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BQ79616-Q1: Sleep mode current of the BQ79616 is 1.5 milli Ampere

Part Number: BQ79616-Q1
Other Parts Discussed in Thread: BQ79616

Dear support,

 We are unable to maintain sleep current requirement  of customer using  BQ79616. Our Conditions during sleep mode are:

  1. Need to monitor temperature of the cell. 3 temperature sensor  (10K NTC) are connected in the system. 10K pull ups resistance are being used in TSREF.
  2. No Cell  Balancing .
  3. No communication.
  4. One RTC device (PCA21125) is connector on CVDD supply (5V). We have used one linear regulator to convert 5V into 3.3V. RTC active current is ~250uA at 3.3V supply.
  5. Requirement of the BMS wakeup is there during fault condition  so it is done through NFault pin.

As per data sheet the worst mode sleep mode current of the BQ79616 is 220uA. But considering some current of active modules it should not go higher than 400uA.

But we got 1.5mA current during sleep mode.

Can you please suggest how to get Sleep Mode current <500uA. Buck converter in the BMS board is completely off so,no current consumption in the MCU device.

Prompt response is highly appreciated.

 

thanks and regards

Subhash Dhyani

  • Hi Subhash,

    Are the OVUV protectors or OTUT protectors running when putting the device into sleep mode? Is TSREF still enabled when putting the device into sleep mode? These draw extra current.

    Regards,

    David

  • Hello David,

    thanks for your prompt reply.

    Yes, OVUV protector and OTUT protector are enabled.

    TSREF is also enabled to check the OTUT thresholds during sleep mode and generate alarm through NFault.

    Is there some mechanism inside the IC to check OTUT Thresholds limits without TSREF enabled and OTUT protectors enabled?

    Is there some mechanism inside the IC to check  OVUV limits without OVUV protector enabled?

    If we add OVUV and OTUT protector max current during sleep mode as shown in the datasheet, it will be 220uA+60uA=280uA

    thanks and regards

    Subhash Dhyani

  • Hi Subhash,

    As TSREF is on while in sleep mode, an additional load such as a resistor from TSREF to a GPIO, and a resistor from GPIO to GND should account for the milli Amp consumption.

    Is there some mechanism inside the IC to check OTUT Thresholds limits without TSREF enabled and OTUT protectors enabled?

    Is there some mechanism inside the IC to check  OVUV limits without OVUV protector enabled?

    If OVUV, OTUT, and TSREF are not enabled, then the IC will not be checking the respective protector for if a fault is occuring when the threshold is not met.

    Regards,

    David

  • Hello David,

    Thanks for your prompt reply.

     We have removed pullup resistance (10K) and the NTC (10K)  from the TSREF just to measure the internal device current.

    But we got 660 micro amps sleep mode current. Here OVUV, OTUT protector  and TSREF was enabled,

    Is 660 Micro Amps sleep mode current justified without load on TSREF?

    Can you please let us know what will be BQ79616 internal circuit current consumption, if there is no load  at  TSREF voltage.

    thanks and regards

    Subhash Dhyani

  • Hi Subhash,

    Considering sleep mode current is typically 120uA, OVUV + OTUT protectors is 40uA, the linear regulator is 250uA, this leaves 250uA for the enabling of TSREF and any trace/capacitor resistances which is expected.

    Regards,

    David