Coin cell for wireless applications, low temperature

Thread Starter

hspalm

Joined Feb 17, 2010
201
Hi,
For this small temperature sensor I'm developing I search guidance on cell selection.

The sensor will sleep at just a couple microamps and transmit every 5-30 minutes with bursts up to 13mA when transmitting. CR2032 works well today but discharges much quicker when put in a freezer. Looking at BR2032 which is recommended for lower currents and has wider temperature range, but will it handle the bursts?

I also saw these, which offer much more capacity at a sacrifice of slightly larger diameters. But rated continious currents at only 30µA, I'm not sure if they can handle the burst currents for the radio?
http://www.digikey.com/en/product-highlight/p/panasonic/br-a-series-lithium-coin-cell-batteries

Any insight on the matter is highly appreciated.
 

DickCappels

Joined Aug 21, 2008
10,187
The datasheet is not encouraging.

Just thinking out loud: If the burst is not too long you might find a capacitor that maintains sufficient capacitance at low temperatures and that capacitor might supply the 30 ma for the duration of the burst.
 

Thread Starter

hspalm

Joined Feb 17, 2010
201
The radio IC (CC1310) actually has a "decouple" pin where it's suggested a 1uF capacitor. Could it be for this reason you're mentioning?
 

DickCappels

Joined Aug 21, 2008
10,187
No, The decoupling capacitor is to create a low impedance across the power supply of the circuit. Otherwise there could be undesirable side effects such as the traces on the PC board radiating and possibly the circuit not working correctly.

That is probably a good place to put a very large capacitor if you can find a suitable capacitor. Ultra capacitors are used to start deisel engines in cold weather.
 
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