External DC DC Converter not working with Arduino

Discussion in 'The Projects Forum' started by leonhart88, Mar 21, 2015.

  1. leonhart88

    Thread Starter AAC Fanatic!

    Feb 23, 2007
    118
    1
    Hi All,

    I'm running into an issue with an Arduino project. I have a power supply at 24V going into a DC DC converter (V7809-1000) which is supposed to have a 9V output. This 9V output is tied to the "Vin" pin on an Arduino Uno.

    What I've noticed is that if I plug the Arduino Uno into my laptop USB port first, and then power on my 24V supply, the output of the DC DC converter is only 5V. Conversely, if I power on the 24V supply first and then plug the USB in, the output is 9V as expected.

    I understand the Arduino has some type of automatic power source switching to determine when to use power from the USB and when to use power from an external source, but I don't think this is the issue here.

    Does anyone have any suggestions on why this may be happening? Will a DC DC converter function improperly if it sees a voltage on its output without a voltage on its input?
     
  2. leonhart88

    Thread Starter AAC Fanatic!

    Feb 23, 2007
    118
    1
    Turns out this issue was solved after putting a reverse bias protection diode in series with the 9V output from the DC DC converter!
     
  3. ebeowulf17

    Well-Known Member

    Aug 12, 2014
    1,127
    165
    Thanks for the update. Love learning tips and tricks from other people's experiences. Glad you got it working.
     
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