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Original question:

BQ76952: BQ7695202 IC

BQ76952: BQ7695202 REG1 3.3V default output?

Cheng Zhang
Prodigy 120 points
Part Number: BQ76952

Tool/software:

HI team,

One quick question for BQ7695202, it says in datasheet that device 3.3V REG1 output by default enabled, does it mean that REG1 will have 3.3V output once battery attached? i.e. able to output 3.3V in shutdown mode. Or it means REG1 output 3.3V automatically after the device wake up into active mode?

Thanks

  • 0
    TI__Prodigy 740 points

    It means REG1 will output 3.3V automatically after the device wakes up into active mode.

    "SHUTDOWN mode:

    SHUTDOWN mode is the lowest power mode of the device, and it is often used for shipment or long-term storage.  In this mode, internal logic is powered down, and all data memory (RAM) register information is lost.  While in SHUTDOWN, the device is completely disabled (including the internal, REG1, and REG2 LDOs).  The CHG, PCHG, DSG, and PDSG FETs are all disabled.  All battery protections are disabled, and no measurements are taken.  There is just a very low power ~5V internal rail that is driven onto TS2 through a ~4.6-MOhm resistor for WAKE detect."

    e2e.ti.com/.../faq-bq76952-how-does-shutdown-mode-work

  • 0 in reply to Gavin Long
    Prodigy 120 points

    Do you mean that even for BQ7695202 version, the device REG1 output 3.3V automatically after it wakes up and enter active mode? Can you double check on this one? I use the EVB to test and found that REG1 automatically output 3.3V after BAT is supplied. Anything wrong/

  • 0 in reply to Cheng Zhang
    TI__Prodigy 740 points

    Yes that is my understanding. I double checked with another Applications Engineer, and he confirmed that if the device is not ON/awake from SHTUTDOWN, the LDO should not be outputting any voltage. But once the battery is attached and the device is powered on and exits shutdown, the BQ7695202 spin will have the REG1 turn on, as it is by default, enabled for that spin.

    I suspect the device has accidentally exited shutdown before turning on the Regulators. If a thermistor is attached from the TS2 pin to VSS, it prevents the device from ever fully entering SHUTDOWN mode.

    Can you confirm if the device is still in shutdown while REG1=3.3V? To check if the device is in SHUTDOWN mode, you can measure the voltage on the REG18 pin. If the device is in SHUTDOWN mode, then the pin will output 0V, otherwise the REG18 LDO will output 1.8V. Additionally the TS2 pin will be weakly pulled up to ~5V with a ~5Mohm Resistor, while it is waiting for a LOW ignal on the TS2/WAKE pin.