BQ34Z651_15 Datasheet, PDF (15/29 Pages) Texas Instruments – SBS 1.1-Compliant Gas Gauge

bq34z651
www.ti.com
FEATURE SET
SLUSAL7 – AUGUST 2011
Primary (1st Level) Safety Features
The bq34z651 supports a wide range of battery and system protection features that can be easily configured.
The primary safety features include:
• Cell over/undervoltage protection
• Charge and discharge overcurrent
• Short circuit protection
• Charge and discharge overtemperature with independent alarms and thresholds for each thermistor
• AFE Watchdog
Secondary (2^nd Level) Safety Features
The secondary safety features of the bq34z651 can be used to indicate more serious faults via the SAFE 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 protection features include:
• Safety overvoltage
• Safety undervoltage
• 2nd-level protection IC input
• Safety overcurrent in charge and discharge
• Safety over-temperature in charge and discharge with independent alarms and thresholds for each thermistor
• Charge FET and zero-volt charge FET fault
• Discharge FET fault
• Cell imbalance detection (active and at rest)
• Open thermistor detection
• Fuse blow detection
• AFE communication fault
Charge Control Features
The bq34z651 charge control features include:
• Supports JEITA temperature ranges. Reports charging voltage and charging current according to the active
temperature range
• Handles more complex charging profiles. Allows for splitting the standard temperature range into two
sub-ranges, and for varying the charging current according to the cell voltage
• Reports the appropriate charging current needed for constant current charging and the appropriate charging
voltage needed for constant voltage charging to a smart charger using SMBus broadcasts
• Determines the chemical state of charge of each battery cell using Impedance Track, and can reduce the
charge difference of the battery cells in a fully charged state of the battery pack, gradually using the cell
balancing algorithm during charging. This prevents fully charged cells from overcharging and causing
excessive degradation and also increases the usable pack energy by preventing premature charge
termination.
• Supports pre-charging/zero-volt charging
• Supports charge inhibit and charge suspend if battery pack temperature is out of temperature range
• Reports charging fault and also indicate charge status via charge and discharge alarms
• Battery heater control to allow battery charging in low ambient temperatures
Gas Gauging
The bq34z651 uses the Impedance Track Technology to measure and calculate the available charge in battery
cells. The achievable accuracy is better than 1% error over the lifetime of the battery and there is no full charge
discharge learning cycle required.
Copyright © 2011, Texas Instruments Incorporated
15