Texas Instruments bq27441-G1 Use and care manual

bq27441-G1
Technical Reference
Literature Number: SLUUAC9A
December 2013–Revised May 2015

Contents
Preface ........................................................................................................................................ 4
1 General Description.............................................................................................................. 6
2 Functional Description.......................................................................................................... 8
2.1 Fuel Gauging................................................................................................................. 8
2.2 Temperature Measurement................................................................................................. 8
2.3 Current Measurement....................................................................................................... 8
2.4 Operating Modes............................................................................................................. 9
2.4.1 SHUTDOWN Mode................................................................................................. 9
2.4.2 POR and INITIALIZATION Modes................................................................................ 9
2.4.3 CONFIG UPDATE Mode .......................................................................................... 9
2.4.4 NORMAL Mode ..................................................................................................... 9
2.4.5 SLEEP Mode....................................................................................................... 10
2.4.6 HIBERNATE Mode................................................................................................ 10
2.5 Pin Descriptions ............................................................................................................ 12
2.5.1 GPOUT Pin ........................................................................................................ 12
2.5.2 Battery Detection (BIN)........................................................................................... 12
3 Application Examples ......................................................................................................... 14
3.1 Data Memory Parameter Update Example ............................................................................. 14
4 Standard Commands .......................................................................................................... 16
4.1 Control(): 0x00 and 0x01.................................................................................................. 17
4.1.1 CONTROL_STATUS: 0x0000 .................................................................................. 18
4.1.2 DEVICE_TYPE: 0x0001.......................................................................................... 18
4.1.3 FW_VERSION: 0x0002........................................................................................... 18
4.1.4 DM_CODE: 0x0004............................................................................................... 18
4.1.5 PREV_MACWRITE: 0x0007..................................................................................... 18
4.1.6 CHEM_ID: 0x0008 ................................................................................................ 19
4.1.7 BAT_INSERT: 0X000C........................................................................................... 19
4.1.8 BAT_REMOVE: 0X000D......................................................................................... 19
4.1.9 SET_HIBERNATE: 0x0011 ...................................................................................... 19
4.1.10 CLEAR_HIBERNATE: 0x0012 ................................................................................. 19
4.1.11 SET_CFGUPDATE: 0x0013.................................................................................... 19
4.1.12 SHUTDOWN_ENABLE: 0x001B............................................................................... 19
4.1.13 SHUTDOWN: 0x001C........................................................................................... 19
4.1.14 SEALED: 0x0020................................................................................................. 19
4.1.15 PULSE_SOC_INT: 0x0023 ..................................................................................... 20
4.1.16 RESET: 0x0041 .................................................................................................. 20
4.1.17 SOFT_RESET: 0x0042.......................................................................................... 20
4.1.18 EXIT_CFGUPDATE: 0x0043 ................................................................................... 20
4.1.19 EXIT_RESIM: 0x0044 ........................................................................................... 20
4.2 Temperature(): 0x02 and 0x03 ........................................................................................... 20
4.3 Voltage(): 0x04 and 0x05 ................................................................................................. 20
4.4 Flags(): 0x06 and 0x07 ................................................................................................... 21
4.5 NominalAvailableCapacity(): 0x08 and 0x09 ........................................................................... 21
4.6 FullAvailableCapacity(): 0x0A and 0x0B ................................................................................ 21
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4.7 RemainingCapacity(): 0x0C and 0x0D .................................................................................. 21
4.8 FullChargeCapacity(): 0x0E and 0x0F .................................................................................. 22
4.9 AverageCurrent(): 0x10 and 0x11........................................................................................ 22
4.10 StandbyCurrent(): 0x12 and 0x13........................................................................................ 22
4.11 MaxLoadCurrent(): 0x14 and 0x15....................................................................................... 22
4.12 AveragePower(): 0x18 and 0x19......................................................................................... 22
4.13 StateOfCharge(): 0x1C and 0x1D........................................................................................ 22
4.14 InternalTemperature(): 0x1E and 0x1F.................................................................................. 22
4.15 StateOfHealth(): 0x20 and 0x21.......................................................................................... 23
4.16 RemainingCapacityUnfiltered(): 0x28 and 0x29........................................................................ 23
