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BQ24253: bq2425x

Matthieu Imbert
Intellectual 820 points
Part Number: BQ24253

Hello,

Replacing unavalaible bq2561x with older part bq2425x. 

Choosing bq24253 standalone: not using any USB power source, nor any I2C controller.

Q1: How do I manage to have EN1/EN2 CHANGE state in order to have the truth table read by bq2425x engine (fig.18 on page 23 of DS)? I.e., charge start according to EN1/EN2 truth table?

Q2: is there a way - WITHOUT any controller reading bq2425x registers - to have both /PG and /CHG Leds unlit (off) when NO Battery is attached to the charger? For instance, /PG going Hi-Z when no battery is present? Or /CE being forced to 0 when no battery is present?

The "Any Boot Battery Detection Algorithm" (par. 9.3.6 & Fig.20, pages 25 & 26) is efficient only if a controller reads Register#1 [B0,B1,B2,B3]=1000 ("No Battery Detected"), and sets /PG and /CHG led status accordingly, right?

Last but not least: /CE is Read Only, thus can't be forced to "0" by bq2425x in case of No Batt Detected, right?

Thank you for your help.

Regards.

Matthieu

  • 0
    TI__Guru**** 152396 points

    HI Matthieu,

    Regarding 1, one of the ENx lines must toggle high to low after D+/D- completes by external switch or GPIO.  ENx default to use external resistors (EN2=0 and EN1=1) so if that is your final setting, you may not need to ever toggle, unless you want to be able to go into HiZ.

    Regarding 2, AnyBoot is designed for use with registers.  I do not know if AnyBoot results in /CHG pin flashing but can check on the bench tomorrow.  /PG is only reporting input status not output status (battery).

    Regarding 3, /CE pin is high impedance input pin only and does not change by itself.  However, if no battery with thermistor is attached, the missing thermistor generates a TS fault that disables charge and also disables AnyBoot.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    Intellectual 820 points

    Hello Jeff,

    Thank you.

    As I thought: better use a fellow controller with all those bq chips.

    Regards.

    Matthieu