What the 3 A peak output and 5000 Vrms isolation mean for your gate-drive BOM
The FOD3120S is an onsemi optocoupler gate driver that delivers a 3 A peak output current across a 5000 Vrms reinforced isolation barrier. That peak current is enough to drive the gate of a medium-power IGBT or MOSFET (typical 50–200 nC total gate charge) without an external booster stage — the 3 A rating is the peak capability, not continuous, so the switching frequency and gate resistor set the average power dissipation in the output stage. The 5000 Vrms isolation rating qualifies the part for motor-drive, solar-inverter, and industrial power-supply BOMs where IEC 60747-5-5 reinforced isolation is required. The UL approval confirms the safety agency listing, which most production buyers need for the final compliance file.
Propagation delay, CMTI, and timing margin at speed
Propagation delay is 400 ns max for both tpLH and tpHL, with a pulse-width distortion ceiling of 100 ns. That 400 ns window sets the minimum dead-time budget in a half-bridge — if the controller inserts 500 ns dead-time, the optocoupler's skew eats 100 ns of it, leaving 400 ns headroom. The 35 kV/µs common-mode transient immunity is the spec that keeps the output state latched during the hard-switching edge of the high-side device; below that figure the output can glitch and shoot through the bridge. Rise and fall times are both 60 ns typical, which is fast enough for switching frequencies up to ~50–100 kHz in a typical gate-drive loop. The output high/low current capability is 2 A each, symmetrical, so the gate charges and discharges at the same rate — that symmetry simplifies dead-time calculation.
Active lifecycle and surface-mount package fit
The 8-SMD Gull Wing package is the surface-mount variant of the through-hole FOD3120, letting a design migrate from through-hole to SMT without changing the functional spec. The supply voltage range of 15 V to 30 V covers standard gate-drive rails (15 V, 18 V, 24 V) used for most IGBT and MOSFET drivers.
Temperature grade and operating environment
Rated for -40°C to 100°C, the FOD3120S covers industrial and outdoor telecom enclosures where the ambient temperature inside the cabinet can reach 85°C. The 1.5 V typical forward voltage and 25 mA max forward current are standard LED-side parameters that any MCU GPIO or PWM output can drive through a series resistor.