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BQ25703A: puzzle me with some parameter

s sun
Prodigy 170 points
Part Number: BQ25703A

Recently, I used the charging chip bq25703a for a new design. The application scenario is to charge 4-cell NiMH batteries. It is assumed that the final voltage which 4-cell NiMH batteries are fully charged is 6V. The parameter of chip about maximum charging voltage is set to 5.8v as fast charging mode.

There are two questions needed to be confirmed:

1.the MAX SYSTEM VOLTAGE REGULATION(the term is mentioned in datasheet) is the voltage at which the battery is expected to be fully charged. Is it right that i understood?

2.when the batteries voltage is charged to about 5.78V , and the adapter input current is only about 100-200mA. Why is the fast charge flag  IN_FCHRG of register(21/20h) which i used to judge the batteries is charged fully still 1  ?

Thank you very much!

  • 0
    TI__Expert 3320 points

    Hi There,

    1, Your understand is correct.

    2,  As long as VBAT is higher than min system voltage the the status will go into fast charge period. The fast charge period include both CC and CV period. After battery go into CV period 5.78V, the fast charge status bit is still 1.

    Regards

    Regards