Single-channel optocoupler for industrial isolation
The HCPL0501 is a single-channel optocoupler from onsemi with a DC input and a transistor-with-base output, rated for 2500Vrms isolation. The 8-SOIC surface-mount package fits standard pick-and-place assembly and saves board space compared to DIP-8 optocouplers. The transistor output with base access gives the designer flexibility to tailor the switching threshold or add base-emitter capacitance for noise filtering.
CTR spread and switching-speed trade-offs
Current transfer ratio (CTR) is specified at 19% min to 50% max at a forward current of 16 mA. That 2.6:1 spread means the output pull-up resistor and the LED drive current must be chosen so the circuit works at the low end without saturating the output transistor at the high end — a common design-in discipline for this family. Typical turn-on time is 450 ns and turn-off is 300 ns, which supports data rates up to roughly 1 MHz. For PWM or serial isolation below that frequency, the propagation delay is well within the timing budget of most PLC input modules or gate-drive feedback paths.
The 8-SOIC package is widely stocked, and the part is not single-sourced — multiple distribution channels carry the onsemi HCPL05 family.