A low-power MOSFET bridge drive circuit for switching power supplies
By employing transistor isolation and drive current feedback mechanisms in the low-power MOS bridge drive circuit of the switching power supply, combined with resistor and capacitor regulation, the problem of high-side voltage acquisition in the same system is solved, achieving low-power and high-flexibility power conversion.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHANGZHOU CHENGLIAN POWER SUPPLY MFG
- Filing Date
- 2025-08-29
- Publication Date
- 2026-07-31
AI Technical Summary
Existing low-power MOSFET bridge drive circuits in switching power supplies require a dedicated boost circuit to obtain high-side voltage within the same system, resulting in limited application range, high power consumption, and low flexibility.
Isolation is achieved using transistors Q1 and Q2, drive current is provided by transistors Q3 and Q4, negative feedback is generated to the base through transistor Q5, and the high-side MOSFET is driven by the low-side voltage and PWM, limiting the peak gate voltage and input/output current. Resistors and capacitors are used for current and voltage regulation.
It achieves low power consumption with wide applicability, low power consumption and high flexibility, and reduces switching loss and conduction loss through circuit optimization.
Smart Images
Figure CN224583079U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a driving circuit, and more particularly to a low-power MOSFET bridge driving circuit for a switching power supply, belonging to the field of driving circuit technology. Background Technology
[0002] The low-power MOSFET bridge drive circuit is an H-bridge / full-bridge topology built on N-channel MOSFETs. It controls the MOSFET gate through an efficient drive circuit to achieve low-power, high-efficiency power conversion. Its core objective is to minimize switching losses and conduction losses. It is widely used in switching power supplies, motor drives, inverters and other fields.
[0003] When a MOSFET is turned on, the gate voltage must be greater than the source voltage. However, when a high-side driven MOSFET is turned on, the source voltage and drain voltage VCC are the same. If a voltage greater than VCC is required in the same system, a dedicated boost circuit is needed. Therefore, the application range is small, the power is high, and the flexibility is low.
[0004] Therefore, it is urgent to improve the low-power MOS bridge drive circuit of the switching power supply to solve the above-mentioned problems. Utility Model Content
[0005] The purpose of this invention is to provide a low-power MOSFET bridge drive circuit for a switching power supply. Transistors Q1 and Q2 are used for isolation, while transistors Q3 and Q4 provide the drive current. The sampled voltage generates a strong negative feedback to the bases of transistors Q1 and Q2 through transistor Q5. The high-side MOSFET is driven by the low-side voltage and PWM. The peak value of the gate voltage is limited, and the input and output currents are also limited. Therefore, this circuit has a wide range of applications, low power consumption, and high flexibility, achieving the goal of low power consumption.
[0006] To achieve the above objectives, the main technical solutions adopted by this utility model include: A low-power MOSFET bridge drive circuit for a switching power supply includes MOSFETs electrically connected to the drive circuit. The drive circuit includes transistors Q1, Q2, Q3, Q4, and Q5. Transistors Q1 and Q2 are connected in parallel and electrically connected to a resistor R12. Transistors Q3 and Q4 are connected in parallel. Transistors Q1 and Q2 are connected in parallel and electrically connected to transistor Q5. A resistor R10 is electrically connected to transistor Q5. Transistors Q3 and Q4 are connected in parallel and electrically connected to resistor R9. Resistors R9 and R10 are electrically connected to the MOSFET.
[0007] Preferably, transistors Q1 and Q2 are connected in parallel and electrically connected to resistors R7 and R8. Resistor R7 is connected to a low-side power supply V1, and resistor R8 is electrically connected to transistor Q2.
[0008] Preferably, a resistor R11 is electrically connected to the resistor R10, and the resistor R11 is connected to the high-side power supply Vh.
[0009] Preferably, the end of the driving circuit away from the MOSFET is connected to a power supply IC via a capacitor, and transistors VT1 and VT2 are connected in parallel between the driving circuit and the power supply IC. A resistor R1 is electrically connected to the base B of transistor VT1, and a resistor R2 is electrically connected to the base B of transistor VT2.
[0010] Preferably, a resistor R4 is electrically connected between the MOSFET and the driving circuit.
[0011] Preferably, a capacitor C2 and a resistor R3 are connected in parallel on the resistor R4, and the capacitor C2 and the resistor R3 are connected in series.
