4170Vrms isolation in a 6-DIP through-hole package
The CNY171M is a single-channel optoisolator from onsemi, with a DC input LED and a phototransistor output that includes a base connection. Its 4170Vrms isolation rating (cite:) makes it a solid choice for breaking ground loops or providing safety isolation in industrial controls, power supplies, and motor drives — no need for a second-stage isolator in many designs. The 40%–80% current transfer ratio at 10 mA forward current (cite:,) is a tight window — you can count on the output transistor delivering at least 4 mA into the load when the LED sees 10 mA. That predictability simplifies the load resistor calculation and keeps the noise margin consistent across temperature.
Switching speed and output drive capability
Typical rise and fall times are 4 µs and 3.5 µs (cite:), with turn-on and turn-off times of 2 µs and 3 µs (cite:). That puts the CNY171M in the general-purpose phototransistor class — fine for 10 kHz PWM or relay-coil drive, but not for high-speed data links. The output transistor can sink up to 50 mA continuous (cite:) and block up to 70 V (cite:). With a 400 mV Vce(sat) max at that current (cite:), the voltage drop across the output is low enough to drive a 5 V logic input or a small relay directly, without a buffer transistor.
Industrial temperature range and package fit
It comes in a standard 6-DIP package with 0.300-inch (7.62 mm) body width (cite:), through-hole mounting (cite:), supplied in a tube (cite:). The 0.100-inch pin pitch matches legacy socket footprints, so it swaps into existing boards without a layout change.
onsemi lists the CNY171M as Active (cite:) and ROHS3 compliant (cite:). The 6-DIP package is a common through-hole footprint, so inventory across multiple distributors is typical. Confirm the date code and lot traceability at quote time.