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bq27425-G2
SLUSB23B – OCTOBER 2012 – REVISED JUNE 2015
bq27425-G2 System-Side Impedance Track™ Fuel Gauge With Integrated Sense Resistor
1 Features
2 Applications
•
•
•
•
•
1
•
•
Single-Series Cell Li-Ion Battery Fuel Gauge
– Resides on System Board
– Supports Embedded or Removable Batteries
– Powered Directly From Battery With Integrated
LDO
– Low-Value Integrated Sense Resistor
(10 mΩ, Typical)
Easy-to-Configure Fuel Gauging Based on
Patented Impedance Track™ Technology
– Reports Remaining Capacity and State of
Charge (SOC) With Smoothing Filter
– Automatically Adjusts for Battery Aging, SelfDischarge, Temperature, and Rate Changes
– Battery State-of-Health (Aging) Estimation
Microcontroller Peripheral Supports:
– 400-kHz I2C Serial Interface
– Configurable SOC Interrupt or
Battery Low Digital Output Warning
– Internal Temperature Sensor or
Host-Reported Temperature
Smart Phones, Feature Phones, and Tablets
Digital Still and Video Cameras
Handheld Terminals
MP3 or Multimedia Players
3 Description
The Texas Instruments bq27425-G2 fuel gauge is an
easy-to-configure microcontroller peripheral that
provides system-side fuel gauging for single-cell LiIon batteries. The device requires minimal user
configuration and system microcontroller firmware
development.
The fuel gauge uses the patented Impedance
Track™ algorithm for fuel gauging, and provides
information such as remaining battery capacity
(mAh), state-of-charge (%), and battery voltage (mV).
Battery fuel gauging with the bq27425-G2 fuel gauge
requires connections only to PACK+ (P+) and PACK–
(P–) for a removable battery pack or embedded
battery circuit. The 15-pin, 2.69 mm × 1.75 mm, 0.5mm pitch chip scale package (DSBGA) is ideal for
space-constrained applications.
Device Information (1)
DEVICE NAME
bq27425-G2
(1)
PACKAGE
DSBGA (15)
BODY SIZE (NOM)
2.69 mm × 1.75 mm
For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
Single Cell Li-Ion
Battery Pack
Voltage
Sense
VBAT
VCC
System
Interface
I2C
bq27425
PROTECTION
IC
To Charger
T
DATA
SRX
GPOUT
BIN
PACK +
REGIN
Integrated
Current
Sense
PACK –
FETs
CHG
DSG
VSS
Copyright © 2016 , Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
bq27425-G2
SLUSB23B – OCTOBER 2012 – REVISED JUNE 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
4
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
4
4
4
5
5
5
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics: Power-On Reset ..............
2.5-V LDO Regulator ................................................
Integrating ADC (Coulomb Counter) Characteristics
Integrated Sense Resistor Characteristics................
ADC (Temperature and Cell Measurement)
Characteristics ...........................................................
7.10 EEPROM Memory Characteristics..........................
7.11 Timing Requirements: I2C-Compatible Interface
Communication ..........................................................
7.12 Typical Characteristics ............................................
8
6
6
8.1
8.2
8.3
8.4
8.5
8.6
9
Overview ................................................................... 9
Functional Block Diagram ....................................... 10
Feature Description................................................. 10
Device Functional Modes........................................ 12
Programming........................................................... 15
Register Maps ......................................................... 27
Application and Implementation ........................ 28
9.1 Application Information............................................ 28
9.2 Typical Application .................................................. 29
10 Power Supply Recommendations ..................... 31
10.1 Power Supply Decoupling ..................................... 31
11 Layout................................................................... 31
11.1 Layout Guidelines ................................................. 31
11.2 Layout Example .................................................... 32
12 Device and Documentation Support ................. 33
12.1
12.2
12.3
12.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
33
33
33
33
7
7
13 Mechanical, Packaging, and Orderable
Information ........................................................... 33
Detailed Description .............................................. 9
13.1 Packaging ............................................................. 33
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (February 2013) to Revision B
•
Page
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section .................................................................................................. 1
Changes from Original (October 2012) to Revision A
Page
•
AVAILABLE OPTIONS table: Replaced "Contact Factory" with orderable quantities for bq27425YZFR-G2A and
bq27425YZFT-G2B ................................................................................................................................................................ 3
•
AVAILABLE OPTIONS table: Added CHEM_ID column ........................................................................................................ 3
•
Recommended Operating Conditions: Added SHUTDOWN mode specifications ................................................................. 4
•
OPERATING MODES: Added text "In SHUTDOWN mode, ...." .......................................................................................... 12
•
Changed Figure 6, POWER MODE DIAGRAM. Added OFF and SHUTDOWN modes to diagram. .................................. 13
•
Changed the CHEM_ID subcommand section: (CHEM_ID: 0x0008) .................................................................................. 17
•
Data Block Summary: Updated Default Value column to show -G2B version differences in (Green Text) ......................... 24
•
Data Block Summary: Changed Units value from Reserve Cap-mAh and Design Capacity from "mA" to "mAh" .............. 24
•
Data Block Summary: Updated several Class/Subclass descriptions to correct [RAM] vs [NVM] indication. ..................... 24
2
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5 Device Comparison Table
PART NUMBER
BATTERY TYPE
bq27425YZFR-G2A
LiCoO2
(4.2 V maximum charge)
0x128
LiMn2O4
(4.3 to 4.35 V maximum charge)
0x312
bq27425YZFT-G2A
bq27425YZFR-G2B
bq27425YZFT-G2B
(1)
(2)
CHEM_ID
(1)
FIRMWARE
VERSION (2)
COMMUNICATION
FORMAT
2.05
(0x0205)
I2C
Refer to the CHEM_ID subcommand to confirm the battery chemistry type.
Refer to the FW_VERSION subcommand to confirm the firmware version.
6 Pin Configuration and Functions
YZP Package
15-Pin DSBGA
(TOP VIEW)
B3
C3
D3
E3
E3
D3
C3
B3
A3
A2
B2
C2
D2
E2
E2
D2
C2
B2
A2
A1
B1
C1
D1
E1
E1
D1
C1
B1
A1
A3
E
xx
xx
Pin A1
Index Area
PIN
NAME
NO.
(BOTTOM VIEW)
D
Pin Functions
I/O (1)
DESCRIPTION
BAT
E2
I
Cell-voltage measurement input. ADC input. Recommend 4.8 V maximum for conversion accuracy.
BIN
C3
I
Battery-insertion detection input. A logic high-to-low transition is detected as a battery insertion event.
Recommend using a pullup resistor >1 MΩ (1.8 MΩ, typical) to VCC for reduced power consumption. An internal
pullup resistor option is also available using the Operation Configuration [BI_PU_EN] register bit.
CE
D2
I
Chip Enable. Internal LDO is disconnected from REGIN when driven low.
GPOUT
A2
O
General Purpose open-drain output. May be configured as a Battery Low indicator or perform SOC interrupt
(SOC_INT) function.
A1, B2
NA
No internal connection. May be left floating.
C2, D3, E3
IO
Reserved for factory use. Must be left floating for proper operation.
REGIN
E1
P
Regulator input. Decouple with 0.1-μF ceramic capacitor to VSS.
SCL
A3
I
Slave I2C serial communications clock input line for communication with system (Master). Use with 10-kΩ pullup
resistor (typical).
SDA
B3
I/O
Slave I2C serial communications data line for communication with system (Master). Open-drain IO. Use with 10-kΩ
pullup resistor (typical).
SRX
B1
IA
Integrated Sense Resistor and Coulomb Counter input typically connected to battery PACK– terminal. For best
performance decouple with 0.1-μF ceramic capacitor to VSS.
VCC
D1
P
Regulator output and bq27425 processor power. Decouple with 1-μF ceramic capacitor to VSS.
VSS
C1
P, IA
NC
(1)
Device ground and Integrated Sense Resistor termination.
IO = Digital input/output, IA = Analog input, P = Power connection
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7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
VREGIN
Regulator input
–0.3
6
V
VCC
Supply voltage
–0.3
2.75
V
VIOD
Open-drain I/O pins (SDA, SCL, GPOUT)
–0.3
6
V
VBAT
BAT input pin
–0.3
6
V
VI
Input voltage to all other pins (SRX, BIN)
–0.3
VCC + 0.3
V
TA
Operating free-air temperature
–40
85
°C
Tstg
Storage temperature
–65
150
°C
(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.
7.2 ESD Ratings
VALUE
Electrostatic
discharge
V(ESD)
(1)
(2)
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±500
Charged device model (CDM), per JEDEC specification JESD22-C101 (2)
±250
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted)
MIN
No operating restrictions
VREGIN
Supply voltage
CREGIN
External input capacitor for internal
LDO between REGIN and VSS
CLDO25
External output capacitor for internal
LDO between VCC and VSS
ICC
NORMAL operating-mode current (1)
Fuel gauge in NORMAL mode.
