2500Vrms isolation in a 4-SOIC — what it buys you
The Renesas NEPOC PS2815-1-V-F3-A is a single-channel phototransistor optocoupler that delivers 2500Vrms galvanic isolation in a compact 4-SOIC surface-mount package. It accepts both AC and DC input signals, so one BOM line covers DC logic-level coupling and AC mains zero-cross detection without an extra rectifier. The transistor output is rated for 40V and 40mA, which is enough to drive a logic input, a relay coil, or an isolated feedback loop in a power supply.
CTR window: 100% to 400% at 1 mA — design the LED drive around the min
The current transfer ratio is specified as 100% minimum and 400% maximum, both measured at 1 mA forward current. That means with 1 mA through the LED, the output transistor can sink at least 1 mA (CTR = 100%) and at most 4 mA (CTR = 400%). For a design that must guarantee the output saturates across all units and temperatures, size the collector load resistor to work with the 100% floor — the 400% ceiling just means the output will saturate harder, which is harmless. The typical forward voltage of 1.15V at 1 mA makes it compatible with 3.3V and 5V logic rails through a single series resistor.
Temperature range: -55°C to 100°C — industrial and cold-start environments
Rated for -55°C to 100°C operating temperature, this optocoupler handles cold-start conditions in outdoor telecom cabinets and the heat inside a motor-drive enclosure. The 100°C upper limit is the ambient temperature, not the junction — derate the collector current if the local board temperature exceeds that. Rise and fall times are 4 µs and 5 µs typical, which is fast enough for 10 kHz to 50 kHz switching in isolated gate drives or serial data links.
The NEPOC series is a current-generation optocoupler family from Renesas, so supply continuity is stable through franchised distribution.