Order
Now
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
bq27546-G1 Single-Cell Li-Ion Battery Fuel Gauge for Battery Pack Integration
1 Features
3 Description
•
The bq27546-G1 Li-Ion battery fuel gauge is a
microcontroller peripheral that provides fuel gauging
for single-cell Li-Ion battery packs. The device
requires minimal system microcontroller firmware
development for accurate battery fuel gauging. The
bq27546-G1 resides within the battery pack or on the
system’s main-board with an embedded battery (nonremovable).
1
•
•
•
•
•
Battery Fuel Gauge for 1-Series (1sXp) Li-Ion
Applications up to 14,500-mAh Capacity
Microcontroller Peripheral Provides:
– Internal or External Temperature Sensor for
Battery Temperature Reporting
– SHA-1/HMAC Authentication
– Lifetime Data Logging
– 64 Bytes of Non-Volatile Scratch Pad FLASH
Battery Fuel Gauging Based on Patented
Impedance Track™ Technology
– Models Battery Discharge Curve for Accurate
Time-To-Empty Predictions
– Automatically Adjusts for Battery Aging,
Battery Self-Discharge, and Temperature/Rate
Inefficiencies
– Low-Value Sense Resistor (5 mΩ to 20 mΩ)
Advanced Fuel Gauging Features
– Internal Short Detection
– Tab Disconnection Detection
HDQ and I2C™ Interface Formats for
Communication with Host System
Small 15-Ball Nano-Free™ (DSBGA) Packaging
The bq27546-G1 uses the patented Impedance
Track™ algorithm for fuel gauging, and provides
information such as remaining battery capacity
(mAh), state-of-charge (%), run-time to empty (min.),
battery voltage (mV), and temperature (°C). It also
provides detections for internal short or tab
disconnection events.
The bq27546-G1 features integrated support for
secure battery pack authentication, using the SHA1/HMAC authentication algorithm.
The device comes in a 15-ball Nano-Free™ DSBGA
package (2.61 mm × 1.96 mm) that is ideal for spaceconstrained applications.
Device Information(1)
PART NUMBER
bq27546-G1
YZF (15)
BODY SIZE (NOM)
2.61 mm × 1.96 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
2 Applications
•
•
•
•
•
PACKAGE
Smartphones
Tablets
Digital Still and Video Cameras
Handheld Terminals
MP3 or Multimedia Players
Simplified Schematic
Single Cell Li -Ion Battery Pack
PACK+
REGIN
VCC
BAT
HDQ
HDQ
SDA
SDA
SCL
SCL
TS
SRP
PROTECTION
IC
SE
CE
CHG
PACK–
SRN
VSS
DSG
FET
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.
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
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
7.10
Absolute Maximum Ratings ...................................... 4
ESD Ratings.............................................................. 4
Recommended Operating Conditions....................... 4
Thermal Information .................................................. 4
Supply Current .......................................................... 5
Digital Input and Output DC Characteristics ............. 5
Power-On Reset........................................................ 5
2.5-V LDO Regulator ................................................ 5
Internal Clock Oscillators .......................................... 5
Integrating ADC (Coulomb Counter)
Characteristics ........................................................... 6
7.11 ADC (Temperature and Cell Voltage)
Characteristics ........................................................... 6
7.12 Data Flash Memory Characteristics........................ 6
7.13 HDQ Communication Timing Characteristics ......... 6
7.14 I2C-Compatible Interface Timing Characteristics .... 7
7.15 Typical Characteristics ............................................ 8
8
Detailed Description .............................................. 9
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........................................ 15
Programming........................................................... 20
Register Maps ......................................................... 22
Application and Implementation ........................ 24
9.1 Application Information............................................ 24
9.2 Typical Applications ................................................ 25
9.3 Application Curves .................................................. 29
10 Power Supply Recommendations ..................... 29
10.1 Power Supply Decoupling ..................................... 29
11 Layout................................................................... 30
11.1 Layout Guidelines ................................................. 30
11.2 Layout Example .................................................... 31
12 Device and Documentation Support ................. 32
12.1
12.2
12.3
12.4
12.5
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
32
32
32
32
32
13 Mechanical, Packaging, and Orderable
Information ........................................................... 32
4 Revision History
Changes from Revision A (December 2015) to Revision B
Page
•
Changed Simplified Schematic .............................................................................................................................................. 1
•
Changed the description for the SRP pin ............................................................................................................................... 3
Changes from Original (May 2015) to Revision A
Page
•
Changed the descriptions for the SRP and SRN pins ........................................................................................................... 3
•
Changed Pin Configuration and Functions ............................................................................................................................ 3
•
Changed Power-On Reset .................................................................................................................................................... 5
•
Added "FULLSLEEP mode" to the introduction in Power Modes ....................................................................................... 15
2
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
5 Device Comparison Table
PART
NUMBER (1)
FIRMWARE
VERSION
PACKAGE (1)
TA
COMMUNICATION
FORMAT
2.00
DSBGA-15
–40°C to 85°C
I2C, HDQ (1)
BQ27546YZFR-G1
BQ27546YZFT-G1
(1)
TAPE AND REEL
QUANTITY
3000
250
2
bq27546-G1 is shipped in I C mode.
6 Pin Configuration and Functions
Pin Functions
NUMBER
NAME
TYPE
DESCRIPTION
Analog input pin connected to the internal coulomb counter where SRP is nearest the CELL–
connection. Connect to a 5-mΩ to 20-mΩ sense resistor.
A1
SRP
B1
SRN
IA
Analog input pin connected to the internal coulomb counter where SRN is nearest the PACK–
connection. Connect to a 5-mΩ to 20-mΩ sense resistor.
C1, C2
VSS
P
Device ground
C3
SE
O
Shutdown Enable output. Push-pull output
D1
VCC
P
Regulator output and processor power. Decouple with a 1.0-µF ceramic capacitor to VSS.
E1
REGIN
P
Regulator input. Decouple with a 0.1-µF ceramic capacitor to VSS.
A2
HDQ
I/O
HDQ serial communications line (Slave). Open-drain
B2
TS
IA
Pack thermistor voltage sense (use 103AT-type thermistor). ADC input
D2
CE
I
E2
BAT
IA
A3
SCL
I
Slave I2C serial communications clock input line for communication with system (Master). Use
with a 10-kΩ pull-up resistor (typical).
B3
SDA
I/O
Slave I2C serial communications data line for communication with system (Master). Open-drain
I/O. Use with a 10-kΩ pull-up resistor (typical).
D3, E3
NC/GPI
O
NC
Do not connect for proper operation. Reserved for future GPIO.
(1)
IA
(1)
Chip Enable. Internal LDO is disconnected from REGIN when driven low.
Cell-voltage measurement input. ADC input. Recommendation is 4.8 V maximum for conversion
accuracy.
IA = Analog input, I/O = Digital input/output, P = Power connection, NC = No connect
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
3
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
7 Specifications
7.1 Absolute Maximum Ratings
Over-operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
VI
Regulator input, REGIN
–0.3
5.5
V
VCC
Supply voltage range
–0.3
2.75
V
VIOD
Open-drain I/O pins (SDA, SCL, HDQ)
–0.3
5.5
V
VBAT
BAT input (pin E2)
–0.3
5.5
V
VI
Input voltage range to all others (pins GPIO, SRP, SRN, TS)
–0.3
VCC + 0.3
V
TA
Operating free-air temperature range
–40
85
°C
TF
Functional temperature range
–40
100
Tstg
Storage temperature range
–65
150
(1)
°C
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
Human Body Model (HBM), per ANSI/ESDA/JEDEC JS-001
V(ESD)
(1)
(2)
Electrostatic Discharge
(1)
, BAT pin
UNIT
1500
Human Body Model (HBM), all pins
2000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±500
V
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 = –40°C to 85°C; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted)
MIN NOM
No operating restrictions
VI
Supply voltage, REGIN
CREGIN
External input capacitor for internal LDO
between REGIN and VSS
CLDO25
tPUCD
No FLASH writes
Nominal capacitor values specified.
Recommend a 5% ceramic X5R type capacitor
External output capacitor for internal LDO located close to the device.
between VCC an VSS
MAX
2.8
4.5
2.45
2.8
V
0.1
µF
1
µF
250
ms
0.47
Power-up communication delay
UNIT
7.4 Thermal Information
bq27546-G1
THERMAL METRIC (1)
YZF (DSBGA)
UNIT
15 PINS
RθJA
Junction-to-ambient thermal resistance
70
RθJCtop
Junction-to-case (top) thermal resistance
17
RθJB
Junction-to-board thermal resistance
20
ψJT
Junction-to-top characterization parameter
1
ψJB
Junction-to-board characterization parameter
18
RθJCbot
Junction-to-case (bottom) thermal resistance
n/a
(1)
4
°C/W
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report (SPRA953).