4.17 RemainingCapacityFiltered(): 0x2A and 0x2B.......................................................................... 23
4.18 FullChargeCapacityUnfiltered(): 0x2C and 0x2D ...................................................................... 23
4.19 FullChargeCapacityFiltered(): 0x2E and 0x2F ......................................................................... 23
4.20 StateOfChargeUnfiltered(): 0x30 and 0x31............................................................................. 23
5 Extended Data Commands .................................................................................................. 25
5.1 OpConfig(): 0x3A and 0x3B............................................................................................... 25
5.2 DesignCapacity(): 0x3C and 0x3D....................................................................................... 25
5.3 DataClass(): 0x3E.......................................................................................................... 25
5.4 DataBlock(): 0x3F .......................................................................................................... 25
5.5 BlockData(): 0x40 through 0x5F.......................................................................................... 26
5.6 BlockDataChecksum(): 0x60.............................................................................................. 26
5.7 BlockDataControl(): 0x61.................................................................................................. 26
5.8 Reserved – 0x62 through 0x7F .......................................................................................... 26
6 Data Memory...................................................................................................................... 28
6.1 Data Memory Interface .................................................................................................... 28
6.1.1 Accessing the Data Memory..................................................................................... 28
6.1.2 Access Modes ..................................................................................................... 28
6.1.3 SEALING and UNSEALING Data Memory Access........................................................... 29
6.2 Data Types Summary ..................................................................................................... 29
6.3 bq27441 Data Memory Summary Tables............................................................................... 29
6.4 bq27441 Data Memory Parameter Descriptions ....................................................................... 33
6.4.1 Configuration Class ............................................................................................... 33
6.4.2 Gas (Fuel) Gauging Class ....................................................................................... 37
6.4.3 Ra Table Class .................................................................................................... 48
6.4.4 Calibration Class .................................................................................................. 49
6.4.5 Security Class ..................................................................................................... 51
Revision History.......................................................................................................................... 53
3
SLUUAC9A–December 2013–Revised May 2015 Contents
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Read This First
SLUUAC9A–December 2013–Revised May 2015
Preface
This document is a detailed Technical Reference Manual (TRM) for using and configuring the bq27441-G1
battery fuel gauge. This TRM document is intended to complement but not supersede information in the
separate bq27441-G1 datasheet.
Formatting Conventions used in this Document:
Information Type Formatting Convention Example
Commands Italics with parentheses and no breaking spaces RemainingCapacity() command
Data Memory Italics,bold, and breaking spaces Design Capacity data
Register bits and flags Brackets and italics [SOC1] bit
Data Memory bits Brackets, italics, and bold [TEMPS] bit
Modes and states ALL CAPITALS UNSEALED mode
Related Documentation from Texas Instruments
To obtain a copy of any of the following TI documents, call the Texas Instruments Literature Response
Center at [phone] or the Support Center at [phone]. When ordering, identify this document
by its title and literature number. Updated documents also can be obtained through the TI Web site at
www.ti.com.
1. bq27441-G1, System-Side Impedance Track™ Fuel Gauge Data Sheet (SLUSBH1)
2. Quickstart Guide for bq27441-G1 (SLUUAP7)
3. bq27441 EVM: System-Side Impedance Track™ Technology User's Guide (SLUUAP4)
Trademarks
Impedance Track is a trademark of Texas Instruments. All other trademarks are the property of their
respective owners.
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Chapter 1
SLUUAC9A–December 2013–Revised May 2015
General Description
The bq27441-G1 battery fuel gauge accurately predicts the battery capacity and other operational
characteristics of a single, Li-based, rechargeable cell. It can be interrogated by a system processor to
provide cell information, such as state-of-charge (SOC). The device is orderable in two predefined
standard configurations:
• The bq27441-G1A fuel gauge is predefined for LiCoO2-based batteries for 4.2-V maximum charge
voltage.
• The bq27441-G1B fuel gauge is predefined for LiCoO2-based batteries for 4.3-V or 4.35-V maximum
charge voltage.
Unlike some other Impedance Track™ fuel gauges, the bq27441-G1 cannot be programmed with specific
battery chemistry profiles. For many battery types and applications, the predefined standard chemistry
profiles available in the bq27441-G1A or bq27441-G1B fuel gauge are sufficient matches from a gauging
perspective.
Information is accessed through a series of commands, called Standard Commands. Further capabilities
are provided by the additional Extended Commands set. Both sets of commands, indicated by the general
format Command(), are used to read and write information contained within the control and status
registers, as well as its data locations. Commands are sent from the system to the gauge using the I2C
serial communications engine, and can be executed during application development, system manufacture,
or end-equipment operation.
The key to the high-accuracy, fuel gauging prediction is Texas Instruments proprietary Impedance Track™
algorithm. This algorithm uses cell measurements, characteristics, and properties to create SOC
predictions that can achieve high accuracy across a wide variety of operating conditions and over the
lifetime of the battery.
The fuel gauge measures the charging and discharging of the battery by monitoring the voltage across a
small-value, external sense resistor. Cell impedance is computed based on current, open-circuit voltage
(OCV), and cell voltage under loading conditions.
