5300Vrms isolation in a 6-SMD Gull Wing
The onsemi CNY1733S is a 1-channel optocoupler with a DC-input LED and a phototransistor output that brings out the base connection. The 5300Vrms isolation rating means this part can bridge a reinforced-insulation barrier between a low-voltage control side and a 70V max collector-side circuit — think PLC digital inputs, motor-drive feedback, or any isolated signal path where the transient immunity matters more than raw speed. Rated for -55°C to 100°C operating, it covers the full industrial temperature envelope including cold-start conditions down to -55°C that a commercial-grade opto would not guarantee.
CTR floor and switching timing
That 2:1 spread means the downstream receiver must tolerate a factor-of-two variation in output current — a Schmitt-trigger input or a comparator with hysteresis handles this cleanly; a bare logic gate may not. Turn-on time is 2µs typ, turn-off 3µs typ, with rise/fall of 1µs and 2µs respectively. For a 10kHz PWM isolation link the 3µs turn-off leaves about 30% of the period in transition — fine for status feedback, tight for a switching power supply loop. Output can sink 50mA continuous at up to 70V Vce, with a 300mV saturation floor at that current — the base-drive margin from the LED side sets how hard the transistor saturates, so the 100mA absolute-max forward current gives headroom to overdrive the LED for lower Vce(sat) at high collector current.
Obsolete — sourcing through surplus channels
onsemi has marked the CNY1733S as Obsolete. The 6-SMD Gull Wing package and the 5300Vrms isolation rating define the physical and electrical fit — any replacement candidate must match both the footprint and the reinforced-insulation class. Surface-mount reflow profile follows standard SnPb or Pb-free profiles for a 6-pin SOIC-style body; no special moisture sensitivity level is stated on the record.