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BQ25895: Charger is not working.

Yash Dave
Intellectual 620 points
Part Number: BQ25895

Hi,

We are using BQ25895 for charging application

The battery charger section, we are observing following issues.

- STAT pin is indicating IC is in charging mode, but we are not observing any charge current flowing into the battery.

- When mains is removed, the output voltage on PMIC pin drops to 3.6 V even though boost operation is enabled via OTG  pin. Cannot observe switching waveform on SW pin.

Plz support with this issue.

Rgds,

Yash

  • 0
    TI__Mastermind 25800 points

    Hey Yash,

    Have you read the I2C registers on the bq25895? 

    Is this a custom board or our bq25895EVM?

    What is the current limit of the main supply? 

    Do you have a load on SYS pin?

    What is your ILIM pin resistor set to? 

    What is your battery voltage (as measured from the BAT pin, during charge and during boost)? 

    Is the OTG bit in memory enabled when you remove main? 

    Regards,

    Joel H

  • 0 in reply to Joel Hernandez II
    Intellectual 620 points
    Hi Joel H,

    Reading I2C registers, it states that it is charging in fast charge mode.

    it is a custom board..

    The battery charging is not working.
    Also, when being powered from Battery, output voltage is 3.5V (Boost circuit not working


    We have also tested by removing the battery protection circuit - still the same result.
    Charging current is always 0 - even in the I2C registers

    one observation is that after power-on watchdog fault is '0'. It's sets after some time


    Whats working:
    When powered from VBUS, output is stable
    When VBUS removed, boost operation from battery works, we get proper output.

    --

    Problem: Battery is not getting charged.
    Reading I2C registers, it states that it is charging in fast charge mode.
    There are no faults - watchdog_fault is '1' but datasheet states it is expected in default mode.

    Kindly support.

    Rgds,
    Yash Dave
  • 0 in reply to Yash Dave
    TI__Mastermind 25800 points

    Hey Yash, 

    Could you post your register read values here on the site. 

    One event that does not indicate a fault is a DPM event (either VINDPM or IINDPM). Please check to make sure the device is not indicating IINDPM. This is read in Register 0x13. 

    Also, you should look at what your input is detected as via Register 0x0B. This has the VBUS STAT bits to indicate what kind of the source you have plugged in. 

    This will also dictate what the IDPM_LIM bits will set to after ICO runs. 

    There is also an ILIM pin for a hardware based input current limit. What is the value of this? 

    And do you have a load on your SYS pin? 

    Please check and confirm these attributes, and we can investigate further. 

    Regards,

    Joel H