SSR doesn't work, how to debug further?

I have an AQV252GA (datasheet) but it doesn’t work.


Wiring should be type “C” (in brackets):

I get no voltage with a DMM between pin 5 and GND-5V (tried with and without a load).

I get 0.95V across pins 1 and 2. That seems a little low (should be 1.14V?). I swapped the resistor for 200ohm and still get 0.95V. That seems a little weird, I’d expect voltage drop to change, but who knows what goes on inside the SSR.

I have 2 of these relays on my board, and both don’t work in the same way.

I see this chart:

At ~25C the dropout voltage is ~1.15V. I measure a 0.95V drop across pins 1 and 2 – if that’s right maybe it’s not enough? But why didn’t it change when I tried a 200ohm resistor? I don’t know what to do from here.

Unrelated code was setting pullups on BOTH the pins. A previous revision of the PCB shuffled the pins around but the code wasn’t updated.

Thanks for following up with your self-resolution!

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