Kiwi and power supply soft-start [power supply must ramp 0-5V in less than 50 msec]


My Kiwi which is remote-controlled was stopped for 2 days. This morning I went to my parent's house where it is located, no led lit on the kiwi but 5V on the supply (which is an industrial Lambda, linear regulated). Once in the attic, I shut down the PS by removing the mains plug, I wait some seconds and put back the power : no succes. I disconnect the Kiwi 5V connector and plug it, bingo, the animal is awaken.

I have repeated several times the same test with the same results.

My feeling is that the Kiwi has some difficulties to handle what we call a "soft start", i.e. a power supply climbing from 0 to 5V in a quite long time, or a partial loss of the supply followed by a voltage recovering. On the products I work on (security products for the industry), we have a sequencing power supply manager to stop and restart all the redondant processors for all the PS failure cases.

What is the policy in the Kiwi about µP reset and PS voltage ?

73's de J-Luc F1JEK


  • Hi J-Luc,

    Maybe you could add something as simple as a relay driven by a transistor and potential divider / zener to the DC supply so that it drops out / cuts in only when the supply volts have established themselves correctly ?


    Martin - G8JNJ
  • jksjks
    edited July 2017
    The power management IC (PMIC) used on the Beagle (TI TPS65217C) has definite restrictions on the 5V input ramp-up rate. I think it has to be under 50 msec. The data sheet for that part is huge and I'm in a place right now where I can't download something that large. So take a look and you should find the spec.

    Note that this is very typical for any modern system-on-chip microprocessor and/or FPGA. They have strict power sequencing requirements and a slowly ramping input power supply is a disaster in that regard. So the PMICs used refuse to power on if the ramp timing is not met. So there is nothing unusual about how the Beagle or Kiwi is responding to this situation.

  • Thanks for your answer. I will take a look. :-)
Sign In or Register to comment.