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BQ25713B: BQ25713B CHRG_OK pin

Di Ma
Intellectual 420 points
Part Number: BQ25713B
Other Parts Discussed in Thread: BQ25713

Hello team,

I have a question regarding the CHRG_OK.

I'm trying to design an MPPT charger, so my input comes from a PV panel. During night-time, CHRG_OK pin goes LOW which is normal and shouldn't be detected as a fault.

1. As I read from 9.3.3.1 section, CHRG_OK pin goes LOW and on Fault condition. Is there any way I can distinguish an input power problem from a fault problem.

2.  Or can I use AC_STAT flag of ChargerStatus register for example? Namely does AC_STAT equal to '0' when a fault occures?

3. Or maybe I should read the bus voltage, and if it is greater than V_VBUS_CONVEN = 3.5V and I have CHRG_OK pin LOW means that a fault has occured.

4. Can I get more information on the cases when CHRG_OK pin goes LOW apart from the input voltage (V_VBUS_CONVEN and ACOV = 24V)?

Regards,

Dmitriy.

Wish you a happy new year!

  • 0
    TI__Expert 4285 points

    Hi Di,

    Your understanding is correct! Option #3 is a better approach to separate other faults. Datasheet section 9.2 also describes CHRG_OK function.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Intellectual 420 points

    As written in the "Pin Functions" table, "any fault" will cause CHRG_OK to be asserted LOW. Could you specify please which faults exactly will trigger CHRG_OK pin LOW? What is the corresponding Fault_flag in the Charger_Status status or other register?

    Please, I need an exact answer since I am designing an autonomous charger using BQ25713. This charger will be working in remote places, where sometimes people cannot even reach to manually do some action on the charger. So I have to be sure that the charger won't just be stucked because of some fault that I don't even understand. 

    Please do your best to provide a complete answer on the meaning of CHRG_OK pin asserted LOW, since I can find such an answer in the datasheet.

  • 0 in reply to Di Ma
    TI__Expert 4285 points

    Hi Di,

    Datasheet 9.3.3.1 is the complete list of faults that will trigger CHRG_OK low.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Intellectual 420 points

    Dear Linhong,

    OK, I understood. Since MOSFET/inductor fault and thermal shutdown fault do not have a corresponding alarm flag in the StatusRegister, I cannot detect UnderVoltage event by just excluding all other Alarm flags of the StatusRegister. So I have to detect the UnderVoltage event by reading the BUS voltage, as you sujested.

    Thank you for your support.

    Regards,

    Dumitru

  • 0 in reply to Di Ma
    TI__Expert 4285 points

    Hi Dumitru,

    Correct!  you need extra information to exclude other scenarios.

    Best Regards,

    Linhong