What Is a MOSFET Gate Driver?
A gate driver (MOSFET/gate driver) is an intermediate chip that supplies high instantaneous current to switch the gate of a power MOSFET or IGBT on and off very fast. It bridges a microcontroller and the power switch.
Why Is It Needed?
A power MOSFET's gate behaves like a capacitor. To turn on and off fast, this capacitance must be charged/discharged in a very short time; a microcontroller pin can't supply this instantaneous current.
The Importance of Switching Speed
A MOSFET heats up little when fully on or fully off; during the transition, however, both current and voltage are high and loss occurs. A gate driver shortens this transition, reducing the switching loss.
| Property | Explanation |
|---|---|
| Peak current | 1-10 A instantaneous |
| Function | Fast gate charge/discharge |
| Types | Low-side, high-side, half-bridge |
Where Is It Used?
In DC-DC converters, motor drives, inverters, class-D amplifiers and switch-mode power supplies.
Dead-Time
In structures like a half-bridge, if the upper and lower MOSFETs conduct at the same time the supply shorts (shoot-through). A gate driver inserts a short "dead-time" between the two so that both switches stay off for a moment, preventing this dangerous condition.
Common Mistakes
- Driving without a driver: driving a MOSFET directly from an MCU pin causes slow transitions and excess heat.
- Gate resistor: a wrong value leads to ringing or slow switching.
- Missing bootstrap: the bootstrap capacitor must not be forgotten in a high-side driver.
Frequently Asked Questions
Is a gate driver a must for every MOSFET?+
What's the difference between high-side and low-side?+
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