5000Vrms isolation in a 4-DIP through-hole package
The Renesas PS2561D-1Y-V-H-A is a single-channel transistor-output optocoupler from the NEPOC series, packaged in a through-hole 4-DIP (0.300", 7.62mm) body. The through-hole DIP package is the traditional industrial standard — easier to hand-rework during prototyping or field repair, and preferred in high-vibration environments where a surface-mount joint might fatigue over time. The 7.62mm pin pitch matches standard 300-mil DIP footprints used across generations of industrial control boards.
CTR range: 80% to 160% at 5mA forward current
The current transfer ratio is specified as 80% minimum and 160% maximum, both measured at 5mA LED forward current. This is a relatively tight bin — it means the designer can count on at least 4mA of collector current from a 5mA LED drive, which is enough to saturate the output transistor and pull a logic input low or drive a low-speed relay coil through a resistor. The 1.2V typical forward voltage drop is standard for an IR LED. With a 50mA continuous output current rating and an 80V Vce maximum, this part can directly drive small relays, solid-state relays, or logic inputs without a buffer transistor in many cases. The 300mV Vce saturation at rated current keeps the on-state voltage drop low enough to not steal headroom from a 5V or 3.3V logic rail.
Switching speed: 3µs rise, 5µs fall — for line-frequency and DC signals
Rise and fall times are 3µs and 5µs typical, respectively. This limits the part to switching frequencies well below 100 kHz — think 50/60 Hz AC zero-crossing detection, DC bus voltage sensing, relay driver latching, or slow digital status signals. It is not intended for high-speed data isolation or serial communication links; for those, look at a digital isolator or a high-speed optocoupler with a logic output.
Temperature range: -55°C to 110°C
The wide range also gives headroom for self-heating in enclosed power supplies where ambient temperature plus internal dissipation could push the local temperature above 85°C.