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BQ25703A: How to improve efficiency of BQ25703A

Star Xu
Genius 9645 points
Part Number: BQ25703A

Hi 

The customer follow the BQ25703AEVM design the schematic. It can work normally, Input voltage is 5V, output voltage is 12.6v (3 lithium batteries), output current is 1A, the charge efficiency is 12.06*1/(4.78*2.825)=89.3%,  Less than 92%. 

Due to low efficiency and serious heating, the circuit board is installed in a sealed plastic shell, so the heat dissipation not good. The MOS will be burnt. Inductor heating is very serious.

Could you please give some suggestions.

Thanks

Star

  • 0
    TI__Expert 3320 points

    Hi Star:
       

        In order to figure out the root cause please help collect below information for analysis:

        1, What is the switching frequency customer is operating? Is there any obvious oscillation during efficiency test?

        2, It is very helpful if there is a thermal picture of customer hardware, the hot spot in the thermal picture will be very helpful to find the root cause.

        3, Does customer using exact same inductor and power FETs as our EVM schematic? Does this issue can be duplicated on different boards?

    Regards

    Shishuo

  • 0 in reply to Shishuo Zhao
    TI__Expert 3320 points

    Dear Customer, we haven’t heard from you in a while, I assume you’ve been able to resolve your issue