What this optocoupler does on the board
The Vishay TCMT1600T3 is a single-channel phototransistor optocoupler in a 4-SOP surface-mount package. It provides 3750Vrms galvanic isolation between input and output, letting you pass a logic-level or low-current AC/DC signal across a safety barrier without a conductive path. The transistor output can switch up to 70V at 50mA, which covers most PLC digital inputs, relay drivers, and isolated feedback loops in industrial controls. The current transfer ratio (CTR) is specified at 80% minimum and 300% maximum when the LED is driven with 5mA forward current. That 80% floor means even with a weak LED drive you still get a reliable logic-high on the output side; the 300% ceiling tells you the output transistor can saturate harder than the input current alone would suggest, which helps when you need to drive a heavier load without increasing the LED current.
Isolation and timing for the signal chain
Rated for 3750Vrms isolation, this part fits basic reinforced-insulation applications in mains-powered equipment — think SMPS feedback, motor-drive interface, or AC-line zero-cross detection where the working voltage stays under 250Vrms. The 3µs rise and 4.7µs fall times (typical) are fast enough for 10 kHz to 20 kHz switching signals but not for high-speed data; if you need 1 Mbps or faster, look at a digital isolator or a high-speed optocoupler instead. Turn-on time is 6µs typical, turn-off 5µs typical. That asymmetry matters if you are driving a load that needs symmetrical switching — you may need to adjust the pull-up resistor on the output side to balance the edges.
Temperature range and environment
The 4-SOP package with 4.40mm body width is a common footprint shared across the TCMT family, so a layout designed for the TCMT1600 will take this T3 variant without a board spin.
Sourcing and compliance
For volume pricing and lead time, submit an RFQ — we source through independent distribution and can confirm availability and current pricing at quote time.