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Original question:

BQ40Z50-R2: Discharging Cycle

BQ40Z50-R2: SMBUS not broadcasting after battery is completely discharged

Jon Key
Intellectual 920 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: EV2400, BQ40Z50

Hi all,

My customer is using BQ40Z50-R2 in their system, and is seeing the following behavior from their battery pack:

1. They discharge the battery to 0% SOC

2. The device enters undervoltage protection mode

3. When system power is applied, the BQ40Z50-R2 does not broadcast SMBUS data to the battery charger

4. The customer must connect to the EV2400 and wake up the gauge

5. Customer trickle chargers the battery until V+ hits 15V, then the BQ40Z50 wakes up and starts broadcasting to the system battery charge and charging at the normal 1/10 C charge current.

The customer wanted to know if there is a way to configure the gauge to either wake up and begin broadcast normal charging instructions with out the trickle charge, or if there is a recommended method to tell the system that the BQ40Z50-R2 is about to go in protection mode and have the system shutdown. Could the BTP function be used here? If so, is there a way to determine the optimal DoD/SOC to toggle the BTP?

Thank you,

Jon

  • 0
    TI__Genius 12215 points

    Hi, Jon

        The gauge does not broad ChargeCurrent() and ChargeVoltage() to charger in SLEEP mode, however, you can wake up the gauge by initiate any transaction to the target device to wake up the device. Once the device wakes up, it will start broadcast charging information to the charger or host

  • 0 in reply to Steven Yao
    TI__Intellectual 920 points

    Hi Steven,

    I believe the gauge is in SHUTDOWN not SLEEP mode because the customer is seeing the battery being completely depleted, and then eventually wakes from sleep mode and allows a trickle current to charge the battery. However, the customer would like to avoid entering shutdown mode during normal operation. 

    Is there a way to set up the gauge to alert the rest of the system that the battery is depleted to a state that is about to enter shutdown mode before that happens?

    Thank you,

    Jon

  • 0 in reply to Jon Key
    TI__Genius 12215 points

    Jon

        Host can check the TDA bit to determine whether the cell is to be depleted, this bit is set to alert the host on various events including cell voltage approaching the Terminate Voltage.