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The bq34210-Q1 fuel gauge incorporates gas gauging and an End-of-Service (EOS) Determination
function to use with a 1-series Li-Ion or Lithium Iron Phosphate (LiFePO4) rechargeable cell or a Nickel
metal hydride (NiMH) based pack with a configuration of 3-series cells.
The gas gauge uses Compensated End-of-Discharge Voltage (CEDV) gauging technology to accurately
predict the battery capacity and other operational characteristics of the battery. It can be interrogated by a
system processor to provide cell information, such as remaining capacity, full charge capacity (FCC), time-
to-empty (TTE), and relative state-of-charge (RSOC), and provide an interrupt signal to the processor.
The integrated EOS Determination function is specifically intended for applications where the battery is
rarely discharged, such as eCall systems, uninterruptible power supplies (UPS), enterprise server backup
systems, and telematics or telecommunications backup modules. In such systems, the battery may remain
in a fully (or near fully) charged state for much of its lifetime, with it rarely or never undergoing a significant
discharge. If the health of the battery in such a system is not monitored regularly, then it may degrade
beyond the level required for a system backup/discharge event, and thus fail precisely at the time when it
is needed most. Monitoring the battery enables the system to take action before the failure occurs.
The EOS Determination function monitors the health of the battery by using infrequent learning phases,
which involve a controlled discharge of ~1% capacity, and provides an alert to the system when the
battery is approaching the end of its usable service. By coordinating battery charging with the learning
phases, the battery capacity available to the system can be maintained above a preselected level to avoid
compromising the ability for the battery to support a system discharge event.
Information is accessed through a series of commands, called Data Commands, and indicated by the
general format Command(). Read and write information within the device control and status registers, as
well as its data memory locations are accessed through these commands. Commands are sent from the
system to the gauge using the I
development, system manufacturing, or end-equipment operation.
The fuel gauge measures charge and discharge activity by monitoring the voltage across a small-value
series sense resistor (5 mΩ to 20 mΩ, typical), which may be used in a low-side (at the CELL- connection)
or a high-side (at the CELL+ connection) configuration.
The external temperature sensing is optimized with the use of a high-accuracy negative temperature
coefficient (NTC) thermistor with 25°C resistance (R25) = 10.0 kΩ ±1% and beta value (B25/85, resistance
at 25°C and at 85°C) = 3435 kΩ ± 1% (such as Semitec NTC 103AT). Alternatively, the fuel gauge can be
configured to use its internal temperature sensor or receive temperature data from the host processor.
The fuel gauge uses temperature to monitor the battery-pack environment, which is used for gas gauging
and cell protection functionality.
To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL,
SLEEP, and SHUTDOWN. The fuel gauge passes automatically between these modes (except for
SHUTDOWN exit, which needs an external stimulus), depending upon the occurrence of specific events,
though a system processor can initiate some of these modes directly. The device also includes a CONFIG
UPDATE mode, which is generally used during initial setup to update various RAM-based parameters
used by the gauge.
1.1
Gas Gauging
The bq34210-Q1 device features the Compensated End-of-Discharge Voltage (CEDV) gauging algorithm,
capable of gauging a maximum capacity of 32 Ah.
Figure 1-1
shows the operational overview of the bq34210-Q1 fuel gauge.
SLUUBE8 – September 2018
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C serial communications engine, and can be run during application
Copyright © 2018, Texas Instruments Incorporated
Chapter 1
SLUUBE8 – September 2018
General Description
General Description
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