Darlington optocoupler with 5.3 kV isolation
The Vishay K825P is a dual-channel Darlington-output optoisolator in an 8-DIP through-hole package. It delivers 5300Vrms isolation between input and output, which is enough to separate logic-level control circuits from higher-voltage loads in industrial and power-supply applications. The Darlington output gives a minimum current transfer ratio of 600% at a forward current of just 1 mA, so a small input signal can switch up to 80 mA per channel on the output side. This makes it a good fit for driving relays, solenoids, or PLC input modules where you want to keep the LED drive current low.
Switching speeds and drive requirements
Turn-on time is 300 µs typical, and turn-off time is 250 µs typical. These are not fast for a logic-level signal — expect to handle switching frequencies well below 1 kHz. The 100 mV max Vce saturation at the output means the Darlington drops very little voltage when on, so the load sees nearly the full supply rail. The input LED has a typical forward voltage of 1.2 V and can handle up to 60 mA continuous forward current. The output side is rated for a maximum of 35 V across the collector-emitter. That voltage and current combination covers typical 24 VDC industrial logic and relay loads.
Operating temperature spans -40°C to 100°C, which covers most industrial enclosures and outdoor cabinets without needing a heated or cooled compartment. The 8-DIP package with 0.300-inch row spacing is a standard through-hole footprint — it fits into a socket or solders directly into a PCB. No special handling beyond basic ESD precautions. The DC input type means the LED is driven by a steady current, not an AC waveform. The output is a Darlington pair, so it inverts the logic — the output transistor is on when the LED is on. Keep that polarity in mind when wiring the load side.
It is RoHS3 compliant, so it meets the current restriction on hazardous substances for EU and most global markets. No end-of-life notice or last-time-buy window is in effect. Sourced through independent distribution channels.