5300Vrms isolation — the spec that defines the BOM slot
The Vishay SFH6286-4 is a single-channel phototransistor optocoupler in a 4-SMD gull-wing package. Its 5300Vrms isolation rating makes it a candidate for galvanically isolated feedback in switch-mode power supplies, motor-drive I/O, and industrial PLC interfaces where you need to separate a high-voltage bus from a low-voltage controller. The AC/DC input capability means the LED can be driven from a rectified AC line or a DC logic signal — useful for zero-crossing detection or line-voltage monitoring without an external bridge.
Current transfer ratio spans 160% minimum to 500% maximum, both specified at a 1 mA LED forward current. That 1 mA test point is low enough to keep the LED drive within a microcontroller GPIO's capability without a transistor buffer. The wide CTR spread means the load resistor on the output transistor needs to be sized for the minimum case to guarantee logic-level swing; the maximum case just means the output saturates harder at the same drive. Forward voltage is 1.1V typical, so a 3.3V supply with a series resistor can comfortably bias the LED.
Switching speed and output ratings
Rise and fall times are 3.5 µs and 5 µs typical; turn-on and turn-off times are 6 µs and 5.5 µs typical. That puts this part in the slow-switching category — fine for 50/60 Hz line sensing, relay drivers, or DC-link voltage feedback, but not for high-speed data or digital isolator replacement. The output transistor is rated for 55V maximum and 50 mA continuous, with a Vce(sat) of 400 mV maximum. That 55V ceiling covers most industrial 24V and 48V rails with margin; the 50 mA output can drive a logic input or a small relay coil directly.