Opto coupler need to operate under Saturation is good or Linear region?

ian field

Joined Oct 27, 2012
6,540
For Long reliability of optocoupler circuit in which operate mode need to choose.
The most common type of opto is best used within a nfb loop because the transfer curve isn't very linear.

Numerous consumer devices use them as switches so the isolated front panel micro can switch the live side of the SMPSU on & off.
 

crutschow

Joined Mar 14, 2008
23,494
For Long reliability of optocoupler circuit in which operate mode need to choose.
As long as the optocoupler is operated well within it's maximum ratings there should be no significant difference in the long term reliability whether it's operated in the linear region or as a switch.
 

WBahn

Joined Mar 31, 2012
24,850
What is the nature of the load? If it is at all inductive and there is no protection, then that can shorten the life considerably.
 

Alec_t

Joined Sep 17, 2013
10,432
Since the GB version of that opto has a CTR specified as 100%, you are operating it right on its limit (input current ~5mA, output current needed for full pull-up = 5mA), with no allowance for load current. That is not a good design.
 
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