Three Common MOS Gate Drive Circuits

Three Common MOS Gate Drive Circuits

In electronic circuits, MOSFET are commonly used as power switching elements, the design of their gate drive circuits significantly affects performance. Today, we will introduce three common MOSFET gate drive circuits.

1. Direct Drive: Direct drive is a relatively simple and straightforward MOSFET gate drive method that directly drives the MOSFET through components such as resistors and diodes. The resistor is used to current and suppress parasitic oscillations, with the resistance typically ranging from 10Ω to 100Ω. The MOSFET provides a discharge path when turned to ensure quick turn-off; the Zener diode/protects the MOSFET's gate and source to prevent overvoltage damage. The diode acceler MOSFET turn-off, improving the circuit's switching efficiency.

2. Complementary Bipolar Transistor Drive: When the MOSFET is used in-power scenarios and the chip output signal driving capability is insufficient, a complementary bipolar transistor drive circuit is required. When the high level is present, bipolar transistor Q3 to drive the MOSFET on; when PWM is low, bipolar transistor Q2 conducts to accelerate MOSFET turn-off. The resistor limits current and suppress parasitic oscillations (resistance 10Ω - 100Ω), R2 provides a discharge path for turn-off, and diode D1 accelerates MOSFET turn-off.

3. Coupled Drive (Using a Drive Transformer for Coupled Drive): In special circuit topologies such as Buck conver or dual-diodes forward converters, if the drive signal and power MOSFETs are not common ground or the MOSFET source is floating, the coupled drive circuit an ideal choice. It uses the principle of electromagnetic induction of the drive transformer to transmit the drive signal, achieving electrical isolation and avoiding ground potential interference, ensuring the operation of the MOSFET.

Different MOSFET gate drive circuits are suitable for different scenarios. Direct drive is simple and low-cost, suitable for lowpower applications with low performance requirements; complementary bipolar transistor drive is suitable for high-power demands; coupled drive is aimed at special cases where there is no common ground or source is floating. In actual design, it is necessary to consider factors such as cost and performance according to specific needs, to make reasonable choices for drive circuits and ensure and efficient operation of the MOSFET.