Steep voltage drop without heatsinks?

Thread Starter

PickyBiker

Joined Aug 18, 2015
88
I have a circuit with available +28VDC and -28VDC. I want to add some small circuits that require 5V at about 500ma and 3.3V at about 150ma, total of about 650ma. Obviously, if I had the 5V, I could use a simple linear regulator like an LM2937-3.3 for the 3.3V. The problem is getting down to 5V from 28V. By my calculation, a straight forward linear regulator or resistor would have to dissipate about 14 watts.

Is there a circuit or chip that can reduce the voltage by some type of switching to avoid all that heat?

Thanks
 

GopherT

Joined Nov 23, 2012
8,012
I have a circuit with available +28VDC and -28VDC. I want to add some small circuits that require 5V at about 500ma and 3.3V at about 150ma, total of about 650ma. Obviously, if I had the 5V, I could use a simple linear regulator like an LM2937-3.3 for the 3.3V. The problem is getting down to 5V from 28V. By my calculation, a straight forward linear regulator or resistor would have to dissipate about 14 watts.

Is there a circuit or chip that can reduce the voltage by some type of switching to avoid all that heat?

Thanks
http://www.tme.eu/gb/details/oki78sr-5_1.5-w36c/dcdc-converters/murata/oki-78sr-515-w36-c/
 

AnalogKid

Joined Aug 1, 2013
8,294
One of the National Semiconductor (now TI) "Simple Switcher" line will work, and they are easy to use. If you want to buy not build, lotsa little regulator modules on ebay.

ak
 
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