BQ20Z45-R1 Datasheet, PDF (12/18 Pages) Texas Instruments – SBS 1.1-Compliant Gas Gauge and Protection Enabled With Impedance Track™

bq20z45-R1
SLUS992 – DECEMBER 2009
www.ti.com
Lifetime Data Logging Features
The bq20z45-R1 offers lifetime data logging, where important measurements are stored for warranty and
analysis purposes. The data monitored include:
• Lifetime maximum temperature
• Lifetime minimum temperature
• Lifetime maximum battery cell voltage
• Lifetime minimum battery cell voltage
• Lifetime maximum battery pack voltage
• Lifetime minimum battery pack voltage
• Lifetime maximum charge current
• Lifetime maximum discharge current
• Lifetime maximum charge power
• Lifetime maximum discharge power
• Lifetime maximum average discharge current
• Lifetime maximum average discharge power
• Lifetime average temperature
Authentication
The bq20z45-R1 supports authentication by the host using SHA-1.
Power Modes
The bq20z45-R1 supports 3 different power modes to reduce power consumption:
• In Normal Mode, the bq20z45-R1 performs measurements, calculations, protection decisions and data
updates in 1 second intervals. Between these intervals, the bq20z45-R1 is in a reduced power stage.
• In Sleep Mode, the bq20z45-R1 performs measurements, calculations, protection decisions and data update
in adjustable time intervals. Between these intervals, the bq20z45-R1 is in a reduced power stage. The
bq20z45-R1 has a wake function that enables exit from Sleep mode, when current flow or failure is detected.
• In Shutdown Mode the bq20z45-R1 is completely disabled.
CONFIGURATION
Oscillator Function
The bq20z45-R1 fully integrates the system oscillators. Therefore the bq20z45-R1 requires no external
components for this feature.
System Present Operation
The bq20z45-R1 checks the PRES pin periodically (1s). If PRES input is pulled to ground by external system, the
bq20z45-R1 detects this as system present.
BATTERY PARAMETER MEASUREMENTS
The bq20z45-R1 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.
Charge and Discharge Counting
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 SR1 and SR2 pins. The integrating ADC measures bipolar
signals from -0.25 V to 0.25 V. The bq20z45-R1 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 bq20z45-R1 continuously integrates the signal over
time, using an internal counter. The fundamental rate of the counter is 0.65 nVh.
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