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Optocoupler question
otter:
How do I read out the Vce from the datasheet below, if I use If=8mA and Ic=120mA?
https://www.onsemi.com/pub/Collateral/MOCD223M-D.PDF
magic:
You can't. Current transfer ratio is only 500% guaranteed and 1000% typical, which means 5x or 10x more Ic than If.
See figure 4. With If=10mA you only get a few times more Ic than with If=1mA, which would be 10mA typical. You could increase collector current by applying even more than 5V while the optocoupler is turned on but come on.
moffy:
The current transfer ratio is min:= 5x, typ:= 10x with Vce = 5v. Therefore with If = 8ma, the CTR falls off a bit so lets say about 35ma is the maximum output current you could rely on at 25C.
Ian.M:
Its worse than that as the O.P's linked datasheet doesn't include any operating lifespan or reliability data. As LED light output is well known* to degrade over the LED's operating life, it would be foolish to design with less than a factor of two margin, i.e. about 17mA Ic, if you want it to have a reasonable chance of reaching 10000 operating hours without failure. If its on all the time 10000 hours is barely enough to outlast a one year warranty!
* e.g. https://www.vishay.com/doc?49267
otter:
If I use the this part instead (new link below), it seems I can get 120-140mA with Vce=1V with If=5mA.
What can be expected if I increase If to 10mA?
Do I need the selection "K" to get this results?
I will consider deratig.
https://www.mouser.se/datasheet/2/698/PN10235EJ04V0DS-1528581.pdf
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