ILOAD > Sleep Current
ISLP
SLEEP mode operating mode
current (1)
Fuel gauge in SLEEP mode.
ILOAD < Sleep Current
IHIB
HIBERNATE operating-mode
current (1)
ISHD
No NVM writes
Nominal capacitor values specified.
Recommend a 5% ceramic X5R
type capacitor located close to the
device.
NOM
MAX
2.8
4.5
2.45
2.8
UNIT
V
0.1
μF
1
μF
118
μA
23
μA
Fuel gauge in HIBERNATE mode.
ILOAD < Hibernate Current
8
μA
SHUTDOWN mode current (1)
Fuel gauge in SHUTDOWN mode.
CE Pin < VIL(CE) maximum
1
μA
VOL(OD)
Output low voltage on open-drain
pins (SCL, SDA, GPOUT)
IOL = 1 mA
VOH(OD)
Output high voltage on open-drain
pins (SDA, SCL, GPOUT)
External pullup resistor connected to
VCC
VIL
Input low voltage, all digital pins
VIH
VCC – 0.5
Input high voltage (BIN)
1.2
VA3
Input voltage (SRX)
Ilkg
Input leakage current (I/O pins)
tPUCD
Power-up communication delay
(1) (2)
V
V
0.6
1.2
Input voltage (BAT)
4
0.4
Input high voltage (SDA, SCL)
VA2
(1)
(2)
0.47
V
V
VSS –
0.125
5
V
VSS – 0.04
0.04
V
0.3
250
μA
ms
Specified by design. Not production tested.
Limited by ISRX maximum recommend input current with some margin for the Integrated Sense Resistor tolerance.
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7.4 Thermal Information
over operating free-air temperature range (unless otherwise noted)
bq27425-G2
THERMAL METRIC
(1)
YZF [DSBGA]
UNIT
15 PINS
RθJA
Junction-to-ambient thermal resistance
70
°C/W
RθJCtop
Junction-to-case (top) thermal resistance
17
°C/W
RθJB
Junction-to-board thermal resistance
20
°C/W
ψJT
Junction-to-top characterization parameter
1
°C/W
ψJB
Junction-to-board characterization parameter
18
°C/W
RθJCbot
Junction-to-case (bottom) thermal resistance
n/a
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953
7.5 Electrical Characteristics: Power-On Reset
TA = –40°C to 85°C, typical values at TA = 25°C and VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
VIT+
Positive-going voltage on VCC
(Regulator output)
VHYS
Power-on reset hysteresis
TEST CONDITIONS
MIN
TYP
MAX
UNIT
1.98
2.20
2.31
V
43
115
185
mV
UNIT
7.6 2.5-V LDO Regulator
TA = –40°C to 85°C, CLDO25 = 1 μF, VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
VREG25
Regulator output voltage
VIH(CE)
CE High-level input voltage
VIL(CE)
CE Low-level input voltage
TEST CONDITION
MIN
NOM
MAX
2.7 V ≤ VREGIN ≤ 4.5 V, IOUT ≤ 5 mA
2.4
2.5
2.6
2.45 V ≤ VREGIN < 2.7 V (low
battery),
IOUT ≤ 3 mA
2.4
VREGIN = 2.7 to 4.5 V
V
2.65
V
0.8
7.7 Integrating ADC (Coulomb Counter) Characteristics
TA = –40°C to 85°C; typical values at TA = 25°C and VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
(1) (2)
VSR
Input voltage
tSR_CONV
Conversion time
TEST CONDITIONS
VSR = V(SRX) – VSS
Input offset
INL
Integral nonlinearity error
ZIN(SR)
Effective input resistance (1)
Ilkg(SR)
Input leakage current (1)
(1)
(2)
TYP
–0.04
Single conversion
Resolution
VOS(SR)
MIN
MAX
UNIT
0.04
V
1
14
s
15
bits
10
±0.007
μV
±0.034
% FSR
2.5
TA = 25°C
MΩ
0.3
μA
Specified by design. Not tested in production.
Limited by ISRX maximum recommend input current with some margin for the Integrated Sense Resistor tolerance.
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7.8 Integrated Sense Resistor Characteristics
TA = –40°C to 85°C; typical values at TA = 25°C and VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
SRXRES
Resistance of Integrated Sense
Resistor from SRX to VSS (1) (2)
TEST CONDITIONS
MIN
TA = 25°C
TYP
10
Long term RMS, average device
utilization.
Recommended Sense Resistor input Peak RMS current, 10% device
current (1) (3)
utilization. (3)
ISRX
Peak pulsed current, 250 ms
maximum, 1% device utilization. (3)
(1)
(2)
(3)
MAX
UNIT
mΩ
2000
mA
2500
mA
3500
mA
MAX
UNIT
Specified by design. Not tested in production.
Firmware compensation applied for temperature coefficient of resistor.
Device utilization is the long term usage profile at a specific condition compared to the average condition.
7.9 ADC (Temperature and Cell Measurement) Characteristics
TA = –40°C to 85°C; typical values at TA = 25°C and VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
VIN(ADC)
Input voltage
GTEMP
Temperature sensor voltage gain
tADC_CONV
Conversion time
TYP
1
–2
Resolution
14
VOS(ADC)
Input offset
ZADC
Effective input resistance (BAT) (1)
Ilkg(ADC)
Input leakage current (1)
(1)
MIN
0.05
125
ms
15
bits
1
Not measuring cell voltage
mV
8
Measuring cell voltage
V
mV/°C
MΩ
100
TA = 25°C
kΩ
0.3
μA
Specified by design. Not tested in production.
7.10 EEPROM Memory Characteristics
TA = –40°C to 85°C; typical values at TA = 25°C and VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
Array Size
256
Data retention (1)
Programming write cycles (1)
(1)
6
TYP
MAX
UNIT
bytes
10
years
100K
cycles
Specified by design. Not production tested
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7.11 Timing Requirements: I2C-Compatible Interface Communication
TA = –40°C to 85°C; typical values at TA = 25°C and VREGIN = 3.6 V (unless otherwise noted)
MIN
NOM
MAX
UNIT
tr
SCL or SDA rise time
300
ns
tf
SCL or SDA fall time
300
ns
tw(H)
SCL pulse duration (high)
600
ns
tw(L)
SCL pulse duration (low)
1.3
μs
tsu(STA)
Setup for repeated start
600
ns
td(STA)
Start to first falling edge of SCL
600
ns
tsu(DAT)
Data setup time
100
ns
th(DAT)
Data hold time
tsu(STOP)
Setup time for stop
t(BUF)
Bus free time between stop and start
fSCL
(1)
Clock frequency
0
ns
600
ns
66
μs
(1)
400
kHz
If the clock frequency (fSCL) is > 100 kHz, use 1-byte write commands for proper operation. All other transactions types are supported at
400 kHz. (See I2C Interface and I2C Command Waiting Time)
tSU(STA)
tw(H)
tf
tw(L)
tr
t(BUF)
SCL
SDA
td(STA)
tsu(STOP)
tf
tr
th(DAT)
tsu(DAT)
REPEATED
START
STOP
START
Figure 1. I2C-Compatible Interface Timing Diagrams
7.12 Typical Characteristics
8.8
VREGIN = 2.7 V
VREGIN = 4.5 V
2.6
fOSC - High Frequency Oscillator (MHz)
VREG25 - Regulator Output Voltage (V)
2.65
2.55
2.5
2.45
2.4
2.35
8.7
8.6
8.5
8.4
8.3
8.2
8.1
8
-40
Temperature (qC)
D001
Figure 2. Regulator Output Voltage vs Temperature
-20
0
20
40
Temperature (qC)
60
80
100
D002
Figure 3. High-Frequency Oscillator Frequency vs
Temperature
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34
5
33.5
4
Reported Temperature Error (qC)
fLOSC - Low Frequency Oscillator (kHz)
Typical Characteristics (continued)
33
32.5
32
31.5
31
30.5
30
-40
-20
0
20
40
Temperature (qC)
60
80
100
2
1
0
-1
-2
-3
-4
-5
-30
-20
D003
Figure 4. Low-Frequency Oscillator Frequency vs
Temperature
8
3
-10
0
10
20
30
Temperature (qC)
40
50
60
D004
Figure 5. Reported Internal Temperature Measurement vs
Temperature
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8 Detailed Description
8.1 Overview
The bq27425 device accurately predicts the battery capacity and other operational characteristics of a single Libased rechargeable cell. The device can be interrogated by a system processor to provide cell information, such
as state-of-charge (SOC).
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 system to 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 gas gauging prediction is Texas Instruments proprietary Impedance Track™
algorithm. This algorithm uses cell measurements, characteristics, and properties to create state-of-charge
predictions that can achieve high accuracy across a wide variety of operating conditions and over the lifetime of
the battery.
