Coin cell for wireless applications, low temperature

Discussion in 'Wireless & RF Design' started by hspalm, Jun 29, 2016.

  1. hspalm

    Thread Starter Active Member

    Feb 17, 2010
    201
    8
    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.
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,653
    632
    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.
     
  3. hspalm

    Thread Starter Active Member

    Feb 17, 2010
    201
    8
    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?
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,653
    632
    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.
     
    hspalm likes this.
  5. hspalm

    Thread Starter Active Member

    Feb 17, 2010
    201
    8
    Should suffice, I'll have me one of those ;)

    Thanks for helping out.
     
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