BQ40Z50 Datasheet, PDF (22/30 Pages) Texas Instruments – 1-Series, 2-Series, 3-Series, and 4-Series Li-Ion Battery Pack Manager

bq40z50
SLUSBS8 – DECEMBER 2013
BATTERY PARAMETER MEASUREMENTS
www.ti.com
Charge and Discharge Counting
The bq40z50 uses an integrating delta-sigma analog-to-digital converter (ADC) for current measurement, and a
second delta-sigma ADC for individual cell and battery voltage and temperature measurement.
The integrating delta-sigma ADC measures the charge/discharge flow of the battery by measuring the voltage
drop across a small-value sense resistor between the SRP and SRN pins. The integrating ADC measures bipolar
signals from –0.1 V to 0.1 V. The bq40z50 detects charge activity when V_SR = V_(SRP) – V_(SRN) is positive, and
discharge activity when V_SR = V_(SRP) – V_(SRN) is negative. The bq40z50 continuously integrates the signal over
time, using an internal counter. The fundamental rate of the counter is 0.26 nVh.
Voltage
The bq40z50 updates the individual series cell voltages at 0.25-second intervals. The internal ADC of the
bq40z50 measures the voltage, and scales and calibrates it appropriately. This data is also used to calculate the
impedance of the cell for the Impedance Track gas gauging.
Current
The bq40z50 uses the SRP and SRN inputs to measure and calculate the battery charge and discharge current
using a 1-mΩ to 3-mΩ typ. sense resistor.
Temperature
The bq40z50 has an internal temperature sensor and inputs for four external temperature sensors. All five
temperature sensor options can be individually enabled and configured for cell or FET temperature usage. Two
configurable thermistor models are provided to allow the monitoring of cell temperature in addition to FET
temperature, which use a different thermistor profile.
Communications
The bq40z50 uses SMBus v1.1 with MASTER mode and packet error checking (PEC) options per the SBS
specification.
SMBus On and Off State
The bq40z50 detects an SMBus off state when SMBC and SMBD are low for two or more seconds. Clearing this
state requires that either SMBC or SMBD transition high. The communication bus will resume activity within
1 ms.
SBS Commands
See the bq40z50 Technical Reference Manual (SLUUA43) for further details.
22
Submit Documentation Feedback
Product Folder Links: bq40z50
Copyright © 2013, Texas Instruments Incorporated