BQ27350PW [TI]
Single Cell Li-Ion Battery Manager With Impedance Track Fuel Gauge Technology; 单节锂离子电池管理器采用Impedance Track电量监测计技术
| 型号： | BQ27350PW |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | Single Cell Li-Ion Battery Manager With Impedance Track Fuel Gauge Technology |
| 文件： | 总33页 (文件大小：485K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
1 INTRODUCTION
1.1 FEATURES
1.2 APPLICATIONS
•
•
•
Comprehensive Battery Fuel Gauge for Single
Cell and 1-Series Li-Ion Applications
•
•
•
•
•
•
POS Terminals
Industrial Data Collection
Smartphones
Secure Battery Authentication Using
SHA-1/HMAC Encryption
PDAs
Calculates and Reports
Digital Cameras
Handheld Terminals
–
–
–
–
Remaining Battery Capacity
Battery Voltage and Temperature
Charge and Discharge Current
Four Time-to-Empty Predictions
1.3 DESCRIPTION
•
Battery Fuel Gauge Based on Patented
Impedance Track™ Technology
The Texas Instruments’ bq27350 is a battery fuel
gauge with secure authentication support for single
cell Li-Ion battery packs. Designed for battery pack
–
Models the Battery Discharge Curve for
Accurate Time-to-Empty Predictions
integration, the device requires
little host
–
Automatically Adjusts for Battery Aging,
Battery Self Discharge, and
microcontroller firmware support for implementation.
The system host processor communicates with the
bq27350 over an I2C interface to obtain remaining
battery capacity, system run-time predictions, and
other critical battery information.
Temperature/Rate Inefficiencies
–
Low Value Sense Resistor (10mΩ or Less)
•
96-Bytes Non-Volatile Scratch Pad Data
Memory
I2C Communications Interface to the Host
The bq27350 uses the patented Impedance Track™
algorithm for its fuel gauging. The gauge provides
information such as state-of-charge (%), run-time to
empty (min.), charge time to full (min.), battery
voltage (V), and pack temperature (°C).
•
•
20-Pin TSSOP Package
The bq27350 also features both integrated and
external
support
for
secure
battery
pack
authentication, using the SHA-1/HMAC authentication
algorithm.
TYPICAL IMPLEMENTATION
PACK+
SCLK
bq27350
Impedance Track™
SHA-1/HMAC
Authentication and
Manufacturing
Data Storage
SDATA
LDO
bq26100
SHA-1/HMAC
Authentication
(optional)
Single-Cell
Protector
*
PACK-
*Optional Thermistor
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this document.
Impedance Track is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007, Texas Instruments Incorporated
bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
Contents
INTRODUCTION .......................................... 1
1
2
3
4.1 DATA COMMANDS .................................. 8
4.2 EXTENDED DATA COMMANDS ................... 13
4.3 DATA FLASH INTERFACE ......................... 16
1.1 FEATURES ........................................... 1
1.2 APPLICATIONS ...................................... 1
1.3 DESCRIPTION ....................................... 1
DEVICE INFORMATION................................. 3
2.1 AVAILABLE OPTIONS ............................... 3
2.2 PIN DIAGRAM........................................ 3
2.3 TERMINAL FUNCTIONS............................. 3
ELECTRICAL SPECIFICATIONS ...................... 4
3.1 ABSOLUTE MAXIMUM RATINGS ................... 4
4.4
MANUFACTURER INFORMATION BLOCKS ...... 16
4.5 ACCESS MODES ................................... 17
4.6
SEALING/UNSEALING DATA FLASH ACCESS ... 17
4.7 DATA FLASH SUMMARY........................... 17
FUNCTIONAL DESCRIPTION ........................ 19
5.1 FUEL GAUGING .................................... 19
5.2 IMPEDANCE TRACK VARIABLES ................. 20
5.3 TEMPERATURE MEASUREMENT................. 21
5.4 OVER-TEMPERATURE INDICATION .............. 22
5
3.2
RECOMMENDED OPERATING CONDITIONS...... 4
3.3 POWER-ON RESET.................................. 4
5.5
CHARGING AND CHARGE TERMINATION
3.4
TEMPERATURE SENSOR CHARACTERISTICS ... 4
INDICATION......................................... 22
3.5 LOW FREQUENCY OSCILLATOR................... 5
3.6 HIGH FREQUENCY OSCILLATOR .................. 5
5.6 POWER MODES.................................... 22
5.7 POWER CONTROL................................. 24
5.8 AUTOCALIBRATION................................ 25
COMMUNICATIONS.................................... 25
6.1 I2C INTERFACE..................................... 26
6.2 AUTHENTICATION ................................. 27
REFERENCE SCHEMATIC............................ 27
3.7
3.8
3.9
INTEGRATING ADC (COULOMB COUNTER)
CHARACTERISTICS ................................. 5
ADC (TEMPERATURE AND CELL VOLTAGE)
CHARACTERISTICS ................................. 5
I2C-COMPATIBLE INTERFACE TIMING
6
7
CHARACTERISTICS ................................. 5
4
GENERAL DESCRIPTION .............................. 7
2
Contents
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bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
2 DEVICE INFORMATION
2.1 AVAILABLE OPTIONS
PACKAGE
TA
TSSOP (PW)(1)
–40°C to 85°C
bq27350PW
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
website at www.ti.com.
2.2 PIN DIAGRAM
SE
VEN
CELL+
CELL-
TS
NC
VCC
VSS
MRST
SRN
SRP
NC
PAUTH
AUTH
TOUT
SDATA
bq27350
NC
NC
SCLK
NC
2.3 TERMINAL FUNCTIONS
TERMINAL
I/O(1)
DESCRIPTION
NAME
SE
NO.
1
I/O
O
System enable. Open-drain output for controlling LDO enable (active low).
Voltage divider enable
VEN
2
TS
3
IA
Thermistor measurement input if external thermistor selected
Positive supply line for powering optional bq26100
Signal line for communicating with optional bq26100
Thermistor power output
I2C Interface bidirectional data line (open-drain)
I2C Interface clock line (open-drain)
PAUTH
AUTH
TOUT
SDATA
SCLK
5
P
6
IO
OA
I/O
I/O
7
8
10
Analog input pin connected to the internal coulomb-counter where SRP is connected to the CELL-
side of the sense resistor
SRP
SRN
14
15
IA
IA
Analog input pin connected to the internal coulomb-counter where SRN is connected to the side of
the sense resistor nearest PACK–
MRST
VSS
16
17
18
19
20
I
Master reset of the bq27350
P
Power ground of the IC
VCC
P
Power supply of the IC
CELL–
CELL+
IA
IA
Negative node of differential cell measurement Input
Positive node of differential cell measurement Input
4, 9, 11,
12, 13
NC
NA
Pins electrically connected internally, and should be left floating for normal operation.
(1) I/O = Digital Input/Output, IA = Analog Input, OA = Analog Output, P = Power Connection
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DEVICE INFORMATION
3
bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
3 ELECTRICAL SPECIFICATIONS
3.1 ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted)(1)
PARAMETER
VALUE
–0.3 to 2.75
– 0.3 to 6
UNIT
V
VCC
V(IOD)
VI
Supply voltage range
Open-drain I/O pins
V
Input voltage range to all other pins
Operating free-air temperature range
Storage temperature range
–0.3 to VCC + 0.3
–40 to 85
V
TA
°C
°C
Tstg
–65 to 150
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
3.2 RECOMMENDED OPERATING CONDITIONS
TA = 25°C, VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
2.5
MAX
UNIT
V
VCC
Supply Voltage
2.4
2.6
ICC
Normal operating mode current(1)
Low-power storage mode current(2)
Hibernate operating mode current(3)
Output voltage low (SDA, VEN)
Output high voltage (SDA)
No flash programming
Sleep mode
150
7.4
µA
µA
µA
V
I(SLP)
I(HIBERNATE)
VOL
Hibernate mode
IOL = 0.5 mA
1.5
0.4
VOH
IOH = –1 mA
VCC–0.5
–0.3
2
V
VIL
Input voltage low (SDA, SCL)
Input voltage high (SDA, SCL)
Input capacitance
0.8
6
V
VIH
CIN
5
pF
V
V(AI1)
V(AI2)
Input voltage range (CELL+, CELL–, TS)
Input voltage range (SRP, SRN)
VSS–0.3
1
VSS–0.20
0.20
V
(1) Load current > sleep current threshold during half of operation. Load current < sleep current threshold during other half.
(2) Low-frequency oscillator, I/O support, and IWAKE comparator circuits on.
(3) I/O support and IWAKE comparator circuits on.
3.3 POWER-ON RESET
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
Negative-going input voltage (VCC
Power-on reset hysteresis
TEST CONDITIONS
MIN
1.7
50
TYP
MAX
UNIT
V
VIT–
)
1.8
1.9
VHYS
125
200
mV
3.4 TEMPERATURE SENSOR CHARACTERISTICS
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
GTEMP
Temperature sensor voltage gain
–2.0
mV/°C
4
ELECTRICAL SPECIFICATIONS
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bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
3.5 LOW FREQUENCY OSCILLATOR
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
32.768
0.25%
0.25%
0.25%
MAX
UNIT
f(LOSC)
f(LEIO)
t(LSXO)
Operating frequency
kHz
TA = 0°C to 60°C
–1.5%
–2.5%
–4.0%
1.5%
2.5%
4.0%
500
(1)(2)
Frequency error
TA = –20°C to 70°C
TA = –40°C to 85°C
Start-up time(3)
µs
(1) The frequency drift is included and measured from the trimmed frequency at VCC = 2.5V, TA = 25°C.
