• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 557 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

BQ25703A: BQ25703A auto charge done question

CCS/BQ25703A: BQ25703A auto charge done question

Bruce Lin_899
Intellectual 870 points
Part Number: BQ25703A

Tool/software: Code Composer Studio

Hi TIer

 Thanks for reply my question. But I think maybe I description not so clear

Your answer :

" To define the charge termination, it should check the converter active or not (keep switching or not).  

When the charger output reaches the voltage regulation point, the charge current could taper down to zero.

But, the converter is still active and regulate the BAT output voltage. It is not off.

To turn off the charge, please set charge current register to zero or set the inhibit bit to 1. "

What is my question:

1. Because the system still have current output, so I think I can't use converter to check the termination.

2. If bat voltage near voltage regulation point, could we have some method to know the current down to zero is the behaver of charger itself?

Thanks for your time for reply my question.

BR

Bruce

  • 0
    TI__Guru 56650 points
    1. Your are right. BQ25703A is a NVDC charger. The converter keep switching when the charge is disable. The termination function needs to cut the charging current path to the battery. So, the BATDRV status can reflect the charge termination which is controlled by host controller.

    2. "If bat voltage near voltage regulation point, could we have some method to know the current down to zero is the behaver of charger itself?" If bq25703A operates in charger voltage regulation (constant voltage mode), the charge current loop is connected to feedback loop and doesn't control the switching FETs. So, I would say the current down to zero is caused by the load. The charger only keeps the output voltage stable.
  • 0 in reply to Wang5577
    Intellectual 870 points
    Hi Wang

    But in this case, my customer don't have gauge circuit. So battery package will not cut current by itself!
    And because have no gauge, they use OCV method to calculate SOC. But current would be auto cut from 190mA to 0mA
    So my customer ask me if BQ25703A have auto cut off current function( I ask this on E2E before, the answer is not.)
    He is so sure that he didn't do this operation.

    BR
    Bruce
  • 0 in reply to Bruce Lin_899
    TI__Guru 56650 points
    Bruce,

    Now, I understand your "auto cut off current function". If they use OCV method to calculate SOC, they can disable the charge before measure OCV.
  • 0 in reply to Wang5577
    Intellectual 870 points

    Hi Wang

    My customer's real problem is that when battery voltage near charge voltage, and plug off then plug in AC

    The charge current would change from 190mA directly sjut down to 0.

    So, that is why I ask about the control method of charge done.

    Because the charge gauge SOC is 96%~99% when this behavor happen, do you have idea how to fix it?

    Thanks!

    BR

    Bruce 

  • 0 in reply to Bruce Lin_899
    TI__Guru 56650 points
    Bruce,

    If the BQ25703A output charge voltage is a little bit lower than the previous output charging voltage, the new cycle charger current could drop to zero. If the gauge SOC is 96%~99% at that time, it could report no full charge.

    I would think the gauge should report full charge 100% SOC if the charging current is zero and charge voltage in output regulation voltage range.