• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 63 subscribers
  • Views 113 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.

BQ25756: the chip lose its function

s sun
Prodigy 170 points
Part Number: BQ25756

Tool/software:

Hi,dear.

Sorry for coming here again.

I solve a problem previously,but a new problem is coming.

I connect the battery to my board and  connect a LED between RGEN and STAT1 that want to show the charger status.

After powering the board(about 50V), the LED is on showing the RGEN is right. But during I increase the voltage to 58V slowly , the battery connector pin is suddenly sparking twice. After that the LED is always off and I measure the RGEN, it is 0V. Obviously, the chip is bad.

How to judge the chip is good and how can I protect the chip from damage later?

Thank you!

  • 0
    TI__Mastermind 31145 points

    Hello s sun,

    No problem at all.

    Thanks for being patient with this though. I am swamped at the moment. I'll get back to you early next week on this question.

    Best Regards,
    Ethan Galloway

  • 0 in reply to Ethan Galloway
    Prodigy 170 points

    HI,dear.

     According to your comments, I am full of anticipation that there will be good message to solve the problem of damage.

    Thank you!

  • 0 in reply to Ethan Galloway
    Prodigy 170 points

    hi,dear.

    To protect the chip from damage or spark, add a diode which can withstand higer voltage such as 150V between the chip and battery. Is it feasible?

    Thank you!

  • +1 in reply to s sun
    TI__Mastermind 31145 points

    Hello s sun,

    Once again, thanks for being patient with this.

    s sun said:
    To protect the chip from damage or spark, add a diode which can withstand higer voltage such as 150V between the chip and battery. Is it feasible?

    Yes, this is possible to do.

    s sun said:
    How to judge the chip is good and how can I protect the chip from damage later?

    You can measure if the chip is good in a few ways. Here's the method I normally use:

    • Can the BQ25756 communicate over I2C when there is power on VAC or SRN?

    • When either EN_ADC=1 or the BQ25756 starts charging, does REGN come up to 5V?

    • Are the 10Ω resistors on SRN/SRP or ACN/ACP still 10Ω? Sometimes, a current surge can cause this resistors to break.

    • To test if the switching FETs are still good, I like using the diode measurement function on a multimeter to measure the FET from both drain to source and source to drain.

    I have a few questions to help debug the damage to your board:

    • Are those 10Ω resistors still good?
    • Is anything else on the circuit damaged?
    • Can you measure SW1 and SW2 with an oscilloscope once you have a working board again?
    • Does setting EN_CONV_FAST_TRANSIENT improve the circuit behavior?

    Let me know if you have any other questions about this.

    Best Regards,
    Ethan Galloway