recommendation for power config nrf51822

[toashwin]

I am planning on using: NRGF51822 CDAB WCSP (= 128KB Flash, 16KB RAM, 3.5x3.5mm) Another main chip I will be using is: LSM303AGR (www.st.com/.../en.DM00177685.pdf)

Both of them can run at 1.8v

I plan to use "two" batteries in series of type: - Battery size 13. (1.4v.) www.hearingaidbatteryshop.com/.../duracell-13-data.pdf

Power management is very critical for! I dont want to be changing batteries for a year.

So what configuration should I be using nrf51822? Internal LDO setup? DC/DC Convertor setup? Low voltage setup with external regulator? - If so what is recommended regulator?

What setup do you for the NRF Beacon development board from Nordic?

Thanks Ashwin

[Øyvind Karlsen]

Hi,

For best power efficiency on the chip use DC/DC, the DC/DC should be switched on in times of high current draw (CPU activity, Radio TX/RX), as that is when it saves the most power.

As for the supply voltage that is up to you to evaluate. You need a battery that can support the inrush current from the chip entering TX mode (~15 mA @ 3V). If you want to use an external regulator that will add to your BoM, and the device might not be very efficient. You also need to ensure that it has a ripple below 100 mV pk-pk.

The nRF beacon kit uses 3V3 (from a CR2032 battery) with DC/DC configuration.

Best regards,

Øyvind

[toashwin]

What do you mean by " the DC/DC should be switched on in times of high current draw ". Do we turn DC/DC on and off? In off state what mode is used? Can you point me to this in document?

Now, my battery (hearing aid battery size 13) will supply 1.1v to 1.4v. Shall I use 2 of them in series?