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BQ24072: BQ24072TRGTR maximum charging current problem

pb ben
Prodigy 170 points
Part Number: BQ24072

Hello.

We have a classic BQ24072TRGTR configuration to have a charging current of 1.5A.
With + 5V at V_USB, EN1 = 0 and EN2 = 1, a 4000mA lithium polymer battery with nothing drawing any more current, we are unable to maintain 1.5A charging current continuously but about 1A.
Does the BQ24072TRGTR normally not keep 1.5 during the entire battery charging time?

Thanks.

  • 0
    Prodigy 170 points

    Attached the schematic.

  • 0 in reply to pb ben
    TI__Mastermind 23220 points

    Hi,

    Welcome to E2E!

    Just a few questions:

    • What is the voltage and current at the OUT pin? If the sum of the charging and system current exceeds the max input current, the output voltage is prioritized and charging current will be reduced. This is known as DPPM mode. Otherwise, once the battery voltage exceeds 
    • What is the voltage at the ISET pin? The current out of ISET is 1/400 of the charge current. The voltage across RISET can be monitored to calculate the current sourced while charging.

    Also to look at your schematic:

    • We do require a capacitor from OUT to VSS ranging from 4.7uF to 47uF
    • Do you have information on the battery NTC? Or are you not going to be using the TS function? I noticed the voltage divider ratio is 20% but noticed a battery NTC test point. Just wanted to clarify.

  • 0 in reply to Anthony P Pham
    TI__Mastermind 23220 points

    Hi,

    Just checking to see if there are any updates here?