(2) The frequency error is measured from 32.768 kHz.
(3) The startup time is defined as the time it takes for the oscillator output frequency to be ±3%.
3.6 HIGH FREQUENCY OSCILLATOR
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
4.194
0.25%
0.25%
0.25%
2.5
MAX
UNIT
f(OSC)
Operating frequency
MHz
TA = 0°C to 60°C
–2.0%
–3.0%
–4.5%
2.0%
3.0%
4.5%
5
(1)(2)
f(EIO)
Frequency error
TA = –20°C to 70°C
TA = –40°C to 85°C
t(SXO)
Start-up time(3)
ms
(1) The frequency error is measured from 4.194 MHz.
(2) The frequency drift is included and measured from the trimmed frequency at VCC = 2.5V, TA = 25°C.
(3) The startup time is defined as the time it takes for the oscillator output frequency to be ±3%.
3.7 INTEGRATING ADC (COULOMB COUNTER) CHARACTERISTICS
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
Input voltage range, V(SRN) and V(SRP)
Resolution
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
V(SR)
V(SR) = V(SRN) – V(SRP)
–0.20
0.20
16
10
bits
V(SROS)
INL
Input offset
After Auto-Calibration
µV
Integral nonlinearity error
Effective input resistance
±0.007 ±0.034
% FSR
MΩ
ZADC_IN
2.5
3.8 ADC (TEMPERATURE AND CELL VOLTAGE) CHARACTERISTICS
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
V
Input voltage range
–0.2
1
Conversion time
31.5
15
ms
Effective resolution
Effective input resistance
14
8
bits
MΩ
3.9 I2C-COMPATIBLE INTERFACE TIMING CHARACTERISTICS
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
SCL/SDA rise time
SCL/SDA fall time
TEST CONDITIONS
MIN
TYP
MAX
UNIT
µs
tr
1
tf
300
ns
tw(H)
SCL pulse width (high)
4
µs
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bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
I2C-COMPATIBLE INTERFACE TIMING CHARACTERISTICS (continued)
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
4.7
4.7
4
TYP
MAX
UNIT
µs
tw(L)
SCL pulse width (low)
Setup for repeated start
Start to first falling edge of SCL
Data setup time
tsu(STA)
td(STA)
tsu(DAT)
µs
µs
250
0
ns
Receive mode
Transmit mode
th(DAT)
Data hold time
ns
300
4
tsu(STOP)
t(BUF)
Setup time for stop
µs
µs
kHz
s
Bus free time between stop and start
Clock frequency
4.7
f(SCL)
100
t(BUSERR)
Bus error timeout
17.3
21.2
Figure 3-1. I2C-Compatible Interface Timing Diagrams
6
ELECTRICAL SPECIFICATIONS
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bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
4 GENERAL DESCRIPTION
The bq27350 accurately predicts the battery capacity and other operational characteristics of a single
Li-based rechargeable cell. It can be interrogated by a host processor to provide cell information, such as
State-of-Charge (SOC), Time-to-Empty (TTE) and Time-to-Full (TTF).
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 bq27350’s control and
status registers, as well as its data flash locations. Commands are sent from host to gauge using the
bq27350’s I2C engine, and can be executed during application development, pack manufacture, or
end-equipment operation.
Cell information is stored inside the bq27350 in non-volatile flash memory. Many of these data flash
locations are accessible during application development and pack manufacture. They cannot, generally,
be accessed directly during end-equipment operation. Access to these locations is achieved by either use
of the bq27350’s companion evaluation software, through individual commands, or through a sequence of
data-flash-access commands. To access a desired data flash location, the correct data flash subclass and
offset must be known.
The bq27350 provides 96 bytes of user-programmable data flash memory, partitioned into 3 32-byte
blocks: Manufacturer Info A,Manufacturer Info B, and Manufacturer Info C. This data space is
accessed through a data flash interface. For specifics on accessing the data flash, refer to the section
entitled DATA FLASH INTERFACE.
The key to the bq27350’s high-accuracy gas gauging prediction is Texas Instrument’s proprietary
Impedance Track™ algorithm. This algorithm combines cell measurements, characteristics, and properties
to create state-of-charge predictions that can achieve better than 1% accuracy across a wide variety of
operating conditions.
The bq27350 measures charge/discharge activity by monitoring the voltage across a small-value series
sense resistor (5 mΩ to 20 mΩ typical) between the cell negative terminal and the low-side protection
FETs. When an application’s load is applied, cell impedance is measured by comparing its Open Circuit
Voltage (OCV) with its measured voltage under loading conditions.
The bq27350 can use an external NTC thermistor (default is Semitec 103AT) for temperature
measurement, or can also be configured to use its internal temperature sensor. The bq27350 uses
temperature to monitor the battery-pack environment, which is used for fuel gauging and cell protection
functionality.
To minimize power consumption, the bq27350 has several power modes: NORMAL, SLEEP,
HIBERNATE, and SHUTDOWN. The bq27350 passes automatically between these modes, depending
upon the occurrence of specific events, though a host processor can initiate some of these modes directly.
More details can be found in the section entitled POWER MODES.
A battery-pack-authentication feature is also implemented on the bq27350. A scratch pad area is used to
both receive challenge information from a host and export SHA-1/HMAC encrypted responses. The
bq27350 can perform the encryption directly, or can act as a pass-through to a bq26100 stand-alone
authentication IC. Specifics can be found in the section entitled AUTHENTICATION.
NOTE
FORMATTING CONVENTIONS:
Commands: italics with parentheses and no breaking spaces, e.g. RemainingCapacity( ).
Data Flash: italics, bold, and breaking spaces, e.g. Design Capacity
Register Bits and Flags: brackets only, e.g. [TDA]
Modes and states: ALL CAPITALS, e.g. UNSEALED mode.
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GENERAL DESCRIPTION
7
bq27350
Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
4.1 DATA COMMANDS
4.1.1 STANDARD DATA COMMANDS
The bq27350 uses a series of 2-byte standard commands to enable host reading and writing of battery
information. Each standard command has an associated command-code pair, as indicated in Table 4-1.
Two consecutive I2C transmissions must be executed both to initiate the command function, and to read
or write the corresponding two bytes of data. Additional options for transferring data, such as spooling, are
described in section I2C INTERFACE. Standard commands are accessible in NORMAL operation.
Read/write permissions depend on the active access mode.
Table 4-1. Standard Commands
COMMAND
CODE
SEALED
ACCESS
UNSEALED
ACCESS
NAME
UNITS
Control( )
CNTL
AR
0x00 / 0x01
0x02 / 0x03
0x04 / 0x05
0x06 / 0x07
0x08 / 0x09
0x0a / 0x0b
0x0c / 0x0d
0x0e / 0x0f
0x10 / 0x11
0x12 / 0x13
0x14 / 0x15
0x16 / 0x17
0x18 / 0x19
0x1a / 0x1b
0x1c / 0x1d
0x1e / 0x1f
0x20 / 0x21
0x22 / 0x23
0x24 / 0x25
0x26 / 0x27
0x28 / 0x29
0x2a / 0x2b
0x2c / 0x2d
N/A
mA
R/W
R/W
R
R/W
R/W
R
AtRate( )
AtRateTimeToEmpty( )
Temperature( )
ARTTE
TEMP
VOLT
FLAGS
NAC
FAC
RM
Minutes
0.1°K
mV
R
R
Voltage( )
R
R
Flags( )
N/A
R
R
NominalAvailableCapacity( )
FullAvailableCapacity( )
RemainingCapacity( )
FullChargeCapacity( )
AverageCurrent( )
TimeToEmpty( )
TimeToFull( )
mAh
R
R
mAh
R
R
mAh
R
R
FCC
AI
mAh
R
R
mA
R
R
TTE
Minutes
Minutes
mA
R
R
TTF
R
R
StandbyCurrent( )
StandbyTimeToEmpty( )
MaxLoadCurrent( )
MaxLoadTimeToEmpty( )
AvailableEnergy( )
AveragePower( )
TTEatConstantPower( )
Reserved
SI
R
R
STTE
MLI
Minutes
mA
R
R
R
R
MLTTE
AE
Minutes
10mWhr
10mW
Minutes
N/A
R
R
R
R
AP
R
R
TTECP
RSVD
CC
R
R
R
R
CycleCount( )
Counts
%
R
R
StateOfCharge( )
SOC
R
R
8
GENERAL DESCRIPTION
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Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
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SLUS754–MARCH 2007
4.1.1.1 Control( ): 0x00/0x01
Issuing a Control( ) command requires a subsequent two-byte sub-command (little endian format:
least-significant byte written to lowest address location). These additional bytes specify the particular
control function desired. The Control( ) command allows the host to control specific features of the
bq27350 during normal operation and additional features when the bq27350 is in different access modes,
as described in Table 4-2.
Table 4-2. Control( ) Subcommands
CNTL
DATA
SEALED
ACCESS
CNTL FUNCTION
CONTROL STATUS
DESCRIPTION
0x0000
0x0001
0x0002
0x0003
0x0004
0x0005
0x0006
0x0007
Yes
Yes
Yes
Yes
No
Reports the status of DF Checksum, Hibernate, IT, etc.
