nPM1300 Setup Guidance

[Johann]

Hey Nordic Team

Just looking for guidance and clarification on the nPM1300 setup. couple of questions on the sample setup below. 

Project Overview

Project is a consumer grade hand held device that charges with USB C or USB 2 connection with a 3.7v Li ion battery and couple of buttons, the current requirements is well within the specifications of the LDO of the nPm1300 chip so that's fine, Im unclear of the output setup to the rest of the system. 

I am using a nrf5340 as the Soc and couple of analog and i2c sensors, My plan is to power the Soc off the "3.3V-SYS" rail and the rest of the sensors on the "3.3V-SEN rail" the idea is to be able to turn the sensors on and off via the LDO switch in software when powered down. 

1) Does this make sense for best shutdown setup and current consumption monitoring ? My initial thought was that the VSYS output would be regulated and the LDO 1 and 2 could be used independently but it does not seem like that's the case. 

2) I know the LDO outputs can be setup via the registers but since the SOC will be powered on boot by LDO1 how do I set the boot up voltage to 3v3? The datasheet notes the max as 2.7V for LDO1 ? 

3) If the above is correct do I just leave VSYS and SYS-VBUS unconnected/used ?

[mathiaso]

Johann said:

and yes I'm asking if all current is measured by the coulomb counter for accurate reporting

It should then be the fuel gauging functionality you're looking for. There's also a page about this in the documentation.

If you want to have a default output voltage on VOUT2 of 3.3V, a resistor in the 250...500kΩ range should be used on the VSET2 pin.
  

As described in the hardware design guidelines, there should be a 1µF decoupling cap on the VBUS pin.
  

How is the SHPHLD button connected?
 

The VBUSOUT pin should have a 1µF decoupling cap.
  

It might be a good idea to evaluate whether should add a smaller cap in the 10 to 100nF range as well to the VSYS output/PVDD input or not.
 

In LDO mode, it's recommended to have two 10µF caps in parallel on each of the LDO outputs.
  

[Johann]

Thank you for the reply, Yes the Cap recommendations will be followed this was a snippet out of a larger design as example. so not all net connection are terminated/ shown. wanted to clarify that the buck1 could not be set by default to 3v3 and that all current downstream of the chip was measurable by the fuel gauge