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Original question:

BQ24640: BQ24640 Output voltage incorrect

BQ24640: BQ24640 set output 12v, only 1.7V

Star Xu
Genius 9645 points
Part Number: BQ24640

Hi

The customer design the schematic with BQ24640, the voltage is set 12V, abnormal output 1.7V (HIDRV=PH=1.7V, LODRV=GND=0V)

Please help check the schematic.

Thanks

Star

  • 0
    TI__Mastermind 29985 points

    Hello,

    Can you please send the full schematic, I am missing the VFB circuit and the output?

    Also, ISET is supposed to be tied with a voltage divider to GND from VREF and needs to be between and 0 and 2 V according to the datasheet.

    Can you please send waveforms of VIN, PH, SRN, and the charge current?

    Thanks,

    Mike Emanuel

    Please click "Resolved" if this answered your question.

  • 0 in reply to Michael Emanuel35
    TI__Genius 9645 points

    Hi Mike

    Thanks for your reply.

    the Schematic as below:

    The oscilloscope suddenly became unusable, but I remember that I measured the waveforms with these points before.

    In order to verify whether it was the influence of TPL0501, it was removed, and I forgot to add the compensation resistor, so the current setting went wrong and it led to 3.3V. Then ISET was connected with a resistor of about 20K in series. The status becomes the same strange output as before. This output is shown in the graph below. In addition, the PG and STAT of the work instructions are displayed normally, and the STAT LED blinked when it is not charging.

    The input voltage is 5-7V and the output is stable at 5V. When the input is greater than 7V, the output will gradually decrease. When the input voltage about 10V, the output was only about 2.7V.

    Thanks

    Star

  • 0 in reply to Star Xu
    TI__Mastermind 24075 points

    Hi Star,

       Do you have a battery connected or are you testing with battery absent and just applying input voltage?