NPM1100 with non-chargeable battery

[MMMarc]

I want to configure the NPM1100 to work with either rechargeable or non-rechargeable batteries (in factory).

Would it work to set mount a suitable resistor to the NTC pin, and fool the circuit into believing it is to hot ? Would this have any negative consequences for functionality or performance, e.g. current consumption ?

[Kazi Afroza Sultana]

Hello,

Yes it is possible to set 1K resistor to the ground. When VBUS is connected, the NTC pin is only behaving as 10kohm impedance voltage source. So, even a direct ground will work here also.

You can see this reference circuit https://infocenter.nordicsemi.com/topic/ps_npm1100/chapters/hw_layout/ref_circuitry/doc/frontpage.html?cp=6_0_0_7_2_2#config_3 

Hope it helps.

Best Regards,

Kazi Afroza Sultana

.

[MMMarc]

Thx!

[PeterLjung]

Just to confirm my understanding ...

By connecting NTC to ground in configuration 3 you will:

- Disable charging of battery
- Still have BUCK regulator enabled through VOUT (1.8-3.0 V)
- Allow regulated output (VOUT) both from VBUS (USB) and/or VBAT (from non rechargeable battery)

This would allow design with very flexible battery options.

[MMMarc]

We ran into a limitation on what batteries to choose. The blocker is Vbat<=4.32. Looking at available schematics it was not obvious that this is a real limitation, might just be that for rechargeable batteries that is as high as they go.
For primary cells, can I go higher, say 4.5V for three alkaline cells ?

[Kazi Afroza Sultana]

Hello,

The maximum operational voltage of VBAT is 4.35V (https://infocenter.nordicsemi.com/topic/ps_npm1100/chapters/recommended_op_conditions/doc/frontpage.html?cp=6_0_0_4#recommended_op_conditions) . So, it is not recommended to go over this.

Best Regards,

Kazi Afroza Sultana