Using the Beaglebone black Revision A6A. I powering it with supplying 5V to the Vdd pins. The 5V is coming from an adjustable regulator with an enable line. Also I have a 10uF tantalum capacitor on the regulator’s output to avoid sending a noisy 5V.
When that enable line goes high, the beaglebone black does not power on all the time. Sometimes the BBB boots properly. However, instead of powering on sometimes, it seems that the power management chip on the BBB is switching Vdd to no load. I still have a similar result with different tantalum cap values.
What is the state of the switch in the power management chip on a rising edge of Vdd? Has anyone else had a problem powering the BBB with Vdd?
The PMIC is sensitive to slow ramping power supplies. A 10uF capacitor is also a little small. You could be seeing a dip in the voltage when the PMIC does kick in and it could in some instances cause it to shutdown.
Gerald
I'm doing almost exactly what you're doing except that my regulator
chip doesn't have an enable line. So far it has worked exactly as it
should, applying power by plugging the 5v supply into pins 1 and 3 on
P9 just powers the BBB up as normal. I only have a .33uF tantalum on
my regulator input and nothing on the output.
Thanks, I have been experimenting with different cap values and am not seeing any irregular voltage drop on the output of my regulator. I might decide to use a DCDC converter. Which regulator are you using?