You can disable in software Vac or Vusb, but not the battery source, that is why so much trouble 22 Июл 2015 г. 1:25 пользователь "Dennis Cote" <denn...@harding.ca> написал:
> On Tuesday, July 21, 2015 at 8:06:49 AM UTC-6, lisarden wrote: > > By the way I with my collegues spent some time on investigating this issue >> and found in the tps65217 datasheet that all three power source Vac, Vusb >> and Vbat should not be enabled at the same time. Only two of them should. >> Because of the reason that BBB is a universal enthusiast's board all three >> power sources are left floating, which contradicts with tps65217 >> architecture. We figured out that if the most of users use only a barrel >> connector or USB then Vbat input should be grounded. I don't know if this >> solution fixes the random reboot issue but at least it complies with the >> TPS65217 architecture. Probably anybody should try to ground the Vbat input >> and see how the board behaves. >> > > > I was reviewing the TPS65217 datasheet and I think this may be the area of > concern (from section 9.3.9.1): > > The linear charger periodically applies a 10-mA current source to the BAT >> pin to check for the presence of a battery. This will cause the BAT >> terminal to float up to > 3 V which may interfere with AC removal detection >> and the ability to switch from AC to USB input. For this reason, it is not >> recommended to use both AC and USB inputs when the battery is absent. > > Since the battery is absent for most BBB users, TI recommends using AC or > USB power, but not both. > > Furthermore, the TPS65217 has internal sinks on the AC and USB inputs, so > it should not be necessary to short either input to ground when it is not > used as long as the input sinks have not been forced off by the software. > > 9.3.9.4 AC and USB Input Discharge >> > > >> AC and USB inputs have 90-µA internal current sinks which are used to >> discharge the input pins to avoid false detection of an input source. The >> AC sink is enabled when USB is a valid supply and VAC is below the >> detection threshold. Likewise, the USB sink is enabled when AC is a valid >> supply and VUSB is below the detection limit. Both current sinks can be >> forced OFF by setting the [ACSINK, USBSINK] bits to 11b. Both bits are >> located in register 0x01 (PPATH). >> > > >> NOTE [ACSINK, USBSINK] = 01b and 10b combinations are not recommended as >> these may lead to unexpected enabling and disabling of the current sinks. 9 > > >> Perhaps someone can check if these are being set to something other than > 00b. > > Dennis Cote > > > -- > 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/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. For more options, visit https://groups.google.com/d/optout.
