nrf52840 usb mode and battery mode

[Davides98]

Hi,

I'm designing a module based on nrf52840.

This module has two type of power supply:
- usb mode
- li-ion battery mode.


My goal is to use usb to charge the battery and to use the for communication,
when I disconect the usb cable, the battery will be power supply and the communication will do from antenna bluetooth.

CASE 1

When I'm in VBUS usb mode go to "Battery Charging" and charge the battery, at the same time go to AP2112K 3.3V and power nrf52840 (VDD and VDDH are connected together).

The mosfet opens the way to the battery (see the voltage regulator)

CASE 2

When I'm in battery mode, there isn't VBUS, the Battery Charge doesn't work but the battery will be the power supply, the mosfet close the way to the battery (see voltage regulator),

go to AP2112K 3.3V and power nrf52840.

In my schematics I connected together VDD and VDDH; 

I have a question...

Is it correct to link VDD and VDD together or is it better to separate them?

I used theese components

USB ESD PROTECTION [USBLC6-2]

BATTERY CHARGER [TP4056 (battery charging) + DW01A (battery protection) + 8205A(dual mosfet)]

VCC REGULATOR (AP2112K 3.3V)

If you have any other recommendations regarding components, please write...

Thanks regard.

0640.schematic.pdf

[Kazi Afroza Sultana]

Hello David,

I have been looking at your design. I will get back to you soon.

Thanks.

Best Regards,

Kazi Afroza Sultana

[Kazi Afroza Sultana]

Hello,

I think what you have mentioned here it would possible to implement. We have thingy:52 , that almost does the same thing. You can see the following block diagram. USB and battery two ways are here for power supply and mosfets act as switches. 

Here is the product specification of thingy:91 https://infocenter.nordicsemi.com/topic/ug_thingy52/UG/thingy52/intro/frontpage.html?cp=14_2 , you can look at for getting the brief idea.

Thanks.

Best Regards,

Kazi Afroza Sultana

[Davides98]

okay so VCC and VDDH connected together and managed by the 3.3V regulator?

[Kazi Afroza Sultana]

In Thingy 52, to provide the circuits with a stable voltage, a DC/DC buck regulator with an output of 3.3 V is used.

[bibiblcbrd]

HI, I'm an nRF52840 newbie here. Has anyone ever designed a PM circuit powered by a single lipo battery or USB Micro B with two Vouts (5V and 3.3V)? The design I'm currently working on is to boost/regulate either the lipo battery or the VUSB to 5V and then regulate it to 3.3V. Is there a recommended PMIC that's under $5 for this? I've been searching for a while now. Thanks.