BQ34Z950 Datasheet, PDF (14/28 Pages) Texas Instruments – SBS 1.1-COMPLIANT GAS GAUGE AND PROTECTION ENABLED WITH IMPEDANCE TRACK WITH OPTIONAL DQ INTERFACE

bq34z950
SLUSBF0A – APRIL 2013 – REVISED MAY 2013
FEATURE SET
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Primary (First-Level) Safety Features
The bq34z950 supports a wide range of battery and system protection features that can easily be configured.
The primary safety features include:
• Cell over/undervoltage protection
• Charge and discharge overcurrent
• Short circuit
• Charge and discharge overtemperature
• AFE watchdog
Secondary (Second-Level) Safety Features
The secondary safety features of the bq34z950 can be used to indicate more serious faults. The secondary
safety protection features include:
• Safety overvoltage
• Safety overcurrent in charge and discharge
• Safety overtemperature in Charge and Discharge
• Charge FET and 0-V charge FET fault
• Discharge FET fault
• AFE communication fault
Charge Control Features
The bq34z950 charge control features include:
• 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 technology, 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 precharging/zero-volt charging
• Supports fast charging
• Supports charge inhibit and charge suspend if the battery pack temperature is out of temperature range
• Reports charging fault and also indicates charge status via charge and discharge alarms
Gas Gauging
The bq34z950 uses 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.
See the Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm application note
(SLUA364) for further details.
Authentication
The bq34z950 supports authentication by the host using SHA-1.
Power Modes
The bq34z950 supports three power modes to reduce power consumption:
• In NORMAL mode, the bq34z950 performs measurements, calculations, protection decisions, and data
updates in 1-s intervals. Between these intervals, the bq34z950 is in a reduced power state.
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