3750Vrms quad-channel optocoupler for industrial isolation
The Toshiba TLP293-4(LA-TR,E is a four-channel DC-input transistor-output optocoupler in a 16-SOIC surface-mount package. It provides 3750Vrms isolation between input and output, with a current transfer ratio (CTR) ranging from 50% to 600% at a forward current of 500µA. The output transistor is rated for up to 80V and 50mA per channel, with a typical Vce saturation of 300mV. Rise and fall times are 2µs and 3µs respectively, with turn-on and turn-off times both at 3µs typical.
CTR range and drive margin
The CTR floor of 50% at 500µA forward current means the output transistor can sink at least 250µA with that drive, which is enough to pull a standard logic input low through a reasonable pull-up resistor. The 600% ceiling gives headroom for degraded LED output over temperature or lifetime — a design that works at the minimum CTR will still function if the actual part lands at the high end. For designs that need tighter CTR binning, check the TLP293-4 family's available grade suffixes; this (LA) variant covers the full 50-600% spread.