The onsemi CNY172300 is a 1-channel optoisolator in a 6-DIP through-hole package — it provides galvanic isolation between a DC input LED and a phototransistor output with the base terminal brought out for bias or feedback. Rated for 5300 Vrms isolation, the part suits applications requiring reinforced insulation between control and load sides — power supplies, motor drives, and industrial I/O modules where transient immunity matters. Current transfer ratio ranges from 63% to 125% at 10 mA forward current, giving the designer a guaranteed minimum gain for logic-level translation across the isolation barrier.
Switching speed and output drive
Typical rise and fall times are 1 µs and 2 µs respectively, with turn-on and turn-off times of 2 µs and 3 µs — fast enough for 100 kHz-level signal isolation but not intended for high-speed data links. Output transistor can sink up to 50 mA continuous with a maximum Vce saturation of 300 mV at rated current — the drop is low enough to drive TTL or CMOS inputs without an extra buffer stage. Maximum output voltage rating of 70 V gives headroom for 48 V rail monitoring and 24 V logic-level interfaces common in factory automation.
The 6-DIP (0.300-inch, 7.62 mm pitch) through-hole package is legacy-friendly — standard 100-mil grid layouts accept it without a footprint change from earlier CNY17-series designs. Supplied in tube packaging — typical for through-hole DIPs; not tape-and-reel, so pick-and-place requires a tube feeder or manual insertion.
Sourcing reality — obsolete status
The base product number CNY172 shares the same die and pinout across CTR bins, so functionally equivalent variants (e.g. CNY172S or CNY172W) may be considered, but their availability and CTR grade must be verified per the BOM requirement. For an obsolete part, date-code consistency and marking authenticity are the first screen — the laser etch on the DIP body should match onsemi's font and plant code for the period. Any sanded or re-marked units are grounds for decap inspection.