The bq27425 device measures charging and discharging of the battery by monitoring the voltage across a smallvalue integrated sense resistor (10 mΩ, typical) located between the system VSS and the battery’s PACK–
terminal. When a cell is attached to the fuel gauge, cell impedance is computed, based on cell current, cell opencircuit voltage (OCV), and cell voltage under loading conditions.
The device uses an integrated temperature sensor for estimating cell temperature. Alternatively, the host
processor can provide temperature data for the fuel gauge.
To minimize power consumption, the fuel gauge has several power modes: INITIALIZATION, NORMAL, SLEEP,
and HIBERNATE. 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. See Operating Modes.
NOTE
The following formatting conventions are used in this document:
Commands: italics with parentheses( ) and no breaking spaces, for example, Control( )
Data Flash: italics, bold, and breaking spaces, for example, Design Capacity
Register bits and flags: italics with brackets [ ], for example, [TDA]
Data Flash bits: italics, bold, and brackets [ ], for example, [LED1]
Modes and states: ALL CAPITALS, for example, UNSEALED mode
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8.2 Functional Block Diagram
CE
REGIN
Divider
2.5-V LDO
+
Power Mgt
Oscillator
System Clock
Temp
Sensor
VCC
SCL
BAT
ADC
Communications
HDQ/I2C
SDA
Coulomb
Counter
Impedance
Track
Engine
Peripherals
Program Memory
SRX
BIN
Data Memory
VSS
Copyright © 2016, Texas Instruments Incorporated
8.3 Feature Description
8.3.1 Fuel Gauging
The bq27425 is an easy-to-configure fuel gauge that measures the cell voltage, temperature, and current to
determine battery state-of-charge (SOC). The fuel gauge monitors the charging and discharging of the battery by
sensing the voltage across an integrated small-value resistor (10 mΩ, typical) between the SRX and VSS pins
and in series with the cell. By integrating charge passing through the battery, the battery 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 SOC and chemical capacity (Qmax). The
initial Qmax values are taken from the Design Capacity. The fuel gauge acquires and updates the batteryimpedance 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.
8.3.2 Fuel Gauging Configurations
The fuel gauge features easy-to-configure data NVM to speed-up fuel gauging design. Users are required to
configure Design Capacity, Termination Voltage, and Operation Configuration (see Operation Configuration
(Op Config) Register for details) to achieve optimal performance. The Impedance Track™ algorithm uses these
parameters along with built-in parameters to achieve accurate battery fuel gauging.
Several built-in parameters are used in the Impedance Track™ algorithm to identify different modes of battery:
• Charging: Chg Current Threshold (default = DesignCapacity / 13.3)
• Discharging: Dsg Current Threshold (default = DesignCapacity / 16.7)
• Relax: Quit Current Threshold (default = DesignCapacity / 25.0)
To achieve accurate fuel gauging, the fuel gauge uses a Constant Power Model for fuel gauging. This model
uses the average discharge power from the beginning of the discharge cycle until present time to compute loadcompensated capacity such as RemainingCapacity( ) and FullChargeCapacity( ) in the Impedance Track™
algorithm.
10
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Feature Description (continued)
8.3.2.1 SOC Smoothing Feature
Rapid changes in operating conditions, such as temperature or discharge current, can lead to sudden changes in
the algorithm's immediate calculation of RemainingCapacity( ), FullChargeCapacity( ), and StateOfCharge( ).
SOC Smoothing provides filtered data to the host resulting in more gradual changes to SOC-related data when
conditions vary and can provide a better end-user experience. The feature is enabled through Op Config
[SMOOTHEN].
8.3.3 GPOUT Pin
The GPOUT pin is a multiplexed pin and the polarity of the pin output can be selected through the [GPIO_POL]
bit of the Operation Configuration. The function is defined by Op Config [BATLOWEN]. If set, the Battery Low
Indicator (BAT_LOW) function for GPOUT pin is selected. If cleared, the SOC interrupt (SOC_INT) function is
selected for GPOUT.
When the BAT_LOW function is activated, the signaling on the multiplexed pin follows the status of the [SOC1]
bit in the Flags( ) register. The fuel gauge has two flags accessed by the Flags( ) function that warn when the
battery SOC has fallen to critical levels. When StateOfCharge( ) falls below the first capacity threshold, 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. The GPOUT pin automatically reflects the status of the
[SOC1] flag when Op Config [BATLOWEN] = 0.
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. Similarly, when StateOfCharge( ) rises above
SOCF Clear Threshold and the [SOCF] flag has already been set, the [SOCF] flag is cleared.
When the SOC_INT function is activated, the GPOUT pin generates 1-ms pulse width under various conditions
as described in Table 1.
Table 1. SOC_INT Function Definition
ENABLE
CONDITION
PULSE
WIDTH
DESCRIPTION
Change in
SOC
(SOCI Delta) ≠ 0
1 ms
During charge, when the SOC is greater than (>) the points, 100% – n × (SOCI
Delta) and 100%;
During discharge, when the SOC reaches (≤) the points 100% – n × (SOCI Delta)
and 0%;
where n is an integer starting from 0 to the number generating SOC no less than
0%
Examples:
For SOCI Delta = 1% (default), the SOC_INT intervals are 0%, 1%, 2%, …, 99%,
and 100%.
For SOCI Delta = 10%, the SOC_INT intervals are 0%, 10%, 20%, …, 90%, and
100%.
State Change
(SOCI Delta) ≠ 0
1 ms
Upon detection of entry to a charge or a discharge state. Relaxation is not
included.
Battery
Removal
[BIE] bit is set in Op
Config
1 ms
When battery removal is detected by the BIN pin.
8.3.4 Battery Detection (BIN)
The function of Op Config [BIE] bit is described in the Table 2. When battery insertion is detected and
INITIALIZATION mode is completed, the fuel gauge transitions to NORMAL mode to start Impedance Track™
fuel gauging. When battery insertion is not detected, the fuel gauge remains in INITIALIZATION mode.
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Table 2. Battery Detection
Op Config [BIE]
BATTERY INSERTION REQUIREMENT
BATTERY REMOVAL REQUIREMENT
1
(1) Host drives BIN pin from logic high to low to signal
battery insertion.
or
(2) A weak pullup resistor can be used (between BIN and
VCC pins). When battery pack with a pulldown resistor is
connected, it can generate a logic low to signal battery
insertion.
(1) Host drives BIN pin from logic low to high to signal
battery removal.
or
(2) When battery pack with a pulldown resistor is removed,
the weak pullup resistor can generate a logic high to signal
battery removal.
0
Host sends BAT_INSERT subcommand to signal battery
insertion.
Host sends BAT_REMOVE subcommand to signal battery
removal.
8.4 Device Functional Modes
8.4.1 Operating Modes
The fuel gauge has different operating modes: POR, INITIALIZATION, NORMAL, CONFIG UPDATE, SLEEP,
and HIBERNATE. Upon power 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 and NVM 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 or certain IO activity.
In SHUTDOWN mode, the LDO is disabled so internal power and all volatile data is lost. Because no gauging
occurs in SHUTDOWN mode, additional gauging error can be introduced if the system has significant battery
charge or discharge activity before re-INITIALIZATION.
12
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Device Functional Modes (continued)
OFF
REGIN pin = OFF,
VCC pin = OFF
Entry to SHUTDOWN
REGIN pin > VREGIN min
SHUTDOWN
REGIN pin > VREGIN min,
VCC pin = OFF
CE pin set LOW
(from any mode)
Exit From SHUTDOWN
CE pin raised HI
Power On Reset [POR]
Copy configuration ROM
defaults to RAM data.
Set Flags[ITPOR] = 1.
via RESET
subcommand
(from any mode)
Exit from CONFIG UPDATE
Flags [CFGUPMODE] = 0 AND [ITPOR] = 0
(via SOFT_RESET or a 240 second timeout)
CONFIG UPDATE
INITIALIZATION
Flags
[BAT _ DET ] = 0
I CC = Normal
Entry to NORMAL
Exit From HIBERNATE
Communication Activity
OR
bq27425 clears CONTROL_STATUS
[HIBERNATE ] = 0
Recommend Host also set Control
Status [HIBERNATE ] = 0
Entry to CONFIG UPDATE
Flags [CFGUPMODE] = 1
(via SET_CFGUPDATE
subcommand)
Exit From NORMAL
Flags [ BAT _ DET ] = 1
Exit From HIBERNATE
V CELL < POR threshold
Host can change RAM and
NVM based data blocks.
(No gauging in this mode.)
Initialize algorithm and data..
Check for battery insertion.
.
(No gauging in this mode.)
Flags [BAT _ DET ] = 0
NORMAL
Fuel gauging and data
updated every 1s
ICC = Normal
Exit From SLEEP
Op Config [SLEEP ] = 0
OR
| AverageCurrent ( ) | > Sleep Current
OR
Current is Detected above I
HIBERNATE
Wakeup From HIBERNATE
Communication to gauge
AND
Comm address is NOT for bq27425
Disable all subcircuits
except GPIO .