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
7.5 Supply Current
TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
NORMAL operating mode current
I(SLP)
Low-power operating mode current (1)
I(FULLSLP)
Low-power operating mode current (1)
I(HIB)
HIBERNATE operating mode current
(1)
Fuel gauge in NORMAL mode.
ILOAD > Sleep Current
(1)
ICC
MIN
(1)
TYP MAX
UNIT
118
μA
Fuel gauge in SLEEP mode.
ILOAD < Sleep Current
62
μA
Fuel gauge in FULLSLEEP mode.
ILOAD < Sleep Current
23
μA
Fuel gauge in HIBERNATE mode.
ILOAD < Hibernate Current
8
μA
Specified by design. Not tested in production.
7.6 Digital Input and Output DC Characteristics
TA = –40°C to 85°C; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
VOL
Output voltage low (HDQ, SDA, SCL,
SE)
IOL = 3 mA
VOH(PP)
Output high voltage (SE)
IOH = –1 mA
VCC–0.5
VOH(OD)
Output high voltage (HDQ, SDA, SCL)
External pullup resistor connected to VCC
VCC–0.5
VIL
Input voltage low (HDQ, SDA, SCL)
VIH
Input voltage high (HDQ, SDA, SCL)
VIL(CE)
CE Low-level input voltage
VIH(CE)
CE High-level input voltage
Ilkg
Input leakage current (I/O pins)
TYP MAX
0.4
VREGIN = 2.8 to 4.5 V
UNIT
V
V
V
–0.3
0.6
V
V
1.2
5.5
2.65
0.8
VREGIN–0.5
0.8
0.3
V
μA
7.7 Power-On Reset
TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
VIT+
Positive-going battery voltage input at
VCC
VHYS
Power-on reset hysteresis
TEST CONDITIONS
MIN
TYP
MAX
2.05
2.15
2.20
115
UNIT
V
mV
7.8 2.5-V LDO Regulator
TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
VREG25
Regulator output voltage, REG25
MIN
TYP
MAX
2.8 V ≤ V(REGIN) ≤ 4.5 V,
IOUT ≤ 16 mA
TEST CONDITION
2.3
2.5
2.6
2.45 V ≤ V(REGIN) < 2.8 V (low battery), IOUT ≤
3 mA
2.3
UNIT
V
V
7.9 Internal Clock Oscillators
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
f(OSC)
Operating frequency
2.097
MHz
f(LOSC)
Operating frequency
32.768
kHz
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
5
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
7.10 Integrating ADC (Coulomb Counter) Characteristics
TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
VSR
Input voltage range, V(SRN) and V(SRP)
VSR = V(SRN) – V(SRP)
tCONV(SR)
Conversion time
Single conversion
MIN
14
VOS(SR)
Input offset
INL
Integral nonlinearity error
ZIN(SR)
Effective input resistance (1)
Ilkg(SR)
Input leakage current (1)
MAX
UNIT
0.125
V
1
Resolution
(1)
TYP
–0.125
s
15
bits
±0.034
FSR
10
±0.007
μV
2.5
MΩ
0.3
μA
Specified by design. Not production tested.
7.11 ADC (Temperature and Cell Voltage) Characteristics
TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V
(unless otherwise noted)
MAX
UNIT
VIN(TS)
Input voltage range (TS)
PARAMETER
VSS – 0.125
VCC
V
VIN(BAT)
Input voltage range (BAT)
VSS – 0.125
5
V
VIN(ADC)
Input voltage range to ADC
G(TEMP)
Temperature sensor voltage gain
tCONV(ADC)
VOS(ADC)
TEST CONDITIONS
TYP
0.05
1
–2.0
Conversion time
Resolution
14
Input offset
Effective input resistance (TS)
Z(BAT)
Effective input resistance (BAT) (1)
Ilkg(ADC)
Input leakage current
bq27546-G1 not measuring external
temperature
8
bq27546-G1 not measuring cell voltage
8
bq27546-G1 measuring cell voltage
V
mV/°C
125
ms
15
bits
1
(1)
Z(TS)
(1)
MIN
mV
MΩ
MΩ
100
kΩ
0.3
μA
Specified by design. Not production tested.
7.12 Data Flash Memory Characteristics
TA = –40°C to 85°C, C(REG) = 0.47 μF, 2.45 V < V(REGIN) = VBAT < 5.5 V; typical values at TA = 25°C and V(REGIN) = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
Data retention (1)
tDR
Flash programming write-cycles (1)
Word programming time
ICCPROG
Flash-write supply current (1)
tDFERASE
Data flash master erase time (1)
(1)
Flash page erase time
TYP
UNIT
Years
20,000
Cycles
5
(1)
MAX
10
(1)
tWORDPROG
tPGERASE
MIN
2
ms
10
mA
200
ms
20
ms
Specified by design. Not production tested.
7.13 HDQ Communication Timing Characteristics
TA = –40°C to 85°C, CREG = 0.47 μF, 2.45 V < VREGIN = VBAT < 5.5 V; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
t(CYCH)
Cycle time, host to bq27546-G1
190
t(CYCD)
Cycle time, bq27546-G1 to host
190
t(HW1)
Host sends 1 to bq27546-G1
0.5
6
Submit Documentation Feedback
NOM
MAX
UNIT
μs
205
250
μs
50
μs
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
HDQ Communication Timing Characteristics (continued)
TA = –40°C to 85°C, CREG = 0.47 μF, 2.45 V < VREGIN = VBAT < 5.5 V; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
NOM
MAX
UNIT
t(DW1)
bq27546-G1 sends 1 to host
32
50
μs
t(HW0)
Host sends 0 to bq27546-G1
86
145
μs
t(DW0)
bq27546-G1 sends 0 to host
80
145
μs
t(RSPS)
Response time, bq27546-G1 to host
190
950
μs
t(B)
Break time
190
t(BR)
Break recovery time
t(RISE)
HDQ line rising time to logic 1 (1.2 V)
μs
40
μs
950
ns
7.14 I2C-Compatible Interface Timing Characteristics
TA = –40°C to 85°C, CREG = 0.47 μF, 2.45 V < VREGIN = VBAT < 5.5 V; typical values at TA = 25°C and VREGIN = VBAT = 3.6 V
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
NOM
MAX
UNIT
tr
SCL/SDA rise time
300
ns
tf
SCL/SDA fall time
300
ns
tw(H)
SCL pulse width (high)
tw(L)
SCL pulse width (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
1000
ns
th(DAT)
Data hold time
0
ns
tsu(STOP)
Setup time for stop
600
ns
tBUF
Bus free time between stop and start
66
μs
fSCL
(1)
(1)
Clock frequency
600
ns
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. (Refer to I2C Interface.)
1.2V
t(RISE)
t(BR)
t(B)
(b) HDQ line rise time
(a) Break and Break Recovery
t(DW1)
t(HW1)
t(DW0)
t(CYCD)
t(HW0)
t(CYCH)
(d) Gauge Transmitted Bit
(c) Host Transmitted Bit
Break
1-bit
R/W
7-bit address
8-bit data
t(RSPS)
(e) Gauge to Host Response
Figure 1. HDQ Timing Diagrams
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
7
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
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 2. I2C-Compatible Interface Timing Diagrams
7.15 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
-40
-20
0
20
40
Temperature (°C)
60
8.7
8.6
8.5
8.4
8.3
8.2
8.1
8
-40
80
5
33.5
4
Reported Temperature Error (qC)
fLOSC - Low Frequency Oscillator (kHz)
34
33
32.5
32
31.5
31
30.5
-20
0
20
40
Temperature (qC)
60
80
100
20
40
Temperature (qC)
60
80
100
D002
3
2
1
0
-1
-2
-3
-4
-5
-30
-20
D003
Figure 5. Low-Frequency Oscillator Frequency Vs.
Temperature
8
0
Figure 4. High-Frequency Oscillator Frequency Vs.
Temperature
Figure 3. Regulator Output Voltage Vs. Temperature
30
-40
-20
D001
-10
0
10
20
30
Temperature (qC)
40
50
60
D004
Figure 6. Reported Internal Temperature Measurement Vs.
Temperature
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
8 Detailed Description
8.1 Overview
The bq27546-G1 accurately predicts the battery capacity and other operational characteristics of a single Libased rechargeable cell. It can be interrogated by a system processor to provide cell information, such as stateof-charge (SOC) and time-to-empty (TTE).
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 bq27546-G1 control and status
registers, as well as its data flash locations. Commands are sent from the system to gauge using the bq27546G1 serial communications engine, and can be executed during application development, pack manufacture, or
end-equipment operation.
Cell information is stored in the bq27546-G1 in non-volatile flash memory. Many of these data flash locations are
accessible during application development. They cannot, generally, be accessed directly during end-equipment
operation. To access to these locations, use the bq27546-G1 companion evaluation software, individual
commands, or a sequence of data-flash-access commands. To access a desired data flash location, the correct
data flash Subclass and offset must be known. For detailed data flash information, see the bq27546-G1
Technical Reference Manual (SLUUB74).
