NRF52840 Li battery and charger

[Tai]

Hi,

We are designing a module based on NRF52840 and Li-Po battery. The battery could be charged by a charger module connected to USB.

I have some question regading our design:

1- Sould we connect Li battery to VHDD? In this case, what should we do with VDD?

2- Can we connect USB V+ to VBUS of nRF52840?

3- what is the best practice for antenna? I could not find any information about antenna in the layout examples.

Thanks

[ketiljo]

1. See this schematic: https://infocenter.nordicsemi.com/topic/ps_nrf52840/ref_circuitry.html?cp=4_0_0_6_2_0#concept_hqh_j22_fq

You can connect the battery to the VDDH pin.

2.. Yes. the VBUS pin must have 5 V for the correct function. This will also detect VBUS when connected to USB

3. You can use any 2.4 GHz antenna. Make sure you have the appropriate tuning components in case you use a chip antenna, see this whitepaper for more: https://infocenter.nordicsemi.com/pdf/nwp_017.pdf

[Tai]

Thanks for your reply.

Which confog should we use? 

What should we connect to VDD_nrf?

[ketiljo]

VDD should only be connected to the other VDD pins. The output of REG0 is connected to VDD internally, see figure 3 here: https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2_0_0