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BQ24253: ILIM setting and

Kazuki Kuramochi
Genius 10505 points
Part Number: BQ24253

Hello Expert,

Our customer have questions for BQ24253.

I confirmed datasheet and it said that EN0/1 setting is applied if there is status change after D+/D- detection.
Our customer plan to configure each pin just connecting GND or power supply rail for achieving 900mA ILIM for using USB3.0 application.
Does it mean that EN0/1 setting doesn't applied if they use D+/D- detection?(except DCP)

As far as my understanding D+/D- detection cannot define Vin_DPM.
However, this pin setting depend on EN0/1 status and truth table seems EN0/1 haven't applied if EN0/1 status don't have any change.
When, what does Vin_DPM setting applied during the timing of D+/D- detection completed?

 Also, I found explanation that this device can support USB3.0 on datasheet p21 but there isn't detailed explanation.
Then, would you tell me suggested setting supporting USB3.0?

By the way, I'd like to change CBOOT from from 33nF to 47nF.
Is this modification acceptable?

Sorry for rushing you  but I want to get answer for these questions by tomorrow.


I'm waiting your answer.



Best regards,
Kazuki Kuramochi

  • +1
    TI__Guru**** 166576 points

    Hi Kuramochi,

    ENx pins are not valid without a status change on one of the pins (high-low or low-high transition) following D+/D- completion. 

    VINDPM default is either 4.36V or 4.25V after D+/D- completes. I have no BQ24253's in house and have ordered some to test on the bench.  However, I suggest that your customer use the external programming option (EN2=0 and EN1=1) to set VINDPM with external resistors.

    USB3.0 comment is a typo.  It refers to the use of I2C register to set ILIM to 900mA which is only possible with the standalone version using the ILIM pin resistor.

    Changing CBOOT to 47nF has not be fully tested and is not recommended.  The converter refresh pulses are designed for CBOOT=33nF+/-20%.  Larger CBOOT capacitors on other devices have lead to non-ideal operation like boost back.

    Regards,
    Jeff

  • 0 in reply to Jeff F
    TI__Genius 10505 points

    Hi Jeff,

    Thank you for your answer.
    I understand.


    Best regards,
    Kazuki Kuramochi