The bq27546-G1 provides 64 bytes of user-programmable data flash memory, partitioned into two (2) 32-byte
blocks: Manufacturer Info Block A and Manufacturer Info Block B. This data space is accessed through a
data flash interface. For specifics on accessing the data flash, see section Manufacturer Information Blocks in the
bq27546-G1 Technical Reference Manual (SLUUB74).
The key to the bq27546-G1 high-accuracy gas gauging prediction is the Texas Instruments proprietary
Impedance Track™ algorithm. This algorithm uses cell measurements, characteristics, and properties to create
state-of-charge predictions that can achieve less than 1% error across a wide variety of operating conditions and
over the lifetime of the battery.
The bq27546-G1 measures charge/discharge activity by monitoring the voltage across a small-value series
sense resistor (5 mΩ to 20 mΩ typ.) located between the CELL– and the battery’s PACK– terminal. When a cell
is attached to the bq27546-G1, cell impedance is learned based on cell current, cell open-circuit voltage (OCV),
and cell voltage under loading conditions.
The bq27546-G1 external temperature sensing is optimized with the use of a high accuracy negative
temperature coefficient (NTC) thermistor with R25 = 10 kΩ ± 1% and B25/85 = 3435K ± 1% (such as Semitec
103AT) for measurement. The bq27546-G1 can also be configured to use its internal temperature sensor. The
bq27546-G1 uses temperature to monitor the battery-pack environment, which is used for fuel gauging and cell
protection functionality.
To minimize power consumption, the bq27546-G1 has different power modes: NORMAL, SLEEP, FULLSLEEP,
and HIBERNATE. The bq27546-G1 passes automatically between these modes, depending upon the occurrence
of specific events, though a system processor can initiate some of these modes directly. More details can be
found in Power Modes.
NOTE
FORMATTING CONVENTIONS IN THIS DOCUMENT:
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: italics with brackets[ ]. e.g. [TDA]
Data flash bits: italics, bold, and brackets[ ]. e.g. [LED1]
Modes and states: ALL CAPITALS. e.g. UNSEALED mode
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
9
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
8.2 Functional Block Diagram
REGIN
Divider
CE
2.5-V LDO
+
Power Mgt
REG25
Oscillator
System Clock
BAT
TS
ADC
Temp
Sensor
VCC
HDQ
SCL
Communications
HDQ/I2C
SDA
SRP
Impedance
Track
Engine
Coulomb
Counter
SRN
Peripherals
Program Memory
SE
Data Memory
VSS
8.3 Feature Description
8.3.1 Fuel Gauging
The bq27546-G1 fuel gauge measures the cell voltage, temperature, and current to determine battery SOC
based on the Impedance Track algorithm. (For more information, refer to the Theory and Implementation of
Impedance Track Battery Fuel-Gauging Algorithm Application Report [SLUA450].) The device monitors charge
and discharge activity by sensing the voltage across a small-value resistor (5-mΩ to 20-mΩ typical) between the
SRP and SRN pins and in series with the cell. By integrating the 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 state of charge and chemical capacity
(Qmax). The initial Qmax values are taken from a cell manufacturer's data sheet multiplied by the number of
parallel cells. It is also used for the value in 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 Impedance Track Variables
The bq27546-G1 fuel gauge has several data flash variables that permit the user to customize the Impedance
Track algorithm for optimized performance. These variables depend on the power characteristics of the
application, as well as the cell itself.
10
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
Feature Description (continued)
8.3.3 Power Control
8.3.3.1 Reset Functions
When the bq27546-G1 detects a software reset by sending [RESET] Control() subcommand, 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.
8.3.3.2 Wake-Up Comparator
The wake-up comparator is used to indicate a change in cell current while the bq27546-G1 is in SLEEP mode.
Pack Configuration uses bits [RSNS1–RSNS0] to set the sense resistor selection. Pack Configuration also
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. Setting both [RSNS1] and [RSNS0] to 0 disables this feature.
Table 1. IWAKE Threshold Settings (1)
(1)
IWAKE
RSNS1
RSNS0
Vth(SRP-SRN)
0
0
0
Disabled
1
0
0
Disabled
0
0
1
+1.0 mV or –1.0 mV
1
0
1
+2.2 mV or –2.2 mV
0
1
0
+2.2 mV or –2.2 mV
1
1
0
+4.6 mV or –4.6 mV
0
1
1
+4.6 mV or –4.6 mV
1
1
1
+9.8 mV or –9.8 mV
The actual resistance value vs. the sense resistor setting is not important; however, the actual voltage
threshold when calculating the configuration is important. The voltage thresholds are typical values
under room temperature.
8.3.3.3 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 bq27546G1 VCC voltage does not fall below its minimum of 2.4 V during flash write operations.
8.3.4 Autocalibration
The bq27546-G1 device provides an autocalibration feature that measures 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.
Autocalibration of the ADC begins on entry to SLEEP mode, except if Temperature() is ≤ 5°C or Temperature() ≥
45°C.
The fuel gauge also performs a single offset calibration when (1) the condition of AverageCurrent() ≤ 100 mA
and (2) {voltage change since the last offset calibration ≥ 256 mV} or {temperature change since last offset
calibration is greater than 8°C for ≥ 60 seconds}.
Capacity and current measurements will continue at the last measured rate during the offset calibration when
these measurements cannot be performed. If the battery voltage drops more than 32 mV during the offset
calibration, the load current has likely increased considerably; therefore, the offset calibration will be stopped.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
11
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
8.3.5 Communications
8.3.5.1 Authentication
The bq27546-G1 device can act as a SHA-1/HMAC authentication slave by using its internal engine. Sending a
160-bit SHA-1 challenge message to the bq27546-G1 fuel gauge causes the gauge to return a 160-bit digest,
based upon the challenge message and a hidden, 128-bit plain-text authentication key. If this digest matches an
identical one generated by a host or dedicated authentication master, and when operating on the same challenge
message and using the same plain text keys, the authentication process is successful.
8.3.5.2 Key Programming (Data Flash Key)
By default, the bq27546-G1 contains a default plain-text authentication key of
0x0123456789ABCDEFFEDCBA9876543210. This default key is intended for development purposes. It should
be changed to a secret key and the part should be immediately sealed before putting a pack into operation. Once
written, a new plain-text key cannot be read again from the fuel gauge while in SEALED mode.
Once the bq27546-G1 is UNSEALED, the authentication key can be changed from its default value by writing to
the Authenticate() Extended Data Command locations. A 0x00 is written to BlockDataControl() to enable the
authentication data commands. The DataFlashClass() is issued 112 (0x70) to set the Security class. Up to 32
bytes of data can be read directly from the BlockData() (0x40...0x5F) and the authentication key is located at
0x48 (0x40 + 0x08 offset) to 0x57 (0x40 + 0x17 offset). The new authentication key can be written to the
corresponding locations (0x48 to 0x57) using the BlockData() command. The data is transferred to the data flash
when the correct checksum for the whole block (0x40 to 0x5F) is written to BlockDataChecksum() (0x60). The
checksum is (255 – x) where x is the 8-bit summation of the BlockData() (0x40 to 0x5F) on a byte-by-byte basis.
Once the authentication key is written, the gauge can then be sealed again.
8.3.5.3 Key Programming (Secure Memory Key)
The bq27546-G1 secure-memory authentication key is stored in the secure memory of the bq27546-G1 device. If
a secure-memory key has been established, only this key can be used for authentication challenges (the
programmable data flash key is not available). The selected key can only be established/programmed by special
arrangements with TI, using TI’s Secure B-to-B Protocol. The secure-memory key can never be changed or read
from the bq27546-G1 fuel gauge.
8.3.5.4 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 Authenticate() address locations (0x40 through
0x53). After a valid checksum for the challenge is written to AuthenticateChecksum(), the bq27546-G1 uses the
challenge to perform the SHA-1/HMAC computation in conjunction with the programmed key. The bq27546-G1
completes the SHA-1/HMAC computation and writes the resulting digest to Authenticate(), overwriting the preexisting challenge. The host should wait at least 45 ms to read the resulting digest. The host may then read this
response and compare it against the result created by its own parallel computation.
8.3.5.5 HDQ Single-Pin Serial Interface
The HDQ interface is an asynchronous return-to-one protocol where a processor sends the command code to
the bq27546-G1 device. With HDQ, the least significant bit (LSB) of a data byte (command) or word (data) is
transmitted first. Note that the DATA signal on pin 12 is open-drain and requires an external pull-up resistor. The
8-bit command code consists of two fields: the 7-bit HDQ command code (bits 0–6) and the 1-bit R/W field (MSB
bit 7). The R/W field directs the bq27546-G1 either to
• Store the next 8 or 16 bits of data to a specified register or
• Output 8 bits of data from the specified register.
The HDQ peripheral can transmit and receive data as either an HDQ master or slave.
