Size Counts!!

Discussion in 'The Projects Forum' started by JDR04, Oct 17, 2013.

  1. JDR04

    Thread Starter Active Member

    May 5, 2011
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    Hoping somebody can help with a small power supply circuit.

    I need to step 9Vdc down to 5Vdc for a microcontroller. Space is very restricted.

    Any suggestions will be appreciated. Thanks - JDR04
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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  3. wmodavis

    Well-Known Member

    Oct 23, 2010
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    A zener diode and a resistor?
     
  4. apqo1

    Well-Known Member

    Oct 5, 2008
    50
    3
    How much current? Consider:
    • Microcontroller overhead
    • Loss through pull-up/down resistors when outputs are low/high
    • Current sourced from micro's outputs
    • Other loads (sensors, motors, LEDs, etc.)

    Are you working with through-hole or SMD?
     
  5. BobTPH

    Active Member

    Jun 5, 2013
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    78L05 in a TO92 case for up to 100mA.

    Bob
     
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  6. #12

    Expert

    Nov 30, 2010
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    Gotta go with, "There's nothing smaller than a TO-92 package". Even a 1/2 watt resistor and a zener have difficulties beating that.
     
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  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I did it several times with nothing more then a 2512 SMD resistor and a pair of 0805 caps, but that was cheating as the PIC has an internal regulator.

    Did it again using a pair of 0201 resistors, an 0201 cap and a very time transistor pair. Fit in perhaps .15 square and it was "wafer thin."
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    If the O.P. can use SMD parts, you can get a lot of 5v linear regulators in the tiny SOT-23 package.
     
  9. #12

    Expert

    Nov 30, 2010
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    If only we knew how much power needs to be dissipated...
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Yeah it would be great if people asking for help actually provided enough information. ;)

    But in the context of using it "for a microcontroller" we know a lot of micro projects only use a handful of mA. SOT-23 sized 5v regulators are common enough in 100mA-200mA capacity.
     
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  11. JDR04

    Thread Starter Active Member

    May 5, 2011
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    Thanks guys, going by some of the advice and questions asked,I need to do a bit more research so I can answer the questions raised.........
     
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