[0012] Preferably, a resistor R6 is electrically connected to the drain D of the MOSFET, and the drain and source S of the MOSFET are electrically connected to the transistor Q4 and grounded.
[0013] This utility model has at least the following beneficial effects: Transistors Q1 and Q2 are used for isolation, while transistors Q3 and Q4 provide drive current. The sampled voltage generates a strong negative feedback to the bases of transistors Q1 and Q2 through transistor Q5. The high-side MOSFET is driven by the low-side voltage and PWM. The peak value of the gate voltage is limited, and the input and output currents are also limited. Therefore, it has a wide range of applications, low power consumption, and high flexibility, achieving the goal of low power consumption. Attached Figure Description
[0014] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is the circuit diagram of this utility model. Detailed Implementation
[0015] The following will describe in detail the implementation of this application with reference to the accompanying drawings and embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.
[0016] like Figure 1 As shown, the low-power MOSFET bridge drive circuit of the switching power supply provided in this embodiment includes MOSFETs electrically connected to the drive circuit. The drive circuit includes transistors Q1, Q2, Q3, Q4, and Q5. Transistors Q1 and Q2 are connected in parallel and electrically connected to resistor R12. Transistors Q3 and Q4 are connected in parallel. Transistors Q1 and Q2 form an inverted totem pole for isolation and to ensure that the two drive transistors Q3 and Q4 do not conduct at the same time. Transistors Q3 and Q4 are used to provide drive current. When conducting, the lowest voltage drop of transistors Q3 and Q4 relative to Vh and GND is only Vce, which is usually only about 0.3V, much lower than Vce of 0.7V. Transistors Q1 and Q2 are connected in parallel and electrically to transistor Q5. Resistor R10 is electrically connected to transistor Q5. Transistors Q3 and Q4 are connected in parallel and electrically to resistor R9. Resistors R9 and R10 are electrically connected to the MOSFET. Resistors R9 and R10 provide the PWM voltage reference. By changing this reference, the circuit can operate at a position where the PWM signal waveform is relatively steep. Resistors R11 and R10 are feedback resistors used to sample the gate voltage. The sampled voltage generates a strong negative feedback to the bases of transistors Q1 and Q2 through transistor Q5, thereby limiting the gate voltage to a finite value. This value can be adjusted by resistors R11 and R10. Transistors Q1 and Q2 are connected in parallel and electrically connected to resistors R7 and R8. Resistor R7 is connected to the low-side power supply V1, and resistor R8 is electrically connected to transistor Q2. Resistor R10 is electrically connected to resistor R11, which is connected to the high-side power supply Vh. Resistor R12 provides a base current limit for transistors Q3 and Q4, and resistor R9 provides a gate current limit for the MOSFETs, which is to limit the ice of transistors Q3 and Q4. If necessary, an accelerating capacitor is connected in parallel with resistor R9 to drive the high-side MOSFETs with low-side voltage and PWM. The peak gate voltage is limited, and the input and output currents are also limited. Therefore, it has a wide range of applications, low power consumption, and high flexibility, achieving the goal of low power consumption.
[0017] Furthermore, such as Figure 1As shown, the end of the drive circuit furthest from the MOSFET is connected to the power supply IC via a capacitor. Transistors VT1 and VT2 are connected in parallel between the drive circuit and the power supply IC. Resistor R1 is electrically connected to the base B of transistor VT1, and resistor R2 is electrically connected to the base B of transistor VT2. The current capacity of a single transistor is limited, but the parallel structure allows the current paths of multiple transistors to run in parallel, thus multiplying the total current handling capacity. Moreover, the parallel structure of transistors VT1 and VT2 can reduce the output impedance, making the circuit easier to match with the load and reducing signal reflection and distortion.
[0018] Furthermore, such as Figure 1 As shown, a resistor R4 is electrically connected between the MOSFET and the drive circuit. A capacitor C2 and a resistor R3 are connected in parallel with the resistor R4. The capacitor C2 and the resistor R3 are connected in series. A resistor R6 is electrically connected to the drain D of the MOSFET. The drain and source S of the MOSFET are electrically connected to the transistor Q4 and grounded. The capacitor C2 and the resistor R3 are connected in series. The purpose of the resistor R4 is to suppress the parasitic inductance on the PCB board and the capacitor C2 to form LC oscillation. The purpose of the capacitor C2 is to block DC and allow AC to pass through, and at the same time prevent the magnetic core from saturating.
