Single-channel optocoupler with 2500Vrms isolation — what it buys the BOM
The Renesas PS2801C-1-V-F3-A is a single-channel DC-input transistor-output optocoupler in a 4-SSOP surface-mount package. The transistor output can switch up to 80V at 30mA, which covers most logic-level and low-power relay interfaces without an external driver.
The current transfer ratio spans 50% to 400% at 5mA forward current. A 50% minimum CTR means that with 5mA on the LED side, the output transistor can sink at least 2.5mA — enough to pull a TTL or CMOS input low with a modest pull-up resistor. The 400% maximum gives headroom for degraded LED output over temperature or lifetime, so the design doesn't need a tight CTR bin. The typical forward voltage is 1.2V, which is standard for an IR LED.
Switching speed: rise/fall and turn-on/turn-off
This is a general-purpose optocoupler, not a high-speed digital isolator — it handles 50 kHz to 100 kHz switching comfortably but won't support fast serial protocols like SPI or I2C. For a 1 kHz PWM motor drive or a 50/60 Hz mains zero-cross detect, the timing is more than adequate.
The 100°C upper limit is the junction temperature; derating the output current above 85°C is good practice per the datasheet's thermal derating curve.
The ROHS3 status covers the full substance restriction set, including the four phthalates.