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BQ25620: some questions

Dylan Sun
Prodigy 105 points
Part Number: BQ25620

Tool/software:

hi,

I have a question for IBAT over current protection fof BQ25620.

When the IBAT over BATFET_OCP 6A, it will be enter HICCUP mode.

how can I recover if we have no external power source.

Does it need to lower IBAT current under 6A?

or does it must be plugged in external power source only?

another question.

If VIN(USB or adaptor) is not plug in ,
and the voltage of VSYS is higher than BAT pin,
Will it have current flowing into the battery through the POWER PATH?

Thanks.

Dylan

  • 0
    TI__Mastermind 31140 points

    Hi Dylan, 

    Thank you for reaching out via E2E. Please see my comments below. 

    Dylan Sun said:
    how can I recover if we have no external power source.

    For this case where we assume no adapter power source is connected the BQ25620 will recover once current draw from SYS (and boost converter if enabled) is reduced. 

    Dylan Sun said:
    Does it need to lower IBAT current under 6A?

    This is correct. plugging in an external power source is not required to recover from IBAT overcurrent. 

    Dylan Sun said:
    If VIN(USB or adaptor) is not plug in ,
    and the voltage of VSYS is higher than BAT pin,
    Will it have current flowing into the battery through the POWER PATH?

    Yes current can flow to BAT pin for this case where VSYS is higher than VBAT. In general the BQ25620 device is not designed to operate in this way. When USB or adapter is not plugged in it is expected that battery is the power source for SYS rather than a separate source. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 105 points

    hi, Garrett:

       Thanks for your reply.

       I want to confirm for power path question.

       We have a PMIC (include battery charger) for USB charger , BQ25620 is for adaptor charger.

       If no adaptor plugged , USB (PMIC) can charge battery through BQ25620? (Red dotted line)

       If it can , does BQ25620's power path  has current /resistance /voltage spec is this condition?

       thanks

       Dylan.

       

  • 0 in reply to Dylan Sun
    TI__Mastermind 31140 points

    Hi Dylan, 

    Please see my comments below. 

    You did not indicate what is the maximum voltage which could be output from PMIC to SYS output of BQ25620, but please be aware the maximum allowable voltage at SYS (when converter is not switching) is 6V. 

    Dylan Sun said:
    If no adaptor plugged , USB (PMIC) can charge battery through BQ25620? (Red dotted line)

    Yes if voltage at SYS pin is higher than voltage at BAT pin with no adapter plugged in BATFET will be on and allow current to flow to charge battery. If voltages are equal then battery will not charge and charge current increases as VSYS increases compared to VBAT. 

    Dylan Sun said:
     If it can , does BQ25620's power path  has current /resistance /voltage spec is this condition?

    I will reiterate the BQ25620 device is not designed to operate in this way therefore, we do not have any specifications for this condition. By default the BATFET is fully on in battery only condition to allow battery to discharge and power SYS rail.

    I strongly recommend you adjust your design to incorporate reverse current protection between PMIC and BQ25620 SYS output to prevent current from flowing from PMIC to SYS pin and then battery. 

    You can also force BATFET off to prevent battery charging in this condition by putting the BQ25620 device in ship mode by setting REG0x18[1:0] = 10b (BATFET_CTRL = 10b). Be aware you would need to plug in adapter or use QON pin to exit ship mode. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    Prodigy 105 points

    hi, Garrett:

    thank you for your comments.

    In our design , the VSYS maximum value is 4.5V
    In our application, are there any recommended charger ICs?
    When VSYS > VBAT, IC POWER PATH can block current flow into the battery.

    THanks.

    Dylan.

  • 0 in reply to Dylan Sun
    TI__Guru** 105590 points

    Hello Dylan,

    Due to the U.S. holiday our response will be delayed, we will respond by end of day tomorrow CST.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    TI__Mastermind 31140 points

    Hi Dylan, 

    Dylan Sun said:

    In our application, are there any recommended charger ICs?
    When VSYS > VBAT, IC POWER PATH can block current flow into the battery.

    Hi Dylan all our single cell buck converter charger ICs with power path have this architecture. Meaning they are not designed to have a separate power source connected at SYS when no VBUS input is present. 

    My best recommendation is to incorporate external reverse current protection into your design between the components as I mentioned in my previous reply. 

    Best Regards,

    Garrett