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BQ24650: BQ24650 circuit not charging Battery

Noaman M
Intellectual 350 points
Part Number: BQ24650

Please see the schematic screenshot attached.

Vin: 12V (DC Adapter) or 5.0V coming from USB

Vbat: 3.7V lipo (4.2V max charging voltage)

Measured:

Vref: 3.3V

Vcc: 12/5V

MPPSET: 1.2 (with a 5V source), 2.94V with a 12V source

TS: 1.6V and 2.19 V (tried 2 different R67 values)

LODRV has pwm pulses

V-regn : 6.0v (with a 12V source), otherwise 5.0 with a 5V source

Vfb: 1.95V (Vbat = 3.93V), charge termination voltage set at 4.1V

The stat1 pin is pulled low (LED on) while stat2 pin is high indicating that charging is in progress but the Vbat remains at battery level and battery never charges. I am not sure what I am missing or doing wrong.

Please help me identify the issue.

Thanks in advance.

Noaman

PH Pin waveform:

LoDRV pin waveform:

  • 0
    Intellectual 350 points

    the schematic did not attach properly with the original post:

  • 0 in reply to Noaman M
    TI__Mastermind 24075 points

    Hi Noaman,

        Do you observe normal charging at VIN - 12V, and no charging even though STAT1 indicates charging with 5V input?,

       

  • 0 in reply to Kedar Manishankar
    Intellectual 350 points

    Hi Kedar,

    No, it does not charge with either 12V or 5V.

    Stat1 indicates charging in either case. One thing I have observed is that stat1 indicates charging even when no battery is present. 

    Regards

    Noaman

  • 0 in reply to Noaman M
    TI__Mastermind 24075 points

    Hi Noaman,

      It looks like you have an issue with HIDRV signal that is used to drive the HSFET. The charge current isn't being sensed so the converter is trying to drive the HSFET on for the full cycle. The schematic looks fine, and the external MOSFET selection doesn't seem like an issue. Most likely the issue is with layout and the routing of the HIDRV or BTST.

    Please also re-test with replacing C39 with a 10uF capacitor

  • 0 in reply to Kedar Manishankar
    Intellectual 350 points

    Hi Kedar,

    Here is the layout of the mosfet section. It is right next to the IC with a very short trace between the BQ24650 and FET.

    I tested with 10uF quickly and did not see any charging.

    We soldered another board and on that board, no LEDs are lit indicating some sort of fault. VCC is good, Battery is present and TS values are as per schematic. Not sure where the fault could be.

    If there could be any other issue, please do let me know.

    Regards

    Noaman

  • 0 in reply to Noaman M
    Intellectual 350 points

    Hi Kedar,

    we got the circuit to work on the 2nd board. May have been soldering issues.

    Regards

    Noaman