Did you look here? http://www.elinux.org/Beagleboard:BeagleBoneBlack#Board_Revisions_and_Changes
*3) Moved the enable for the VDD_3V3B regulator to VDD_3V3A rail. Change was made to reduce the delay between the ramp up of the 3.3V rails. No evidence of this being an issue, but it really needs to be as close to the same as possible.* So, you have to shutdown VDD_3V3A to shutdown the VDD_3V3B. Gerald On Wed, Dec 18, 2013 at 4:38 PM, <andersenbe3...@gmail.com> wrote: > I ran into a similar finding on the A6 board. Interestingly, the A5C > works correctly. These are with a battery connected. > > I'm investigating a proper shutdown and power-off if the main 5V is > removed. I have a Li-Ion battery connected to keep everything running > until a proper shutdown/power-off can occur. > Using the method in "Re: [beagleboard] Chip power down and PMIC_POWER_EN" > while in Uboot, I can see that the A5C shuts everything down including the > VDD_3V3B supply (see schematic). The A6 does not. > > Now if there is no battery connected, they both power-off. > > So what's happening? > > Brad > > > On Thursday, October 25, 2012 2:23:40 PM UTC-7, Andrew Bradford wrote: > >> On Thu, 25 Oct 2012 16:13:48 -0500 >> Gerald Coley <ger...@beagleboard.org> wrote: >> >> > You are correct. This is something we just ran into yesterday and we >> > are looking at a solution. The solution is being tested and will not >> > be something that shows up in the near future, but hopefully soon. It >> > MAY be something that could be done with a wire mod, but it is too >> > early to tell. Should know more by Monday. >> >> Thanks! So I'm not crazy, that's good to know. :) >> Even if the wire mod is complex, it'd be great if you could share it. >> >> >> > On Thu, Oct 25, 2012 at 4:07 PM, Andrew Bradford < >> > and...@bradfordembedded.com> wrote: >> > >> > > If I disable LDO3 in the TPS65217, VDD_3V3A should turn off. >> > > VDD_3V3A turning off should disable U8 linear regulator causing >> > > VDD_3V3EXP to turn off. >> > > >> > > It doesn't. >> > > >> > > Disabling LDO3 in the TPS65217 causes VDD_3V3A to drop to >> > > approximately 2.4 V. This is not low enough to disable the U8 >> > > linear regulator's enable pin. Further, disabling LDO4 after this >> > > only causes VDD_3V3A to drop to approximately 1.2 V. Again, this >> > > is not enough to disable U8 linear regulator's enable pin. >> > > >> > > I've tested on an A3 and an A6 bone. >> > > >> > > I realize there's grave impacts to disabling LDO3 or LDO4, ie: much >> > > of the board won't work any more although the ARM core and DDR will >> > > still be operating. That's OK for my experiments. >> > > >> > > How can I turn off VDD_3V3EXP from software without completely >> > > turning off all rails on the TPS65217? Is it possible? >> > > >> > > I'm trying to do this in order to debug an issue we see with a >> > > custom cape at power down when running on 3.7 V lithium battery. >> > > With our cape attached, VDD_3V3EXP latches on even when the rest of >> > > the BeagleBone is powered off. This is due to SYS_5V staying >> > > present due to the battery and U8 linear regulator not powering >> > > down before the latch action occurs. The TPS65217 and AM3359 are >> > > both in the proper states, I can boot due to power button press >> > > once in the OFF state (defined by the TPS65217 data sheet). But >> > > keeping VDD_3V3EXP running will ruin the battery life while in the >> > > OFF state. >> > > >> > > On the cape, we pull up to VDD_3V3EXP for things like MMC/SD and >> > > I2C. I believe this is part of the problem as there may be power >> > > back feeding through the pull-ups enough to cause the latch >> > > situation. But we believe we're following the recommended pull-up >> > > strategy documented in the Bone SRM. >> > > >> > > Has any one else seen issues like this when attempting to enter the >> > > TPS65217 OFF state with capes attached that use pull-ups to >> > > VDD_3V3EXP while running on 3.7 V lithium battery power? If so, >> > > what capes work? >> > > >> > > Yes, I realize this is quite a corner case. Sadly, it's an >> > > important one for me. >> > > >> > > Thanks, >> > > Andrew >> > > >> > > -- >> > > >> > > >> > > >> > >> > >> >> -- 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. For more options, visit https://groups.google.com/groups/opt_out.
