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what is smallest recommended gas gauge/protection circuit for single cell Li-Ion pack

Cliff Brake
Intellectual 420 points
Other Parts Discussed in Thread: BQ27541-V200, BQ27505-J5, BQ27350

Hello,

I'm looking for recommendations for a protection circuit and gas gauge chip for a single cell Li-Ion pack (actually two 2200mAHr cells in parallel).  We need to support both 4.2V and 4.3V cells (could be different designs, different ICs), and the packaging is very aggressive, so we need parts that are as small as possible.  Ideally, we would like a combined protection/gas gauge circuit.

Thanks,
Cliff 

  • 0
    TI__Expert 4115 points

    Hello Cliff,

    I do apologize for the delayed response.  Our single cell gauges can work with this application (the 2 batteries in parallel).  Are you looking for a gauge that would be on the system side or a gauge that would be on the actual battery pack (pack side)?  If your application is going to be system side I would suggest looking into the bq27505-J5 and if your application is going to be pack side I would suggest looking into the bq27541-v200.  Both of those devices offer the smallest package for that particular "side" of fuel gauging.  The bq27505-J5 is ~2.5 mm x 2 mm and the bq27541-v200 is ~2.5 mm x 4 mm.

    As far as protection is concerned, can I ask what type of protection you are looking for?  Overvoltage?  Overcurrent?  We do offer protection ICs; however, I do not know if they will offer all of the protection you might be looking for in your application.  It does appear that we do not have a combined protection and gauging IC that will fit your application, but a space conservative solution should not be a problem. 

    Do you know the space requirements?  Also, would you need any type of authentication in your application? 

  • 0 in reply to Jared Casey
    Intellectual 420 points

    Hi Jared,

    Thanks for the suggestions.  Ideally, we will put the gauge in the pack if we have room.  For protection, we are looking for overvoltage, undervoltage, and overcurrent.  The board size is roughly a 16.35mm diameter circle (our cell diameter).  

    Thanks,
    Cliff 

  • 0 in reply to Cliff Brake
    TI__Expert 4115 points

    Cliff,

    Then I would suggest the bq27541-v200 IC for your application.  As far as protection is concerned, the Ricoh 5402 series pack protector IC is a device that we have recommended in the past.  If you refer to one of our application handbooks (for instance slua458) that protector is mentioned when talking about the bq27350 which is a previous part to the bq27541-v200 (please note that the bq27350 is NRND - not recommended for new designs).  I am not for certain on their package size, but I believe you would be looking for something ~ 3 mm x 2 mm.  Also, the protection FETS are listed in the handbook as well.  Hope this helps.