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BQ25703A: Switch MOS has no waveform, REGN has 6V

Cherry Zhou
Mastermind 22235 points
Part Number: BQ25703A
Other Parts Discussed in Thread: EV2400

Hi team,

Issue: The switch section does not work, and 2 boards are the same problem. But the 6 V of REGN is good. The customer is trying to capture the G-pole waveform of the MOS at the beginning of power up, but there are no waveforms. Measured pin voltages are as follows: 

VBUS=12V,SW1=SW2=1.1V,BTST1=BTST2=5.42V,HIDRV1=HIDRV2=1.1V,LODRV1=LODRV2=0V.REGN=5.75V

Could you help check this case? Thanks.

Best Regards,

Cherry

  • 0
    TI__Guru**** 170526 points

    HI Cherry,

    Can the customer provide register dump?  The status and fault registers likely report the issue.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Mastermind 22235 points

    Hi Jeff,

    Thank you for the support.

    The registers read as follows:

    device = 0x78
    0x00 = 0x0e
    0x01 = 0xe2
    0x30 = 0x11
    0x31 = 0x02
    0x32 = 0xb7
    0x33 = 0x02
    0x34 = 0x00
    0x35 = 0x00
    0x36 = 0x54
    0x37 = 0x4a
    0x38 = 0x20
    0x39 = 0x81
    0x3A = 0x00
    0x3B = 0x20
    0x20 = 0x00
    0x21 = 0xa0
    0x22 = 0x00
    0x23 = 0x00
    0x02 = 0x00
    0x03 = 0x00
    0x04 = 0xa0
    0x05 = 0x41
    0x0D = 0x30
    0x0f = 0x41
    0x25 = 0x41
    0x0A = 0x40
    0x0B = 0x1d
    0x06 = 0x00
    0x07 = 0x00
    0x09 = 0x00
    0x26 = 0x00
    0x27 = 0x89
    0x28 = 0x00
    0x29 = 0x00
    0x2A = 0x00
    0x2B = 0x00
    0x2C = 0x00
    0x2D = 0x00

    Thanks and regards,

    Cherry

  • 0 in reply to Cherry Zhou
    TI__Intellectual 1805 points

    Hi Cherry,

    I noticed that the BATFET is placed backwards, I believe this is where the issue is coming from. It should actually work in buck mode since that FET needs to be on full but it would not work for boost mode. 

    Kind Regards,

    Jacob

  • 0 in reply to Jacob Rook
    TI__Genius 10295 points

    Hi Jacob,

    The reverse PMOS is marked on the schematic diagram, and the customer has adjusted the direction, but it still does not work. In addition, the G pole voltage of HIDRV is equal to the voltage of SW1. Is this normal?

    Regards,

    Annie

  • 0 in reply to Annie Liu
    TI__Intellectual 1805 points

    Hi Annie, 

    Could you order the customer an EVM, and EV2400 if they do not have one, and ask the customer to follow the user guide found at https://www.ti.com/product/BQ25703A to make sure they are setting things up correctly?

    In the meantime, could you also ask them to provide scope captures of VBUS, VSYS, VBAT, and the switch nodes?

    Kind Regards,

    Jacob