The fuel gauge uses an integrated temperature sensor for estimating cell temperature. Alternatively, the
system processor can provide temperature data for the fuel gauge.
To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL,
SLEEP, HIBERNATE, and SHUTDOWN. The fuel gauge passes automatically between these modes,
depending upon the occurrence of specific events, though a system processor can initiate some of these
modes directly.
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Chapter 2
SLUUAC9A–December 2013–Revised May 2015
Functional Description
2.1 Fuel Gauging
The bq27441-G1 battery fuel gauge measures the cell voltage, temperature, and current to determine
battery SOC. The fuel gauge monitors the charging and discharging of the battery by sensing the voltage
across a small-value, external sense resistor (10 mΩ, typical) between the SRN and SRP pins. By
integrating the charge passing through the battery, the battery SOC is adjusted during the charging or
discharging of the battery.
The total battery capacity is found by comparing states of charge before and after applying the load with
the amount of charge passed. When an application load is applied, the impedance of the cell is measured
by comparing the OCV obtained from a predefined function for the present SOC with the measured
voltage under load. Measurements of OCV and charge integration determine chemical SOC and chemical
capacity (Qmax). The initial value for Qmax is defined by Design Capacity and should match the cell
manufacturers' data sheet. The fuel gauge acquires and updates the battery-impedance profile during
normal battery usage. The impedance profile, SOC, and the Qmax value are used to determine
FullChargeCapacity() and StateOfCharge(), specifically for the present load and temperature.
FullChargeCapacity() is reported as capacity available from a fully-charged battery under the present load
and temperature until Voltage() reaches the Terminate Voltage.NominalAvailableCapacity() and
FullAvailableCapacity() are the uncompensated (no or light load) versions of RemainingCapacity() and
FullChargeCapacity(), respectively.
The fuel gauge has two flags, [SOC1] and [SOCF], accessed by the Flags() command that warn when the
battery SOC has fallen to critical levels. When StateOfCharge() falls below the first capacity threshold, as
specified in SOC1 Set Threshold, the [SOC1] (state-of-charge initial) flag is set. The flag is cleared once
StateOfCharge() rises above SOC1 Set Threshold. All units are in mAh.
When StateOfCharge() falls below the second capacity threshold, SOCF Set Threshold, the [SOCF]
(state-of-charge final) flag is set, serving as a final discharge warning. If SOCF Set Threshold = –1, the
flag is inoperative during discharge. Similarly, when StateOfCharge() rises above SOCF Clear Threshold
and the [SOCF] flag has already been set, the [SOCF] flag is cleared. All units are in %.
2.2 Temperature Measurement
The fuel gauge measures temperature via its internal on-chip sensor. This internal temperature data will
be used by the Impedance Track™ algorithm if the OpConfig [TEMPS] bit is cleared. Alternatively, if the
OpConfig [TEMPS] bit is set, the system processor can set the temperature for the fuel gauging algorithm
by writing to the Temperature() register.
Regardless of which sensor is used for measurement, the system processor can request the current
battery temperature being used by the algorithm by calling the Temperature() function.
2.3 Current Measurement
The fuel gauge measures current by sensing the voltage across a small-value, external sense resistor (10
mΩ, typical) between the SRN and SRP pins. Internally, voltage passes through a gain stage before
conversion by the coulomb counter. The current measurement data is available via the AverageCurrent()
command.
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2.4 Operating Modes
The fuel gauge has different operating modes: POR, INITIALIZATION, NORMAL, CONFIG UPDATE,
SLEEP, and HIBERNATE. Upon powering up from OFF or SHUTDOWN, a power-on reset (POR) occurs
and the fuel gauge begins INITIALIZATION. In NORMAL mode, the fuel gauge is fully powered and can
execute any allowable task. Configuration data in RAM can be updated by the host using the CONFIG
UPDATE mode. In SLEEP mode, the fuel gauge turns off the high-frequency oscillator clock to enter a
reduced-power state, periodically taking measurements and performing calculations. In HIBERNATE
mode, the fuel gauge is in a very-low-power state, but can be woken up by communication.
2.4.1 SHUTDOWN Mode
In SHUTDOWN mode, the LDO output is disabled so internal power and all RAM-based volatile data are
lost. The host can command the gauge to immediately enter SHUTDOWN mode by first enabling the
mode with a SHUTDOWN_ENABLE subcommand (Section 4.1.12) followed by the SHUTDOWN
subcommand (Section 4.1.13). To exit SHUTDOWN mode, the GPOUT pin must be raised from logic low
to logic high for at least 200 µs.
