This application note introduces power MOSFET gate driver circuits using high current super-β transistors.
The note introduces the challenges of driving power MOSFETs at high switching frequencies and describes the required gate‑drive current and voltage characteristics. It presents a complimentary emitter‑follower driver topology and discusses how resistance in the charge path can be used to control turn‑on timing.
Several transistor families from ZETEX are listed with their power‑dissipation and frequency capabilities, and performance graphs illustrate gate‑charge curves, driver current waveforms, and example circuits for different MOSFET ratings.
| FMMT618 power dissipation (SOT23) | 625 mW |
|---|---|
| FMMT618 transition frequency | ≈150 MHz |
| Gate charge for 100 V 300 mA TO220 MOSFET | ≈8 nC |
Approximately 8 nC of gate charge is needed.
Around 1.5 A of driver current is required.