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BQ24166: Battery not charging!

Michael Eller0
Prodigy 80 points
Part Number: BQ24166
Other Parts Discussed in Thread: BQ24165

Hello,

I tried to follow the reference design schematic as closely as possible, but my board is not charging the attached battery (3.7V single-cell LiPo from sparkfun). The CHG LED is always illuminated, and it's been plugged in for days. I unplugged the main power and let the battery die. After plugging the power back in and waiting overnight, the battery is still dead. I'm not using USB power input or the TS function.

Does anyone see any obvious issues with this schematic? I replaced R4 (ISET) with a 100 Ohm res. and no change. I realize the VPDM bottom resistor is 100k, while the datasheet recommends a 10k (whoops). But I think the ratio is still OK. I haven't gotten out the scope yet, so I'm just crowdsourcing ideas / areas of potential problems.

  • 0
    TI__Guru**** 152386 points

    Hi Michael,

    At what voltage is TS pin?  To TS function on this device, you have to place equal sized resistor divider from DRV to TS to GND.

    Also, with USB# all pulled hi, the device is in HiZ mode, even though you are using IN for input power.  You will need to set an input current limit for USB input using d/s table 1 on page 17 even though you are not using it.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hi Jeff,

    Thanks for the reply! The TS pin is connected to the DRV pin. In the datasheet page 9 - "Connect TS to DRV to disable the TS function." Is this incorrect?

    Similarly for the IUSB values: page 8 - "USB1, USB2 and USB3 have no effect on the IN input." Did I misread that? Does Hi-Z mode still disable the IN input?

    Best,

    Michael

  • 0 in reply to Michael Eller0
    TI__Guru**** 152386 points

    Hi Michael,

    You are correct on the TS pin! 

    But just above Table 1 is the following statement:

    Driving IUSB1, IUSB2, and IUSB3 all high places the bq24165/6/7 in High Impedance mode where the buck converter is shutdown regardless if an input is connected to USB or IN.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hi Jeff,

    Ah okay. Thank you! That is most likely my problem then.