Reports the device type (eg: "bq27350")
Reports the firmware version on the device type
Reports the hardware version of the device type
Enables a DF checksum to be generated and reports on a read
Returns reset data
DEVICE TYPE
FW VERSION
HW VERSION
DFCHECKSUM
RESET DATA
Reserved
No
No
Not to be used
PREV_MACWRITE
No
Returns previous MAC command code
Reports the chemical identifier of the ImpedanceTrack™
configuration
CHEMID
0x0008
Yes
BOARD OFFSET
CC INT OFFSET
SET HIBERNATE
CLEAR HIBERNATE
SEALED
0x0009
0x000b
0x0011
0x0012
0x0020
0x0021
0x0022
0x0040
0x0041
No
No
Yes
Yes
No
No
No
No
No
Forces the device Board Offset to be measured and stored
Forces the device to measure and store the internal CC offset
Forces DF:Pack Configuration [HIBERNATE] to 1
Forces DF:Pack Configuration [HIBERNATE] to 0
Places the bq27350 in SEALED access mode
Enables the ImpedanceTrack™ algorithm
IT ENABLE
IFCHECKSUM
CALMODE
Reports the instruction flash checksum
Places the bq27350 in calibration mode
RESET
Forces a full reset of the bq27350
CONTROL STATUS: 0x0000
Instructs the gas gauge to return status information to Control addresses 0x00/0x01. The status
word should include the following information.
Table 4-3. CONTROL STATUS Flags
Flags( )
High Byte
Low Byte
bit7
–
bit6
FAS
–
bit5
SS
–
bit4
CSV
–
bit3
CCA
bit2
BCA
bit1
–
bit0
–
–
LDMD
RUP_DIS
VOK
QEN
FAS = Full access sealed (Sealed = 1)
SS = Sealed state (Sealed = 1)
CSV = Indicates a valid DF checksum has been generated
BCA = Board calibration active
RUP_DIS = Indicates Ra table updates disabled
QEN = QMAX updates enabled if set
CCA = Coulomb counter calibration active
LDMD = Indicates Z-track alg, using const. power mode
VOK = Indicates voltages are OK for QMAX update if set
DEVICE TYPE: 0x0001
Instructs the gas gauge to return the device type to addresses 0x00/0x01.
FW_VERSION: 0x0002
Instructs the gas gauge to return the firmware version to addresses 0x00/0x01.
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Single Cell Li-Ion Battery Manager
With Impedance Track Fuel Gauge Technology
www.ti.com
SLUS754–MARCH 2007
HW_VERSION: 0x0003
Instructs the gas gauge to return the hardware version to addresses 0x00/0x01.
DF CHECKSUM: 0x0004
Instructs the gas gauge to compute the checksum of the data flash memory. The checksum value
is written and returned to addresses 0x00/0x01 (UNSEALED mode only). The checksum will not be
calculated in SEALED mode; however, the checksum value can still be read.
RESET_DATA: 0x0005
Instructs the gas gauge to return the reset data to addresses 0x00/0x01, with the low-byte being
the number of partial resets and the high-byte the number of full resets.
PREV_MACWRITE: 0x0007
Instructs the gas gauge to return the previous command written to addresses 0x00/0x01.
CHEM ID: 0x0008
Instructs the gas gauge to return the chemical identifier for the ImpedanceTrack™ configuration to
addresses 0x00/0x01.
BOARD_OFFSET: 0x0009
Instructs the gas gauge to compute the coulomb counter offset with internal short and without
internal short applied across the SR inputs. The difference between the two measurements is the
Board Offset. The Board Offset shall be written to data flash and should also be returned to
addresses 0x00/0x01. User will need to prevent any charge or discharge current from flowing
during the process. This function is only available when the gas gauge is UNSEALED. When
SEALED, this command will only read back the Board Offset value stored in data flash.
CC_INT_OFFSET: 0x000B
Instructs the gas gauge to compute the coulomb counter offset with internal short applied across
the SR inputs. The offset value shall be written to Data Flash and should also be returned to
addresses 0x00/0x01. This function is only available when the gas gauge is UNSEALED. When
SEALED, this command will only read back the CC_INT_OFFSET value stored in data flash.
SET_HIBERNATE: 0x0011
Instructs the gas gauge to force Pack Configuration’s [HIBERNATE] bit to 1. This will allow the
gauge to enter the HIBERNATE power mode after the transition to SLEEP power state is detected.
CLEAR_HIBERNATE: 0x0012
Instructs the gas gauge to force Pack Configuration’s [HIBERNATE] bit to 0. This will prevent the
gauge from entering the HIBERNATE power mode after the transition to SLEEP power state is
detected.
SEALED: 0x0020
Instructs the gas gauge to transition from UNSEALED state to SEALED state. The gas gauge
should always be set to SEALED state for use in customer’s end equipment.
IT ENABLE: 0x0021
This command forces the gas gauge to begin the Impedance Track™ algorithm, sets
UpdateStatus to 0x04 and causes the [VOK] and [QEN] flags to be set in the CONTROL STATUS
register. [VOK] is cleared if the voltages are not suitable for a Qmax update. Once set, [QEN]
cannot be cleared. This command is only available when the gas gauge is UNSEALED.
IF CHECKSUM: 0x0022
This command instructs the gas gauge to compute the instruction flash checksum. In UNSEALED
mode, the checksum value is returned to addresses 0x00/0x01. The checksum will not be
calculated in SEALED mode; however, the checksum value can still be read.
10
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CAL MODE: 0x0040
This command instructs the gas gauge to enter calibration mode. This command is only available
when the gas gauge is UNSEALED.
RESET : 0x0041
This command instructs the gas gauge to perform a full reset. This command is only available
when the gas gauge is UNSEALED.
4.1.1.2 AtRate( ): 0x02/0x03
The AtRate( ) read-/write-word function is the first half of a two-function call-set used to set the AtRate
value used in calculations made by the AtRateTimeToEmpty( ) function. The AtRate( ) units are in mA.
The AtRate( ) value is a signed integer and both positive and negative values will be interpreted as a
discharge current value. The AtRateTimeToEmpty( ) function returns the predicted operating time at the
AtRate value of discharge. The default value for AtRate( ) is zero and will force AtRate( ) to return 65535.
4.1.1.3 AtRateTimeToEmpty( ): 0x04/0x05
This read-word function returns an unsigned integer value of the predicted remaining operating time if the
battery is discharged at the AtRate( ) value in minutes with a range of 0 to 65534. A value of 65535
indicates AtRate( ) = 0. The gas gauge updates AtRateTimeToEmpty( ) within 1s after the host sets the
AtRate( ) value. The gas gauge automatically updates AtRateTimeToEmpty( ) based on the AtRate( )
value every 1s.
4.1.1.4 Temperature( ): 0x06/0x07
This read-word function returns an unsigned integer value of the temperature in units of 0.1°K measured
by the gas gauge and has a range of 0 to 6553.5°K. The source of the measured temperature is
configured by the [TEMPS] bit in Pack Configuration register (see EXTENDED COMMANDS).
Table 4-4. Temperature Sensor Selection
TEMPS
Temperature( ) source
Internal Temperature Sensor
TS Input (default)
0
1
4.1.1.5 Voltage( ): 0x08/0x09
This read-word function returns an unsigned integer value of the measured cell-pack voltage in mV with a
range of 0 to 6000mV.
4.1.1.6 Flags( ): 0x0a/0x0b
This read-word function returns the contents of the gas-gauge status register, depicting current operation
status.
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Table 4-5. Flags Bit Definitions
bit7
OTC
bit6
OTD
–
bit5
–
bit4
–
bit3
–
bit2
XCHG
RCA
bit1
CHG_INH
TDA
bit0
CHG
DSG
High Byte
Low Byte
CC_OFF
–
–
FC
OTC = Over-Temperature in Charge condition is detected
CC_OFF = Coulomb Counter Offset measurement is being performed
OTD = Over-Temperature in Discharge condition is detected
FC = Fully Charged, set when Charge termination condition is met
RCA = Remaining Capacity Alert
XCHG = Charge Suspend Alert (temp outside the range –5°C to 55°C)
CHG_INH = Charge Inhibit: unable to begin charging (temp outside the range 0°C to 45°C)
TDA = Terminate Discharge Alert
CHG = (Fast)charging allowed
DSG = Discharging detected
4.1.1.7 NominalAvailableCapacity( ): 0x0c/0x0d
This read-only command pair returns the uncompensated (no or light load) battery capacity remaining.
Units are 1mAh per bit.
4.1.1.8 FullAvailableCapacity( ): 0x0e/0x0f
This read-only command pair returns the uncompensated (no or light load) capacity of the battery when
fully charged. Units are 1mAh per bit. FullAvailableCapacity( ) is updated at regular intervals, as specified
by the IT algorithm.
4.1.1.9 RemainingCapacity( ): 0x10/0x11
This read-only command pair returns the compensated battery capacity remaining. Units are 1mAh per bit.
4.1.1.10 FullChargeCapacity( ): 0x12/13
This read-only command pair returns the compensated capacity of the battery when fully charged. Units
are 1mAh per bit. FullChargeCapacity( ) is updated at regular intervals, as specified by the IT algorithm.
4.1.1.11 AverageCurrent( ): 0x14/0x15
This read-only command pair returns a signed integer value that is the average current flow through the
sense resistor. It is updated every 1 second. Units are 1mA per bit.
4.1.1.12 TimeToEmpty( ): 0x16/0x17
This read-only function returns an unsigned integer value of the predicted remaining battery life at the
present rate of discharge, in minutes. A value of 65535 indicates battery is not being discharged.
