• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 509 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.

BQ24600: IC temperature remains high. even after charging completed.

Saif Tareen
Prodigy 20 points
Part Number: BQ24600


Hello,

I have a battery charger based off the TI BQ24600 IC. the design is as per the reference design in the specification sheet. I have a 4S1P Li-Ion battery pack with a built in BMS. 

schematic diagram attached for references. 

I did a few charging tests. (data attached). During charging I measured the temperature of the Charging IC (BQ24600) and the Switching MOSFET (in the main-power-path) I see that after the battery is charged and the charging drops down to 0 (actually shown as 0.3 amps due to measurement faults) the temperature of the Charging IC and the Mosfet does not go down to room-temperature and remains around 60 deg C.

It seems like the charging IC is not going into sleep and so keeps warm. the Specification document says, when VCC < Battery voltage, IC will go to sleep. my supply voltage is 19V and Battery voltage is maxed out at 16V. if I lower Power supply voltage (VCC) to 16V, the battery voltage does not rise above 14.4V and charging current drops to zero.

I would appreciate any help.

  • 0
    TI__Genius 10240 points

    Hi Saif,

    Could you provide the PH waveform after the charging is done? Please refer to the datasheet P5, there is a 2mA current typical from the adapter after the charging done (CE=High). Please try to reduce the input voltage to check whether the temperature changes.      

    BQ24600 is a buck step-down charger, so the input voltage has to be higher than the battery voltage to get the battery charged.

    Best regards,

    Eric

  • 0
    Prodigy 15 points

    Hi Eric,

    I think Saif's question, is once the charging is complete, why doesn't the BQ24600 go into sleep mode and the two MOSFETS stop switching and those components go to room temp?

     It appears this chip is not operating correctly and continues to operate and switch even after the charging is complete.   We had a similar issue.  

    Thoughts? 

    Regards,

    Elan

  • 0
    Prodigy 20 points

    Hello Ezhao,

    Thanks for your help.

    I did repeat the test using a laptop power supply (lowered the charging voltage from 24V to 19.6 volts). the BQ24600 IC temperature steady-stated at 52 deg C (compared to 58 C using 24V) but it did not go to room temperature. Lowering the charging voltage any further stops charging with battery voltage at 15VDC. My target voltage is 16Vdc for the 4S pack.

    Would it help if I use a resistor divider and my MCU measures battery voltage. When fully charged, it sends out a "LOW" signal to CE pin of BQ24600 to force it to sleep?

    Would it be a better idea to use the STAT pin of the BQ24600 to tell my MCU that the charging is complete and then send out a "LOW" signal to CE pin of BQ24600 to force it to sleep?

    Elan: Were  you able to find a solution to your similar issue?

    Thanks and regards,

    Saif.

  • 0 in reply to Saif Tareen
    TI__Mastermind 41785 points

    Hi Saif,

    Can you please try disconnecting the input voltage following charge completing?

    It would also be helpful to check the status of the STAT pin and the /PG pin when you observe charge complete to verify the status. It is possible the device could be in battery absent. This will require pullup resistors to evaluate. In addition, you could use the STAT pin with MCU to pull the CE pin low or even disconnect the adapter.

    Last, please provide the PH waveform and SRN waveform after charge has completed.

    Regards,

    Mike Emanuel