4000Vrms isolation in an 8-SOIC footprint
The Vishay SFH6343T is a single-channel transistor-output optocoupler in an 8-SOIC package, providing 4000Vrms of galvanic isolation between a DC input LED and a phototransistor output. The 8-SOIC (0.154", 3.90mm width) footprint keeps the coupling on a standard SOIC-8 land pattern, which simplifies layout for designs already using that package for other components.
The current transfer ratio (CTR) is specified at 19% minimum and 50% maximum when the LED forward current is 16mA. That spread means the receiving logic must tolerate a factor-of-2.6 variation in output current across temperature and unit-to-unit; a pull-up resistor or a Schmitt-trigger input on the receiving side is the usual fix. The 25mA absolute maximum forward current gives headroom for driving the LED at 16mA nominal without stressing the junction.
Temperature range and output rating
The output transistor is rated for 25V maximum collector-emitter voltage and 8mA output current per channel — sufficient for 5V and 3.3V logic families, but not for driving relays or high-current loads directly. The 1.6V typical forward voltage of the input LED is standard for infrared emitters and works with 3.3V or 5V logic outputs through a current-limiting resistor.