12
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
HDQ serial communication is normally initiated by the host processor sending a break command to the bq27546G1 device. A break is detected when the DATA pin is driven to a logic-low state for a time t(B) or greater. The
DATA pin should then be returned to its normal ready high logic state for a time t(BR). The bq27546-G1 fuel
gauge is now ready to receive information from the host processor.
The bq27546-G1 device is shipped in I2C mode. TI provides tools to enable the HDQ peripheral. The HDQ
Communication Basics Application Report (SLUA408A) provides details of HDQ communication.
8.3.5.6 HDQ Host Interruption Feature
The default bq27546-G1 gauge behaves as an HDQ slave-only device when HDQ mode is enabled. If the HDQ
interrupt function is enabled, the bq27546-G1 is capable of mastering and also communicating to an HDQ
device. There is no mechanism for negotiating what is to function as the HDQ master and care must be taken to
avoid message collisions. The interrupt is signaled to the host processor with the bq27546-G1 mastering an HDQ
message. This message is a fixed message that will be used to signal the interrupt condition. The message itself
is 0x80 (slave write to register 0x00) with no data byte being sent as the command, and is not intended to
convey any status of the interrupt condition. The HDQ interrupt function is disabled by default and needs to be
enabled by command.
When the SET_HDQINTEN subcommand is received, the bq27546-G1 device detects any of the interrupt
conditions and asserts the interrupt at 1-s intervals until the CLEAR_HDQINTEN command is received or the
count of HDQHostIntrTries has lapsed.
The number of tries for interrupting the host is determined by the data flash parameter named
HDQHostIntrTries.
8.3.5.6.1 Low Battery Capacity
This feature works identically to SOC1. It uses the same data flash entries as SOC1 and triggers interrupts as
long as SOC1 = 1 and HDQIntEN = 1.
8.3.5.6.2 Temperature
This feature triggers an interrupt based on the OTC (Overtemperature in Charge) or OTD (Overtemperature in
Discharge) condition being met. It uses the same data flash entries as OTC or OTD and triggers interrupts as
long as either the OTD or OTC condition is met and HDQIntEN = 1.
8.3.5.7 I2C Interface
The fuel 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 a write or read, respectively.
Host Generated
S
0 A
ADDR[6:0]
Fuel Gauge Generated
CMD[7:0]
A
A P
DATA[7:0]
S
ADDR[6:0]
1
(a)
S
ADDR[6:0]
0 A
A
DATA[7:0]
N P
(b)
CMD[7:0]
A Sr
ADDR[6:0]
1
A
DATA[7:0]
N P
...
DATA[7:0]
(c)
S
ADDR[6:0]
0 A
CMD[7:0]
A Sr
ADDR[6:0]
1
A
DATA[7:0]
A
N P
(d)
Figure 7. Supported I2C formats: (a) 1-byte write, (b) quick read, (c) 1 byte-read, and (d) incremental read
(S = Start, Sr = Repeated Start, A = Acknowledge, N = No Acknowledge, and P = Stop).
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 bq27546-G1 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).
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
13
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
Attempt to write a read-only address (NACK after data sent by master):
S
0
ADDR[6:0]
A
A
CMD[7:0]
A
DATA[7:0]
P
Attempt to read an address above 0x7F (NACK command):
S
0
ADDR[6:0]
CMD[7:0]
A
N P
Attempt at incremental writes (NACK all extra data bytes sent):
S
ADDR[6:0]
CMD[7:0]
0 A
A
DATA[7:0]
A
DATA[7:0]
N
A
...
...
N P
Incremental read at the maximum allowed read address:
S
ADDR[6:0]
0 A
A Sr
CMD[7:0]
1
ADDR[6:0]
A
DATA[7:0]
Address
0x7F
N P
DATA[7:0]
Data From
addr 0x7F
Data From
addr 0x00
The I2C engine releases both SDA and SCL if the I2C bus is held low for t(BUSERR). If the fuel 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.
8.3.5.7.1 I2C Time Out
The I2C engine will release both SDA and SCL if the I2C bus is held low for about 2 seconds. If the bq27546-G1
device were holding the lines, releasing them frees for the master to drive the lines.
8.3.5.7.2 I2C Command Waiting Time
To ensure there are correct results of a command with the 400-KHz I2C operation, a proper waiting time should
be added between issuing command and reading results. For subcommands, the following diagram shows the
waiting time required between issuing the control command the reading the status with the exception of the
checksum command. A 100-ms waiting time is required between the checksum command and reading result. For
read-write standard commands, 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 should not issue all standard commands
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]
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]
66ms
A
DATA [7:0]
N P
A
DATA [7:0]
A
66ms
Waiting time between control subcommand and reading results
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]
66ms
Waiting time between continuous reading results
Figure 8. I2C Command Waiting Time
14
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
8.3.5.7.3 I2C Clock Stretching
I2C clock stretches can occur during all modes of fuel gauge operation. In the SLEEP and HIBERNATE modes, a
short clock stretch will occur on all I2C traffic as the device must wake-up to process the packet. In NORMAL and
SLEEP modes, clock stretching will only occur for packets addressed for the fuel gauge. The timing of stretches
will vary as interactions between the communicating host and the gauge are asynchronous. The I2C clock
stretches may occur after start bits, the ACK/NAK bit, and first data bit transmit on a host read cycle. The
majority of clock stretch periods are small (≤ 4 ms) as the I2C interface peripheral and CPU firmware perform
normal data flow control. However, less frequent but more significant clock stretch periods may occur when data
flash (DF) is being written by the CPU to update the resistance (Ra) tables and other DF parameters, such as
Qmax. Due to the organization of DF, updates need to be written in data blocks consisting of multiple data bytes.
An Ra table update requires erasing a single page of DF, programming the updated Ra table and a flag. The
potential I2C clock stretching time is 24-ms max. This includes 20-ms page erase and 2-ms row programming
time (×2 rows). The Ra table updates occur during the discharge cycle and at up to 15 resistance grid points that
occur during the discharge cycle.
A DF block write typically requires a max of 72 ms. This includes copying data to a temporary buffer and
updating DF. This temporary buffer mechanism is used for protection from power failure during a DF update. The
first part of the update requires 20 ms time to erase the copy buffer page, 6 ms to write the data into the copy
buffer, and the program progress indicator (2 ms for each individual write). The second part of the update is
writing to the DF and requires 44-ms DF block update time. This includes a 20-ms each page erase for two
pages and a 2-ms each row write for two rows.
In the event that a previous DF write was interrupted by a power failure or reset during the DF write, an
additional 44-ms max DF restore time is required to recover the data from a previously interrupted DF write. In
this power failure recovery case, the total I2C clock stretching is 116-ms max.
Another case where I2C clock stretches is at the end of discharge. The update to the last discharge data will go
through the DF block update twice because two pages are used for the data storage. The clock stretching in this
case is 144-ms max. This occurs if there has been a Ra table update during the discharge.
8.4 Device Functional Modes
8.4.1 Power Modes
The bq27546-G1 device has four power modes: NORMAL, SLEEP, FULLSLEEP, and HIBERNATE.
• In NORMAL mode, the bq27546-G1 is fully powered and can execute any allowable task.
• In SLEEP mode, the fuel gauge exists in a reduced-power state, periodically taking measurements and
performing calculations.
• During FULLSLEEP mode, the bq27545-G1 periodically takes data measurements and updates its data set.
However, a majority of its time is spent in an idle condition.
• In HIBERNATE mode, the fuel gauge is in a very low power state, but can be awoken by communication or
certain I/O activity.
Figure 9 shows the relationship among these modes. Details are described in the sections that follow.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
15
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
Device Functional Modes (continued)
POR
Exit From HIBERNATE
VCELL < POR threshold
Exit From HIBERNATE
Communication Activity
NORMAL
OR
The device clears Control Status
[HIBERNATE] = 0
Recommend Host also set Control
Status [HIBERNATE] = 0
Fuel gauging and data
updated every 1s
Exit From SLEEP
Pack Configuration [SLEEP] = 0
OR
| AverageCurrent( ) | > Sleep Current
OR
Current is Detected above IWAKE
Entry to SLEEP
Pack Configuration [SLEEP] = 1
AND
| AverageCurrent( ) |≤ Sleep Current
SLEEP
Fuel gauging and data
updated every 20 seconds
HIBERNATE
Wakeup From HIBERNATE
Communication Activity
AND
Comm address is NOT for the device
Disable all device
subcircuits except GPIO.
