bq20z45-R1

SLUS992 – DECEMBER 2009

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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:

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Lifetime maximum temperature

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Lifetime minimum temperature

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Lifetime maximum battery cell voltage

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Lifetime minimum battery cell voltage

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Lifetime maximum battery pack voltage

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Lifetime minimum battery pack voltage

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Lifetime maximum charge current

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Lifetime maximum discharge current

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Lifetime maximum charge power

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Lifetime maximum discharge power

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Lifetime maximum average discharge current

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Lifetime maximum average discharge power

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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:

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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.

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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.

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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

time, using an internal counter. The fundamental rate of the counter is 0.65 nVh.

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