[0019] like Figure 1 As shown, the principle of the low-power MOS bridge drive circuit for the switching power supply provided in this embodiment is as follows: Transistors Q1 and Q2 form an inverted totem pole for isolation, while ensuring that the two driving transistors Q3 and Q4 do not conduct simultaneously. Transistors Q3 and Q4 provide the driving current. When conducting, the lowest voltage drop of transistors Q3 and Q4 relative to Vh and GND is only Vce, which is usually only about 0.3V, much lower than Vce's 0.7V. Transistors Q1 and Q2 are connected in parallel and electrically to transistor Q5. Resistor R10 is electrically connected to transistor Q5. Transistors Q3 and Q4 are connected in parallel and electrically to resistor R9. Resistors R9 and R10 are electrically connected to the MOSFET. Resistors R9 and R10 provide the PWM voltage reference. By changing this reference, the circuit can operate at a position where the PWM signal waveform is relatively steep. Resistors R11 and R10 are feedback resistors used to sample the gate voltage. The sampled voltage generates a strong negative feedback to the bases of transistors Q1 and Q2 through transistor Q5, thereby limiting the gate voltage to a finite value. This value can be adjusted by resistors R11 and R10. Transistors Q1 and Q2 are connected in parallel and electrically connected to resistors R7 and R8. Resistor R7 is connected to the low-side power supply V1, and resistor R8 is electrically connected to transistor Q2. Resistor R10 is electrically connected to resistor R11, which is connected to the high-side power supply Vh. Resistor R12 provides a base current limit for transistors Q3 and Q4, and resistor R9 provides a gate current limit for the MOSFETs, which is to limit the ice of transistors Q3 and Q4. If necessary, an accelerating capacitor is connected in parallel with resistor R9 to drive the high-side MOSFETs with low-side voltage and PWM. The peak gate voltage is limited, and the input and output currents are also limited. Therefore, it has a wide range of applications, low power consumption, and high flexibility, achieving the goal of low power consumption.
[0020] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" as used throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.
[0021] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes that element.
[0022] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.
Claims
1. A low-power MOSFET bridge drive circuit for a switching power supply, comprising MOSFETs electrically connected to the drive circuit, characterized in that, The driving circuit includes transistors Q1, Q2, Q3, Q4, and Q5. Transistors Q1 and Q2 are connected in parallel and electrically connected to a resistor R12. Transistors Q3 and Q4 are connected in parallel. Transistors Q1 and Q2 are connected in parallel and electrically connected to transistor Q5. A resistor R10 is electrically connected to transistor Q5. Transistors Q3 and Q4 are connected in parallel and electrically connected to resistor R9. Resistors R9 and R10 are electrically connected to the MOSFET.
2. The low-power MOSFET bridge drive circuit for a switching power supply according to claim 1, characterized in that: The transistors Q1 and Q2 are connected in parallel and electrically connected to resistors R7 and R8. Resistor R7 is connected to the low-end power supply V1, and resistor R8 is electrically connected to transistor Q2.
3. The low-power MOSFET bridge drive circuit for a switching power supply according to claim 1, characterized in that: A resistor R11 is electrically connected to the resistor R10, and the resistor R11 is connected to the high-side power supply Vh.
4. The low-power MOSFET bridge drive circuit for a switching power supply according to claim 1, characterized in that: The end of the drive circuit away from the MOSFET is connected to a power IC via a capacitor, and transistors VT1 and VT2 are connected in parallel between the drive circuit and the power IC. A resistor R1 is electrically connected to the base B of transistor VT1, and a resistor R2 is electrically connected to the base B of transistor VT2.
5. The low-power MOSFET bridge drive circuit for a switching power supply according to claim 1, characterized in that: A resistor R4 is electrically connected between the MOSFET and the driving circuit.
6. The low-power MOSFET bridge drive circuit for a switching power supply according to claim 5, characterized in that: A capacitor C2 and a resistor R3 are connected in parallel on the resistor R4, and the capacitor C2 and the resistor R3 are connected in series.
7. The low-power MOSFET bridge drive circuit for a switching power supply according to claim 1, characterized in that: A resistor R6 is electrically connected to the drain D of the MOSFET, and the drain and source S of the MOSFET are electrically connected to the transistor Q4 and grounded.