiments, the control signal may include a set signal SET that instructs the high-side power transistor Q to turn on, and a reset signal RESET that instructs the high-side power transistor Q to turn off. In this case, an abnormality in the control signal is manifested by the set signal SET and the reset signal RESET being simultaneously valid (i.e., when the set signal SET and the reset signal RESET are simultaneously valid, the detection signal indicates an abnormality in the control signal). In some embodiments, when the set signal SET changes from invalid to valid, the action signal LS_out changes from invalid to valid; when the reset signal RESET changes from invalid to valid, the action signal LS_out changes from valid to invalid.

[0021] In some embodiments, both the set signal SET and the reset signal RESET are high level valid, and the rising edge of these two signals indicates the high side power transistor is in operation. Figure 6As shown, at time t1, the set signal SET transitions from low to high, and the action signal LS_out transitions to high. At time t2, the reset signal RESET transitions from low to high, and the action signal LS_out transitions to low. However, during the time period t3-t4, both the set signal SET and the reset signal RESET are active simultaneously. This indicates that the control signal is abnormal, and the detection signal abnormal is high. During the rest of the time period, the control signal is normal, and the detection signal abnormal remains low.

[0022] like Figure 4 As shown, in some embodiments, the detection module 310 includes a NOR gate U1, a first input terminal and a second input terminal of the NOR gate U1 receive a set signal SET and a reset signal RESET respectively, and an output terminal of the NOR gate U1 outputs a detection signal abnormal.

[0023] like Figure 4 As shown, in some embodiments, the boost module 330 boosts the set signal SET and the reset signal RESET to the voltage domain where the detection module 310 is located.

[0024] In some embodiments, the driving module 320 may determine the logic level of the driving signal based on whether the action signal is valid, for example Figure 6 The action signal LS_out shown is valid at a high level, and the logic level of the driving signal GATEH is a high level when the action signal LS_out is valid.

[0025] In some embodiments, the driver module 320 controls the voltage rise rate of the drive signal based on the logic level of the drive signal and the detection signal. Specifically, when the detection signal indicates that the control signal is abnormal, the voltage of the drive signal whose control logic level is high cannot be expressed as a spike voltage, that is, the voltage rise rate of the control drive signal is low. The voltage rise rate of the drive signal is related to the pull-up current of the drive signal. The larger the pull-up current, the smaller the voltage rise rate. Therefore, the driver module can be further configured to control the size of the pull-up current associated with the drive signal based on the logic level of the drive signal and the detection signal to control the voltage rise rate of the drive signal. Here, the positive pull-up current refers to the current that causes the voltage of the drive signal to rise.

[0026] In some embodiments, the driver module 320 may be further configured to: determine that the logic level of the drive signal is low when the action signal is invalid; determine that the logic level of the drive signal is high and control the pull-up current to a first current when the action signal is valid and the detection signal indicates that the control signal is abnormal; and determine that the logic level of the drive signal is high and control the pull-up current to a second current when the action signal is valid and the detection signal indicates that the control signal is normal, wherein the first current is less than the second current. Here, both the first current and the second current are not less than zero.

[0027] In some embodiments, the driver module 320 may include: a first component unit configured to output a first component current when the action signal is valid; and a second component unit configured to output a second component current when the action signal is valid and the detection signal indicates that the control signal is normal. The pull-up current is the sum of the currents output by the first and second component units. That is, the current output of the first component unit depends on whether the action signal is valid. If valid, the first component current is output; if invalid, the output current is zero. The current output of the second component unit depends on the action signal and the detection signal. If the action signal is valid and the detection signal indicates that the control signal is normal, the second component current is output; otherwise, the output current is zero. Therefore, the pull-up current of the drive signal has three scenarios: when the action signal is invalid, the pull-up current is zero; when the action signal is valid and the detection signal indicates that the control signal is normal, the pull-up current is the sum of the first and second component currents; and when the action signal is valid and the detection signal indicates that the control signal is abnormal, the pull-up current is the first component current. Here, both the first and second component currents are greater than zero. It can be seen that the pull-up current decreases when the control signal is abnormal.