4.1.1.13 TimeToFull( ): 0x18/0x19
This read-only function returns an unsigned integer value of predicted remaining time until the battery
reaches full charge, in minutes, based upon AverageCurrent( ). The computation should account for the
taper current time extension from the linear TTF computation based on a fixed AverageCurrent( ) rate of
charge accumulation. A value of 65535 indicates the battery is not being charged.
4.1.1.14 StandbyCurrent( ): 0x1a/0x1b
This read-only function returns a signed integer value of the measured standby current through the sense
resistor. The StandbyCurrent( ) is an adaptive measurement. Initially it reports the standby current
programmed in Initial Standby, and after spending some time in standby, reports the measured standby
current.
The register value is updated every 1 second when the measured current is above the Deadband (3mA
default) and is less than or equal to 2 x Initial Standby. The first and last values that meet this criteria
should not be averaged in, since they may not be stable values. To approximate a 1 minute time constant,
each new StandbyCurrent( ) value is computed as follows:
StandbyCurrent( )NEW = (239/256) × StandbyCurrent( )OLD + (17/256) × AverageCurrent( ).
12
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4.1.1.15 StandbyTimeToEmpty( ): 0x1c/0x1d
This read-only function returns an unsigned integer value of the predicted remaining battery life at the
standby rate of discharge, in minutes. The computation should use Nominal Available Capacity (NAC), the
uncompensated remaining capacity, for this computation. A value of 65535 indicates battery is not being
discharged.
4.1.1.16 MaxLoadCurrent( ): 0x1e/0x1f
This read-only function returns a signed integer value, in units of mA, of the maximum load conditions.
The MaxLoadCurrent( ) is an adaptive measurement which is initially it reports the maximum load current
programmed in Initial Max Load Current. If the measured current is ever greater than Initial Max Load
Current, then MaxLoadCurrent( ) updates to the new current. MaxLoadCurrent( ) is reduced to the
average of the previous value and Initial Max Load Current whenever the battery is charged to full after
a previous discharge to an SOC less than 50%. This prevents the reported value from maintaining an
unusually high value.
4.1.1.17 MaxLoadTimeToEmpty( ): 0x20/0x21
This read-only function returns an unsigned integer value of the predicted remaining battery life at the
maximum load current discharge rate, in minutes. A value of 65535 indicates that the battery is not being
discharged.
4.1.1.18 AvailableEnergy( ): 0x22/0x23
This read-only function returns an unsigned integer value of the predicted charge or energy remaining in
the battery. The value is reported in units of mWh.
4.1.1.19 AveragePower( ): 0x24/0x25
This read-word function returns an unsigned integer value of the average power of the current discharge.
A value of 0 indicates that the battery is not being discharged. The value is reported in units of mW.
4.1.1.20 TimeToEmptyAtConstantPower( ): 0x26/0x27
This read-only function returns an unsigned integer value of the predicted remaining operating time if the
battery is discharged at the AveragePower( ) value in minutes.
A value of 65535 indicates
AveragePower( ) = 0. The gas gauge automatically updates TimeToEmptyatContantPower( ) based on the
AveragePower( ) value every 1s.
4.1.1.21 CycleCount( ): 0x2a/0x2b
This read-only function returns an unsigned integer value of the number of cycles the battery has
experienced with a range of 0 to 65535. One cycle occurs when accumulated discharge ≥ CC Threshold.
4.1.1.22 StateOfCharge( ): 0x2c/0x2d
This read-only function returns an unsigned integer value of the predicted remaining battery capacity
expressed as a percentage of FullChargeCapacity( ), with a range of 0 to 100%.
4.2 EXTENDED DATA COMMANDS
Extended commands offer additional functionality beyond the standard set of commands. They are used in
the same manner; however unlike standard commands, extended commands are not limited to 2-byte
words. The number of commands bytes for a given extended command ranges in size from single to
multiple bytes, as specified in Table 4-6. For details on the SEALED and UNSEALED states, refer to the
section Access Modes.
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Table 4-6. Extended Data Commands
COMMAND
CODE
SEALED
UNSEALED
NAME
UNITS
ACCESS(1)(2)
ACCESS(1)(2)
Reserved
RSVD
PKCFG
DCAP
0x34 / 0x39
0x3a / 0x3b
0x3c / 0x3d
0x3e
N/A
N/A
mAh
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
R
R
R
R
PackConfiguration( )
DesignCapacity( )
DataFlashClass( ) (2)
DataFlashBlock( ) (2)
Authenticate( )/BlockData( )
R
R
DFCLS
N/A
R/W
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
DFBLK
0x3f
A/DF
0x40…0x53
0x54
AuthenticateCheckSum( )/BlockData( )
BlockData( )
ACKS/DFD
DFD
0x55…0x5f
0x60
BlockDataCheckSum( )
BlockDataControl( )
DeviceNameLength( )
DeviceName( )
DFDCKS
DFDCNTL
DNAMELEN
DNAME
RSVD
R/W
N/A
R
0x61
0x62
0x63...0x69
0x6a...0x7f
R
R
Reserved
R
R
(1) SEALED and UNSEALED states are entered via commands to CNTL 0x00/0x01
(2) In sealed mode, data flash CANNOT be accessed through commands 0x3e and 0x3f.
4.2.1 PackConfiguration( ): 0x3a/0x3b
This Read-Word function allows the host to read the configuration of selected features of the bq27350
pertaining to power modes and transitioning between them. These features must set direct by data flash
writes to location subclass = 64, offset = 0 while in UNSEALED mode. Only the HIBERNATE function can
be modified while SEALED mode with the Control( ) command.
Table 4-7. Pack Configuration Bit Definitions
Operation
Cfg
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
High Byte
Low Byte
RESCAP
–
BUSLOW
SLEEP
–
–
–
IWAKE
–
RSNS1
–
RSNS0
TEMPS
SHUTDOWN HIBERNATE
RMFCC
RESCAP = If set, no-load rate of compensation is applied to the reserve capacity calculation
BUSLOW = If set, the Interface Bus being low becomes a requirement to enter SLEEP mode
IWAKE/RSNS1/RSNS0 = These bits configure the current wake function (ref. Table 5-3)
SHUTDOWN = If set, SE is set high before going into HIBERNATE and set low in NORMAL mode
HIBERNATE = If set and conditions are suitable for SLEEP mode, then the gas gauge enters HIBERNATE instead of SLEEP
SLEEP = If set, the gas gauge can enter SLEEP mode if operating conditions allow
RMFCC = If set, on valid charge termination RM is updated with the value from FCC
TEMPS = Selects Temperature( ) source, 0 = Internal, 1 = External
4.2.2 DesignCapacity( ): 0x3c/0x3d
SEALED and UNSEALED Access: This command returns the theoretical or nominal capacity of a new
pack. The value is stored in Design Capacity and is expressed in mAh.
4.2.3 DataFlashClass( ): 0x3e
UNSEALED Access: This command sets the data flash class to be accessed. The class to be accessed
should be entered in hexadecimal.
SEALED Access: This command is not available in SEALED mode.
14
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4.2.4 DataFlashBlock( ): 0x3f
UNSEALED Access: This command sets the data flash block to be accessed. When “0x00” is written to
BlockDataControl( ), DataFlashBlock( ) holds the block number of the data flash to be read or written.
Example: writing a 0x00 to DataFlashBlock( ) specifies access to the first 32 byte block and a 0x01
specifies access to the second 32 byte block, and so on.
SEALED Access: This command directs which data flash block will be accessed by the BlockData( )
command. Writing a 0x00 to DataFlashBlock( ) specifies the BlockData( ) command will transfer
authentication data. Issuing a 0x01, 0x02 or 0x03 instructs the BlockData( ) command to transfer
Manufacturer Info Blocks A, B, or C, respectively.
4.2.5 AuthenticateData/BlockData( ): 0x40…0x53
UNSEALED Access: This data block has two functions. It is used for the authentication challenge and
response and is part of the 32 byte data block when accessing data flash.
SEALED Access: It is used for the authentication challenge and response and is part of the 32 byte data
block when accessing Manufacturer Info Blocks A, B, or C.
4.2.6 AuthenticateChecksum/BlockData( ): 0x54
UNSEALED Access: This byte holds the authenticate checksum when writing the authentication challenge
to the bq27350 and is part of the 32 byte data block when accessing data flash.
SEALED Access: This byte holds the authenticate checksum when writing the authentication challenge to
the bq27350 and is part of the 32 byte data block when accessing Manufacturer Info Blocks A, B, or C.
4.2.7 BlockData( ): 0x55…0x5f
UNSEALED Access: This data block is the remainder of the 32 byte data block when accessing data
flash.
SEALED Access: This data block is the remainder of the 32 byte data block when accessing
Manufacturer Info Blocks A, B, or C.
4.2.8 BlockDataChecksum( ): 0x60
UNSEALED Access: This byte contains the checksum for the 32 bytes of block data read or written to
data flash.
SEALED Access:This byte contains the checksum for the 32 bytes of block data written to Manufacturer
Info Blocks B or C.
4.2.9 BlockDataControl( ): 0x61
UNSEALED Access: This command is used to control data flash access. Writing 0x00 to this command
enables BlockData( ) to access general data flash. Writing a 0x01 to this command enablesBlockData( ) to
access authentication challenge and response.
SEALED Access: This command is not available in SEALED mode.
4.2.10 DeviceNameLength( ): 0x62
UNSEALED and SEALED Access: This byte contains the length of the Device Name.