Entry to FULLSLEEP
If Full Sleep Wait Time = 0,
Host must set Control Status
[FULLSLEEP]=1
Exit From WAIT_HIBERNATE
WAITFULLSLEEP
Host must set Control Status
[HIBERNATE] = 0
AND
VCELL > Hibernate Voltage
Exit From WAIT_HIBERNATE
Cell relaxed
AND
| AverageCurrent() | < Hibernate
Current
FULLSLEEP Count Down
Entry to FULLSLEEP
Count 0, Exit From WAITFULLSLEEP
Guage ignores Control Status Any Communication Cmd
[FULLSLEEP]
Fuel gauging and data
updated every 20 seconds
In low power state of SLEEP
mode. Gas gauging and data
updated every 20 seconds
Exit From SLEEP
(Host has set Control Status
[HIBERNATE] = 1
OR
VCELL < Hibernate Voltage
System Shutdown
System Sleep
Figure 9. Power Mode Diagram
8.4.1.1 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, 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.
8.4.1.2 SLEEP Mode
SLEEP mode is entered automatically if the feature is enabled (Pack Configuration [SLEEP]) = 1) and
AverageCurrent() is below the programmable level Sleep Current. Once entry into SLEEP mode is qualified, but
prior to entering it, the bq27546-G1 performs an ADC autocalibration to minimize offset.
While in SLEEP mode, the fuel gauge can suspend serial communications as much as 4 ms by holding the
comm line(s) low. This delay is necessary to correctly process host communication, since the fuel gauge
processor is mostly halted in SLEEP mode.
16
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
Device Functional Modes (continued)
During SLEEP mode, the bq27546-G1 periodically takes data measurements and updates its data set. However,
a majority of its time is spent in an idle condition.
The bq27546-G1 exits SLEEP if any entry condition is broken, specifically when (1) AverageCurrent() rises
above Sleep Current, or (2) a current in excess of IWAKE through RSENSE is detected when the IWAKE comparator
is enabled.
8.4.1.3 FULLSLEEP Mode
FULLSLEEP mode is entered automatically when the bq27546-G1 is in SLEEP mode and the timer counts down
to 0 (Full Sleep Wait Time > 0). FULLSLEEP mode is entered immediately after entry to SLEEP if Full Sleep
Wait Time is set to 0 and the host sets the [FULLSLEEP] bit in the CONTROL_STATUS register using the
SET_FULLSLEEP subcommand.
The gauge exits the FULLSLEEP mode when there is any communication activity. The [FULLSLEEP] bit can
remain set (Full Sleep Wait Time > 0) or be cleared (Full Sleep Wait Time ≤ 0) after exit of FULLSLEEP mode.
Therefore, EVSW communication activity might cause the gauge to exit FULLSLEEP mode and display the
[FULLSLEEP] bit as clear. The execution of SET_FULLSLEEP to set [FULLSLEEP] bit is required when Full
Sleep Wait Time ≤ 0 in order to re-enter FULLSLEEP mode. FULLSLEEP mode can be verified by measuring
the current consumption of the gauge. In this mode, the high frequency oscillator is turned off. The power
consumption is further reduced in this mode compared to SLEEP mode.
While in FULLSLEEP mode, the fuel gauge can suspend serial communications as much as 4 ms by holding the
comm line(s) low. This delay is necessary to correctly process host communication, since the fuel gauge
processor is mostly halted in SLEEP mode.
The bq27546-G1 exits FULLSLEEP if any entry condition is broken, specifically when (1) AverageCurrent() rises
above Sleep Current, or (2) a current in excess of IWAKE through RSENSE is detected when the IWAKE comparator
is enabled.
8.4.1.4 HIBERNATE Mode
HIBERNATE mode should be used for long-term pack storage or when the host system needs to enter a lowpower state and minimal gauge power consumption is required. This mode is ideal when the host is set to its
own HIBERNATE, SHUTDOWN, or OFF mode. The gauge waits to enter HIBERNATE mode until it has taken a
valid OCV measurement (cell relaxed) and the value of the average cell current has fallen below Hibernate
Current. When the conditions are met, the fuel gauge can enter HIBERNATE due to either low cell voltage or by
having the [HIBERNATE] bit of the CONTROL_STATUS register set. The gauge remains in HIBERNATE mode
until any communication activity appears on the communication lines and the address is for the bq27546-G1
device. In addition, the SE pin SHUTDOWN mode function is supported only when the fuel gauge enters
HIBERNATE due to low cell voltage.
When the gauge wakes up from HIBERNATE mode, the [HIBERNATE] bit of the CONTROL_STATUS register is
cleared. The host is required to set the bit in order to allow the gauge to re-enter HIBERNATE mode if desired.
Because the fuel gauge is dormant in HIBERNATE mode, the battery should not be charged or discharged in this
mode, because any changes in battery charge status will not be measured. If necessary, the host equipment can
draw a small current (generally infrequent and less than 1 mA) for purposes of low-level monitoring and updating;
however, the corresponding charge drawn from the battery will not be logged by the gauge. Once the gauge
exits to NORMAL mode, the IT algorithm will take approximately 3 s to re-establish the correct battery capacity
and measurements, regardless of the total charge drawn in HIBERNATE mode. During this period of reestablishment, the gauge reports values previously calculated prior to entering HIBERNATE mode. The host can
identify exit from HIBERNATE mode by checking if Voltage() < Hibernate Voltage or [HIBERNATE] bit is cleared
by the gauge.
If a charger is attached, the host should immediately take the fuel gauge out of HIBERNATE mode before
beginning to charge the battery. Charging the battery in HIBERNATE mode will result in a notable gauging error
that will take several hours to correct. It is also recommended to minimize discharge current during exit from
HIBERNATE.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
17
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
Device Functional Modes (continued)
8.4.2 System Control Function
The fuel gauge provides system control functions that allow the fuel gauge to enter SHUTDOWN mode in order
to power-off with the assistance of an external circuit or provide interrupt function to the system. Table 2 shows
the configurations for SE and HDQ pins.
Table 2. SE and HDQ Pin Functions
COMMUNICATION
MODE
[INTSEL]
SE PIN FUNCTION
I2C
0 (default)
Interrupt Mode
HDQ
HDQ PIN FUNCTION
Not Used
(1)
HDQ Mode (2)
2
I C
1
(1)
(2)
Interrupt Mode
Shutdown Mode
HDQ
HDQ Mode (2)
The [SE_EN] bit in Pack Configuration can be enabled to use the [SE] and [SHUTDWN] bits in the
CONTROL_STATUS() function. The SE pin shutdown function is disabled.
The HDQ pin is used for communication and the HDQ Host Interrupt Feature is available.
8.4.2.1 SHUTDOWN Mode
In SHUTDOWN mode, the SE pin is used to signal the external circuit to power-off the fuel gauge. This feature is
useful to shut down the fuel gauge in a deeply discharged battery to protect the battery. By default, SHUTDOWN
mode is in NORMAL state. By sending the SET_SHUTDOWN subcommand or setting the [SE_EN] bit in the
Pack Configuration register, the [SHUTDWN] bit is set and enables the shutdown feature. When this feature is
enabled and [INTSEL] is set, the SE pin can be in NORMAL state or SHUTDOWN state. The SHUTDOWN state
can be entered in HIBERNATE mode (only if HIBERNATE mode is enabled due to low cell voltage). All other
power modes will default the SE pin to NORMAL state. Table 3 shows the SE pin state in NORMAL or
SHUTDOWN mode. The CLEAR_SHUTDOWN subcommand or clearing [SE_EN] bit in the Pack Configuration
register can be used to disable SHUTDOWN mode.
The SE pin will be high impedance at power-on reset (POR), and the [SE_POL] does not affect the state of SE
pin at POR. Also, [SE_PU] configuration changes will only take effect after POR. In addition, the [INTSEL] only
controls the behavior of the SE pin; it does not affect the function of [SE] and [SHUTDWN] bits.
Table 3. SE Pin State
SHUTDOWN Mode
[INTSEL] = 1 and
([SE_EN] or [SHUTDOWN] = 1)
[SE_PU]
[SE_POL]
NORMAL State
SHUTDOWN State
0
0
High Impedance
0
0
1
0
High Impedance
1
0
1
0
1
1
0
1
8.4.2.2 INTERRUPT Mode
By using the INTERRUPT mode, the system can be interrupted based on detected fault conditions, as specified
in Table 6. The SE or HDQ pin can be selected as the interrupt pin by configuring the [INTSEL] bit based on . In
addition, the pin polarity and pullup (SE pin only) can be configured according to the system's needs, as
described in Table 4 or Table 5.
Table 4. SE Pin in Interrupt Mode ([INTSEL] = 0)
18
[SE_PU]
[INTPOL]
INTERRUPT CLEAR
0
0
High Impedance
0
0
1
0
High Impedance
1
0
1
0
1
1
0
1
Submit Documentation Feedback
INTERRUPT SET
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
Table 5. HDQ Pin in Interrupt Mode ([INTSEL] = 1)
[INTPOL]
INTERRUPT CLEAR
INTERRUPT SET
0
High Impedance
0
1
0
High Impedance
Table 6. Interrupt Mode Fault Conditions
INTERRUPT CONDITION
Flags() STATUS
BIT
SOC1 Set
[SOC1]
Always
This interrupt is raised when the [SOC1] flag is set.
