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BQ24171: LSFET current limit

Kai Nomiyama
Expert 5545 points
Part Number: BQ24171

Hi Team,

I have a question about bq24171 LSFET current limit.

When I took a look at bq24171 datasheet, I saw bq24171 has cycle-by-cycle current limit but it looks there is no current limit at LSFET.

- charge overcurrent comparator(cycle-by-cycle)

- hsfet overcurrent comparator(cycle-by-cycle)

- charge undercurrent comparator(cycle-by-cycle)

However, there is following Rdson of the MOSFET"s" comment in 9.3.19 MOSFET Short Circuit and Inductor Short Circuit Protection.

"The IC has a short circuit protection feature. Its cycle-by-cycle current monitoring feature is achieved through monitoring the voltage drop across Rdson of the MOSFETs"

Does this mean LSFET also has cycle-by-cycle current limit?

If yes, could you let me know that Electrical Characteristics?

Regards,

Kai

  • 0
    TI__Guru**** 165766 points

    Hi Kai,

    The LSFET current is the output current = charge current at each 1-D cycle.  There is a Charge Overcurrent Comparator (cycle-by-cycle) specification at top of d/s page 10 that measures the current through the SNS resistor (voltage across SRP and SRN).  

    Regards,
    Jeff 

  • 0 in reply to Jeff F
    TI__Expert 5545 points

    Hi Jeff,

    My customer is worry about PVDD-SW short event.

    BQ24171 monitors inductor current so when PVDD-SW is shorted, current flows LSFET and BQ24171 LSFET will get damage.

    Are there any devices supporting JEITA with monitoring LSFET current, it means are there any devices supporting PVDD-SW short event protection function?

    Regards,

    Kai

  • 0 in reply to Kai Nomiyama
    TI__Guru**** 165766 points

    Kai,

    Per datasheet section 9.3.19 MOSFET Short Circuit and Inductor Short Circuit Protection:

    The IC has a short circuit protection feature. Its cycle-by-cycle current monitoring feature is achieved through monitoring the voltage drop across Rdson of the MOSFETs. The charger will be latched off, but the ACFET keep on to power the system. The only way to reset the charger from latch-off status is remove adapter then plug adapter in again. Meanwhile, STAT is blinking to report the fault condition.

    The details of circuitry are TI proprietary.

    Regards,

    Jeff