LM317 power and heat

Thread Starter

NOISEBOB

Joined Jul 7, 2019
13
Hello

I need to power a bunch of circuits that ask for 3v and 4.5v and I'm thinking to built a simple circuit using two LM317's and powering it with a 9v power supply..

Would heat be an issue? Do I need heat sinks?

Is there a cleverer way of powering down from 9v to 3v and 4.5v?

Everything is DC BTW..
 

ericgibbs

Joined Jan 29, 2010
8,873
hi Bob,
If you keep the dissipation in the LM317 below say 2W then it should be OK.
So 9Vdc in and 3Vdc out thats a 6v drop across the LM317,,, so Watts/Volts = Current.... 2W/6V = 0.33A max

For the other 9V - 4.5V drop thats 2W/4.5V = 0.44Amps max

OK.?
E
 

dendad

Joined Feb 20, 2016
3,080
If you find the regs do overheat, try these..
3A buck converter.jpg
Ebay specials!
Some versions have trim pots to adjust them, some are fixed, and the best have solder pads on the back to select a range of fixed volts, as well as variable.
 
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