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BQ25890: VSYS Load regulation

Genius 4660 points
Part Number: BQ25890

1.Please check attached VSYS Load regulation.

VSYS load regulation.pptx

2.If you have  VSYS Load regulation data with battery open,please send it to us.

3.Please let us know Figure 5 condition.

CHG_CONFIG=Enable ?

CE_=LO ?

  • 1. When ISYS is greater than 3.7A, could you please read VBUS and VSYS ADC values (REG11 and REG0F)? The bq25890 is basically a step-down DC-DC converter. The input should be high enough to support the desired output. Please refer to www.ti.com/.../slyt569.pdf to calculate VBUS_MIN needed in order to maintain VSYS@3.7A and check if the VBUS pin voltage meet the VBUS_MIN needed or not.
    2. No data available.
    3. Charge is disabled.
    Thanks!
  • Ning-san
    Thank you for your reply.

    REG11 is 9A
    REG0F is 0

    Is this related to VBUS_MIN ? Battery is open.
    Is this related to VINDPM ?

  • For one-shot ADC conversion (REG02[6] = 0), please set REG02[7]=1 first, then read back ADC registers for the current ADC values.
    When BAT pin is floating, VSYS is the output of the converter.
    If VINDPM is not set properly, the adaptor voltage could drop too low when the load current is high and is unable to support the desired output voltage. Please refer to www.ti.com/.../slyt569.pdf for the details.
    Thanks!
  • Ning-san

    Thank you for your reply

    They changed power supply from USB 5V to  10.02V.

    And VINDPM setting change from relative to absolute.

    They could see good regulation up to 3.6A.Please see below.

    But when load current is higher than 3.6A,VSYS voltage goes drop.(VSYSMIN settting is 3.5V)

    Please let us know setting information and condition when this part can output 5A load with good regulation.

  • What is the VINDPM setting for 10.02V input? Is there any charge current in addition to the SYS load? It will be very helpful if all the register values when SYS>3.6A are provided. Thanks!
  • Ning-san

    Thank you for your reply.

    There is not any charge current in addition to the SYS load.
    We got resister values you mentioned. Please check below.

    HEX BIN
    0 3F 00111111
    1 6 00000110
    2 10 00010000
    3 1E 00011110
    4 18 00011000
    5 13 00010011
    6 4F 01001111
    7 8B 10001011
    8 49 01001001
    9 44 01000100
    A 73 01110011
    B A7 10100111
    C 0 00000000
    D 4E 01001110
    E 0 00000000
    F 44 01000100
    10 7F 01111111
    11 DA 11011010
    12 0 00000000
    13 8 00001000
    14 1D 00011101

    Please let us know setting information and condition when this part can output 5A load with good regulation.
  • Since TS ADC reads 80.055% (REG10=7F), there should be NTC fault, but NTC fault shows Normal (REG0C[2:0]=000). Could you please double-check all the register readings?
    BTW, Charge should be disabled during the test, but REG03[4]=1.
    Thanks!
  • Since no response is received for a couple of weeks, this thread is considered solved and closed.