Entry to SLEEP
Op Config [SLEEP ] = 1
AND
| AverageCurrent ( ) | < Sleep Current
WAKE
SLEEP
Fuel gauging and data
updated every 20 seconds
I CC = Hibernate
Exit From
WAIT _HIBERNATE
I CC = Sleep
Host must set CONTROL_STATUS
[HIBERNATE ] = 0
AND
VCELL > Hibernate Voltage
Exit From WAIT _ HIBERNATE
Cell relaxed
AND
| AverageCurrent () | < Hibernate
Current
OR
Cell relaxed
AND
V CELL < Hibernate Voltage
WAIT _HIBERNATE
Entry to System Shutdown
Fuel gauging and data
updated every 20 seconds
Host has set CONTROL_STATUS
[HIBERNATE ] = 1
OR
VCELL < Hibernate Voltage
I CC = Sleep
System Shutdown
Figure 6. Power Mode Diagram
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Device Functional Modes (continued)
8.4.1.1 POR and INITIALIZATION Modes
Upon Power On Reset (POR), the fuel gauge copies ROM-based configuration defaults to RAM and begins
INITIALIZATION mode where essential data is initialized and will remain in INITIALIZATION mode as haltedCPU state when an adapter, or other power source is present to power the bq27425 (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 CONTROL_STATUS [QMAX_UP] and
[RES_UP] bits are cleared to allow fast learning of Qmax and impedance.
Some commands, issued by a system processor, can be processed while the bq27425 is halted in this mode.
The gauge will wake up to process the command, and then return to the halted state awaiting battery insertion.
The current consumption of INITIALIZATION mode is similar to NORMAL mode.
8.4.1.2 CONFIG UPDATE Mode
If the application requires different configuration data for the bq27425. The host can update both NVM and RAM
based parameters using the Control( ) SET_CFGUPDATE subcommand to enter CONFIG UPDATE mode as
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_RESETsubcommand to exit CONFIG UPDATE mode and clear both Flags( ) [ITPOR] and
[CFGUPMODE] bits. After a time-out of approximately 240 seconds (4 minutes), the gauge will automatically exit
CONFIG UPDATE mode if it has not received a SOFT_RESET subcommand from the host.
8.4.1.3 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.
8.4.1.4 SLEEP Mode
SLEEP mode is entered automatically if the feature is enabled (Operation Configuration [SLEEP]) = 1) and
AverageCurrent( ) is less than the programmable level Sleep Current (default = 10 mA). Once entry into SLEEP
mode has been qualified, but before entering it, the bq27425 performs an ADC autocalibration to minimize offset.
During SLEEP mode, the bq27425 periodically takes data measurements and updates its data set. However, a
majority of its time is spent in an idle condition.
The bq27425 exits SLEEP if any entry condition is broken, specifically when: AverageCurrent( ) rises above
Sleep Current (default = 10 mA).
8.4.1.5 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 a system equipment is set to its own
HIBERNATE, SHUTDOWN, or OFF modes.
Before the fuel gauge can enter HIBERNATE mode, the system must set the [HIBERNATE] bit of the
CONTROL_STATUS register. The 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 gauge can
also enter HIBERNATE mode if the cell voltage falls below Hibernate Voltage. The gauge will remain in
HIBERNATE mode until the system issues a direct I2C command to the gauge. I2C communication that is not
directed to the gauge will only briefly wake it up and the gauge immediately returns to HIBERNATE mode.
It is the system’s responsibility to wake the bq27425 after it has gone into HIBERNATE mode and to prevent a
charger from charging the battery before the [OCVTAKEN] bit is set which signals an OCV reading is taken. After
waking, the gauge can proceed with the initialization of the battery information.
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8.5 Programming
8.5.1 Standard Data Commands
The fuel gauge uses a series of 2-byte standard commands to enable system reading and writing of battery
information. Each standard command has an associated command-code pair, as indicated in Table 3. Because
each command consists of two bytes of data, 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 I2C Interface. Standard commands are accessible in
NORMAL operation. Read/Write permissions depend on the active access mode, SEALED or UNSEALED (for
details on the SEALED and UNSEALED states, see Access Modes.)
NOTE
Data values read by the host may be invalid during initialization for a period of up to 3
seconds.
Table 3. Standard Commands
NAME
COMMAND
CODE
UNIT
SEALED ACCESS
Control( )
CNTL
0x00 and 0x01
NA
RW
Temperature( )
TEMP
0x02 and 0x03
0.1°K
RW
Voltage( )
VOLT
0x04 and 0x05
mV
R
FLAGS
0x06 and 0x07
NA
R
NominalAvailableCapacity( )
0x08 and 0x09
mAh
R
FullAvailableCapacity( )
0x0A and 0x0B
mAh
R
Flags( )
RemainingCapacity( )
RM
0x0C and 0x0D
mAh
R
FullChargeCapacity( )
FCC
0x0E and 0x0F
mAh
R
AverageCurrent( )
0x10 and 0x11
mA
R
Debug1( )
0x16 and 0x17
num
R
AveragePower( )
0x18 and 0x19
mW
R
0x1C and 0x1D
%
R
0x1E and 0x1F
0.1°K
R
0x20 and 0x21
%
R
Debug2( )
0x2C and 0x2D
num
R
Debug3( )
0x32 and 0x33
num
R
0x3A and 0x3B
NA
R
0x3C and 0x3D
mAh
R
StateOfCharge( )
SOC
IntTemperature( )
StateOfHealth( )
OperationConfiguration( )
DesignCapacity( )
SOH
OpConfig
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8.5.1.1 Control(): 0x00 and 0x01
Issuing a Control( ) command requires a subsequent 2-byte subcommand. These additional bytes specify the
particular control function desired. The Control( ) command allows the system to control specific features of the
bq27425 during normal operation and additional features when the bq27425 is in different access modes, as
described in Table 4.
Table 4. Control( ) Subcommands
CNTL FUNCTION
CNTL DATA
SEALED ACCESS
CONTROL_STATUS
0x0000
Yes
Reports the status of device.
DEVICE_TYPE
0x0001
Yes
Reports the device type (0x0425).
FW_VERSION
0x0002
Yes
Reports the firmware version of the device.
PREV_MACWRITE
0x0007
Yes
Returns previous MAC command code.
CHEM_ID
0x0008
Yes
Reports the chemical identifier of the Impedance Track™ configuration
BAT_INSERT
0x000c
Yes
Forces the Flags() [BAT_DET] bit set when the Op Config [BIE] bit is 0.
BAT_REMOVE
0x000d
Yes
Forces the Flags() [BAT_DET] bit clear when the Op Config [BIE] bit is
0.
SET_HIBERNATE
0x0011
Yes
Forces CONTROL_STATUS [HIBERNATE] to 1.
CLEAR_HIBERNATE
0x0012
Yes
Forces CONTROL_STATUS [HIBERNATE] to 0.
SET_CFGUPDATE
0x0013
No
Forces Flags( ) [CFGUPMODE] to 1 and gauge enters CONFIG
UPDATE mode.
SEALED
0x0020
No
Places the bq27425 in SEALED access mode.
RESET
0x0041
No
Performs a full device reset.
SOFT_RESET
0x0042
No
Gauge exits CONFIG UPDATE mode.
16
DESCRIPTION
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8.5.1.1.1 CONTROL_STATUS: 0x0000
Instructs the fuel gauge to return status information to Control() addresses 0x00 and 0x01. The status word
includes the following information.
Table 5. CONTROL_STATUS Bit Definitions
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
High Byte
RSVD
RSVD
SS
CALMODE
CCA
BCA
QMAX_UP
RES_UP
Low Byte
RSVD
HIBERNATE
RSVD
SLEEP
LDMD
RUP_DIS
VOK
RSVD
High Byte
RSVD = Reserved.
SS = Status bit indicating the bq27425 is in the SEALED state. Active when set.
CALMODE = Status bit indicating the bq27425 is in calibration mode. Active when set.
CCA = Status bit indicating the Coulomb Counter Auto-Calibration routine is active. The CCA routine will take place approximately
3 minutes and 45 seconds after the initialization as well as periodically as conditions permit. Active when set.
BCA = Status bit indicating the board calibration routine is active. Active when set.
QMAX_UP = Status bit indicating Qmax has Updated. True when set. This bit is cleared after power-on reset or when Flags()
[BAT_DET] bit is set. When this bit is cleared, it enables fast learning of battery Qmax.
RES_UP = Status bit indicating that resistance has been updated. True when set. This bit is cleared after power on reset or when
Flags() [BAT_DET] bit is set. Also this bit can only be set after Qmax is updated. ([QMAX_UP] is set). When this bit is
cleared, it enables fast learning of battery impedance.
Low Byte
HIBERNATE = Status bit indicating a request for entry into HIBERNATE from SLEEP mode has been issued. True when set. Default is 0.
SLEEP = Status bit indicating the bq27425 is in SLEEP mode. True when set.
