High-voltage switching — 800 V N-channel in a TO-220FM
The R8011KNXC7G is an 800 V, 11 A N-channel MOSFET from ROHM Semiconductor in a through-hole TO-220-3 Full Pack package (supplier device package TO-220FM). It is built for high-speed switching applications such as flyback converters, offline power supplies, and motor-drive circuits where the drain-to-source voltage rating of 800 V provides the safety margin for rectified mains up to 400 VDC bus.
Conduction and switching — Rds(on) and gate charge
The total gate charge of 37 nC at 10 V means the gate driver must supply about 37 nC per switching cycle. For a 100 kHz switching frequency, the average gate drive current is 3.7 mA, easily met by most MOSFET drivers, but the peak current capability of the driver determines the turn-on and turn-off times. Input capacitance is 1200 pF at 100 V drain-source — this contributes to the switching losses and should be factored into the driver's output impedance and the gate resistor selection.
Board integration — the TO-220FM footprint
The TO-220-3 Full Pack (TO-220FM) is a fully isolated package — the metal tab is electrically isolated from the die, so it can be mounted directly to a heatsink without an insulating pad. The through-hole leads require a 0.100-inch pitch footprint on the PCB; the centre lead is the drain, the left and right are gate and source respectively.