What the 5000Vrms isolation rating means for your BOM
The TLP385(Y,E is a single-channel transistor-output optocoupler from Toshiba, built for galvanic isolation between a DC input and a transistor output. Its 5000Vrms isolation voltage qualifies it for safety-barrier applications in industrial power supplies, motor drives, and PLC I/O modules where reinforced isolation is required between the control and load sides. The 80V output maximum gives headroom for driving 24V or 48V logic rails directly, and the 50mA per-channel output is sized for small relays, solenoids, or level-shifting into a downstream gate driver.
CTR range — the design margin you need to budget
The current transfer ratio is specified at 50% minimum to 150% maximum, measured at 5mA forward current. That 3:1 spread means the driven-side collector current can vary from 2.5mA to 7.5mA with a 5mA LED drive. In a production BOM, you size the pull-up resistor and the downstream input threshold for the minimum CTR case; the maximum just means the output saturates faster. The 300mV Vce saturation at the rated output current keeps the logic-low voltage well within TTL or CMOS thresholds.
Switching speed and timing
Rise and fall times are 2µs and 3µs typical, and turn-on/turn-off times are both 3µs typical. That puts the practical switching frequency around 100 kHz or lower — fine for isolating status signals, fault flags, or PWM at a few tens of kHz, but not for high-speed data or fast-switching power supplies. The 1.25V typical forward voltage is standard for an IR LED, and the 50mA absolute-max forward current gives a safe ceiling for pulsed drive.
Package and footprint
Housed in a 6-SOIC package with 4 leads, the TLP385(Y,E uses the standard 4-pin SOIC footprint for single-channel optocouplers. The 0.173-inch body width and 4.40mm height fit the common SOIC-4 land pattern. Surface-mount assembly with Tube handling — no tape-and-reel option on this suffix, so plan for tube-fed pick-and-place or manual loading.
Temperature range and environment
Rated for -55°C to 110°C operating temperature, this optocoupler covers the full industrial range and extends into cold-start environments like outdoor telecom cabinets or engine-bay electronics. The 110°C upper limit is below the 125°C military-grade threshold, but it handles the typical industrial enclosure ambient plus self-heating margin.
Lifecycle and compliance
Listed as Active with RoHS compliance. The RoHS status clears it for EU and most global regulatory requirements without an exemption.