[0028] Figure 5 Shown Figure 3 An example circuit diagram of the driver module is shown. Figure 6 Shown Figure 5 Schematic diagram of the waveform of the relevant signal. Figure 5 As shown, in some embodiments, the first component unit in the driving module 320 may include switch tubes M1 and M4, and the second component unit may include switch tubes M2 and M3. Figure 6As shown, during the time period t1-t2, the detection signal "abnormal" is low, indicating that the control signal is normal. Consequently, the pull-up current Ip_gate is high, causing the voltage of the drive signal GATEH to rise rapidly. During the time period t3-t4, the detection signal "abnormal" is high, indicating that the control signal is abnormal. Consequently, the pull-up current Ip_gate is low, and the voltage rise rate of the drive signal GATEH is significantly reduced. When the control signal is abnormal, the voltage rise rate of the drive signal GATEH slows down, reducing the probability of voltage spikes. This effectively suppresses overshoot and oscillation of the gate voltage of the high-side power transistor, reduces resonance and noise, electromagnetic interference (EMI), and switching losses caused by gate voltage variations, and ensures the safety of the high-side power transistor and subsequent circuits.

[0029] The embodiment of the present invention also discloses a power supply control system for a switching power supply system, including the driving circuit as described above. The power supply control system can be applied to Figure 1 The switching power supply system with the flyback architecture shown can also be applied to other switching power supply systems including half-bridge topology.

[0030] The present invention may be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the circuit configuration described in a particular embodiment or the circuit structure in a particular figure may be modified without departing from the basic spirit of the present invention. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and all modifications coming within the meaning and scope of equivalents of the claims are intended to be included within the scope of the present invention.

Claims

1. A drive circuit for use in a switching power supply system, the switching power supply system comprising a half-bridge structure, the drive circuit being connected to a high-side power transistor of the half-bridge structure and comprising: a detection module configured to generate an action signal for controlling the on / off of the high-side power transistor based on a control signal, and to generate a detection signal indicating whether the control signal is abnormal, wherein the control signal is obtained based on the state of the high-side power transistor; and The driving module is configured to determine a logic level of a driving signal for driving the high-side power transistor based on the action signal, and control a voltage rising speed of the driving signal based on the logic level of the driving signal and the detection signal.

2. The driving circuit according to claim 1, wherein: The driving module is further configured to control a magnitude of a pull-up current associated with the driving signal based on a logic level of the driving signal and the detection signal, so as to control a voltage rising speed of the driving signal.

3. The driving circuit according to claim 2, wherein: The driver module is further configured to: determining that the logic level of the driving signal is a low level when the action signal is invalid; When the action signal is valid and the detection signal indicates that the control signal is abnormal, determining that the logic level of the drive signal is a high level and controlling the pull-up current to be a first current; as well as When the action signal is valid and the detection signal indicates that the control signal is normal, the logic level of the drive signal is determined to be high and the pull-up current is controlled to be a second current, and the first current is smaller than the second current.

4. The driving circuit according to claim 2, wherein: The driving module includes: a first component unit configured to output a first component current when the action signal is valid; and The second component unit is configured to output a second component current when the action signal is valid and the detection signal indicates that the control signal has no abnormality, and the pull-up current is the sum of the currents output by the first component unit and the second component unit.

5. The driving circuit according to any one of claims 1 to 4, wherein: The control signal includes a set signal indicating that the high-side power tube is turned on, and a reset signal indicating that the high-side power tube is turned off. When the set signal and the reset signal are valid at the same time, the detection signal indicates that the control signal is abnormal. The driving circuit according to claim 5 , wherein: The detection module includes a NOR gate, wherein a first input terminal and a second input terminal of the NOR gate receive the set signal and the reset signal respectively, and an output terminal of the NOR gate outputs the detection signal.

7. The driving circuit according to claim 5, wherein: When the set signal changes from invalid to valid, the action signal changes from invalid to valid; when the reset signal changes from invalid to valid, the action signal changes from valid to invalid.

8. The driving circuit according to claim 1, wherein: It also includes a boost module configured to boost the control signal to a voltage domain where the detection module is located.

9. A power control system used in a switching power supply system, comprising the drive circuit according to any one of claims 1 to 8.

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