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BQ24250: BQ24250 CE#, ISET ICHG hardware and software setting and standby current question

Shaquille Chen
Intellectual 1770 points
Part Number: BQ24250

Hi Team,

My customer have some questions that I cannot find the answer on datasheet.

Please help to support the questions below:

1. Either pull CE# pin high or set 0x01[1] =1 can disable charge?

2. Will device follow ICHG at I2C mode? Will the current be limit by ISET at any moment? Or it will follow the lowest one?

3. What's the quiescent current at battery only? DS just show Iq of SYSOFF and High-Z.

4. Will the Iq different at battery only based on different CE# setting.

Thanks

Shaq.

  • 0
    TI__Guru**** 166076 points
    Shaquille,

    Regarding 1, yes. /CE bit or pin high disables charge regardless of other bit or pin setting.
    Regarding 2, ICHG is set by ISET pin resistor in standalone mode, which is also the default for I2C mode. In I2C mode, ICHG can be changed from ISET pin setting to a fixed value.
    Regarding 3, when no input voltage is applied and only the battery is attached, the IC is in HiZ mode. The HiZ mode Iq = 16uA typ and 22uA max per the datasheet.
    Regarding 4, in battery only (HiZ) /CE does not apply.
  • 0 in reply to Jeff F
    TI__Genius 16145 points

    Hi Jeff,

    For Regarding2: Which one will dominate charge current? is it Iset pin or register setting?

    for example: if Iset pin setting is lower than register, is charge current will follow Iset pin setting? or is it controlled by register in HOST mode?

    Another question is " Is low standby mode equal to H-Zi mode?"

    Thanks

  • 0 in reply to Paul Yeh
    TI__Guru**** 166076 points

    Paul,

    In the ISET register, the default setting is the external ISET resistor.  In standalone mode, the ISET resistor controls the charge current.  In HOST mode, the ISET register controls the charge current.  If the external ISET resistor is selected in the ICHRG register during HOST mode then the external ISET resistor controls the current.  If not selected, then the register value selected controls the current.  

    Standby mode is used twice in the datasheet.  In the pin functions table in reference to /CE=high, the datasheet incorrectly refers to this as standby mode instead of simply charge disabled.  Later in the register table, standby mode is interchangeable used to refer to HiZ mode.

  • 0 in reply to Jeff F
    TI__Intellectual 1770 points
    Hi Jeff,

    I got it . When setting 0x03[7:3] = 11111, the charging current been set dominate by ISET resistor.

    So, the standby mode which have the less power consumption happens when Vin < UVLO .

    Thanks
    Shaq
  • 0 in reply to Shaquille Chen
    TI__Guru**** 166076 points

    Correct.

    There is also an I2C bit to force HiZ.