Re: Optocoupler datasheets

On 29/05/2024 16:15, bitrex wrote:

Optocoupler datasheets seem like kind of a mess, I try not to use them too often in situations where there's any kind of power budget because other than "shove some relatively huge current through the LED like 5-10 mA" it's hard to know what you can get away with.
 A light load on the transistor side will definitely reduce the forward current required (and of course slow the speed to a crawl) but who can say by how much while still ensuring the thing will turn on sufficiently to saturate the output?
 The CTR varies widely from process variation, varies with temperature, varies with collector emitter voltage, varies with forward current, and the data sheets are full of caveats like "At I_f < 1 mA, note CTR variation may increase" and "Graphs are representative, not indicative of actual performance." ????
 Any suggestions for how to approach methodically/mathematically selecting drive current would be appreciated, thank you! ("Don't bother" a valid option)

Not really answering the question, but there's more than one way to skin a cat...
https://www.nve.com/Isolators
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Cheers
Clive