In this answer, there is a schematic showing the internals of a 7805 voltage regulator, reproduced below:

7805 equivalent circuit

First of all, what is the sense pin in the first place? Every 7805 I've ever seen had three pins, Vin, Vout, and ground. Is it internally connected to Vout?

But the main question I want to ask is this: What's with all the shorted-out resistors on that sense line? Is there a reason they're there? Surely something as common as the 7805 doesn't go through individual laser trimming on each die, does it?


1 Answer 1


The 78xx family uses the same die.

Vsense is connected to Vout in the standard family.

The difference between a 7805, 7812, 7815, 7824 etc is which of the shorted-out resistors (R12, R26 etc) gets opened to program the correct voltage. They form a programmable voltage divider from the output to the sense input with R10 and R13.

  • \$\begingroup\$ Ah, thank you! That was exactly the answer I was looking for. \$\endgroup\$
    – Hearth
    Commented Apr 29, 2018 at 18:46

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