LDMD = Status bit indicating the algorithm is using constant-power model. True when set. Default is 1.
Note: The bq27425 always uses constant-power model.
RUP_DIS = Status bit indicating the bq27425 Ra table updates are disabled. Updates are disabled when set.
VOK = Status bit indicating cell voltages are OK for Qmax updates. True when set.
8.5.1.1.2 DEVICE_TYPE: 0x0001
Instructs the fuel gauge to return the device type to addresses 0x00 and 0x01. The value returned is 0x0425.
8.5.1.1.3 FW_VERSION: 0x0002
Instructs the fuel gauge to return the firmware version to addresses 0x00 and 0x01. See for the expected data
value.
8.5.1.1.4 PREV_MACWRITE: 0x0007
Instructs the fuel gauge to return the previous command written to addresses 0x00 and 0x01. The value returned
is limited to less than 0x0015.
8.5.1.1.5 CHEM_ID: 0x0008
Instructs the fuel gauge to return the chemical identifier for the Impedance Track™ configuration to addresses
0x00 and 0x01. See for the expected data value.
8.5.1.1.6 BAT_INSERT: 0X000C
This subcommand forces the Flags() [BAT_DET] bit to set when the battery insertion detection is disabled
through Op Config [BIE] = 0. In this case, the gauge does not detect battery insertion from the BIN pin logic
state, but relies on the BAT_INSERT host subcommand to indicate battery presence in the system. This
subcommand also starts Impedance Track™ gauging.
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8.5.1.1.7 BAT_REMOVE: 0X000D
This subcommand forces the Flags() [BAT_DET] bit to clear when the battery insertion detection is disabled
through Op Config [BIE] = 0. In this case, the gauge does not detect battery removal from the BIN pin logic
state, but relies on the BAT_REMOVE host subcommand to indicate battery removal from the system.
8.5.1.1.8 SET_HIBERNATE: 0x0011
Instructs the fuel gauge to force the CONTROL_STATUS [HIBERNATE] bit to 1. If the necessary conditions are
met, this enables the gauge to enter the HIBERNATE power mode after the transition to SLEEP power state is
detected. The [HIBERNATE] bit is automatically cleared upon exiting from HIBERNATE mode.
8.5.1.1.9 CLEAR_HIBERNATE: 0x0012
Instructs the fuel gauge to force the CONTROL_STATUS [HIBERNATE] bit to 0. This prevents the gauge from
entering the HIBERNATE power mode after the transition to SLEEP power state is detected. It can also be used
to force the gauge out of HIBERNATE mode.
8.5.1.1.10 SET_CFGUPDATE: 0x0013
Instructs the fuel gauge to set the Flags() [CFGUPMODE] bit to 1 and enter CONFIG UPDATE mode. This
command is only available when the fuel gauge is UNSEALED.
NOTE
A SOFT_RESET subcommand is typically used to exit CONFIG UPDATE mode to resume
normal gauging.
8.5.1.1.11 SEALED: 0x0020
Instructs the fuel gauge to transition from UNSEALED state to SEALED state. The fuel gauge should always be
set to SEALED state for use in end equipment.
8.5.1.1.12 RESET: 0x0041
This command instructs the fuel gauge to perform a full device reset and reinitialize RAM data to the default
values from ROM. The gauge sets the Flags() [ITPOR] bit and enters the INITIALIZE mode. See Figure 6. This
command is only available when the fuel gauge is UNSEALED.
8.5.1.1.13 SOFT_RESET: 0x0042
This command instructs the fuel gauge to perform a partial (soft) reset from any mode with an OCV
measurement. The Flags() [ITPOR, CFGUPMODE] bits are cleared and a resimulation occurs to update
StateOfCharge( ). See Figure 6. This command is only available when the fuel gauge is UNSEALED.
18
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8.5.1.2 Temperature( ): 0x02 and 0x03
This read-/write-word function returns an unsigned integer value of the temperature in units of 0.1°K measured
by the fuel gauge. If Op Config [TEMPS] bit = 0 (default), a read command will return the internal temperature
sensor value and write command will be ignored. If Op Config [TEMPS] bit = 1, a write command sets the
temperature to be used for gauging calculations while a read command returns to temperature previously written.
8.5.1.3 Voltage( ): 0x04 and 0x05
This read-only function returns an unsigned integer value of the measured cell-pack voltage in mV with a range
of 0 to 6000 mV.
8.5.1.4 Flags( ): 0x06 and 0x07
This read-word function returns the contents of the gas gauge status register, depicting the current operating
status.
Table 6. Flags Bit Definitions
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
High Byte
OT
UT
RSVD
RSVD
RSVD
EEFAIL
FC
CHG
Low Byte
OCVTAKEN
RSVD
ITPOR
CFGUPMODE
BAT_DET
SOC1
SOCF
DSG
High Byte
OT = Over-Temperature condition is detected. [OT] is set when Temperature( ) ≥ Over Temp (default = 55°C). [OT] is cleared
when Temperature( ) < Over Temp – Temp Hys.
UT = Under-Temperature condition is detected. [UT] is set when Temperature( ) ≤ Under Temp (default = 0°C). [UT] is cleared
when Temperature( ) > Under Temp + Temp Hys.
RSVD = Bits 5:3 are reserved.
EEFAIL = EEPROM Write Fail. True when set. This bit is set after a single EEPROM write failure. All subsequent EEPROM writes
are disabled. A power-on reset or RESET subcommand is required to clear the bit to re-enable EEPROM writes.
FC = Full-charge is detected. If the FC Set% (default =100%) is a positive threshold , [FC] is set when SOC ≥ FC Set % and is
cleared when SOC ≤ FC Clear % (default = 98%). Alternatively, if FC Set% = –1, [FC] is set when the fuel gauge has
detected charge termination.
CHG = Fast charging allowed. If the TCA Set% (Terminate Charge Alarm Set %) is a positive threshold (default = 99%), [CHG]
is cleared when SOC ≥ TCA Set % and is set when SOC ≤ TCA Clear % (default = 95%). Alternatively, if TCA Set% =
–1, the TCA thresholds are disabled and the [CHG] bit is cleared when the fuel gauge has detected a taper condition.
Low Byte
OCVTAKEN = Cleared on entry to relax mode and set to 1 when OCV measurement is performed in relax
RSVD = Reserved.
ITPOR = Indicates a power-on reset or RESET subcommand has occurred. True when set. This bit is cleared after the
SOFT_RESET subcommand is received.
CFGUPMODE = Fuel gauge is in CONFIG UPDATE mode. True when set. Default is 0. See CONFIG UPDATE Mode for details.
BAT_DET = Battery insertion detected. True when set. When Op Config [BIE] is set, [BAT_DET] is set by detecting a logic-high-tolow transition at BIN pin. When Op Config [BIE] is low, [BAT_DET] is set when host issues BAT_INSERT subcommand
and is clear when host issues BAT_REMOVE subcommand.
SOC1 = If set, StateOfCharge() ≤ SOC1 Set Threshold. The [SOC1] bit will remain set until StateOfCharge() ≥ SOC1 Clear
Threshold.
SOCF = If set, StateOfCharge() ≤ SOCF Set Threshold. The [SOCF] bit will remain set until StateOfCharge() ≥ SOCF Clear
Threshold.
DSG = Discharging detected. True when set.
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8.5.1.5 NominalAvailableCapacity( ): 0x08 and 0x09
This read-only command pair returns the uncompensated (less than C/20 load) battery capacity remaining. Units
are mAh.
8.5.1.6 FullAvailableCapacity( ): 0x0A and 0x0B
This read-only command pair returns the uncompensated (less than C/20 load) capacity of the battery when fully
charged. Units are mAh. FullAvailableCapacity( ) is updated at regular intervals, as specified by the IT algorithm.
8.5.1.7 RemainingCapacity( ): 0x0C and 0x0D
This read-only command pair returns the compensated battery capacity remaining. Units are mAh.
8.5.1.8 FullChargeCapacity( ): 0x0E and 0x0F
This read-only command pair returns the compensated capacity of the battery when fully charged. Units are
mAh. FullChargeCapacity( ) is updated at regular intervals, as specified by the IT algorithm.
8.5.1.9 AverageCurrent( ): 0x10 and 0x11
This read-only command pair returns a signed integer value that is the average current flow through the sense
resistor. In NORMAL mode, it is updated once per second and is calculated by dividing the 1-second change in
coulomb counter data by 1 second. Large current spikes of short duration will be averaged out in this
measurement. Units are mA.
8.5.1.10 AveragePower( ): 0x18 and 0x19
This read-only function returns an signed integer value of the average power during battery charging and
discharging. It is negative during discharge and positive during charge. A value of 0 indicates that the battery is
not being discharged. The value is reported in units of mW.
8.5.1.11 StateOfCharge( ): 0x1C and 0x1D
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%.
