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BQ25303JEVM: Efficency problem.

Kfir Maymon
Prodigy 90 points
Part Number: BQ25303JEVM

Hi experts, 

Im trying to choose battery charger for 3.7 (4.2v max) 4000mAh battery,

I'm trying to use bq25303jevm,

I swap the 2 amp charge limit resistor to 16k to get about 2.5A charge current.

This is the setup:

Vin 5v, 5A power supply input to the board,

0.01ohm resistor in series to the battery.

Input current 2.5A, output 3.8v 2A.

The problem is that im getting low efficiency (about 60%).

Why is that? 

  • 0
    TI__Guru 57331 points

    Hi,

    When the efficiency is about 60%, what are the charger operating conditions such as VBUS (voltage at VBUS pin), IVBUS, VBAT (voltage at BAT pin), IBAT, PMID pin voltage, REGN pin voltage and TS pin voltage?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    Prodigy 90 points

    Sorry but after some testing I found that i put icharge resistor value of 10k,

    I think that this was the problem, 

    After i change it to 16k the efficiency rise to 92%.

    Thanks for the fast response.