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BQ2980: DSG and CHG FETs not turning ON

Achal Singhal
Prodigy 10 points
Part Number: BQ2980

Tool/software:



Hi,

Please refer to the schematic for the BQ298018. I have connected a battery to the BATT and GND Terminals. The battery voltage is 3.3V. But I'm not getting any output at the PACK+ and PACK- terminals. I tried giving a supply to the PACK terminals through a bench power supply (4.2V) but the IC did not turn on. Is there something wrong with the schematic or any connection? Any help would be appreciated.

Edit: The JP201 is closed on the PCB with a solder blob

Thanks

  • 0
    TI__Genius 13015 points

    Hello Achal,

    The BQ2980 initially powers up in SHUTDOWN mode. To enter NORMAL mode, both Vbat and Vpack must meet the UV recovery requirement. This is mentioned more in Section 7.4.1.1 Power-On-Reset (POR) in the datasheet.

    You can also try shorting Vbat and Vpack briefly to do this initially.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Prodigy 10 points

    Hi,

    I tried the following:

    1. Provided charging voltage at the PACK+ and PACK- terminals (4.2V and 4.3V)
    2. Shorted Vbat+ and Vpack+

    None of these worked. I checked the voltage at the CHG and DSG FETs. The voltage at DSG FET is 0V and CHG FET is 0.3-0.4V.

  • 0 in reply to Achal Singhal
    TI__Genius 13015 points

    Hello Achal,

    Do you mind sharing the waveforms of the voltages on CTR, BAT, and VDD when you attempt to start up the device?

    Something else to note, when selecting a FET for the BQ298x, is that the device limits the Vgs below 8V. This is further mentioned in Section 8.2.1.3 Selection of Power FET of the datasheet. Do you mind removing the MOSFET and seeing if there's a voltage on the DSG/CHG pins? We typically recommend a MOSFET with a max leakage current of 1uA.

    Best Regards,
    Alexis