2.4.2 POR and INITIALIZATION Modes
Upon POR, the fuel gauge copies ROM-based configuration defaults to RAM and begins INITIALIZATION
mode where essential data is initialized. It will remain in INITIALIZATION mode as a halted-CPU state
when an adapter or other power source is present to power the fuel gauge (and system), yet no battery
has been detected. The occurrence of POR or a Control() RESET subcommand will set the Flags()
[ITPOR] status bit to indicate that RAM has returned to ROM default data.
When battery insertion is detected, a series of initialization activities begin including an OCV
measurement. In addition, the CONTROL_STATUS [QMAX_UP] and [RES_UP] bits are cleared to allow
unfiltered learning of Qmax and impedance. Completion of INITIALIZATION mode is indicated by the
CONTROL_STATUS [INITCOMP] bit.
2.4.3 CONFIG UPDATE Mode
If the application requires different configuration data for the fuel gauge, the system processor can update
RAM-based Data Memory parameters using the Control() SET_CFGUPDATE subcommand to enter the
CONFIG UPDATE mode. Operation in this mode is indicated by the Flags() [CFGUPMODE] status bit. In
this mode, fuel gauging is suspended while the host uses the extended data commands to modify the
configuration data blocks.
To resume fuel gauging, the host sends a Control() SOFT_RESET,EXIT_CFGUPMODE, or EXIT_RESIM
subcommand to exit the CONFIG UPDATE mode which clears both Flags() [ITPOR] and [CFGUPMODE]
bits. After a timeout of approximately 240 seconds (4 minutes), the gauge will automatically exit the
CONFIG UPDATE mode if it has not received a SOFT_RESET,EXIT_CFGUPMODE, or EXIT_RESIM
subcommand from the host.
2.4.4 NORMAL Mode
The fuel gauge is in NORMAL mode when not in any other power mode. During this mode,
AverageCurrent(),Voltage(), and Temperature() measurements are taken once per second, and the
interface data set is updated. Decisions to change states are also made. This mode is exited by activating
a different power mode.
Because the gauge consumes the most power in NORMAL mode, the Impedance Track™ algorithm
minimizes the time the fuel gauge remains in this mode.
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2.4.5 SLEEP Mode
SLEEP mode is entered automatically if the feature is enabled (OpConfig [SLEEP] = 1) and
AverageCurrent() is below the programmable level Sleep Current (default = 10 mA). Once entry into
SLEEP mode has been qualified, but prior to entering it, the fuel gauge performs an ADC autocalibration
to minimize the offset.
During SLEEP mode, the fuel gauge remains in a very-low-power idle state and automatically wakes up
briefly every 20 seconds to take data measurements.
After taking the measurements on the 20-second interval, the fuel gauge will exit SLEEP mode when
AverageCurrent() rises above Sleep Current (default = 10 mA). Alternatively, an early wake-up before the
20-second internal is possible if the instantaneous current detected by an internal hardware comparator is
above an approximate threshold of ±30 mA.
2.4.6 HIBERNATE Mode
HIBERNATE mode could be used when the system equipment needs to enter a very-low-power state, and
minimal gauge power consumption is required. This mode is ideal when system equipment is set to its
own HIBERNATE, SHUTDOWN, or OFF mode.
Before the fuel gauge can enter HIBERNATE mode, the system must use the SET_HIBERNATE
subcommand to set the [HIBERNATE] bit of the CONTROL_STATUS register. The fuel gauge waits to
enter HIBERNATE mode until it has taken a valid OCV measurement and the magnitude of the average
cell current has fallen below Hibernate Current. The fuel gauge can also enter HIBERNATE mode if the
cell voltage falls below the Hibernate Voltage. The fuel gauge will remain in HIBERNATE mode until the
system issues a direct I2C command to the fuel gauge. I2C communication that is not directed to the fuel
gauge will only briefly wake it up and the fuel gauge immediately returns to HIBERNATE mode.
It is the responsibility of the system to wake the fuel gauge after it has gone into HIBERNATE mode and
to prevent a charger from charging the battery before the Flags() [OCVTAKEN] bit is set which signals an
initial OCV reading has been taken. For maximum initialization accuracy, any significant charge or
discharge current should be postponed until the CONTROL_STATUS [INITCOMP] bit is set. This could
take up to 10 seconds. After waking, the fuel gauge can proceed with the initialization of the battery
information. During HIBERNATE mode, RAM-based data values are maintained, but gauging status is
lost. Upon exit from HIBERNATE mode, the fuel gauge will immediately reacquire measurements and
reinitialize all gauging predictions.
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