Power Supply - Electrician Talk - Professional Electrical Contractors Forum

Hicksynet · 07-01-2009, 04:31 AM

Hi

I'm having a bit of trouble regulating voltage and current from my power supply its a S-150-5 (5v 30A) but i want to reduce it to 3.3v 150ma to drive TLC5940's, i have tried using a LM317 to get the voltage down to about 3.3v but every time i connect one of the chips it blows. All i can think of is the current is still to high. if anyone has any ideas it would be really helpful

thanks

bobelectric · 07-01-2009, 05:20 AM

Sounds like we got a foreign station!

76nemo · 07-01-2009, 05:53 AM

Quote:

Originally Posted by Hicksynet

Hi

I'm having a bit of trouble regulating voltage and current from my power supply its a S-150-5 (5v 30A) but i want to reduce it to 3.3v 150ma to drive TLC5940's, i have tried using a LM317 to get the voltage down to about 3.3v but every time i connect one of the chips it blows. All i can think of is the current is still to high. if anyone has any ideas it would be really helpful

thanks

The LM317 has a min. input V of 4.2V's. I can't say that's your problem, but I can say that's what I have down.

My bad, read that too quickly.

76nemo · 07-01-2009, 06:08 AM

Can you post a schematic possibly?

Hicksynet · 07-01-2009, 06:39 AM

I'm using the following

And I'm Using a 130ohm for R1 and a 220ohm for R2

this has me puzzled

Speedy Petey · 07-01-2009, 07:51 AM

Please go to www.diychatroom.com
Thanks.