4.2.11 DeviceName( ): 0x63…0x69
UNSEALED and SEALED Access: This block contains the device name that is programmed in Device
Name.
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4.2.12 Reserved – 0x6A – 0x7F
4.3 DATA FLASH INTERFACE
4.3.1 ACCESSING THE DATA FLASH
The bq27350 data flash is a non-volatile memory that contains bq27350 initialization, default, cell status,
calibration, configuration, and user information. The data flash can be accessed in several different ways,
depending on what mode the bq27350 is operating in and what data is being accessed.
Commonly accessed data flash memory locations, frequently read by a host, are conveniently accessed
through specific instructions, already described in the DATA COMMANDS section. These commands are
available when the bq27350 is either in UNSEALED or SEALED modes.
Most data flash locations, however, can only be accessed in UNSEALED mode by using the bq27350
evaluation software or by performing data flash block transfers. These locations should be optimized
and/or fixed during the development and manufacture processes. They become part of a golden pack file
and can then be written to multiple battery packs. Once established, the values generally remain
unchanged during end-equipment operation.
To access data flash locations individually, the block containing the desired data flash location(s) must be
transferred to the command register locations, where they can be read to the host or changed directly.
This is accomplished by sending the set-up command BlockDataControl( ) (code 0x61) with data 0x00. Up
to 32 bytes of data can be read directly from the BlockData( ) command locations 0x40…0x5f, externally
altered, then re-written to the BlockData( ) command space. Alternatively, specific locations can be read,
altered, and re-written if their corresponding offsets are used to index into the BlockData( ) command
space. Finally, data residing in the command space is transferred to data flash, once a correct checksum
for the whole block is written to BlockDataChecksum( ) (command number 0x60).
Occasionally, a data flash CLASS will be larger than the 32-byte block size. In this case, the
DataFlashBlock( ) command is used to designate which 32-byte block the desired locations reside in. The
correct command address is then given by 0x40 + offset modulo 32. For example, to access Terminate
Voltage in the Gas Gauging class, DataFlashClass( ) is issued 80 (0x50) to set the class. Because the
offset is 48, it must reside in the second 32-byte block. Hence DataFlashBlock( ) is issued 0x01 to set the
block offset, and the offset used to index into the BlockData( ) memory area is 0x40 + 48 modulo 32 =
0x40 + 16 = 0x40 + 0x10 = 0x50.
Reading and writing subclass data are block operations 32 bytes in length. Data can be written in shorter
block sizes, however. Blocks can be shorter than 32 bytes in length. Writing these blocks back to data
flash will not overwrite data that extends beyond the actual block length.
None of the data written to memory are bounded by the bq27350 — the values are not rejected by the gas
gauge. Writing an incorrect value may result in hardware failure due to firmware program interpretation of
the invalid data. The data written is persistent, so a Power-On-Reset does not resolve the fault.
4.4 MANUFACTURER INFORMATION BLOCKS
The bq27350 contains 96 bytes of user programmable data flash storage: Manufacturer Info Block A,
Manufacturer Info Block B, Manufacturer Info Block C. The method for accessing these memory
locations is slightly different, depending on whether the device is in UNSEALED or SEALED modes.
When in UNSEALED mode and “0x00” is written to BlockDataControl( ), accessing the Manufacturer Info
Blocks is identical to accessing general data flash locations. First, a DataFlashClass( ) command is used
to set the subclass, then a DataFlashBlock( ) command sets the offset for the first data flash address
within the subclass. The BlockData( ) command codes contain the referenced data flash data. When
writing the data flash, a checksum is expected to be received by BlockDataChecksum( ). Only when the
checksum is received and verified is the data actually written to data flash.
16
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As an example, the data flash location for Manufacturer Info Block B is defined as having a Subclass =
58 and an Offset = 32 through 63 (32 byte block). The specification of Class = "System Data" is not
needed to address Manufacturer Info Block B, but is used instead for grouping purposes when viewing
data flash info in the bq27350 evaluation software.
When in SEALED mode or “0x01” has been written to BlockDataControl( ), data flash is no longer
available in the manner used in UNSEALED mode. Rather than issuing subclass information, a
designated Manufacturer Information Block is selected with the DataFlashBlock( ) command. Issuing a
0x01, 0x02, or 0x03 with this command causes the corresponding information block (A, B, or C,
respectively) to be transferred to the command space 0x40…0x5f for editing or reading by the host. Upon
successful writing of checksum information to BlockDataChecksum( ), the modified block is returned to
data flash. Note: Manufacturer Info Block A is "read only" when in SEALED mode.
4.5 ACCESS MODES
The bq27350 provides three security modes in which control data flash access permissions according to
Table 4-8. Public Access refers to those data flash locations, specified in Table 4-9, that are accessible to
the user. Private Access refers to reserved data flash locations used by the bq27350 system. Care should
be taken to avoid writing to Private data flash locations when performing block writes in Full Access mode,
by following the procedure outlined in ACCESSING THE DATAFLASH.
Table 4-8. Data Flash Access
Security Mode
BOOTROM
FULL ACCESS
UNSEALED
SEALED
DF – Public Access
DF – Private Access
N/A
R/W
R/W
R
N/A
R/W
R/W
N/A
Although FULL ACCESS and UNSEALED modes appear identical, FULL ACCESS allows the bq27350 to
directly transition to BOOTROM mode and write access keys. The UNSEAL mode lacks these abilities.
4.6 SEALING/UNSEALING DATA FLASH ACCESS
The bq27350 implements a key-access scheme to transition between SEALED, UNSEALED, and
FULL-ACCESS modes. Each transition requires that a unique set of 2 keys be sent to the bq27350 via the
Control( ) control command (these keys are unrelated to the keys used for SHA-1/HMAC authentication).
The keys must be sent consecutively, with no other data being written to the Control( ) register in between.
Note that to avoid conflict, the keys must selected different from the codes presented in the CNTL DATA
column of Table 4-2 Control( ) subcommands.
When in SEALED mode the Control Status( )’s [SS] bit is set, but when the UNSEAL keys are correctly
received by the bq27350, the [SS] bit is cleared. When the full access keys are correctly received then the
Control Status( )[FAS] bit is cleared.
Both the sets of keys for each level are 2 bytes each in length and are stored in data flash. The UNSEAL
key (stored at Unseal Key 0 and Unseal Key 1) and the FULL-ACCESS key (stored at Full Access Key
0 and Full Access Key 1) can only be updated when in FULL-ACCESS Mode. The order of the bytes
entered through the Control( ) command is the reverse of what is read from the part. For example, if the
1st and 2nd word of Unseal Key 0 read returns 0x1234 and 0x5678, then the Control( ) should supply
0x3412 and 0x7856 to unseal the part.
4.7 DATA FLASH SUMMARY
Table 4-9 summarizes the data flash locations available to the user, including their default, minimum, and
maximum values.
