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Questions about the insides of this optocoupler (TLP250) (lemmy.world)

submitted 1 week ago by poplargrove to c/[email protected]

6 comments fedilink hide all child comments

I haven't really been able to find much on this. I recognize the totem-pole and what that's for. Would love help understanding:

What's the triangle?
What's the rectangle immediately after?
Why are there two outputs instead of one? A lecture I watched claimed this is common.

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[–] [email protected] 7 points 1 week ago* (last edited 1 week ago) (1 children)

Triangle is an amplifier and rectangle is a black box ("don't worry what's in here, we promise it's not gremlins").

I suspect that the box might be a biasing array for driving the two output transistors, but then I would also expect two wires to come out of it (one for each transistor) rather than a single combined wire.

Broadcom's datasheet for their version of the part seems to be more akin to what I'm thinking:

Could be either. You'd have to decap the chip to find out, the datasheet writers thought these details were not important.

I have no idea why two of the output pins are tied together. They're not using many of the pins on this package so maybe they thought "why not". I've also seen dual-optocouplers in this same 8 pin package where pins 6 & 7 are the outputs of the two separate couplers.

[–] [email protected] 3 points 1 week ago

rectangle is a black box (“don’t worry what’s in here, we promise it’s not gremlins”).

It's where they store the magic smoke.