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bq78350-R1

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SLUSCD0B – AUGUST 2015 – REVISED NOVEMBER 2018

Product Folder Links: bq78350-R1

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Copyright © 2015–2018, Texas Instruments Incorporated

Feature Description (continued)

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Discharge FET fault

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Cell imbalance detection

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Open thermistor detection

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AFE communication fault

8.3.3 Charge Control Features

The bq78350-R1 charge control features include:

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Provides a range of options to configure the charging algorithm and its actions based on the application

requirements

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Reports the appropriate charging current needed for constant current charging, and the appropriate charging

voltage needed for constant voltage charging

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Supports pre-charging/0-volt charging

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Supports charge inhibit and charge suspend if battery pack temperature is out of temperature range

8.3.4 Fuel Gauging

The bq78350-R1 device uses Compensated End-of-Discharge Voltage (CEDV) technology to measure and

calculate the available charge in battery cells. The bq78350-R1 device accumulates a measure of charge and

discharge currents and compensates the charge current measurement for the temperature and state-of-charge of

the battery. The bq78350-R1 device estimates self-discharge of the battery and also adjusts the self-discharge

estimation based on temperature.

8.3.5 Lifetime Data Logging

The bq78350-R1 device offers lifetime data logging, where important measurements are stored for warranty and

analysis purposes. The data monitored includes:

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Lifetime maximum temperature

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Lifetime minimum temperature

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Lifetime maximum battery cell voltage per cell

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Lifetime minimum battery cell voltage per cell

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Cycle count

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Maximum charge current

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Maximum discharge current

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Safety events that trigger SafetyStatus() updates. (The 12 most common are tracked.)

8.3.6 Authentication

The bq78350-R1 device supports authentication by the host using SHA-1.

8.3.7 Battery Parameter Measurements

The bq78350-R1 device digitally reads bq769x0 registers containing recent values from the integrating analog-to-

digital converter (CC) for current measurement and a second delta-sigma ADC for individual cell and

temperature measurements.

8.3.7.1 Current and Coulomb Counting

The integrating delta-sigma ADC (CC) in the companion bq769x0 AFE 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 15-bit integrating ADC measures bipolar signals from –0.20 V to 0.20 V with 15-µV resolution. The AFE

reports charge activity when VSR = V(SRP) – V(SRN) is positive, and discharge activity when VSR = V(SRP) – V(SRN)

is negative. The bq78350-R1 device continuously monitors the measured current and integrates the digital signal

from the AFE over time, using an internal counter.

To support large battery configurations, the current data can be scaled to ensure accurate reporting through the

SMBus. The data reported is scaled based on the setting of the SpecificationInfo() command.