BQ40Z60_16 Datasheet, PDF (21/47 Pages) Texas Instruments – Programmable Battery Management Unit

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bq40z60
SLUSAW3C – DECEMBER 2014 – REVISED JULY 2015
9.3 Feature Description
The bq40z60 consists of an integrated analog front end, charge controller, and fuel gauge. The following sections
provide an overview of the device features. For additional details, refer to the bq40z60 Technical Reference
Manual (SLUUA04).
9.3.1 Safety Features
The bq40z60 provides support for primary safety, including:
• Cell Over/Undervoltage Protection
• Charge and Discharge Overcurrent
• Short Circuit Protection
• Charge and Discharge Overtemperature
The secondary safety features of the bq40z60 can be used to indicate more serious faults via the FUSE pin. This
pin can be used to blow an in-line fuse to permanently disable the battery pack from charging or discharging. The
secondary safety features provide protection against:
• Safety Over/Undervoltage Permanent Failure
• Safety Overtemperature Permanent Failure
• Safety FET Overtemperature Permanent Failure
• Qmax Imbalance Permanent Failure
• Impedance Imbalance Permanent Failure
• Capacity Degradation Permanent Failure
• Cell Balancing Permanent Failure
• Fuse Failure Permanent Failure
• Voltage Imbalance at Rest Permanent Failure
• Voltage Imbalance Active Permanent Failure
• Charge/Discharge FET Permanent Failure
• Second Level Protector Permanent Failure
• Instruction Flash Checksum Permanent Failure
• Open Cell Connection Permanent Failure
• Data Flash Permanent Failure
• Open Thermistor Permanent Failure
9.3.2 Analog Front End (AFE) Details
The analog front end (AFE) consists of circuits responsible for managing internal power and interfacing to outside
components for measuring current, voltage, and temperature. The bq40z60 AFE includes an active-high interrupt
output connected internally to the fuel gauge to notify it of important changes in some of the AFE registers.
The bq40z60 manages its supply voltage dynamically according to operating conditions. When V_BAT >
V_{SWITCHOVER–} + V_HYS, the AFE connects an internal switch to BAT and uses this pin to supply power to its internal
1.8-V LDO, which subsequently powers all device logic and flash operations. Once BAT decreases to V_BAT <
V_{SWITCHOVER–}, the AFE disconnects its internal switch from BAT and connects another switch to VCC, allowing
sourcing of power from a charger (if present). An external capacitor connected to PBI provides a momentary
supply voltage to help guard against system brownouts due to transient short-circuit or overload events that pull
VBAT below V_{SWITCHOVER–}.
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