8.5.1.12
IntTemperature( ): 0x1E and 0x1F
This read-only function returns an unsigned integer value of the internal temperature sensor in units of 0.1°K
measured by the fuel gauge. If Op Config [TEMPS] = 0, this command will return the same value as
Temperature( ).
8.5.1.13 StateOfHealth( ): 0x20 and 0x21
0x20 SOH percentage: this read-only function returns an unsigned integer value, expressed as a percentage of
the ratio of predicted FCC(25°C, SOH LoadI) over the DesignCapacity(). The FCC(25°C, SOH LoadI) is the
calculated full charge capacity at 25°C and the SOH LoadI which is programmed in factory (default = –400 mA).
The range of the returned SOH percentage is 0x00 to 0x64, indicating 0 to 100% correspondingly.
0x21 SOH Status: this read-only function returns an unsigned integer value, indicating the status of the SOH
percentage:
• 0x00: SOH not valid (initialization)
• 0x01: Instant SOH value ready
• 0x02: Initial SOH value ready
– Calculation based on default Qmax
– May not reflect SOH for currently inserted pack
• 0x03: SOH value ready
– Calculation based on learned Qmax
– Most accurate SOH for currently inserted pack following a Qmax update
• 0x04 through 0xFF: Reserved
20
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8.5.1.14 OperationConfiguration( ): 0x3A and 0x3B
This read-only function returns the contents of the NVM Operation Configuration (Op Config) register and is
most useful for system level debug to quickly determine device configuration.
8.5.1.15
DesignCapacity( ): 0x3C and 0x3D
This read-only function returns the value stored in Design Capacity and is expressed in mAh. This is intended to
be the theoretical or nominal capacity of a new pack and is used as an input for the algorithm to scale the
normalized resistance tables and for the calculation of StateOfHealth().
8.5.1.16 DebugX( ):
Several read-only functions such as Debug1( ), Debug2( ), Debug3( ) provide information useful for debug
purposes. For factory use only.
8.5.2 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 command bytes for a given extended command ranges in size from single to multiple bytes, as
specified in Table 7.
Table 7. Extended Commands
NAME
COMMAND CODE
UNIT
SEALED
ACCESS (1) (2)
UNSEALED
ACCESS (1) (2)
DataClass( )
(2)
0x3E
NA
NA
RW
DataBlock( )
(2)
0x3F
NA
RW
RW
0x40 through 0x5F
NA
R
RW
BlockDataCheckSum( )
0x60
NA
RW
RW
BlockDataControl( )
0x61
NA
NA
RW
0x62 through 0x7F
NA
R
R
BlockData( )
Reserved
(1)
(2)
SEALED and UNSEALED states are entered through commands to Control( ) 0x00 and 0x01.
In SEALED mode, data cannot be accessed through commands 0x3E and 0x3F.
8.5.2.1 OperationConfiguration( ): 0x3A and 0x3B
SEALED and UNSEALED Access: This command returns the Operation Configuration register setting.
8.5.2.2 DesignCapacity( ): 0x3C and 0x3D
SEALED and UNSEALED Access: This command returns the value is stored in Design Capacity and is
expressed in mAh. This is intended to be the theoretical or nominal capacity of a new pack and is used as an
input for the algorithm to scale the normalized resistance tables.
8.5.2.3 DataClass( ): 0x3E
UNSEALED Access: This command sets the data class to be accessed. The class to be accessed should be
entered in hexadecimal.
SEALED Access: This command is not available in SEALED mode.
8.5.2.4 DataBlock( ): 0x3F
UNSEALED Access: This command sets the data block to be accessed. When 0x00 is written to
BlockDataControl( ), DataBlock( ) holds the block number of the data to be read or written. Example: writing a
0x00 to DataBlock( ) specifies access to the first 32-byte block and a 0x01 specifies access to the second 32byte block, and so on.
SEALED Access: Issuing a 0x01 instructs the BlockData( ) command to transfer the Manufacturer Info block.
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8.5.2.5 BlockData( ): 0x40 through 0x5F
UNSEALED Access: This data block is the remainder of the 32-byte data block when accessing general block
data.
SEALED Access: This data block is used to access the Manufacturer Info block. No other NVM or RAM data
blocks are accessible in SEALED mode.
8.5.2.6 BlockDataChecksum( ): 0x60
UNSEALED Access: This byte contains the checksum on the 32 bytes of block data read or written. The leastsignificant byte of the sum of the data bytes written must be complemented ( [255 – x], for x being the leastsignificant byte) before being written to 0x60. For a block write, the correct complemented checksum must be
written before the BlockData( ) will be transferred to NVM or RAM.
SEALED Access: This byte contains the checksum for the 8 bytes of the Manufacturer Info block.
8.5.2.7 BlockDataControl( ): 0x61
UNSEALED Access: This command is controls the data access mode. Writing 0x00 to this command enables
BlockData( ) to access NVM and RAM.
SEALED Access: This command is not available in SEALED mode.
8.5.2.8 Reserved: 0x62 through 0x7F
8.5.3 Block Data Interface
8.5.3.1 Accessing Block Data
The fuel gauge contains both re-writable EEPROM non-volatile memory (NVM) and ROM-based data blocks.
Upon device RESET, the ROM-based data blocks are copied to associated volatile RAM space to initialize
default configuration and data constants to be used by the fuel gauging algorithm. Re-writable NVM-based data
blocks contain information expected to change such as: calibration, customer data, and Impedance Track fuel
gauging data tables. If the application requires a change to the NVM or RAM configuration data, the host can
update the data blocks in CONFIG UPDATE mode. RAM-based data changes are temporary and must be
applied by the host using CONFIG UPDATE mode after each device RESET; while changes to the NVM data
blocks are permanent. The data blocks can be accessed in several different ways, depending on the access
mode and what data is being accessed.
Commonly accessed data block locations, frequently read by a system, are conveniently accessed through
specific instructions, already described in Extended Data Commands. These commands are available when the
fuel gauge is either in UNSEALED or SEALED mode.
Most data block locations, however, are only accessible in UNSEALED mode by use of the evaluation software
or by data block transfers. These locations should be optimized and/or fixed during the development and
manufacture processes. Once established, the values generally remain unchanged during end-equipment
operation.
To access data locations individually, the block containing the desired data NVM locations must be transferred to
the command register locations, where they can be read to the system or changed directly. This is accomplished
by sending the set-up command BlockDataControl( ) (0x61) with data 0x00. Up to 32 bytes of data can be read
directly from the BlockData( ) (0x40 through 0x5F), externally altered, then rewritten to the BlockData( )
command space. Alternatively, specific locations can be read, altered, and rewritten if their corresponding offsets
are used to index into the BlockData( ) command space. Finally, the data residing in the command space is
transferred to the associated data block, once the correct checksum for the whole block is written to
BlockDataChecksum( ) (0x60).
Occasionally, a data CLASS will be larger than the 32-byte block size. In this case, the DataBlock( ) command
designates in which 32-byte block the desired locations reside. The correct command address is then given by
0x40 + offset modulo 32. For example, to access Sleep Current in the Gas Gauging class, the DataClass( ) is
issued 82 (0x52) to set the class. Because the offset is 34, it resides in the second 32-byte block. Hence,
DataBlock( ) is issued 0x01 to set the block offset, and the offset used to index into the BlockData( ) memory
area is 0x40 + 34 modulo 32 = 0x40 + 2 = 0x40 + 2 = 0x42.
22
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Reading and writing subclass data are block operations up to 32 bytes in length. If, during a write, the data
length exceeds the maximum block size, then the data is ignored.
None of the data written to memory are bounded by the fuel gauge, the values are not rejected by the fuel
gauge. Writing an incorrect value may result in hardware failure due to firmware program interpretation of the
invalid data. The data written to NVM blocks is not persistent, so a power-on reset does resolve the fault.
8.5.4 Access Modes
The fuel gauge supports SEALED and UNSEALED access modes to control data NVM access permissions
according to Table 8.
Table 8. Data NVM Access
DATA NVM
MANUFACTURER
INFO
UNSEALED
RW
RW
SEALED
None
R
SECURITY MODE
8.5.4.1 Sealing and Unsealing Data Blocks
The fuel gauge implements a key-access security scheme to transition from a SEALED state to the UNSEALED
state. Devices are shipped from the factory in the UNSEALED state and should be SEALED before use in endequipment. The Sealed to Unseal key can only be updated in the UNSEALED state.
To SEAL from UNSEALED: The host sends the SEALED subcommand 0x0020 to the Control( ) register. After
receiving the SEALED subcommand, the CONTROL_STATUS [SS] bit is set within 2 seconds.
To UNSEAL from SEALED: Host sends the keys to the Control( ) register. The keys must be sent
consecutively, with no other data written to Control( ).
NOTE
To avoid conflict with normal subcommands, the keys must be different from the codes
presented in the CNTL DATA column of the Table 4 table.
The first word is Key 0 and the second word is Key 1. The order of the keys sent are Key 1 followed by Key 0.
