Gate drive optoisolator for industrial power stages
The FOD3125 is a single-channel gate drive optoisolator from onsemi's OPTOPLANAR® series, designed to drive IGBTs and MOSFETs in motor drives, UPS systems, and industrial power supplies. It provides 5000Vrms of galvanic isolation between the controller and the power stage, with a peak output current of 3A to handle gate charge delivery at switching frequencies up to several hundred kilohertz. The through-hole 8-DIP package (0.300-inch body width) is a standard footprint for high-isolation optocouplers, making it a drop-in replacement in existing designs without layout changes.
Parametric strengths for switching applications
The 3A peak output current and 2A source/sink capability allow the FOD3125 to drive medium-power IGBTs and MOSFETs directly, reducing the need for a separate buffer stage. Typical rise and fall times of 60ns keep switching losses low, while a maximum propagation delay of 400ns and pulse width distortion of 100ns maintain timing accuracy in PWM loops. Common-mode transient immunity of 35kV/µs minimum is the standout spec for motor drive environments: it prevents the output from false-triggering when the power stage switches at high dv/dt, which is a common failure mode in cheaper optocouplers. The operating temperature range from -40°C to 125°C covers both cold-start conditions and the elevated ambient inside a sealed inverter enclosure. The input side requires a forward voltage of 1.5V typical with a maximum DC forward current of 25 mA, compatible with standard 3.3V or 5V logic outputs through a current-limiting resistor.
Sourcing and lifecycle status
It is ROHS3 compliant and UL approved. The through-hole 8-DIP package is widely stocked across distribution channels; lead times are typically manageable for a mature optoisolator line. For BOM planning, the part is single-sourced to onsemi, but the OPTOPLANAR® series has been stable for years with no PCN activity.
Package and design-in notes
The 8-DIP package (0.300-inch row spacing, 7.62mm body width) is a through-hole format that suits both prototyping and production. The 8-PDIP supplier device package has a standard 2.54mm pin pitch, which simplifies manual assembly and rework. No exposed thermal pad — the part relies on the DIP body's natural convection for heat dissipation, so derate the output current if ambient exceeds 85°C.