Operation from only a LiPo battery

[zcab911]

We are developing a standalone application.  The bulk power is provided by LiPo battery, which can vary from 4.2V to 3.0V as the battery discharges.  I have the system connected as follows:

VDDH is connected to the battery
DCCH is connected to VDD through a 10uH inductor
VDD also has a 4.7uF cap to ground
VBUS is NOT connected
DCC is connected through a 10uH inductor to DEC4
DEC4 is has a 4.7uF capacitor to ground

We are unable to see any GPIO activity, and are unable to get any switching activity noticeable on DCCH, even with the DCDCCE0 set to 1.  Any ideas?

[Jared]

Hi

Which device are you using? Did you follow the reference circuitry?

Jared 

[zcab911]

We are using the NRF52840.  We are currently using a module from Fanstel, but will be moving to a chip solution next.  I have implemented in accordance with Figure 16 of the datasheet.  BT is working, but I cannot get any GPIO to work, or even get the DCCH working or switching into the inductor.

Is there any reason VBUS needs to be connected if we are not using USB, and all that is required is VDDH?

[zcab911]

In the end, it turned out to be programming connector issue.  The VDD was not connected to the programming connector, and there was no evidence that code was not being injected into the target CPU.  We are working properly with a LiPo battery.