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Table 4-9. Data Flash Summary
Subclass
ID
Data
Type
Min
Value
Max
Value
Default
Class
Subclass
Offset
Name
Units
Value
550
2
Configuration
Configuration
Configuration
Configuration
Configuration
Configuration
2
2
2
2
2
2
Safety
Safety
Safety
Safety
Safety
Safety
0
2
3
5
7
8
OT Chg
I2
U1
I2
0
0
0
0
0
0
1200
60
0.1°C
s
OT Chg Time
OT Chg Recovery
OT Dsg
1200
1200
60
500
600
2
0.1°C
0.1°C
s
I2
OT Dsg Time
OT Dsg Recovery
U1
I2
1200
550
0.1°C
Configuration
Configuration
Configuration
Configuration
34
36
36
36
Charge
2
2
6
8
Charging Voltage
Taper Current
I2
I2
0
0
0
0
20000
1000
1000
60
4200
100
100
40
mV
mA
mV
s
Charge
Termination
Charge
Termination
Taper Voltage
I2
Charge
Termination
Current Taper Window
U1
Configuration
Configuration
Configuration
Configuration
Configuration
Configuration
Configuration
48
48
48
48
48
48
48
Data
Data
Data
Data
Data
Data
Data
0
8
RCA Set
I2
I1
0
–256
–32767
0
700
0
100
–10
mAh
mA
Initial Standby Current
Initial Max Load Current
Cycle Count
9
I2
0
–1000
0
mA
17
19
23
39
U2
I2
65535
32767
65535
x
Count
mAh
mAh
CC Threshold
100
0
1400
1500
bq27350
Design Capacity
Device Name
I2
S8
x
Configuration
Configuration
49
49
Discharge
Discharge
0
1
TDA Set %
I1
I1
–1
–1
100
100
6
8
%
%
TDA Clear %
Manufacturer
Info
System Data
System Data
System Data
Configuration
58
58
58
64
0 – 31
32 – 63
64 – 95
0
Block A [0 – 31]
Block B [0 – 31]
Block C [0 – 31]
Pack Configuration
H1
H1
H1
H2
0x00
0x00
0xff
0xff
0x00
0x00
Manufacturer
Info
Manufacturer
Info
0x00
0xff
0x00
Registers
0x0000
0xffff
0x0131
Configuration
Configuration
68
68
Power
Power
0
7
Flash Update OK Voltage
Sleep Current
I2
I2
2400
0
4200
100
2800
10
mV
mA
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
80
80
80
80
80
80
80
IT Cfg
IT Cfg
IT Cfg
IT Cfg
IT Cfg
IT Cfg
IT Cfg
0
Load Select
U1
U1
I2
0
255
255
1
1
Load Mode
0
0
48
63
65
67
69
Terminate Voltage
User Rate-mA
User Rate-mW
Reserve Cap-mAh
Reserve Cap-mWh
–32768
32767
9000
14000
9000
14000
3000
mV
mA
I2
0
0
0
0
0
0
0
0
I2
10mW
mAh
I2
I2
10mWh
Current
Thresholds
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
81
81
81
81
81
81
0
2
4
6
8
9
Dsg Current Threshold
Chg Current Threshold
Quit Current
I2
I2
0
0
0
0
0
0
2000
2000
1000
8191
255
75
75
mA
mA
mA
s
Current
Thresholds
Current
Thresholds
I2
50
Current
Thresholds
Dsg Relax Time
U2
U1
U1
1800
60
Current
Thresholds
Chg Relax Time
Quit Relax Time
s
Current
Thresholds
63
1
s
18
GENERAL DESCRIPTION
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Table 4-9. Data Flash Summary (continued)
Subclass
ID
Data
Type
Min
Value
Max
Value
Default
Value
Class
Subclass
Offset
Name
Qmax Cell 0
Units
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
Gas Gauging
82
82
82
82
82
State
State
State
State
State
0
2
I2
I2
0
32767
32767
0x06
1500
1500
0x0
mAh
mAh
Qmax Pack
0
6
Update Status
Avg I Last Run
Avg P Last Run
H1
I2
0x00
–32768
–32768
9
32767
32767
–2000
–3022
mA
11
I2
mW
Ra Table
Ra Table
88
88
R_a0
R_a0
0
Cell0 R_a flag
H2
I2
0x0000
183
0x0000
183
0xff55
160
2
-10Ω
2 – 30
Cell0 R_a [0 –14]
Ra Table
Ra Table
89
89
R_a0x
R_a0x
0
xCell0 R_a flag
H2
I2
0xffff
183
0xffff
183
0xffff
160
2
-10Ω
2 – 30
xCell0 R_a [0 –14]
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
Calibration
104
104
104
104
104
104
104
Data
Data
Data
Data
Data
Data
Data
0
4
CC Gain
F4
F4
I2
0.1
0.1
4
0.9419
0.9419
1225
–1667
0
CC Delta
4
8
Ref Voltage
CC Offset
0
32767
32767
32767
127
10
12
14
15
I2
–32768
–32767
–128
–128
Board Offset
Int Temp Offset
Ext1 Temp Offset
I2
I1
0
I1
127
0
Calibration
107
Current
1
Deadband
U1
0
255
3
mA
5 FUNCTIONAL DESCRIPTION
5.1 FUEL GAUGING
The bq27350 measures the cell voltage, temperature, and current to determine battery SOC. The
bq27350 monitors charge and discharge activity by sensing the voltage across a small-value resistor
(5mΩ to 20 mΩ typ.) between the SRP and SRN pins and in-series with the cell. By integrating charge
passing through the battery, the cell’s SOC is adjusted during battery charge or discharge.
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 present SOC with the measured voltage
under load. Measurements of OCV and charge integration determine chemical state of charge and
Chemical Capacity (Qmax). The initial Qmax value is taken from a cell manufacturers' data sheet
multiplied by the number of parallel cells. It is also used for the value in Design Capacity. The bq27350
acquires and updates the battery-impedance profile during normal battery usage. It uses this profile, along
with SOC and the Qmax value, 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 bq27350 has two flags accessed by the Flags( ) function that warns when the cell’s SOC has fallen to
critical levels. When RemainingCapacity( ) falls below the first capacity threshold, specified in RCA Set,
the [RCA] (“Remaining Capacity Alert”) flag is set. The flag is cleared once RemainingCapacity( ) rises
above RCA Set. All units are in mAh.
When StateOfCharge( ) falls below the second capacity threshold, TDA Set %, the [TDA] (“Terminate
Discharge Alert”) flag is set, serving as a final discharge warning. If TDA Set % = -1, the flag is inoperative
during discharge.
Similarly, when StateOfCharge( ) rises above TDA Clear % and the [TDA] flag has already been set, the
[TDA] flag will be cleared, provided TDA Set % ≠– 1. All units are in percentages.
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5.2 IMPEDANCE TRACK VARIABLES
The bq27350 has several data flash variables that permit the user to customize the Impedance Track
algorithm for optimized performance. These variables are dependent upon the power characteristics of the
application as well as the cell itself.
Load Mode
Load Mode is used to select either the constant current or constant power model for the Impedance Track™ algorithm as used in
Load Select (see Load Select). When Load Mode is 0, the Constant Current Model is used (default). When 1, the Constant
Power Model is used.
Load Select
Load Select defines the type of power or current model to be used to compute load-compensated capacity in the Impedance
Track™ algorithm. If Load Mode = 0 (‘Constant Current’) then the options presented in Table 5-1 are available.
Table 5-1. Constant-Current Model Used When Load Mode = 0
LoadSelect Value
Current Model Used
Average discharge current from previous cycle: There is an internal register that records the average discharge
current through each entire discharge cycle. The previous average is stored in this register.
0
Present average discharge current: This is the average discharge current from the beginning of this discharge
cycle until present time.
1(default)
2
3
4
5
6
Average Current: based on AverageCurrent( )
Current: based off of a low-pass-filtered version of AverageCurrent( ) (τ =14s)
Design Capacity / 5: C Rate based off of Design Capacity /5 or a C / 5 rate in mA.
AtRate (mA): Use whatever current is in AtRate( )
User_Rate-mA: Use the value in User_Rate( ). This gives a completely user configurable method.
If Load Mode = 1 (‘Constant Power’) then the following options are available:
Table 5-2. Constant-Power Model Used When Load Mode = 1
LoadSelect Value
Power Model Used
Average discharge power from previous cycle: There is an internal register that records the average discharge
power through each entire discharge cycle. The previous average is stored in this register.
0
Present average discharge power: This is the average discharge power from the beginning of this discharge cycle
until present time.
1(default)
2
3
4
5
6
Average Current×Voltage: based off the AverageCurrent( ) and Voltage( ).
Current ×Voltage: based off of a low-pass-filtered version of AverageCurrent( )(τ=14s) and Voltage( )
Design Energy / 5: C Rate based off of Design Energy /5 or a C / 5 rate in mA.
AtRate (10 mW): Use whatever value is in AtRate( ).
User_Rate-10mW: Use the value in User_Rate( ) mW. This gives a completely user configurable method.
Reserve Cap-mAh
Reserve Cap-mAh determines how much actual remaining capacity exists after reaching 0 RemainingCapacity( ), before
Terminate Voltage is reached. A no-load rate of compensation is applied to this reserve.
Reserve Cap-mWh
Reserve Cap-mWh determines how much actual remaining capacity exists after reaching 0 AvailableEnergy( ), before
Terminate Voltage is reached. A no-load rate of compensation is applied to this reserve capacity.
20
FUNCTIONAL DESCRIPTION
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Dsg Current Threshold
This register is used as a threshold by many functions in the bq27350 to determine if actual discharge current is flowing into or
out of the cell. The default for this register is 100mA which should be sufficient for most applications. This threshold should be
set low enough to be below any normal application load current but high enough to prevent noise or drift from affecting the
measurement.
Chg Current Threshold
This register is used as a threshold by many functions in the bq27350 to determine if actual charge current is flowing into or out
of the cell. The default for this register is 50mA which should be sufficient for most applications. This threshold should be set low
enough to be below any normal charge current but high enough to prevent noise or drift from affecting the measurement.
Quit Current, Dsg Relax Time, Chg Relax Time, and Quit Relax Time
The Quit Current is used as part of the Impedance Track™ algorithm to determine when the bq27350 enters relaxation mode
from a current flowing mode in either the charge direction or the discharge direction. The value of Quit Current is set to a default
value of 10mA and should be above the standby current of the host system, but not exceed the C/20 rate..
Either of the following criteria must be met to enter relaxation mode:
1. | AverageCurrent( ) | < | Quit Current | for Dsg Relax Time.
2. | AverageCurrent( ) | < | Quit Current | for Chg Relax Time.
After about 30 minutes in relaxation mode, and when voltage change rate satisfies the criteria dV/dt < 4uV/sec, the bq27350
attempts to take accurate OCV readings. If state of charge (SOC) change from the previous OCV reading exceeds 37% when a
new reading is taken, the total cell capacity, Qmax, is updated. These updates are used in the Impedance Track™ algorithms. It
is critical that the battery voltage be relaxed during OCV readings and that the current is not higher than C/20 when attempting
to go into relaxation mode.
Quit Relax Time specifies the minimum time required for AverageCurrent( ) to remain above the QuitCurrent threshold before
exiting relaxation mode.
Qmax
Qmax contains the maximum chemical capacity of a cell and is determined by comparing states of charge, before and after
applying a load, with the amount of charge that passed. It also corresponds to capacity at very low rate of discharge such as
C/20 rate. For high accuracy, this value is periodically updated by the bq27350 during operation. The initial value of Qmax
should be set to the battery cell capacity specified in its datasheet.
Update Status
There are 2 bits in this register that are important
– Bit 1 (0x02) indicates that the bq27350 has learned new Qmax parameters and is accurate.
– Bit 2 (0x04) indicates whether Impedance Track™ algorithm is enabled.
The remaining bits are reserved. Bits 1 and 2 are user-configurable; however, bit 1 is also a status flag that can be set by the
bq27350. These bits should never be modified except when creating a golden image file as explained in the application note
“Preparing Optimized Default Flash Constants for specific Battery Types” (see SLUA334.pdf). Bit 1 is updated as needed by the
bq27350 and Bit 2 is set with Control( ) command 0x0021.
