Electronic – How Zero Crossing optoisolator to work with 220VAC

acopto-isolatorzero crossing

I want to use a H11AA1 to detect Zero Crossing, but I am not sure how circuit should look like. How much voltage should LED receive inside H11AA1?

Here is datasheet:
http://www.vishay.com/docs/83608/h11aa1.pdf

By my calculation, please correct me if I am wrong.
Forward continuous current from datasheet 60mA.

Resistor should be 220/0.06= 3.6k
With wattage 220*0.06=13.2W

Here is some circuit which I found but not seem legit…

enter image description here

Best Answer

The maximum current through the LEDs has to be limited to 60mA. That would not be the normal operating current for that optoisolator.

The 230VAC RMS with 66K ohm series resistors allows a current of 230/66K = 3.4mA RMS through the LEDs. The peak current would be 4.8mA when the AC voltage reaches its very peak value.

These conditions should allow that optocoupler to work just fine.

Why do you have a doubt about the circuit now?

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