3750Vrms isolation in a 4-SMD gull-wing package
The Renesas NEPOC PS2701-1-P-A is a single-channel transistor-output optocoupler in a 4-SMD package with gull-wing leads, rated for 3750Vrms isolation. It delivers a DC-coupled transistor output with a current transfer ratio (CTR) guaranteed between 150% and 300% at a forward current of 5mA. The output transistor is rated for 80mA continuous collector current and 40V collector-emitter voltage, with a typical Vce(sat) of 300mV. Switching speed is specified with 3µs rise and 5µs fall times (typical), suitable for low-to-medium speed isolation in industrial control, PLC I/O modules, motor drive feedback, and power supply feedback loops.
CTR window and LED drive budgeting
The 150% to 300% CTR window at 5mA forward current is the key parameter for design-in. A guaranteed minimum CTR of 150% means a 5mA LED drive yields at least 7.5mA of collector current at the output transistor, enough to saturate a TTL/CMOS logic input or drive a small relay coil through a base resistor. The 300% maximum caps the sensitivity, preventing false turn-on from leakage or noise pickup on long input traces. Design the LED drive current at 5mA nominal; the CTR window ensures the output side sees a clean logic-level swing without over-driving the LED beyond its 50mA absolute maximum.
The 100°C upper limit provides margin above the typical 85°C industrial ceiling, useful in sealed enclosures or near power components. The -55°C low end covers cold-start scenarios in unheated equipment shelters.
Output drive capability
The output transistor handles up to 80mA continuous collector current with a 40V collector-emitter breakdown. At 80mA the Vce(sat) typically sits at 300mV, keeping dissipation low. This is sufficient to drive a small signal relay (e.g., 5V/20mA coil), a logic input, or a low-side switch for an indicator LED. For loads above 80mA or inductive switching, add an external driver transistor or flyback diode. The 40V rating allows direct interface to 24V industrial logic levels with headroom.
Switching speed and timing
It handles 50/60 Hz mains zero-cross detection, DC bus voltage sensing, and slow digital isolation (e.g., status feedback from a contactor or limit switch) without issue. For applications requiring sub-microsecond propagation delays or switching above 100 kHz, a digital isolator or high-speed optocoupler would be needed.
It is ROHS3 compliant, suitable for designs requiring lead-free assembly.