The FODM453R2 is a single-channel optoisolator from onsemi with a DC input LED and a phototransistor output. It provides 3750Vrms galvanic isolation between the input and output sides, which is the typical rating for basic isolation in industrial control, PLC digital inputs, and isolated sensor interfaces. The surface-mount footprint suits automated assembly lines.
Current transfer ratio (CTR) is specified at 20% minimum and 50% maximum, both measured at If=16 mA. The 20% floor is the number to use for pull-up resistor sizing and logic-level threshold calculations. Typical turn-on time is 400 ns and turn-off is 350 ns, giving a combined propagation delay of roughly 750 ns. This limits the usable switching frequency to about 500 kHz for a 50% duty-cycle square wave before pulse-width distortion becomes significant. For lower-speed signals like 24 VDC PLC inputs or relay coil drives, the speed is more than adequate.
The maximum output voltage is 20V and the continuous output current per channel is 8 mA. These ratings match the typical 5V or 3.3V logic supply rails used on the secondary side of an isolated interface.