The TI E2E™ design support forums will undergo maintenance from Sept. 28 to Oct. 2. If you need design support during this time, contact your TI representative or open a new support request with our customer support center.

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

[FAQ] BQ2980: Protector Behavior for Severely Depleted Battery (0V Charging)

Part Number: BQ2980
Other Parts Discussed in Thread: BQ2970, BQ2982

How do different TI protectors handle depleted batteries?  Will charging be allowed?

  • TI’s protectors allow charging of a battery even if the voltage is so low that the protector itself is not fully powered. This feature is referred to as zero-V (0V) charging.  Different protectors handle 0V charging differently.  There are two categories of parts: those with 0V charging enabled and those with 0V charging disabled.

    0V Charging Enabled:

    (3 regions of operation)

    1: Inhibit

    2: 0V charging

    3: Normal operation

    The device is in the inhibit region of operation if the battery voltage is below V0INH.  In this region, charging is disabled. This inhibit region is present in both the BQ2970 and BQ2980.  The V0INH voltage is located in the device datasheet (as shown below for the BQ2970).

    The device is in the 0V region of operation if the following conditions are met:

    • The battery voltage is above V0INH
    • The battery voltage is below the minimum Vbat voltage for the device
    • The voltage difference between PACK + and PACK- pins is > V0CHG (as shown below for the BQ2970)

    The device is in the normal mode of operation when the battery voltage is above the minimum Vbat voltage for the device.

    0V Charging Disabled:

    (2 regions of operation)

    1: Disabled

    2: Normal operation

    The device is in the disabled region of operation if the battery voltage is below the minimum Vbat for the device.  

    The device is in the normal region of operation if the battery voltage is above the minimum Vbat for the device.  

    Summary:

    If a customer does not want to charge an over-depleted battery, they should use a device with 0V charging disabled, so charging can only occur after the device is fully powered. The BQ2982 is an example of a device with 0V charging disabled, so the battery will never be charged if its voltage drops below the minimum Vbat voltage of 1.5V even if a charger is attached.