3750Vrms isolation for industrial bus isolation
The TLP184(TPL,SE is a single-channel phototransistor optocoupler from Toshiba, built for galvanic isolation in industrial and power-conversion interfaces. Its 3750Vrms isolation rating suits it for separating low-voltage control logic from higher-voltage field-side circuits, such as PLC digital inputs, AC mains zero-cross detection, or motor-drive feedback paths. The AC/DC input type means the LED can be driven with either polarity, simplifying the circuit when the input signal is bipolar or when you need to detect both half-cycles of an AC waveform without an external bridge rectifier.
CTR spread and drive design margin
The current transfer ratio spans from 50% to 600% at a forward current of 5mA. That wide spread means the designer must bias the LED and size the output pull-up resistor for the minimum CTR to guarantee logic-level switching across all temperature and lot conditions. The upside is the headroom at the high end — the same circuit will still work with a high-CTR unit, just with faster switching and lower output saturation voltage.
The 80V output maximum and 50mA per-channel current give enough headroom for driving logic inputs, low-power relays, or DC loads in 24V and 48V systems.
Switching speed for signal isolation
That puts the usable signal bandwidth in the low tens of kilohertz — fine for 50/60 Hz AC detection, slow digital status signals, or PWM feedback at a few kHz, but not for high-speed data or fast-switching gate drives.
Supplied in a 6-SOIC package with 4 leads (the two center pins are omitted for creepage distance), body size 4.40mm width.