5300Vrms isolation in a 6-DIP package
The 4N28W provides 5300Vrms galvanic isolation between the DC input and the transistor output — sufficient for isolating control signals from high-voltage power circuits in industrial and medical equipment. The 6-DIP (0.400" row spacing) through-hole package suits legacy board layouts and retrofit replacements. Input is DC-coupled with a forward voltage of 1.18V typical at 10mA; the output transistor with base access allows external bias adjustment or a base resistor for switching threshold control.
Speed and current transfer ratio
Typical turn-on and turn-off times are 2µs each, placing the 4N28W in the medium-speed class for optoisolators — adequate for 100 kbps serial isolation or low-frequency PWM feedback. The minimum current transfer ratio is 10% at 10mA forward current, meaning the output transistor sinks at least 1mA with 10mA input drive. Vce saturation is 500mV maximum at the rated output current — the output voltage drop when the transistor is fully on stays under half a volt, preserving headroom for the downstream logic rail.
Temperature range and compliance
Rated for -55°C to 100°C operating temperature, covering industrial and extended-temperature environments. The maximum output voltage is 30V, and the forward current can reach 100mA peak — derate for continuous use above 10mA per the CTR curve.