Isolation and signal transfer for high-voltage domains
The onsemi CNY173 is a single-channel optocoupler in a 6-DIP through-hole package, designed to pass a DC signal across a 5300 Vrms isolation barrier. The transistor output with base access gives the designer flexibility to tailor switching thresholds or add a pull-up network on the secondary side. Current transfer ratio spans 100% to 200% at a forward current of 10 mA, so the output transistor saturates reliably across the full CTR spread without overdriving the LED. The 70 V output ceiling and 50 mA continuous output current handle logic-level interface and low-power load switching in industrial control and power-supply feedback loops.
Temperature range and switching speed for industrial environments
Rated for -55°C to 100°C operating ambient, the CNY173 spans the full industrial temperature band. The 1 µs rise and 2 µs fall times (typical) support switching up to a few hundred kilohertz — adequate for isolated gate drive, AC mains zero-cross detection, or serial data isolation at moderate baud rates. Turn-on and turn-off times of 2 µs and 3 µs (typical) mean the output settles within a few microseconds of the input edge. The 300 mV Vce(sat) maximum at the rated forward current keeps the on-state voltage drop low enough to drive a TTL or CMOS input without a secondary buffer.
onsemi has marked the CNY173 as obsolete. No direct pin-compatible successor is listed on the official record. Independent distribution and surplus channels hold remaining inventory; quantities are lot-specific and confirmed at RFQ. For a BOM line that requires this exact 6-DIP footprint, 5300 Vrms isolation, and 100-200% CTR band, the existing stock is the only drop-in path without a board spin.