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Battery can't be charged by BQ24071.

Alex Liang
Prodigy 50 points
Other Parts Discussed in Thread: BQ24071, BQ24070, BQ24072

Dear All,

         BQ24071 is used in my design for power management.

         5V and battery can power the system normally.

        But the 5V can't charge the battery.

        Would you please tell me the maybe reason.

       Thanks.

Alex.

  • 0
    TI__Mastermind 32400 points

    Hi Alex,

     

     

    Can you please provide me with the status of STAT1 and STAT2 as you try to charge up your battery? Also what the value of Vbat?

     

     

     

    Thanks!

    Tahar

  • 0 in reply to Tahar Allag
    Prodigy 50 points

    Hi Tahar.

    Thank you for your reply.

    STAT1 and STAT2 are all OFF, while the Vbat is 3.7V.

     

    Thanks!

    Alex

  • 0 in reply to Alex Liang
    TI__Mastermind 32400 points

    Hi Alex,

     

     

    Having both STAT1 and STA2 OFF and based on the table 2, the following states can be possible.

     

    • The charge suspended (temperature):  But this not the case because your TS pin is grounded through a 10K resistor. To make sure this not what causing the problem, try changing the value of that resistor and see if that helps
    • Timer fault: Your timer is disabled but make sure it is 3.3V  
    • Sleep mode: That happens if the input is removed from the circuit.  

     

    The other thing that I see in your circuit that may cause some issues is on pin CE, MODE, and ISET2 are connect to OUT via resistors, I will try to connect it to the IN (5V) instead and make sure your Vout is well regulated. What is the value of your Vout anyway?

     

    Please try these and let me know  

     

     

    Thanks!

    Tahar

  • 0 in reply to Tahar Allag
    Prodigy 50 points

    Hi Tahar,

        1.I am sure TS pin is grounded through a 10k resistor.

        2.I am sure it is 3.3V

    Just now, the STAT1 is ON, STAT2 is OFF. I found that it is not stable,some times it is OK, but in most cases, it doesn't work properly.

    I also think the reason is pin CE, MODE and ISET2 are connect to OUT. Some times, the Vout is 0V when I need to short circuit between OUT and IN, and then VOUT is same as VIN. Some times After I short circuit them, STAT1 is ON and STAT2 is OFF, but most of times STAT1 and STAT2 are all OFF.

    When I design the circuit, I hesitated on where pin CE, MODE and ISET2 should be connected. When they connect the IN, will it work properly only while the IN is present? When IN is absent, the VOUT will be 0V, althought the battey is also connected.

    where should pin CE, MODE and ISET2 be connected?

     

    Thanks!

    Alex

  • 0 in reply to Alex Liang
    TI__Mastermind 32400 points

    Hi Alex,

     

     

    Usually CE, MODE and ISET2 go to control signals. The CE (Chip Enable) digital input is used to disable or enable the IC. A high-level signal on this pin enables the chip, and a low-level signal disables the device and initiates the standby mode. If you connect CE to Input and the input is absent, then the chip is disabled. If you connect it to your output and Vout=0, then the IC is disabled too. You need to have your CE high all the time in order to have the IC enabled.

     

    With the MODE input low, the bq24070/1 defaults to USB-mode charging, and the supply current is limited by the ISET2 pin (100 mA for ISET2 = Low, 500 mA for ISET2 = High). If an input source is not available, then the battery is selected as the source.

     

    Thanks!

    Tahar

  • 0 in reply to Tahar Allag
    TI__Mastermind 32400 points

    One more question Alex, What does put your output to 0V? do you have to short the OUT to IN in your application? if you have a high rail in you system, you can use it to guaranty an all time CE high.

     

     

    Thanks

    Tahar

  • 0 in reply to Tahar Allag
    Prodigy 50 points

    Hi Tahar,

               In my application, CE is connected to OUT, the OUT is 0V whenever the IN is present or absent, while the CE is also LOW, the chip is disabled. So I need to short the OUT to IN one time(only one time), which make CE is HIGH, enable the chip, and then the OUT is 5V, then I needn't keep on to short them.

              I think the BQ24071 has a bug, the pin CE should LOW VALID like BQ24072, maybe BQ24072 is upgraded from BQ24071.

             what's your opinion?

     

    Thanks.

    Alex