Re: Cooling a TO-220 7812 regulator

On Sun, 15 Sep 2024 16:58:01 +0530, Pimpom <Pimpom@invalid.invalid>
wrote:

I'm going to use a standard 7812 TO-220 regulator on a single-sided 1 oz
board with the dissipation varying as below:
>
- Idle at 120-150mW
- 0.5W for 1-5 minutes at irregular intervals
- Up to 4W for 1 second at the start of each 0.5W phase
>
The interval between the 1-5-minute periods is variable and may be 1 to
10 minutes.
>
The ground pin is soldered to ~2 sq.in. of copper on the PCB.
>
Options:
1) As described. No extra heatsinking.
2) Mount it on a small Al heatsink.
3) Place the regulator horizontally on the underside and bolt it to the
copper.
>
Tamb = ~35ºC max
>
Do you think option 1) is enough? Or should I go for 2) or 3)?

Option 1 sounds fine to me. It will barely get warm.

You don't need it, but internal plane layers help spread out heat too.

https://www.dropbox.com/scl/fo/l0pfn2qtj9pylri0kxnbs/ADjThVe5WV989K8DgotdKVI?rlkey=z4gtiaxmnybem099s6l9yz20m&dl=0

https://www.dropbox.com/scl/fo/dcua00tr8fgxtudnqzhzr/APMIydE2mZFz5e2aFRd-2TY?rlkey=2y16ic2watsnfnthzcf7zbt0i&dl=0