recommend battery measuring method

[Peter]

Hi all,

From this forum and the examples given in the "sdk" find two approaches to measuring the battery voltage:

• using external divider 10M/2.2M+22nF
• using integrated divider 1:3 of VCC. The first method uses additional components and has even a small additional power consumption. In the source code of second method I see compensation of voltage drop over diode (can't find this diode in the datasheet). Тhis is likely to cause an increase in the error. What is the exact value of voltage drop and how repetitive it is in different ICs.

Which method do you recommend?

Best regards, Peter

[Dan Danknick]

Peter,

I believe the 270mV diode compensation is related to the power input structure on the Evaluation Board where USB, coin cell and external Vin all meet up to product Vcc_nRF. Check out Figure 9 in the nRF51822 Evaluation Kit User Guide v1.1.

In a custom solution with just the CR2032 you'll want to set that to zero (or use #ifdef EVBOARD to modify it by project build flags).

Dan

[Peter]

Hi Dan,

Your response completely clarifies the problem. Thank you very much for your cooperation.

Peter