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BQ76930: REGOUT issue

Akilan G
Intellectual 285 points
Part Number: BQ76930
Other Parts Discussed in Thread: BQ78350, , BQ78350-R1

Hello sir,

we are working on bq76930 with Bq78350-r1 circuit with the help of Bq76930 EVM reference. We are facing an issue with REGOUT pin from AFE, which give perfect 2.5v output till the power shunt to Bq78350 from AFE. Once the shunt is closed, the 2.5v is dropped to 0.8v. We check the schematics but not sure why the voltage to controller is dropping. Any clue ? 

Thanks,

Akilan G 

  • 0
    TI__Expert 6085 points
    are you referring to the TI_EVM and TI schematics OR your own schematics? The ONLY way the REGOUT is pulled this low < 1V, the load on REGOUT is drawing > 40mA or is being to shorted to GND. Typical bq78350-R1 takes < 1mA from the REGOUT of the AFE.
  • 0 in reply to Vish Nadarajah
    Intellectual 285 points
    Hello sir,

    Thank you for replying, yes I am referring to TI_EVM schematics. Luckily, I found out the issue which is the Bq78350-r1 was not soldered properly. After soldering the issue was solved. The BQ studio is working . Charging and discharging too good. But the issue now is only the last cell is fluctuating with the difference of 0.15V. (Example : real 6th cell voltage is 4 V but it is fluctuating 4 v to 3.85 V and vice versa). Because of this there is an cell balancing issue only with 4th, 5th and 6th cell and also issue in charging the battery to full capacity. It would be great if could give me a clue.

    Note : I am using 6 cells and removed some simulating purpose circuits from EVM_Ti schematics.

    Thanks,

    Akilan G
  • 0 in reply to Akilan G
    Intellectual 285 points
    Hello sir,

    I just found out that the fluctuation is happening in the last cell due to the voltage drop in the diode from VC10 to bat, so bypassed the path through 1 k resistor from C10 to Batt. Now working good.

    Thanks

    Akilan G