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I have a BBB and it works quite well however when I power it over the Barrel connector or over the vdd pins rather then use the usb connection it doesn't automatically boot. When I put the barrel connector and usb in at the same time and then remove the usb it continues running. This is running on ubuntu arm. I have tested that the power supply is between 4.95 and 5.04 V and is capable of sustaining this to just over 1 Ampere

Edit it appear the BBB does boot when supplied with 4.7 V lab power supply at ~0.4A power consumption. So that suggest something is wrong with the power supply. But how do I test it seeing I was able to verify that it can supply 1A at 5V.

This power supply works by feeding a 12V battery into a step down to convert it down to 5V if that matters. power-supply power linux beaglebone-black beagleboard

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  • $\begingroup$ What's the amperage of your non-usb power supply? (Barrel and Vdd) $\endgroup$
    – Scott Downey
    Jan 27, 2015 at 16:54
  • $\begingroup$ max 1A/ 4.95-5.05 V $\endgroup$
    – Thijser
    Jan 27, 2015 at 16:55
  • $\begingroup$ I'd recommend trying a 2A power supply. $\endgroup$
    – Scott Downey
    Jan 27, 2015 at 16:59
  • $\begingroup$ But the BBB doesn't normally use more then 0.6A maximum and can be powered over usb (max 0.5A) $\endgroup$
    – Thijser
    Jan 27, 2015 at 17:00

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Why do so many people keep "Underestimating the complexity of power supply design"?

I'm sure that you already know that every digital electronic device pulls a very brief (transient) surge of power when it is first plugged in and turned on -- at much higher current and power levels than the steady-state current and steady-state power during normal operation.

I'm guessing that your 12V to 5V power supply limits its output current.

Switching-mode power supplies, such as the one on the BeagleBone that converts that 5V to the even lower voltage used by its CPU, often interact badly (latch up) with current-limited power supplies during the start-up transient.

Have you looked at the BeagleBoard FAQ, which says "The power adapter is required to provide 5V ... at least 2A (or 10W) is recommended"?

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