Modifying the SparkFun Nano Power Switch

June 24, 2019

I recently obtained a SparkFun Nano Power Timer (PRT-15353) .his is a useful board that will power a device on at a given repeat rate. When to DONE it will power the device off. It will repeat this forever. It  consumes around only 35nA.

One problem with the first version of the board is that the TPL5110 on the board has an option to use a one-shot mode. When the power button is pressed, the unit will power the output for a given time and then power off and wait for the next button press. On the current revision of the board Pin 6 when controls this feature is connected directly to VCC. This puts it in repetition timer mode. To put it into one shor mode this pin needs to be grounded. Elias The Sparkiest at SparkFun has promised (will consider) that this will be changed in the next revision.

However they have over 100 in stock has k so it may take a while. I have figured out how to modify the current boards.

Do this at your own Risk!!!! This procedure is delicate and Tricky! There is a high probablity that you will damage your board and make it unusable. Neither SparkFunnor I are responsible if you break it!!!

OK. Now that we got that out of the way –

  1. You need to disconnect Pin 6 from VCC. Due the way the VCC trace is routed it is not possible to just cut the trace. VERY CAREFULLY un-solder pin 6 from the trace. The pin is very delicate and has a high probability for breaking off. (Ask me how I know :-)). Just bend the pin up a little bit.
  2. As an alternative take an Xacto Knife (new and sharp blade!) an slowly and carefully cut Pin 6 where it turns horizontal to meet the trace. Bend it very gently.
    Cut Pin 6

    DO this at your own Risk. This is a delicate and tricky operation. I AM NOT RESPONSIBLE FOR DAMAGE TO YOUR BOARD!!!


  3. Using an ohmmeter insure that Pin 6 is not connected to VCC. Check Pin 6 to Pin 1. Also check Pin 6 to the leg of the push-button. Do not proceed if you see continuity!!
  4. Finally solder a small piece of wire (I used wire-wrap Wire) connecting Pin 6 to ground. Pin 2 would be  be good for this.


    Add Jumper wire from Pin 2 to Pin 6

  5. Now test it out!