Battery High
[BATHI]
Always
This interrupt is raised when the [BATHI] flag is set.
Battery Low
[BATLOW]
Always
This interrupt is raised when the [BATLOW] flag is
set.
Over-Temperature Charge
[OTC]
OT Chg Time ≠ 0
This interrupt is raised when the [OTC] flag is set.
Over-Temperature
Discharge
[OTD]
OT Dsg Time ≠ 0
This interrupt is raised when the [OTD] flag is set.
Internal Short Detection
[ISD]
[SE_ISD] = 1 in Pack
Configuration B
This interrupt is raised when the [ISD] flag is set.
Tab Disconnect Detection
[TDD]
[SE_TDD] = 1 in Pack
Configuration B
This interrupt is raised when the [TDD] flag is set.
Imax
[IMAX]
[IMAXEN] = 1 in Pack
Configuration D
This interrupt is raised when the [IMAX] flag is set.
[SOC1]
[BTP_EN] = 1 in Pack
Configuration C. The BTP
interrupt supersedes all other
interrupt sources, which are
unavailable when BTP is active.
This interrupt is raised when RemainingCapacity() ≤
BTPSOC1Set() or RemainingCapacity() ≥
BTPSOC1Clear() during battery discharge or
charge, respectively. The interrupt remains asserted
until new values are written to both the
BTPSOC1Set() and BTPSOC1Clear() registers.
Battery Trip Point (BTP)
ENABLE CONDITION
COMMENT
8.4.3 Security Modes
The bq27546-G1 provides three security modes (FULL ACCESS, UNSEALED, and SEALED) that control data
flash access permissions. Data flash refers to those data flash locations that are accessible to the user.
Manufacture Information refers to the two 32-byte blocks.
8.4.3.1 Sealing and Unsealing Data Flash
The bq27546-G1 implements a key-access scheme to transition between SEALED, UNSEALED, and FULL
ACCESS modes. Each transition requires that a unique set of two keys be sent to the bq27546-G1 via the
Control() command. The keys must be sent consecutively with no other data being written to the Control()
register in between.
NOTE
To avoid conflict, the keys must be different from the codes presented in the CNTL DATA
column of Table 8 subcommands.
When in SEALED mode the [SS] bit of CONTROL_STATUS is set, but when the UNSEAL keys are correctly
received by the bq27546-G1, the [SS] bit is cleared. When the full-access keys are correctly received the
CONTROL_STATUS [FAS] bit is cleared.
Both Unseal Key and Full-Access Key have two words and are stored in data flash. The first word is Key 0 and
the second word is Key 1. The order of the keys sent to bq27546-G1 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
an example, if the Unseal Key is 0x56781234, key 1 is 0x1234 and key 0 is 0x5678. Then Control() should
supply 0x3412 and 0x7856 to unseal the part. The Unseal Key and the Full-Access Key can only be updated
when in FULL ACCESS mode.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
19
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
8.5 Programming
8.5.1 Standard Data Commands
The bq27546-G1 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 7. Each
protocol has specific means to access the data at each Command Code. DataRAM is updated and read by the
gauge only once per second. Standard commands are accessible in NORMAL operation mode.
Table 7. Standard Commands
COMMAND CODE
UNIT
SEALED ACCESS
Control()
COMMAND NAME
0x00 and 0x01
—
RW
AtRate()
0x02 and 0x03
mA
RW
UnfilteredSOC()
0x04 and 0x05
%
R
Temperature()
0x06 and 0x07
0.1°K
R
Voltage()
0x08 and 0x09
mV
R
Flags()
0x0A and 0x0B
—
R
NomAvailableCapacity()
0x0C and 0x0D
mAh
R
FullAvailableCapacity()
0x0E and 0x0F
mAh
R
RemainingCapacity()
0x10 and 0x11
mAh
R
FullChargeCapacity()
0x12 and 0x13
mAh
R
AverageCurrent()
0x14 and 0x15
mA
R
TimeToEmpty()
0x16 and 0x17
min
R
FullChargeCapacityFiltered()
0x18 and 0x19
mAh
R
SafetyStatus()
0x1A and 0x1B
—
R
FullChargeCapacityUnfiltered()
0x1C and 0x1D
mAh
R
Imax()
0x1E and 0x1F
mA
R
RemainingCapacityUnfiltered()
0x20 and 0x21
mAh
R
RemainingCapacityFiltered()
0x22 and 0x23
mAh
R
BTPSOC1Set()
0x24 and 0x25
mAh
RW
BTPSOC1Clear()
0x26 and 0x27
mAh
RW
InternalTemperature()
0x28 and 0x29
0.1°K
R
CycleCount()
0x2A and 0x2B
Counts
R
StateofCharge()
0x2C and 0x2D
%
R
StateofHealth()
0x2E and 0x2F
% / num
R
ChargingVoltage()
0x30 and 0x31
mV
R
ChargingCurrent)
0x32 and 0x33
mA
R
PassedCharge()
0x34 and 0x35
mAh
R
DOD0()
0x36 and 0x37
hex
R
SelfDischargeCurrent()
0x34 and 0x35
mA
R
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
bq27546-G1 during normal operation and additional features when the bq27546-G1 is in different access modes,
as described in Table 8.
Table 8. Control() Subcommands
SUBCOMMAND
CODE
SEALED
ACCESS
CONTROL_STATUS
0x0000
Yes
Reports the status of DF Checksum, Impedance Track, and so on
DEVICE_TYPE
0x0001
Yes
Reports the device type of 0x0541 (indicating bq27546-G1)
SUBCOMMAND NAME
20
DESCRIPTION
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
Table 8. Control() Subcommands (continued)
SUBCOMMAND
CODE
SEALED
ACCESS
FW_VERSION
0x0002
Yes
Reports the firmware version on the device type
HW_VERSION
0x0003
Yes
Reports the hardware version on the device type
RESET_DATA
0x0005
Yes
Returns reset data
PREV_MACWRITE
0x0007
Yes
Returns previous Control() subcommand code
CHEM_ID
0x0008
Yes
Reports the chemical identifier of the Impedance Track configuration
BOARD_OFFSET
0x0009
No
Forces the device to measure and store the board offset
SUBCOMMAND NAME
DESCRIPTION
CC_OFFSET
0x000A
No
Forces the device to measure the CC offset
DF_VERSION
0x000C
Yes
Reports the data flash version of the device
SET_FULLSLEEP
0x0010
Yes
Sets the CONTROL_STATUS[FULLSLEEP] bit to 1
SET_SHUTDOWN
0x0013
Yes
Sets the CONTROL_STATUS[SHUTDWN] bit to 1
CLEAR_SHUTDOWN
0x0014
Yes
Clears the CONTROL_STATUS[SHUTDWN] bit to 1
SET_HDQINTEN
0x0015
Yes
Forces CONTROL_STATUS [HDQHOSTIN] to 1
CLEAR_HDQINTEN
0x0016
Yes
Forces CONTROL_STATUS [HDQHOSTIN] to 0
STATIC_CHEM_CHKSUM
0x0017
Yes
Calculates chemistry checksum
ALL_DF_CHKSUM
0x0018
Yes
Reports checksum for all data flash excluding device specific variables
STATIC_DF_CHKSUM
0x0019
Yes
Reports checksum for static data flash excluding device specific variables
SYNC_SMOOTH
0x001E
Yes
Synchronizes RemCapSmooth() and FCCSmooth() with RemCapTrue()
and FCCTrue()
SEALED
0x0020
No
Places the fuel gauge in SEALED access mode
IT_ENABLE
0x0021
No
Enables the Impedance Track algorithm
IMAX_INT_CLEAR
0x0023
Yes
Clears an Imax interrupt that is currently asserted on the RC2 pin
CAL_ENABLE
0x002D
No
Toggle CALIBRATION mode
RESET
0x0041
No
Forces a full reset of the fuel gauge
EXIT_CAL
0x0080
No
Exit CALIBRATION mode
ENTER_CAL
0x0081
No
Enter CALIBRATION mode
OFFSET_CAL
0x0082
No
Reports internal CC offset in CALIBRATION mode
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
21
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
8.6 Register Maps
8.6.1 Pack Configuration Register
Some bq27546-G1 pins are configured via the Pack Configuration data flash register, as indicated in Table 9.
This register is programmed/read via the methods described in the bq27546-G1 Technical Reference Manual
(SLUUB74). The register is located at Subclass = 64, offset = 0.
Table 9. Pack Configuration Bit Definition
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
High Byte
RESCAP
CALEN
INTPOL
INTSEL
RSVD
IWAKE
RSNS1
RSNS0
Default =
0
0
0
1
0
0
0
1
Low Byte
GNDSEL
RFACTSTEP
SLEEP
RMFCC
SE_PU
SE_POL
SE_EN
TEMPS
Default =
0
1
1
1
0
1
1
1
0x11
0x77
RESCAP = No-load rate of compensation is applied to the reserve capacity calculation. True when set.
