NRF51822 with AA Batteries

RE: NRF51822 with AA Batteries

energy — Fri, 01 Jul 2016 08:44:20 GMT

Hi, do you have a reference design for powering using 2AA (or AAA) bateries that implement your 4 requirements ? I guess, something using p-mos, zener 3V3, TVS. Which capacitance value do you recommand to filter the spikes when installing the battery if there is no external peripheral than the nrf51822 to be powered at startup ? Is it possible to get more than 3,6V with 2x AA (or AAA) ? Thanks

RE: NRF51822 with AA Batteries

Nate — Fri, 08 Apr 2016 18:21:14 GMT

I don't think it is possible to exceed 3.6V with AA batteries, but after having looked at some specs on rechargable batteries it would seem that I may want an external boost regulator after all because rechargable AA batteries are only 1.2V at full charge. I hadn't even thought of reverse polarity protection, so I will research some circuits for that. It would appear that directly using the LDO may be more suited for other applications where reversing the power source poles isn't a factor. I appreciate the input.

RE: NRF51822 with AA Batteries

Dave_couling — Fri, 08 Apr 2016 04:14:06 GMT

Its not necessary using an external LDO if the following conditions are met:

You have reverse polarity protection - highly necessary for a battery as often accidentally installed backwards as a AA or AAA
Assure under no circumstances the maximum input voltage is exceeded +3.6V
Add capacitance so can filter the power, and handle spikes went installing the Battery
A TVS is recommended to protect the nRF51 from voltage spikes from installing the battery.