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. 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.
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. Lifecycle status is Active per onsemi, and the part is ROHS3 compliant. Sourced per RFQ against your target quantity.