The onsemi CNY17F4TM is a single-channel optoisolator in the CNY17 family, DC input with transistor output, housed in a 6-DIP (0.400", 10.16mm) through-hole package. Isolation is rated at 4170Vrms, making it suitable for galvanic isolation in industrial control interfaces, power supply feedback loops, and logic-level shifting where the primary-to-secondary voltage stress stays within that ceiling. Current transfer ratio (CTR) is specified at 160% minimum to 320% maximum, tested at If=10mA — this wide band means the part drives a logic input or a low-current relay coil without an additional gain stage, but the min/max spread must be budgeted in the threshold design.
Switching performance and temperature range
Turn-on time is 2µs typical, turn-off 3µs typical, with rise/fall times of 4µs and 3.5µs respectively — these place the part in the medium-speed class for optocouplers, adequate for 10-50 kHz switching supplies or serial data rates below 100 kbps. Operating temperature spans -40°C to 100°C, covering industrial enclosures and outdoor telecom cabinets without derating the isolation or CTR. Output transistor withstands up to 70V collector-emitter and 50mA continuous current — typical for driving a PLC digital input module or a 24V logic gate.
No pin-compatible direct replacement is documented by the manufacturer, so a BOM substitution requires a parametric search within the CNY17 family or a functionally equivalent optocoupler series.