Gate drive optocoupler with 3 A peak output
The onsemi FOD3125S is a single-channel gate drive optocoupler from the OPTOPLANAR® series, designed to drive IGBTs and power MOSFETs in inverter and motor drive stages. Its 3 A peak output current directly charges the gate capacitance for fast switching without an external booster stage. With 5000 Vrms isolation and a common-mode transient immunity of 35 kV/µs minimum, this part maintains signal integrity across the isolation barrier in noisy industrial environments — a key spec for motor-drive and UPS designs where high dv/dt transients couple across the barrier.
Switching speed and timing margins
Propagation delay is 400 ns max for both tpLH and tpHL, with a pulse-width distortion ceiling of 100 ns. The 60 ns typical rise and fall times keep dead-time margins tight in half-bridge topologies — the 400 ns delay sets the minimum dead-time floor the controller must respect. The output supply range spans 15 V to 30 V, covering standard gate-drive rails for IGBTs (15 V on) and accommodating higher-voltage MOSFETs. The 1.5 V typical forward voltage and 25 mA max forward current keep the LED drive within a standard microcontroller GPIO's sink capability through a series resistor.
Housed in an 8-SMD Gull Wing package with a surface-mount footprint, the FOD3125S mates with standard 8-SMD land patterns. The 8 mm creepage distance typical for this package supports the 5000 Vrms isolation rating in a two-layer PCB layout — the clearance under the component body is the limiting factor, not the pin spacing. The bulk packaging is suited for prototype builds and low-volume production; tape-and-reel options are available through the supply chain.