Isolation and input flexibility
The TLP290(SE is a single-channel photocoupler rated for 3750Vrms isolation between input and output — sufficient for reinforced insulation in mains-referenced circuits such as AC-line monitoring, relay drivers, and isolated feedback loops. Unlike many photocouplers that accept only DC forward current, this part accepts both AC and DC input, which simplifies the BOM in applications that sense AC line zero-cross or need bidirectional signal transfer.
CTR spread and switching speed
The current transfer ratio ranges from 50% minimum to 600% maximum, both specified at If=5 mA — the wide spread means the designer must design for the minimum to guarantee logic-level output at the load, while the maximum affects the saturation margin and pull-up resistor value. Typical turn-on and turn-off times are 3 µs each, with rise and fall times of 2 µs and 3 µs respectively — suited to low-frequency signal and power-control interfaces.
Temperature grade and output ratings
The output transistor is rated for 80 V maximum collector-emitter voltage and 50 mA continuous current, with a typical Vce(sat) of 300 mV at the rated current — adequate for driving logic inputs, low-power relays, or DC loads within the current limit.