20 Mbps isolation for motor-drive and industrial fieldbus
The FODM8071R2 is a single-channel digital optocoupler from onsemi that delivers 20 Mbps data rate across a 3750 Vrms isolation barrier. This puts it squarely in the range needed for industrial fieldbus interfaces (Profibus, DeviceNet, CAN) and high-speed gate-drive feedback paths where the update rate must stay below 50 ns per edge.
Propagation delay and CMTI — the timing and transient limits
Maximum propagation delay is 55 ns for both tpLH and tpHL, with typical rise/fall times of 5.8 ns and 5.3 ns respectively. For a closed-loop controller running at 1 MHz PWM, the total loop delay from the optocoupler is under 110 ns round-trip — well within the dead-time budget of most IGBT/MOSFET gate drivers. Common-mode transient immunity is rated at 20 kV/µs minimum. In a motor-drive application where the inverter midpoint swings 600 V in 100 ns, the dV/dt at the isolation barrier exceeds 6 kV/µs — the FODM8071R2's CMTI margin provides a 3× safety factor against data corruption. The push-pull totem-pole output eliminates the external pull-up resistor that standard open-collector optocouplers require. This saves one component per channel and removes the RC time-constant that would otherwise add to the propagation delay at the receiver side.
Supply range and logic compatibility
The output swings rail-to-rail, so it interfaces directly with the input of an MCU, FPGA, or ASIC on the same supply rail. Forward voltage is 1.35 V typical at the LED side, with a maximum DC forward current of 20 mA. At 3.3 V logic drive, a series resistor of 100 Ω sets the LED current to about 18 mA — within the 20 mA ceiling and above the minimum threshold for guaranteed output switching. Output current per channel is 10 mA, sufficient to drive a single standard CMOS or TTL load. For fan-out to multiple gates, a buffer stage is recommended.
Package, temperature grade, and lifecycle
Housed in a 5-lead 6-SOIC mini-flat package (5-Mini-Flat), the body width is 4.40 mm — narrower than a standard 8-pin SOIC. The 5-lead variant saves PCB area while maintaining the 3750 Vrms creepage distance. The surface-mount package is compatible with standard reflow profiles (MSL level not stated in evidence — confirm with the manufacturer for moisture sensitivity).