5000Vrms isolation — what it buys you in system safety
The Renesas PS2561FL-1Y-A is a single-channel, DC-input phototransistor optocoupler rated for 5000Vrms isolation between input and output. That isolation voltage is the primary spec that drives its use in industrial power supplies, motor drives, and medical equipment where galvanic separation is a safety or noise-mitigation requirement. The transistor output with base access gives you flexibility to tailor switching thresholds with an external resistor, or to disable the output during power-up sequencing.
CTR margin — planning for LED aging and temperature drift
Current transfer ratio is specified at 300% minimum to 600% maximum at a forward current of 5mA. That wide CTR band means the part can tolerate LED degradation over life and temperature excursions without dropping below the logic threshold at the receiver. For a design targeting a 10-year service life in an outdoor enclosure, the 300% floor at 5mA gives you headroom to derate the LED drive current and still maintain a clean logic high at the output. The typical forward voltage of 1.2V at 5mA is standard for IR LEDs in this class.
Temperature range and output drive — deployment context
Operating temperature from -55°C to 110°C covers cold-start in telecom cabinets and hot-side sensing in engine-bay electronics. Vce saturation is 300mV maximum at rated current, so the voltage drop across the opto won't steal headroom from the downstream load.
Package and assembly
Supplied in a 4-SMD gull-wing package (4-SMD case code) for surface-mount assembly. Gull-wing leads are inspectable and reworkable with standard hot-air tools. The package is compatible with reflow profiles typical for MSL-rated components; verify floor-life handling per the manufacturer's moisture sensitivity level. The tube shipping format is common for this package size and protects leads during handling.