CALEN = Calibration mode is enabled.
INTPOL = Polarity for Interrupt pin. (See INTERRUPT Mode.)
INTSEL = Interrupt Pin select: 0 = SE pin, 1 = HDQ pin. (See INTERRUPT Mode.)
RSVD = Reserved. Must be 0.
IWAKE/RSNS1/RSNS0 = These bits configure the current wake function (see Wake-Up Comparator).
GNDSEL = The ADC ground select control. The VSS (pins C1, C2) is selected as ground reference when the bit is clear.
Pin A1 is selected when the bit is set.
RFACTSTEP = Enables Ra step up/down to Max/Min Res Factor before disabling Ra updates.
SLEEP = The fuel gauge can enter sleep, if operating conditions allow. True when set. (See SLEEP Mode.)
RMFCC = RM is updated with the value from FCC, on valid charge termination. True when set.
SE_PU = Pull-up enable for SE pin. True when set (push-pull).
SE_POL = Polarity bit for SE pin. SE is active high when set (makes SE high when gauge is ready for shutdown).
SE_EN = Indicates if set the shutdown feature is enabled. True when set.
TEMPS = Selects external thermistor for Temperature() measurements. True when set.
22
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
8.6.2 Pack Configuration B Register
Some bq27546-G1 pins are configured via the Pack Configuration B data flash register, as indicated in
Table 10. This register is programmed/read via the methods described in the bq27546-G1 Technical Reference
Manual (SLUUB74). The register is located at Subclass = 64, offset = 2.
Table 10. Pack Configuration B Bit Definition
Default =
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
ChgDoD
EoC
SE_TDD
VconsEN
SE_ISD
RSVD
LFPRelax
DoDWT
FConvEn
1
0
1
0
0
1
1
1
0x67
ChgDoDEoC = Enable DoD at EoC recalculation during charging only. True when set. The default setting is recommended.
SE_TDD = Enable Tab Disconnection Detection. True when set.
VconsEN = Enable voltage consistency check. True when set. The default setting is recommended.
SE_ISD = Enable Internal Short Detection. True when set.
RSVD = Reserved. Must be 0.
LFPRelax = Enable LiFePO4 long relaxation mode. True when set.
DoDWT =
Enable DoD weighting feature of gauging algorithm. This feature can improve accuracy during relaxation in a
flat portion of the voltage profile, especially when using LiFePO4 chemistry. True when set.
FConvEn = Enable fast convergence algorithm. The default setting is recommended.
8.6.3 Pack Configuration C Register
Some bq27546-G1 algorithm settings are configured via the Pack Configuration C data flash register, as
indicated in Table 11. This register is programmed/read via the methods described in the bq27546-G1 Technical
Reference Manual (SLUUB74). The register is located at Subclass = 64, offset = 3.
Table 11. Pack Configuration C Bit Definition
Default =
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RSVD
RSVD
RelaxRCJumpOK
SmoothEn
SleepWk
Chg
RSVD
RSVD
RSVD
0
0
0
1
1
0
0
0
0x18
RSVD = Reserved. Must be 0.
RelaxRCJumpOK =
Allow SOC to change due to temperature change during relaxation when SOC smoothing algorithm is enabled.
True when set.
SmoothEn = Enable SOC smoothing algorithm. True when set.
SleepWkChg = Enables compensation for the passed charge missed when waking from SLEEP mode.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
23
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
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 bq27546-G1 measures the cell voltage, temperature, and current to determine battery SOC based on
Impedance Track™ algorithm (see Theory and Implementation of Impedance Track Battery Fuel-Gauging
Algorithm Application Note (SLUA450) for more information). The bq27546-G1 monitors charge and discharge
activity by sensing the voltage across a small-value resistor (5 mΩ to 20 mΩ typ.) between the SRP and SRN
pins and in series with the cell. By integrating charge passing through the battery, the battery’s SOC is adjusted
during battery charge or discharge.
24
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
bq27546-G1
9.2 Typical Applications
2
1
TP2
Vin Max: 4.2 V
Current Max: 3 A
TP1
TB1
CELL +
CELL +
CELL –
CELL –
C1
0.1 µF
C2
0.1 µF
J3
2
1
Place C1 close to BAT pin
Place C2 close to REGIN pin
CE
3
ON
OFF
VCC
C3
1 µF
TP6
VCC
REGIN
SE
VCC
CE
C4
SDA B3
VSS C1
SRN B1
TS B2
HDQ A2
SCL A3
SRP A1
.47 µf
Ext Thermistor
RT1
10 kΩ
NC/GPIO
E3
NC/GPIO
E2
BAT
E1
D2
D3
D1
C3
C2
VSS
TS
0.1 µF
C7
Place R1, R3, C5, C6, C7
Close to GG
R2
0.01
R3
100
R15
330
C13
0.1 µF
R4
100
R6
100
R7
100
D1
R17
R9
100
R10
100
AZ23C5V6-7
100
R8
AZ23C5V6-7
D2
1k
1
2
J7
J6
VCC
R12
4.7 k
4
3
2
1
1
VCC
1
2
Q1:B
J8
J9
VSS
HDQ
SDA
VSS
3
J10
SCL
1
2
4
R15
10 k
2
R14
10 k
Q1:A
SI6926DQ
C15
0.1 µF
U2/Q1A/Q1B
Low-pass filter for coulomb counter input should be placed
as close as possible to gas gauge IC. Connection to sense
resistor must be of Kelvin connection type.
U2
MM3511
6
3
V–
DOUT
2
5
VDD COUT
1
4 VSS
DS
SI6926DQ
C14
0.1 µF
TP5
TB2
PACK–/Load–
PACK+/Load+
PACK+
TP9
2
1
TP10
PACK–
Product Folder Links: bq27546-G1
25
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
TP7
VCC
SE
TP5
R1
100
0.1 µF
C6
0.1 µF
C5
TP8
R7, R8, and R9 are optional pull-down resistors if pull-up resistors are applied.
Figure 10. Schematic
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
Typical Applications (continued)
9.2.1 Design Requirements
Several key parameters must be updated to align with a given application's battery characteristics. For highest
accuracy gauging, it is important to follow-up this initial configuration with a learning cycle to optimize resistance
and maximum chemical capacity (Qmax) values prior to sealing and shipping systems to the field. Successful
and accurate configuration of the fuel gauge for a target application can be used as the basis for creating a
"golden" file that can be written to all gauges, assuming identical pack design and Li-Ion cell origin (chemistry,
lot, and so on). Calibration data is included as part of this golden file to cut down on system production time. If
using this method, it is recommended to average the voltage and current measurement calibration data from a
large sample size and use these in the golden file. Table 12 shows the items that should be configured to
achieve reliable protection and accurate gauging with minimal initial configuration.
Table 12. Key Data Flash Parameters for Configuration
NAME
DEFAULT
UNIT
RECOMMENDED SETTING
Design Capacity
1000
mAh
Set based on the nominal pack capacity as interpreted from the cell
manufacturer's data sheet. If multiple parallel cells are used, should be set to N
× Cell Capacity.
Design Energy Scale
1
—
Reserve Capacity-mAh
0
mAh
Set to desired runtime remaining (in seconds/3600) × typical applied load
between reporting 0% SOC and reaching Terminate Voltage, if needed.
Cycle Count Threshold
900
mAh
Set to 90% of configured Design Capacity.
Should be configured using TI-supplied Battery Management Studio (bqStudio)
software. Default open-circuit voltage and resistance tables are also updated in
conjunction with this step.
Do not attempt to manually update reported Device Chemistry as this does not
change all chemistry information. Always update chemistry using the bqStudio
software tool.
Set to 10 to convert all power values to cWh or to 1 for mWh. Design Energy
is divided by this value.
Chem ID
0100
hex
Load Mode
1
—
Set to applicable load model, 0 for constant current or 1 for constant power.
Load Select
1
—
Set to load profile which most closely matches typical system load.
Qmax Cell 0
1000
mAh
Set to initial configured value for Design Capacity. The gauge will update this
parameter automatically after the optimization cycle and for every regular
Qmax update thereafter.
Cell0 V at Chg Term
4200
mV
Set to nominal cell voltage for a fully charged cell. The gauge will update this
parameter automatically each time full charge termination is detected.
Terminate Voltage
3200
mV
Set to empty point reference of battery based on system needs. Typical is
between 3000 and 3200 mV.
Ra Max Delta
44
mΩ
Set to 15% of Cell0 R_a 4 resistance after an optimization cycle is completed.
Charging Voltage
4200
mV
Set based on nominal charge voltage for the battery in normal conditions
(25°C, and so on). Used as the reference point for offsetting by Taper Voltage
for full charge termination detection.
Taper Current
100
mA
Set to the nominal taper current of the charger + taper current tolerance to
ensure that the gauge will reliably detect charge termination.
