I have a static 1.5A resistive load on the supply which has a 1A minimum load. That would leave me with 10.5 A of wiggle room. Out of which I need just less than 2A.
I'll revisit the supply level, but I'm fairly certain that I am well within those ranges. On Wed, Jan 17, 2018 at 4:06 PM, Graham <gra...@flex-radio.com> wrote: > Still sounds like a power problem. > > A lot of 12 Amp supplies might go out of regulation at almost no load. > They typically need to be loaded to ten percent of max rated output load > to be within Voltage spec. > > The Beagle supply needs to stay between 4.5 and 5.5 Volts under all load > conditions. > > I recommend you stay between 4.75 and 5.25 to have noise margin against > the PMIC going into self-protect. > > --- Graham > > == > > On Wednesday, January 17, 2018 at 2:03:32 PM UTC-6, epar...@gmail.com > wrote: >> >> Hello, >> >> I just finished reading a lot of posts on the topic of starting up the >> BBB and various issues that folks have had. I didn't see anything that >> reflected my situation, so I'm going to reach out in hopes that someone in >> the group can cast some light on this. >> >> I have a BBB with a custom Cape. The Cape is designed to interface the >> BBB to a cap-touch color screen. The Cape contains the backlight power >> supply for the display and the obligatory EEPROM for ID, addressing pins, >> etc. Very similar to the BB-CAPE-DISP-CT43 <http://tinyurl.com/ybj9s68m> >> available for purchase. >> >> What is different in my case is that I'm supplying power to the Cape >> (5V). The power then goes to the Cape connector on P9, pins 5 & 6. This >> would be equivalent to supplying power to the BBB via the barrel connector. >> >> The BBB is internally booting (no SD, etc) with custom code. I have >> written the shipping code image into the board and I get the same results. >> >> I've made several dozen of these assemblies now, and so far I have two >> that exhibit this odd behavior. >> >> The symptom: The BBB will attempt to start, will shut down, and will try >> to start once more at a rate of about once per second. Sometimes this only >> happens a couple of times, other times I simply give up after 60 of these >> failed boot cycles. There is no consistency to the number of tries a board >> will go through. >> >> I'm using a very robust power supply that meets or exceeds the PMIC slew >> rate requirements. The supply is capable of supplying 12A @ 5VDC. >> >> When the BBB is attempting to boot, the blue LED adjacent to the barrel >> connector (commonly referred to as the Power LED) will flash briefly. >> >> There are occasions when a 'bad' assembly will boot without issue, but >> most frequently it comes up in this flashing state. >> >> I've checked for the usual suspects, bad solder joints, interconnects, >> etc, without finding anything. I know that my inrush current is on the >> order of 1.7 to 1.8 A at the initial startup, but that drops off >> significantly after the caps are charged up. >> >> Has anyone out there experienced this pulsing behavior and found a root >> cause and possibly a fix? >> >> One thought that I had was to monitor the bebug port (X1), but is there >> even enough up time to have this be useful? >> >> Thank you to everyone in advance for your insight. >> >> >> >> >> >> >> -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to a topic in the > Google Groups "BeagleBoard" group. > To unsubscribe from this topic, visit https://groups.google.com/d/ > topic/beagleboard/IbYlM9n9DIY/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > beagleboard+unsubscr...@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/beagleboard/ffe872d5-cadb-460f-8f1f-709727d1d7a1%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/ffe872d5-cadb-460f-8f1f-709727d1d7a1%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAEaoV1TQTrsM-0D%2BubMX028Mcz9ZKNVQvuff9U2EHpAanatsgA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
