Darlington optocoupler for high-voltage industrial I/O
The Renesas NEPOC PS2535L-1-F3-A is a single-channel Darlington-output optocoupler in a 4-SMD gull-wing package. It provides 5000Vrms galvanic isolation between a DC-input LED and a high-voltage Darlington phototransistor output, making it a fit for motor drives, PLC I/O modules, relay drivers, and AC-line sensing where you need to switch a 350V rail from a logic-level signal. The Darlington configuration delivers a current transfer ratio (CTR) of 400% minimum to 5500% maximum at 1 mA forward current, so a 1 mA LED drive can switch up to 55 mA on the output side. That gain margin lets you drive the LED directly from a 3.3V or 5V GPIO without a buffer transistor, saving board space and BOM cost.
350V output and 120 mA per channel — sizing the load
The output transistor is rated for 350V collector-emitter and 120 mA continuous current per channel. That combination covers 24VAC/DC industrial loads, 120VAC relays, and small solenoids directly. The 1V Vce(saturation) at 120 mA means about 120 mW dissipation in the output device — fine for the 4-SMD package in still air, but if you're switching near the current limit at high duty cycles, check the thermal derating against the -55°C to 100°C operating range. Rise and fall times are 18 µs and 5 µs typical, so this part suits low-frequency switching (relays, contactors, valve drivers) rather than high-speed data isolation. For sub-microsecond isolation, you'd step up to a digital isolator or high-speed optocoupler.
Active lifecycle — no obsolescence pressure
The NEPOC series is Renesas's established optocoupler family with broad distribution support.
Package and rework notes
The 4-SMD gull-wing package is a straightforward surface-mount footprint — no hidden leads, no thermal pad. Standard MSL 3 handling applies: bake before reflow if the moisture-barrier bag has been open longer than the floor-life window.