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BQ25790: some questions about datasheet

Yuan Tan63
Expert 3280 points
Part Number: BQ25790

Hi,

here is some questions about datasheet:

（1）charging current up to 5A

what's the charging voltage when current meet 5A? when customer can realize 5A charging current?

（2）is there any limitation for input and output of BUCK-BOOST?

（3）what's the OOA means?

（4）what's the VSYSMIN和VSYSMAX means?

（5）when charging power is set (like 8.4V/3A), adapter's maximum load is 5V/3A,  is there any protection inside IC? like limiting the charging power?

thanks!

Best regards,

Yuan Tan

  • 0
    TI__Guru**** 166176 points

    Hi Yuan,

    Regarding 1, you can use the datasheet efficiency curves on page 17 to predict efficiency for different input voltages and use the power balance of efficiency=Pout/Pin= VBATREG*5A/(VBUS*3.25A), where max input current=3.25A, to predict minimum input voltage needed.

    Regarding 2, yes recommended operating conditions in d/s section 7.3 page 7 gives input range from 3.6V to 24V and output up to 18.8V.

    Regarding 3, OOA means out of audio.  It applies to pulse frequency modulation (PFM) switching that is used to improve efficiency at light load.

    Regarding 4, this charger has NVDC power-path which means that, when VBUS is applied, the SYS output will be the higher of the MINSYS (SYSMIN) setting or the battery voltage.  This allows for system startup even if the battery is depleted.

    Regarding 5, yes.  the host software controls the input current limit and the charge current.  If the desired charge current + system load is too much for the input source, the charge current is reduced to prevent collapsing the input source and to keep the system running.  The battery will even supplement the system load if required.

    Regards,

    Jeff