Steep voltage drop without heatsinks?

Discussion in 'General Electronics Chat' started by PickyBiker, Jan 10, 2016.

  1. PickyBiker

    Thread Starter Member

    Aug 18, 2015
    56
    1
    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
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,991
    3,736
    http://www.tme.eu/gb/details/oki78sr-5_1.5-w36c/dcdc-converters/murata/oki-78sr-515-w36-c/
     
  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,516
    1,246
    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
     
  4. PickyBiker

    Thread Starter Member

    Aug 18, 2015
    56
    1
    Yup... Found dirt cheap buck converters on ebay. Just the ticket. Thanks!
     
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