What the 5000Vrms and CTR 80-160% mean for your BOM
The FOD817A300W is a single-channel optoisolator from onsemi's FOD817 family, built for galvanic isolation between a DC input and a transistor output. The 5000Vrms isolation rating supports reinforced insulation in mains-connected power supplies, motor drives, and PLC I/O modules — enough to pass IEC 60950-1 basic insulation for 250VAC working voltage. The 'A' CTR bin — 80% minimum, 160% maximum at 5mA forward current — gives you a predictable LED-to-output current gain. At 5mA input, the output can sink up to 50mA with a Vce saturation of 200mV typical. That 80% floor means you can guarantee the output drives a 5V logic input without adding a pull-up resistor.
Through-hole 4-DIP and temperature range for industrial environments
The 4-DIP (0.400-inch, 10.16mm) through-hole package is the standard footprint for wave-solder assembly and manual rework — no hot-air profile needed. The -55°C to 110°C operating range covers outdoor telecom cabinets, engine-bay electronics, and cold-chain storage, not just office-grade 0-70°C. The 4µs rise and 3µs fall times limit switching to low-frequency signals like 50/60Hz line sync or DC bus fault detection.
Active lifecycle and ROHS3 compliance — no end-of-life concern
ROHS3 compliant — no exemption-based lead in the solder terminations.
How the 'A' CTR bin compares to FOD817B and FOD817C
Within the FOD817 family, the CTR bin is the only parametric difference. The FOD817A300W (80-160%) sits between the FOD817B (130-260%) and the FOD817C (200-400%). If your design needs more output current at the same 5mA input, step up to the B or C bin — the pinout, package, and isolation rating are identical. No second-source cross is needed; all are onsemi.