Hi Stuart, I tried to use the PocketBeagle with the battery and also found the extra current draw. Ultimately I communicated with Octavo and got the following reply. The OSD3358-SM SiP used on the pocketbeagle internally connects the LDO1 regulator to both the RTC clock input (VDDS_RTC) as well as the VDDS input. The extra current is taken by the connection to the VDDS power input. The answer from Octavo is copied below.
https://octavosystems.com/forums/topic/unexpected-current-consumption-with-pmic-sleep-mode-for-battery-charging/#post-6895 "The additional current consumption comes from the fact that the OSD335x and OSD335x-SM use TPS65217C PMIC. If you look in the application note from TI (http://www.ti.com/lit/ug/slvu551i/slvu551i.pdf), you can see that in the case of the TPS65217C, both VDDS and VDDS_RTC are connected to the LDO1 output of the PMIC. The additional current consumption that you see is a result of the VDDS power input being connected to the LDO1. Unfortunately, the connection between VDDS and LDO1 is internal within the SiP and cannot be modified on the OSD335x and OSD335x-SM. However, we are in the process of characterizing the OSD335x C-SiP to see if it can support the power use case where VDDS is not connected to LDO1. We should have that characterization finalized in early January. Additionally, the TL5209 is enabled with an internal pull up within the OSD335x family of devices. In the OSD335x and OSD335x-SM, this connection cannot be modified. However, in the OSD335x C-SiP, there is a pin, SYS_VDD1_CTL, that will allow a user to disable the TL5209." On Monday, October 21, 2019 at 5:47:36 PM UTC-6, Stuart Longland wrote: > > Hi all, > > We've got a project built around the PocketBeagle single board computer > which uses a single LiPo 18650 cell as a back-up supply. > > The cell is connected to the PocketBeagle along with a 10kOhm > thermister, as per recommendations. > > We're find that after running `poweroff` from the shell, and seeing all > LEDs on the PocketBeagle turn off, cells that start with a healthy > voltage of around 4V, are found to have a voltage of just 2.2V when > measured a fortnight later. > > The cells we're using are these ones: > > https://core-electronics.com.au/polymer-lithium-ion-battery-18650-cell-2600mah-solder-tab.html > > > …and the circuit is fairly simple (attached). We've seen this on two > revisions of our project. The first revision did not include a RTC, but > in spite of this, still suffers the problem. > > Is there a reason why the batteries are getting so heavily drained? Is > there a work-around without having to resort to MOSFET switching of the > battery? > > Regards, > -- > Stuart Longland (aka Redhatter, VK4MSL) > > I haven't lost my mind... > ...it's backed up on a tape somewhere. > -- 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/00917c28-4b48-43c2-9645-df044bf7087f%40googlegroups.com.