The order of the bytes for each key entered through the Control( ) command is the reverse of what is read from
the part. For example, if the 4-byte Sealed to Unseal key is 0x56781234, key 1 is 0x1234 and key 0 is 0x5678.
So, the host should write 0x3412 followed by 0x7856 to unseal the part. After receiving the correct key sequence
the CONTROL_STATUS [SS] bit is cleared.
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8.5.5 Data Block Summary
Table 9. Data Block Summary
VALUE
CLASS
Configuration
[RAM]
SUBCLASS
ID
2
36
49
68
SUBCLASS
Safety [RAM]
Charge Termination
[RAM]
Manufacturer Info [NVM]
Gas Gauging
[NVM/RAM]
80
IT Cfg [RAM]
MAX
DEFAULT
(-G2B)
UNIT
(EVSW
Unit)*
0
Overtemperature
I2
–1200
1200
550
0.1°C
(°C)
2
Undertemperature
I2
–1200
1200
0
0.1°C
(°C)
4
Temperature Hysteresis
U1
0
255
50
0.1°C
(°C)
3
TCA Set %
I1
–1%
100%
99%
4
TCA Clear %
I1
–1%
100%
95%
5
FC Set %
I1
–1%
100%
100%
6
FC Clear %
I1
–1%
100%
98%
0
SOC1 Set Threshold
U1
0%
255%
10%
1
SOC1 Clear Threshold
U1
0%
255%
15%
2
SOCF Set Threshold
U1
0%
255%
2%
3
SOCF Clear Threshold
U1
0%
255%
5%
9
Hibernate I
I2
0
700
3
mA
11
Hibernate V
I2
2400
3000
2550
mV
Block A 0 through 7
H1
0x00
0xFF
0x00
Current Thresholds
[RAM]
State [NVM]
0 through 7
55
Max Delta Voltage
I2
–32000
32000
200
57
TermV Valid t
U1
0
255
2
mV
s
0
Dsg Current Threshold
I2
0
2000
167
0.1 h
2
Chg Current Threshold
I2
0
2000
133
0.1 h
4
Quit Current
I2
0
1000
250
0.1 h
0xFF
0x04
(0x34)
2
Update Status
H1
0x00
3
Reserve Cap-mAh
I2
0
9000
0
5
Op Config
H2
0x0000
0xFFFF
0x89F8
12
Design Capacity
I2
0
32767
1340
(1000)
mAh
0
32767
4960
(3800)
mWh
mAh
14
Design Energy
I2
18
Terminate Voltage
I2
2800
3700
3200
mV
22
SOHLoadI
I2
–32767
0
50
mA
29
SOCI Delta
U1
0%
100%
1%
30
Taper Current
I2
0
1000
75
mA
5000
4100
(4200)
mV
32
Taper Voltage
I2
0
34
Sleep Current
I2
0
100
10
mA
36
V at Charge Termination
I2
0
5000
4190
(4290)
mV
38
Transient Factor Charge
U1
0
255
179
num
39
Transient Factor Discharge
U1
0
255
179
num
40
RDL Tempco
F4
1.0E–20
4.0E+1
0.000393
num
88
0 through 28
Cell0 R_a 0 through 14
I2
183
183
[Table]
2–10Ω
(num)
89
R_a RAM
[RAM]
0 through 28
Cell0 R_a 0 through 14
I2
183
183
[Table]
2–10Ω
(num)
0
CC Offset
I2
–32768
32767
–1312
mV
2
Board Offset
I1
–128
127
0
uV
°0.1°C
(°C)
104
105
107
24
MIN
R_a NVM
[NVM]
Ra Tables
[NVM/RAM]
Calibration
[NVM]
DATA
TYPE
Power [RAM]
58
82
NAME
Discharge [RAM]
System Data
[NVM]
81
OFFSET
Data [NVM]
3
Int Temp Offset
I1
–128
127
0
4
Pack V Offset
I1
–128
127
0
mV
4.0E+1
0.47095
num
(2–10Ω)
0
CC Gain
F4
1.0E–1
4
CC Cal Temp
I2
0
32767
2982
0.1K
2.9826E+4
1.193046E
+6
559538.8
num
(2–10Ω)
CC Cal [NVM]
Current [RAM]
19
CC Delta
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Table 9. Data Block Summary (continued)
VALUE
CLASS
Security
SUBCLASS
ID
112
SUBCLASS
OFFSET
Codes [RAM]
DATA
TYPE
NAME
0
Sealed to Unsealed
H4
MIN
MAX
DEFAULT
(-G2B)
0x0000
0000
0xFFFF
FFFF
0x3672
0414
UNIT
(EVSW
Unit)*
8.5.6 Detecting Charge Termination
The fuel gauge detects charge termination when:
• AverageCurrent( ) < Taper Current (default = 75 mA) for 80 seconds
• During the same 80 seconds, the accumulated change in capacity > 0.25 mAh / 40 seconds
• Voltage( ) > (Charging Voltage – 100 mV)
When this occurs, the Flags( )[CHG] bit is cleared. Also, if the [RMFCC] bit of Operation Configuration is set,
then RemainingCapacity( ) is set equal to FullChargeCapacity( ).
8.5.7 Communications
8.5.7.1 I2C Interface
The fuel gauge supports the standard I2C read, incremental read, quick read, one-byte write, and incremental
write functions. The 7-bit device address (ADDR) is the most significant 7 bits of the hex address and is fixed as
1010101. The first 8 bits of the I2C protocol are, therefore, 0xAA or 0xAB for write or read, respectively.
Host generated
S
ADDR[6:0]
0 A
Gauge generated
CMD [7:0]
A
DATA [7:0]
A P
S
ADDR[6:0]
1 A
(a) 1-byte write
S
ADDR[6:0]
0 A
DATA [7:0]
N P
(b) quick read
CMD [7:0]
A Sr
ADDR[6:0]
1 A
DATA [7:0]
N P
(c) 1- byte read
S
ADDR[6:0]
0 A
CMD [7:0]
A Sr
ADDR[6:0]
1 A
DATA [7:0]
A ...
DATA [7:0]
N P
(d) incremental read
S
ADDR[6:0]
0 A
CMD[7:0]
A
DATA [7:0]
A
DATA [7:0]
A
...
A P
(e) incremental write
(S = Start , Sr = Repeated Start , A = Acknowledge , N = No Acknowledge , and P = Stop).
Figure 7. I2C Interface Read/Write
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 fuel gauge 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).
The following command sequences are not supported:
Attempt to write a read-only address (NACK after data sent by master):
Figure 8. Attempt to Write a Read-Only Address
Attempt to read an address above 0x6B (NACK command):
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Figure 9. Attempt to Read an Address Above 0x6B
8.5.7.2 I2C Time Out
The I2C engine releases both SDA and SCL if the I2C bus is held low for 2 seconds. If the fuel gauge is holding
the lines, releasing them frees them for 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.
8.5.7.3 I2C Command Waiting Time
To ensure proper operation at 400 kHz, a t(BUF) ≥ 66 μs bus-free waiting time must be inserted between all
packets addressed to the fuel gauge. In addition, if the SCL clock frequency (fSCL) is > 100 kHz, use individual 1byte write commands for proper data flow control. The following diagram shows the standard waiting time
required between issuing the control subcommand the reading the status result. For read-write standard
command, a minimum of 2 seconds is required to get the result updated. For read-only standard commands,
there is no waiting time required, but the host must not issue any standard command more than two times per
second. Otherwise, the gauge could result in a reset issue due to the expiration of the watchdog timer.
S
ADDR [6:0]
0 A
CMD [7:0]
A
DATA [7:0]
A P
66ms
S
ADDR [6:0]
0 A
CMD [7:0]
A
DATA [7:0]
A P
66ms
S
ADDR [6:0]
0 A
CMD [7:0]
A Sr
ADDR [6:0]
1 A
DATA [7:0]
A
DATA [7:0]
N P
66ms
N P
66ms
Waiting time inserted between two 1-byte write packets for a subcommand and reading results
(required for 100 kHz < fSCL £ 400 kHz)
S
ADDR [6:0]
0 A
CMD [7:0]
A
DATA [7:0]
S
ADDR [6:0]
0 A
CMD [7:0]
A Sr
ADDR [6:0]
A
1 A
DATA [7:0]
A P
DATA [7:0]
A
66ms
DATA [7:0]
Waiting time inserted between incremental 2-byte write packet for a subcommand and reading results
(acceptable for fSCL £ 100 kHz)
S
ADDR [6:0]
DATA [7:0]
0 A
A
CMD [7:0]
DATA [7:0]
A Sr
N P
ADDR [6:0]
1 A
DATA [7:0]
A
DATA [7:0]
A
66ms
Waiting time inserted after incremental read
Figure 10. I2C Command Waiting Time
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8.5.7.4 I2C Clock Stretching
A clock stretch can occur during all modes of fuel gauge operation. In SLEEP and HIBERNATE modes, a short
clock stretch occurs on all I2C traffic as the device must wake up to process the packet. In the other modes
(INITIALIZATION, NORMAL) clock stretching only occurs for packets addressed for the fuel gauge. The majority
of clock stretch periods are small as the I2C interface performs normal data flow control. However, less frequent
yet more significant clock stretch periods may occur as blocks of NVM are updated. The following table
summarizes the approximate clock stretch duration for various fuel gauge operating conditions.
