Isolation and signal transfer — what the ratings mean
The VOS617A-3T is a single-channel phototransistor optocoupler in a 4-SOIC surface-mount package. It provides galvanic isolation of 3750Vrms between the DC input LED and the transistor output. The current transfer ratio (CTR) is specified at 100% minimum and 200% maximum, measured at a forward current of 5mA. This CTR band is tight enough to allow consistent logic-level translation without overdriving the LED — a 5mA input reliably saturates the output transistor for 5V or 3.3V logic families, assuming the collector load resistor is sized for the minimum CTR. The 400mV maximum Vce saturation at the output side ensures low voltage drop when the transistor is on, preserving noise margin in the receiving logic.
Switching speed and timing budget
Rise and fall times are both 3µs typical; turn-on time is 6µs typical, turn-off 4µs typical.
Lifecycle and compliance
It is fully RoHS3 compliant, with no exemptions that would complicate EU or global market shipments.