What this opto does on your board
The FODM217CV is a single-channel phototransistor optoisolator from onsemi's FODM217 series, designed to pass a DC logic-level signal across a 3750Vrms galvanic isolation barrier. It is the kind of part you reach for when a PLC digital input, motor-drive feedback, or a microcontroller I/O needs to talk to a higher-voltage domain without a ground loop or a shock hazard. The current transfer ratio (CTR) is specified at 200% minimum and 400% maximum when the LED is driven with 5mA forward current — that means the output transistor can sink 10mA to 20mA at the collector, which is enough to pull a 5V logic input low through a 2.2kΩ pull-up resistor. The 80V output rating gives headroom for 24V industrial rails.
Switching speed and drive margin
Turn-on and turn-off times are both 3µs typical, with rise and fall times of 2µs and 3µs respectively. That puts the usable data rate around 100 kbps — fine for status feedback, relay commands, and slow serial links, but not for high-speed fieldbus or isolated SPI. The 400mV Vce saturation at the output keeps the logic-low voltage well inside the TTL threshold. The LED forward voltage is 1.2V typical, and the maximum continuous forward current is 50mA. A 330Ω series resistor from a 5V logic output will bias the LED at roughly 12mA, which is well within the safe operating area and still above the 5mA test condition for the CTR.
Package and temperature grade
Housed in a 4-SOP package (4.40mm body width), the FODM217CV is a surface-mount part that reflows on a standard SOIC-4 footprint. The operating temperature range of -55°C to 110°C covers industrial and outdoor equipment without derating — the cold end matters for outdoor cabinets in winter, the hot end for enclosures near motors or power supplies. Lifecycle status is Active per onsemi, and the part is ROHS3 compliant. Sourced per RFQ against your target quantity.