65. Optocoupler for MCU Signal Isolation

Aarav is designing an industrial control board where a 3.3V microcontroller sends a control signal to an external 24V relay driver stage.

To protect the MCU from noise and voltage spikes on the relay side, he wants to use an optocoupler for galvanic isolation between the two sections.

The optocoupler's input LED will be driven at around 5mA to 10mA from a GPIO pin through a series resistor.

The output transistor will drive a small signal into the relay driver stage.

He wants a through-hole DIP-4 package for easy prototyping.

Help him select a suitable transistor output optocoupler from DigiKey.

Make sure it has enough isolation voltage, adequate CTR for signal transfer, and works reliably in industrial temperatures.