Avg I Last Run
The bq27350 logs the current averaged from the beginning to the end of each discharge cycle. It stores this average current
from the previous discharge cycle in this register. This register should never need to be modified. It is only updated by the
bq27350 when required.
Avg P Last Run
The bq27350 logs the power averaged from the beginning to the end of each discharge cycle. It stores this average power from
the previous discharge cycle in this register. To get a correct average power reading the bq27350 continuously multiplies
instantaneous current times Voltage( ) to get power. It then logs this data to derive the average power. This register should
never need to be modified. It is only updated by the bq27350 when the required.
The Ra Tables
This data is automatically updated during device operation. No user changes should be made except for reading the values from
another pre-learned pack for creating “Golden Image Files”. Profiles have format Cell0 R_a M, where M is the number indicating
state of charge to which the value corresponds.
5.3 TEMPERATURE MEASUREMENT
The bq27350 can measure temperature via the on-chip temperature sensor or via the TS input depending
on the setting of the [TEMPS] bit PackConfiguration( ). The bit is set by using the PackConfiguration( )
function, described in the section entitled EXTENDED COMMAND SUMMARY.
Temperature measurements are made by calling the Temperature( ) function (see STANDARD
COMMANDS for specific information).
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When an external thermistor input is used, TOUT (pin 7) is used to power the thermistor and TS (pin 3) to
measure the thermistor voltage. The bq27350 then correlates the voltage to temperature assuming the
thermistor is a Semitec 103AT or similar device.
5.4 OVER-TEMPERATURE INDICATION
The bq27350 can set safety flag indications based on measure temperature both in charge and discharge
states.
Over-Temperature: Charge
If during charging, Temperature( ) exceeds the threshold of OT Chg for a period of OT Chg Time and
AverageCurrent( ) > Chg Current Threshold, then the [OTC] bit of Flags( ) is set. Note: if OT Chg Time =
0 then feature is completely disabled.
When Temperature( ) falls below OT Chg Recovery, the [OTC] of Flags( ) is reset.
Over-Temperature: Discharge
If, during discharging, Temperature( ) exceeds the threshold of OT Dsg for a period of OT Dsg Time, and
AverageCurrent( ) ≤ -Dsg Current Threshold, then the [OTD] bit of Flags( ) is set. Note: if OT Dsg Time
= 0 then feature is completely disabled.
When Temperature( ) falls below OT Dsg Recovery, the [OTD] bit of Flags( ) is reset.
5.5 CHARGING AND CHARGE TERMINATION INDICATION
For proper bq27350 operation, the cell charging voltage must be specified by the user. The default value
for this variable is Charging Voltage = 4200mV.
The bq27350 detects charge termination when (1) during 2 consecutive periods of Current Taper
Window, the AverageCurrent( ) is < Taper Current and (2) during the same periods, the accumulated
change in capacity > 0.25mAh /Taper Current Window and (3) Voltage( ) > Charging Voltage -
Charging Taper Voltage. When this occurs, the [FC] bit of Flags( ) is set and [CHG] bit is cleared. Also, if
the [RMFCC] bit of Pack Configuration is set, then RemainingCapacity( ) is set equal to
FullChargeCapacity( )
5.6 POWER MODES
The bq27350 has four power modes: NORMAL, SLEEP, HIBERNATE, and SHUTDOWN (in descending
order of power consumption). In NORMAL mode, the bq27350 is fully powered and can execute any
allowable task. In SLEEP mode the gas gauge exists in a reduced-power state, periodically taking
measurements and performing calculations. In HIBERNATE mode the gas gauge is in its lowest power
state, only to be woken by communications activity or an increase in the magnitude of battery current.
Finally in SHUTDOWN mode, all bq27350 circuits are turned off and power is removed from the device;
the IC can be restarted by reapplying sufficient voltage to the device.
The relationship between these modes is shown in Figure 5-1. Details are described in the sections that
follow.
22
FUNCTIONAL DESCRIPTION
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NORMAL
Gas gauging and data
updated every1s,
Exit From SHUTDOWN
2s after both charger is attached
AND
Protection FETs close/are closed
Exit From HIBERNATE
Interface activity
ICC = Normal
OR
Current is Detected above IWAKE
OR
Device reset
Entry to SLEEP
PkCfg[SLEEP] =1
AND
| AverageCurrent( ) |≤SleepCurrent
AND
[( If PkCfg[BUSLOW] = 1 for
Exit From SLEEP
|AverageCurrent( )| > SleepCurrent
OR
HIBERNATE
t
BUSLOW ≥ 5 seconds)
SHUTDOWN
Current is Detected above IWAKE
OR
OR
(PkCfg[BUSLOW] = 0 )]
Gas gauging and data
updating is OFF
Interface Activity when
PkCfg[BUSLOW] = 1
Gas gauging and data
updating is OFF
ICC = 0
ICC = Hibernate
Entry to HIBERNATE
SLEEP
PkCfg[HIBERNATE] = 1
AND
Entry to SLEEP still conditions met
Entry to SHUTDOWN
No Charger Present
Gas gauging and data
Updating every 5 seconds
Exit From PRE_SHUTDOWN
Interface activity
OR
Current is Detected above IWAKE
OR
Device reset
ICC = Sleep
Entry to PRE_SHUTDOWN
PkCfg [SHUTDOWN] = 1
PRE_SHUTDOWN
Gas gauging and data
updating is OFF
DSG FET Turned OFF
SE pin = High
ICC = Hibernate
Figure 5-1. Power Mode Diagram
5.6.1 NORMAL MODE
The gas gauge is in NORMAL mode when not in any other power mode. During this mode,
AverageCurrent( ), Voltage( ) and Temperature( ) measurements are taken, and the interface data set is
updated. Decisions to change states are also made. This mode is exited by activating a different power
mode.
5.6.2 SLEEP MODE
SLEEP mode is entered when (1) AverageCurrent( ) is below a programmable level Sleep Current and
(2) if the [BUSLOW] bit of Pack Configuration( ) is set and the data bus (both SCL and SDA low pins) is
low for 5s. [SLEEP] bit of Control Status( ) is set when the bq27350 enters SLEEP mode. Once entry to
SLEEP has been qualified, but prior to entry to sleep mode, the bq27350 performs an ADC autocalibration
to minimize offset. Entry into SLEEP mode can be disabled by setting the [SLEEP] bit of Pack
Configuration( ), where "0" = disabled and "1" = enabled. During SLEEP mode, the bq27350 periodically
wakes to take data measurements and update the data set, after which it then returns directly to SLEEP.
The bq27350 exits SLEEP if any entry condition is broken, a change in protection status occurs, or a
current in excess of IWAKE through RSENSE is detected.
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5.6.3 HIBERNATE MODE
To enter HIBERNATE mode, the [HIBERNATE] bit of PackConfiguration( ) needs to be set when the
device enters SLEEP mode. The HIBERNATE mode is exited if (1) communication is detected, (2) a
device reset occurs, or (3) if current through RSENSE is above IWAKE. If the Pack Configuration
[HIBERNATE] bit is cleared, the bq27350 will not enter HIBERNATE mode. Upon exiting HIBERNATE
mode, the device is returned to NORMAL mode.
5.6.4 SHUTDOWN MODE
SHUTDOWN mode requires the use of an external LDO with an enable feature (active low). To enter
SHUTDOWN, the PackConfiguration( ) [SHUTDOWN] bit needs to be set when the bq27350 enters
HIBERNATE. A charger must not be present and the DSG FET of protector must be turned OFF. If the
[SHUTDOWN] bit of PackConfiguration( ) is set, the bq27350 raise its SE pin high on entry into
HIBERNATE. This action, in conjunction with the deactivation of the DSG FET (low-side protector
implementation), shuts down the LDO and, hence, the bq27350. The LDO recovers when a charger is
applied for more than 2s.
5.7 POWER CONTROL
5.7.1 RESET FUNCTIONS
When the bq27350 detects either a hardware or software reset (MRST pin driven low or the [RESET] bit
of Control( ) initiated, respectively), it determines the type of reset and increments the corresponding
counter. This information is accessible by issuing the command Control( ) function with the RESET_DATA
subcommand.
As shown in Figure 5-2 if a partial reset was detected, a RAM checksum is generated and compared
against the previously stored checksum. If the checksum values do not match, the RAM is reinitialized (a
“Full Reset”). The stored checksum is updated every time RAM is altered.
DEVICE RESET
Generate Active
RAM checksum
value
NO
Stored
checksum
Re-initialize all
RAM
Do the Checksum
Values Match?
YES
NORMAL
OPERATION
Active RAM
changed ?
NO
YES
Store
checksum
Generate New
checksum value
Figure 5-2. Partial Reset Flow Diagram
24
FUNCTIONAL DESCRIPTION
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5.7.2 WAKE-UP COMPARATOR
The wake up comparator is used to indicate a change in cell current while the bq27350 is in either Sleep
or Hibernate modes. PackConfiguration( ) uses bits [RSNS1-RSNS0] to set the sense resistor selection.
PackConfiguration( ) uses the [IWAKE] bit to select one of two possible voltage threshold ranges for the
given sense resistor selection. An internal interrupt is generated when the threshold is breached in either
charge or discharge directions. A setting of 0x00 of RSNS1..0 disables this feature.
