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BQ51050B: "Low" charge current accuracy?

Krunal Desai
Prodigy 160 points
Part Number: BQ51050B

Hi folks! 

I am designing the bq51050b into an application as it is hard to beat the integration of a Qi receiver + Li-Ion battery charger in a single IC, and the price point is terrific. That said, in doing some research on the part on these forums, I noticed some folks mentioning issues at "low" charge currents. I see the minimum charge current specified in the datasheet is 500mA.

I think I will likely want to be in the 100-250mA range (current baseline is a 500mAh battery, which would give a 1C charge rate @ 500mA, but I would like to shrink this if possible to the 300mAh range). What kind of issues could I potentially see using the part in these ranges? Poor termination current accuracy is something I've seen mentioned -- would that result in over-charge or under-charge?

And a stupid second question -- this IC doesn't require battery power to operate, correct? I.E. if I have a cell whose safety circuit has kicked in due to UVLO / under-voltage protection, the bq51050b will still power up in the presence of a Qi field and can recover the battery from that situation?

Thanks!

  • 0
    TI__Guru* 75786 points
    Sorry for the late reply I was trying to find a little more info, but no luck.
    The problem has to do with the behavior of KILIM at low current, it will lose accuracy and has a wide deviation from unit to unit. Result is early termination or no termination. The no termination condition can trip the 10 hour safety timer resulting in a fault shutdown.
    We recommend to set termination at about 50mA to avoid the above problem.