Table 10. I2C Clock Stretching
GAUGING
MODE
OPERATING CONDITION / COMMENT
SLEEP
HIBERNATE
Clock stretch occurs at the beginning of all traffic as the device wakes up.
≤ 4 ms
Clock stretch occurs within the packet for flow control (after a start bit, ACK or first data bit).
≤ 4 ms
Normal Ra table NVM updates.
24 ms
INITIALIZATION
NORMAL
APPROXIMATE
DURATION
NVM block writes.
72 ms
Restored NVM block write after loss of power.
116 ms
End of discharge Ra table NVM update.
144 ms
8.6 Register Maps
8.6.1 Operation Configuration (Op Config) Register
Gauge operation is configured through the Operation Configuration (Op Config) data NVM register, as
indicated in Table 11. This register is programmed and read through the methods described in Fuel Gauging
Configurations.
Table 11. Op Config Register Definition
BIT 7
High Byte SMOOTHEN
Default =
1
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RSVD0
BIE
BI_PU_EN
RSVD1
RSVD0
RSVD0
RSVD1
0
0
0
1
0
0
1
0x89
Low Byte
RSVD1
RSVD1
SLEEP
RMFCC
RSVD1
BATLOWEN
GPIOPOL
TEMPS
Default =
1
1
1
1
1
0
0
0
0xF8
SMOOTHEN = Enables the SOC smoothing feature. (See SOC Smoothing Feature.) True when set.
BIE = Battery Insertion Enable. If set, the battery insertion is detection through BIN pin input. If cleared, the detection
relies on the host to issue BAT_INSERT subcommand to indicate battery presence in the system.
BI_PU_EN = Enables internal weak pullup on BIN pin. True when set. If false, an external pullup resistor is expected.
SLEEP = The fuel gauge can enter sleep, if operating conditions allow. True when set.
RMFCC = RM is updated with the value from FCC on valid charge termination. True when set.
BATLOWEN = If set, the BAT_LOW function for GPOUT pin is selected. If cleared, the SOC_INT function is selected for
GPOUT.
GPIO_POL = GPOUT pin is active-HIGH if set or active-LOW if cleared.
TEMPS = Selects the temperature source. Enables the host to write Temperature( ) if set. If cleared, the internal
temperature sensor is used for Temperature( ).
RSVD0 = Reserved. Default is 0. (Set to 0 for proper operation)
RSVD1 = Reserved. Default is 1. (Set to 1 for proper operation)
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The Texas Instruments bq27425-G2 fuel gauge is a microcontroller peripheral that provides system-side fuel
gauging for single-cell Li-Ion batteries. The device requires minimal user configuration and system
microcontroller firmware. Battery fuel gauging with the bq27425-G2 fuel gauge requires connections only to
PACK+ (P+) and PACK– for a removable battery pack or embedded battery circuit.
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9.2 Typical Application
BQ27425YZF
0.01
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Figure 11. Reference (EVM) Schematic
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9.2.1 Design Requirements
As shipped from the TI factory, many bq27425-G2 parameters in NVM are left in the unprogrammed state (zero)
while some parameters directly associated with the CHEMID are preprogrammed. This partially programmed
configuration facilitates customization for each end application. Upon device reset, the contents of NVM are
copied to associated volatile RAM-based Data Memory blocks. For proper operation, all parameters in RAMbased Data Memory require initialization — either by updating Data Memory parameters in a lab or evaluation
situation or by programming the NVM for customer production.
Table 9 shows the design parameter values that are present in the device.
9.2.2 Detailed Design Procedure
9.2.2.1 BAT/REGIN Voltage Sense Input
A ceramic capacitor at the input to the BAT/REGIN pin is used to bypass AC voltage ripple to ground, greatly
reducing its influence on battery voltage measurements. It proves most effective in applications with load profiles
that exhibit high-frequency current pulses (that is, cell phones) but is recommended for use in all applications to
reduce noise on this sensitive high-impedance measurement node.
9.2.2.2 Integrated LDO Capacitor
The fuel gauge has an integrated LDO with an output on the VCC pin of approximately 2.5 V. A capacitor of
value at least 1 μF should be connected between the VCC pin and VSS. The capacitor should be placed close to
the gauge IC and have short traces to both the VCC pin and VSS.
9.2.3 Application Curves
8.8
VREGIN = 2.7 V
VREGIN = 4.5 V
2.6
fOSC - High Frequency Oscillator (MHz)
VREG25 - Regulator Output Voltage (V)
2.65
2.55
2.5
2.45
2.4
2.35
8.7
8.6
8.5
8.4
8.3
8.2
8.1
8
-40
Temperature (qC)
-20
0
20
40
Temperature (qC)
D001
34
5
33.5
4
33
32.5
32
31.5
31
30.5
30
-40
-20
0
20
40
Temperature (qC)
60
80
100
30
100
D002
3
2
1
0
-1
-2
-3
-4
-5
-30
-20
D003
Figure 14. Low-Frequency Oscillator Frequency vs
Temperature
80
Figure 13. High-Frequency Oscillator Frequency vs
Temperature
Reported Temperature Error (qC)
fLOSC - Low Frequency Oscillator (kHz)
Figure 12. Regulator Output Voltage vs Temperature
60
-10
0
10
20
30
Temperature (qC)
40
50
60
D004
Figure 15. Reported Internal Temperature Measurement vs
Temperature
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SLUSB23B – OCTOBER 2012 – REVISED JUNE 2015
10 Power Supply Recommendations
10.1 Power Supply Decoupling
The battery connection on the BAT pin is used as an input for voltage measurement of the battery. A capacitor of
value of at least 0.1 μF should be connected between BAT and VSS. The capacitor should be placed close to the
gauge IC and have short traces to both the BAT pin and VSS.
The battery connection on the REGIN pin is used to supply power to the gauge. A capacitor of value of at least
0.1 μF should be connected between REGIN and VSS. The capacitor should be placed close to the gauge IC and
have short traces to both the REGIN pin and VSS.
The fuel gauge has an integrated LDO with an output on the VCC pin of approximately 2.5 V. A capacitor of
value at least 1 μF should be connected between the VCC pin and VSS. The capacitor should be placed close to
the gauge IC and have short traces to both the VDD pin and VSS.
11 Layout
11.1 Layout Guidelines
A capacitor of at least 1 μF is connected between the VCC pin and VSS. The capacitor should be placed close to
the gauge IC and have short traces to both the VCC pin and VSS.
• A capacitor at least 0.1 μF must be connected between the BAT pin and VSS if the connection between the
battery pack and the gauge BAT pin has the potential to pick up noise. The capacitor should be placed close
to the gauge IC and have short traces to both the VDD pin and VSS.
• If the external pullup resistors on the SCL and SDA lines will be disconnected from the host during low-power
operation, TI recommends using external 1-MΩ pulldown resistors to VSS to avoid floating inputs to the I2C
engine.
• The value of the SCL and SDA pullup resistors should take into consideration the pullup voltage and the bus
capacitance.
• If the GPOUT pin is not used by the host, the pin should still be pulled up to VDD with a 4.7-kΩ or 10-kΩ
resistor.
• The BIN pin should not be shorted directly to VCC or VSS.
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SLUSB23B – OCTOBER 2012 – REVISED JUNE 2015
www.ti.com
11.2 Layout Example
SCL
R5
R6
SDA
R7
R8
BIN
C2
PACK+
REGIN
NC
BAT
CE
C1
CE
VCC
BIN
NC
VSS
SDA
NC
SRX
SCL
GPOUT
NC
C4
NC
GPOUT
PACK–
Via connects to Power Ground
Star ground right at PACK –
for ESD return path
Figure 16. Layout Schematic
32
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bq27425-G2
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SLUSB23B – OCTOBER 2012 – REVISED JUNE 2015
12 Device and Documentation Support
12.1 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.2 Trademarks
Impedance Track, E2E are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
12.3 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
13.1 Packaging
13.1.1 Package Dimensions
Table 12. YZF Package Dimensions
PACKAGED DEVICES
D
E
BQ27425-G2A
2.69 ± 0.030 mm
1.75 ± 0.030 mm
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
BQ27425YZFR-G2A
ACTIVE
DSBGA
YZF
15
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27425
BQ27425YZFR-G2B
ACTIVE
DSBGA
YZF
15
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27425
G2B
BQ27425YZFT-G2A
ACTIVE
DSBGA
YZF
15
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27425
BQ27425YZFT-G2B
ACTIVE
DSBGA
YZF
15
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27425
G2B
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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