Table 5-3. IWAKE Threshold Settings(1)
RSNS1
RSNS0
IWAKE
Vth(SRP-SRN)
Disabled
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
Disabled
+1.25 mV or –1.25 mV
+2.5 mV or –2.5 mV
+2.5 mV or –2.5 mV
+5 mV or –5 mV
+5 mV or –5 mV
+10 mV or –10 mV
(1) The actual resistance value vs. the setting of the sense resistor is not important just the actual voltage
threshold when calculating the configuration.
5.7.3 FLASH UPDATES
Data Flash can only be updated if Voltage( ) ≥ Flash Update OK Voltage. Flash programming current can
cause an increase in LDO dropout. The value of Flash Update OK Voltage should be selected such that
the bq27350 Vcc voltage does not fall below its minimum of 2.4V during Flash write operations. For the
TPS71525 LDO shown in the Reference Schematic, the default value of 2800mV is appropriate.
5.8 AUTOCALIBRATION
The bq27350 provides an autocalibration feature that will measure the voltage offset error across SRP
and SRN from time-to-time as operating conditions change. It subtracts the resulting offset error from
normal sense resistor voltage, Vsr, for maximum measurement accuracy.
The gas gauge performs a single offset calibration when (1) the interface lines stay low for a minimum of
Bus Low Time and (2) Vsr > Deadband.
The gas gauge also performs a single offset when (1) the condition of AverageCurrent( ) ≤ Autocal Min
Current and (2) {voltage change since last offset calibration ≥ Delta Voltage} or {temperature change
since last offset calibration is greater than Delta Temperature for ≥ Autocal Time}.
Capacity and current measurements should continue at the last measured rate during the offset calibration
when these measurements cannot be performed. If the battery voltage drops more than Cal Abort during
the offset calibration, the load current has likely increased considerably; hence, the offset calibration will
be aborted.
6 COMMUNICATIONS
The bq27350 uses I2C communications identical to the bq27200, and interfaces directly with TI-OMAP and
other standard I2C-master devices.
The bq27350 also uses an SDQ interface to communicate with security products, such as the bq26100.
The bq27350 is only acting as a format translator between I2C and SDQ.
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6.1 I2C INTERFACE
The gas gauge supports the standard I2C read, incremental read, one-byte write quick read, and
functions. The 7-bit device address (ADDR) is the most significant 7 bits of the hex address and is fixed as
1010101. The 8-bit device address is therefore 0xAA or 0xAB for write or read, respectively.
Host generated
bq27200 generated
(a) 1-byte write
(b) quick read
(c) 1-byte read
(d) incremental read
(S = Start, Sr = Repeated Start, A = Acknowledge, N = No Acknowledge, and P = Stop).
Figure 6-1. Supported I2C Formats
The “quick read” returns data at the address indicated by the address pointer. The address pointer, a
register internal to the I2C communication engine, increments whenever data is acknowledged by the
bq27350 or the I2C master. “Quick writes” function in the same manner and are a convenient means of
sending multiple bytes to consecutive command locations (such as two-byte commands that require two
bytes of data).
Attempt to write a read-only address (NACK after data sent by master):
Attempt to read an address above 0x7F (NACK command):
Attempt at incremental writes (NACK all extra data bytes sent):
Incremental read at the maximum allowed read address:
The I2C engine releases both SDA and SCL if the I2C bus is held low for t(BUSERR). If the gas gauge was
holding the lines, releasing them frees the master to drive the lines. If an external condition is holding
either of the lines low, the I2C engine enters the low-power sleep mode.
26
COMMUNICATIONS
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6.2 AUTHENTICATION
The bq27350 can act as a SHA-1/HMAC authentication slave, either by using its internal engine or by
using an external bq26100 (contains secure memory). In both implementations, sending a 160-bit SHA-1
challenge message to the bq27350 will cause the IC to return a 160-bit digest, based upon the challenge
message and hidden plain-text authentication keys. When this digest matches an identical one, generated
by a host or dedicated authenication master operating on the same challenge message and using the
same plain text keys, the authentication process is successful.
The
bq27350
contains
a
default
plain-text
authentication
key
of
0x0123456789ABCDEFFEDCBA987654321. If using the bq27350's internal authentication engine, the
default key can be used for development purposes, but should be changed to a secret key and the part
immediately sealed, before putting a pack into operation. If using the a bq26100 for external
authentication, the key must be changed to 16 bytes of "0x00".
6.2.1 KEY PROGRAMMING
When the bq27350's SHA-1/HMAC internal engine is used, authentication keys are stored as plain-text in
memory. A plain-text authentication key can only be written to the bq27350 while the IC is in UNSEALED
mode. Once the IC is UNSEALED, a 0x00 is written to BlockDataControl( ) to enable the authentication
data commands. Next, subclass ID and offset are specified by writing 0x70 and 0x00 to DataFlashClass( )
and DataFlashBlock( ), respectively. The bq27350 is now prepared to receive the 16-byte plain-text key,
which must begin at command location 0x4C. The key is accepted once a successful checksum has been
written to BlockDataChecksum( ), FOR THE ENTIRE 32-BYTE BLOCK (0x40 through 0x5f), NOT JUST
THE 16-BYTE KEY.
When using an external bq26100 authentication IC, authentication keys are stored within the bq26100's
secure memory. The bq26100 uses a split-key system of two 64-bit keys, instead of a single 128-bit key.
Details on programming these keys can be found in the bq26100 data sheet.
6.2.2 EXECUTING AN AUTHENTICATION QUERY
To execute an authentication query in UNSEALED mode, a host must first write 0x01 to the
BlockDataControl( ) command, to enable the authentication data commands. If in SEALED mode, 0x00
must be written to DataFlashBlock( ), instead. Next, the host writes a 20-byte authentication challenge to
the AuthenticateData( ) address locations (0x40 through 0x53). After a valid checksum for the challenge is
written to AuthenticateChecksum( ), the bq27350 uses the challenge to perform it own the SHA-1/HMAC
computation, in conjunction with its programmed keys. The resulting digest is written to
AuthenticateData( ), overwriting the pre-existing challenge. The host may then read this response and
compare it against the result created by its own parallel computation.
7 REFERENCE SCHEMATIC
The reference circuit on the next page shows an I2C communication implementation of the bq27350. D1
and associated resistors provide added protection against ESD appearing on the communication lines.
Capacitors C4/C8 and C15/C16 are also used for ESD protection and are paired together for increased
voltage handling ability and redundancy protection, should one capacitor fail in a shorted state.
Optional circuits for external authentication, using the bq26100 (U1), and external temperature
measurements (R12, R14, and C10) are also shown.
Common-mode and differential filters (R7-19 and C12-14) remove noise at input of the coulomb counter
input. U4, Q4, and associated passives form the Li+ cell protector, while U3, C5, and C9 comprise the
LDO IC and its input/output capacitors. R5 and C7 provide a delayed "power good" signal to the MRST
input.
Q3, R13, and D2 act as an LDO disable circuit (LDO is off when PACK- and SE pin are both "high").
Finally, Q1, Q2, R1, R2 and R4 form a precision voltage divider that reduces cell voltage to levels suitable
for the bq27350.
Submit Documentation Feedback
REFERENCE SCHEMATIC
27
PACKAGE OPTION ADDENDUM
www.ti.com
7-May-2007
PACKAGING INFORMATION
Orderable Device
BQ27350PW
Status (1)
ACTIVE
ACTIVE
ACTIVE
ACTIVE
Package Package
Pins Package Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
Qty
Type
Drawing
TSSOP
PW
20
20
20
20
70 Green (RoHS & CU NIPDAU Level-1-260C-UNLIM
no Sb/Br)
BQ27350PWG4
BQ27350PWR
BQ27350PWRG4
TSSOP
TSSOP
TSSOP
PW
PW
PW
70 Green (RoHS & CU NIPDAU Level-1-260C-UNLIM
no Sb/Br)
2000 Green (RoHS & CU NIPDAU Level-1-260C-UNLIM
no Sb/Br)
2000 Green (RoHS & CU NIPDAU Level-1-260C-UNLIM
no Sb/Br)
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
21-May-2007
TAPE AND REEL INFORMATION
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
21-May-2007
Device
Package Pins
Site
Reel
Reel
A0 (mm)
B0 (mm)
K0 (mm)
P1
W
Pin1
Diameter Width
(mm) (mm) Quadrant
(mm)
(mm)
BQ27350PWR
PW
20
TAI
330
16
6.95
7.1
1.6
8
16
Q1
TAPE AND REEL BOX INFORMATION
Device
Package
Pins
Site
TAI
Length (mm) Width (mm) Height (mm)
BQ27350PWR
PW
20
346.0
346.0
33.0
Pack Materials-Page 2
MECHANICAL DATA
MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999
PW (R-PDSO-G**)
PLASTIC SMALL-OUTLINE PACKAGE
14 PINS SHOWN
0,30
0,19
M
0,10
0,65
14
8
0,15 NOM
4,50
4,30
6,60
6,20
Gage Plane
0,25
1
7
0°–8°
A
0,75
0,50
Seating Plane
0,10
0,15
0,05
1,20 MAX
PINS **
8
14
16
20
24
28
DIM
3,10
2,90
5,10
4,90
5,10
4,90
6,60
6,40
7,90
9,80
9,60
A MAX
A MIN
7,70
4040064/F 01/97
NOTES: A. All linear dimensions are in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash or protrusion not to exceed 0,15.
D. Falls within JEDEC MO-153
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