Taper Voltage
100
mV
Sets the voltage window for qualifying full charge termination. Can be set
tighter to avoid or wider to ensure possibility of reporting 100% SOC in outer
JEITA temperature ranges that use derated charging voltage.
Dsg Current Threshold
60
mA
Sets threshold for gauge detecting battery discharge. Should be set lower than
minimal system load expected in the application and higher than Quit Current.
Chg Current Threshold
75
mA
Sets the threshold for detecting battery charge. Can be set higher or lower
depending on typical trickle charge current used. Also should be set higher
than Quit Current.
Quit Current
40
mA
Sets threshold for gauge detecting battery relaxation. Can be set higher or
lower depending on typical standby current and exhibited in the end system.
Avg I Last Run
–299
mA
Current profile used in capacity simulations at onset of discharge or at all times
if Load Select = 0. Should be set to nominal system load. Is automatically
updated by the gauge every cycle.
Avg P Last Run
–1131
mW
Power profile used in capacity simulations at onset of discharge or at all times
if Load Select = 0. Should be set to nominal system power. Is automatically
updated by the gauge every cycle.
26
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
Typical Applications (continued)
Table 12. Key Data Flash Parameters for Configuration (continued)
NAME
DEFAULT
UNIT
RECOMMENDED SETTING
15
mA
Sets the threshold at which the fuel gauge enters SLEEP mode. Take care in
setting above typical standby currents else entry to SLEEP may be
unintentionally blocked.
Charge T0
0
°C
Sets the boundary between charging inhibit and charging with T0 parameters.
Charge T1
10
°C
Sets the boundary between charging with T0 and T1 parameters.
Charge T2
45
°C
Sets the boundary between charging with T1 and T2 parameters.
Charge T3
50
°C
Sets the boundary between charging with T2 and T3 parameters.
Charge T4
60
°C
Sets the boundary between charging with T3 and T4 parameters.
Charge Current T0
50
% Des Cap
Sets the charge current parameter for T0.
Charge Current T1
50
% Des Cap
Sets the charge current parameter for T1.
Charge Current T2
50
% Des Cap
Sets the charge current parameter for T2.
Charge Current T3
50
% Des Cap
Sets the charge current parameter for T3.
Sleep Current
Charge Current T4
0
% Des Cap
Sets the charge current parameter for T4.
Charge Voltage T0
210
20 mV
Sets the charge voltage parameter for T0.
Charge Voltage T1
210
20 mV
Sets the charge voltage parameter for T1.
Charge Voltage T2
207
20 mV
Sets the charge voltage parameter for T2.
Charge Voltage T3
205
20 mV
Sets the charge voltage parameter for T3.
Charge Voltage T4
0
20 mV
Sets the charge voltage parameter for T4.
Chg Temp Hys
5
°C
Adds temperature hysteresis for boundary crossings to avoid oscillation if
temperature is changing by a degree or so on a given boundary.
Chg Disabled
Regulation V
4200
mV
Sets the voltage threshold for voltage regulation to system when charge is
disabled. It is recommended to program to same value as Charging Voltage
and maximum charge voltage that is obtained from Charge Voltage T0–4
parameters.
CC Gain
10
mΩ
Calibrate this parameter using TI-supplied bqStudio software and calibration
procedure in the TRM. Determines conversion of coulomb counter measured
sense resistor voltage to current.
CC Delta
10
mΩ
Calibrate this parameter using TI-supplied bqStudio software and calibration
procedure in the TRM. Determines conversion of coulomb counter measured
sense resistor voltage to passed charge.
CC Offset
–1418
Counts
Calibrate this parameter using TI-supplied bqStudio software and calibration
procedure in the TRM. Determines native offset of coulomb counter hardware
that should be removed from conversions.
Board Offset
0
Counts
Calibrate this parameter using TI-supplied bqStudio software and calibration
procedure in the TRM. Determines native offset of the printed circuit board
parasitics that should be removed from conversions.
mV
Calibrate this parameter using TI-supplied bqStudio software and calibration
procedure in the TRM. Determines voltage offset between cell tab and ADC
input node to incorporate back into or remove from measurement, depending
on polarity.
Pack V Offset
0
9.2.2 Detailed Design Procedure
9.2.2.1 BAT Voltage Sense Input
A ceramic capacitor at the input to the BAT 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.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
27
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
9.2.2.2 SRP and SRN Current Sense Inputs
The filter network at the input to the coulomb counter is intended to improve differential mode rejection of voltage
measured across the sense resistor. These components should be placed as close as possible to the coulomb
counter inputs and the routing of the differential traces length-matched to best minimize impedance mismatchinduced measurement errors.
9.2.2.3 Sense Resistor Selection
Any variation encountered in the resistance present between the SRP and SRN pins of the fuel gauge will affect
the resulting differential voltage and derived current it senses. As such, it is recommended to select a sense
resistor with minimal tolerance and temperature coefficient of resistance (TCR) characteristics. The standard
recommendation based on best compromise between performance and price is a 1% tolerance, 100-ppm drift
sense resistor with a 1-W power rating.
9.2.2.4 TS Temperature Sense Input
Similar to the BAT pin, a ceramic decoupling capacitor for the TS pin is used to bypass AC voltage ripple away
from the high-impedance ADC input, minimizing measurement error. Another helpful advantage is that the
capacitor provides additional ESD protection since the TS input to system may be accessible in systems that use
removable battery packs. It should be placed as close as possible to the respective input pin for optimal filtering
performance.
9.2.2.5 Thermistor Selection
The fuel gauge temperature sensing circuitry is designed to work with a negative temperature coefficient-type
(NTC) thermistor with a characteristic 10-kΩ resistance at room temperature (25°C). The default curve-fitting
coefficients configured in the fuel gauge specifically assume a 103AT-2 type thermistor profile and so that is the
default recommendation for thermistor selection purposes. Moving to a separate thermistor resistance profile (for
example, JT-2 or others) requires an update to the default thermistor coefficients in data flash to ensure highest
accuracy temperature measurement performance.
9.2.2.6 REGIN Power Supply Input Filtering
A ceramic capacitor is placed at the input to the fuel gauge internal LDO to increase power supply rejection
(PSR) and improve effective line regulation. It ensures that voltage ripple is rejected to ground instead of
coupling into the internal supply rails of the fuel gauge.
9.2.2.7 VCC LDO Output Filtering
A ceramic capacitor is also needed at the output of the internal LDO to provide a current reservoir for fuel gauge
load peaks during high peripheral utilization. It acts to stabilize the regulator output and reduce core voltage
ripple inside of the fuel gauge.
28
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
9.3 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
-40
-20
0
20
40
Temperature (°C)
60
8.7
8.6
8.5
8.4
8.3
8.2
8.1
8
-40
80
33.5
4
Reported Temperature Error (qC)
fLOSC - Low Frequency Oscillator (kHz)
5
33
32.5
32
31.5
31
30.5
0
20
40
Temperature (qC)
20
40
Temperature (qC)
60
80
100
80
100
D002
3
2
1
0
-1
-2
-3
-4
-5
-30
-20
D003
Figure 13. Low-Frequency Oscillator Frequency Vs.
Temperature
60
Figure 12. High-Frequency Oscillator Frequency Vs.
Temperature
34
-20
0
D001
Figure 11. Regulator Output Voltage Vs. Temperature
30
-40
-20
-10
0
10
20
30
Temperature (qC)
40
50
60
D004
Figure 14. Reported Internal Temperature Measurement
Vs. Temperature
10 Power Supply Recommendations
10.1 Power Supply Decoupling
Both the REGIN input pin and the VCC output pin require low equivalent series resistance (ESR) ceramic
capacitors placed as close as possible to the respective pins to optimize ripple rejection and provide a stable and
dependable power rail that is resilient to line transients. A 0.1-µF capacitor at the REGIN and a 1-µF capacitor at
VCC will suffice for satisfactory device performance.
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
29
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
11 Layout
11.1 Layout Guidelines
11.1.1 Sense Resistor Connections
Kelvin connections at the sense resistor are as critical as those for the battery terminals. The differential traces
should be connected at the inside of the sense resistor pads and not along the high-current trace path to prevent
false increases to measured current that could result when measuring between the sum of the sense resistor and
trace resistance between the tap points. In addition, the routing of these leads from the sense resistor to the
input filter network and finally into the SRP and SRN pins needs to be as closely matched in length as possible
or else additional measurement offset could occur. It is further recommended to add copper trace or pour-based
"guard rings" around the perimeter of the filter network and coulomb counter inputs to shield these sensitive pins
from radiated EMI into the sense nodes. This prevents differential voltage shifts that could be interpreted as real
current change to the fuel gauge. All of the filter components need to be placed as close as possible to the
coulomb counter input pins.
11.1.2 Thermistor Connections
The thermistor sense input should include a ceramic bypass capacitor placed as close to the TS input pin as
possible. The capacitor helps to filter measurements of any stray transients as the voltage bias circuit pulses
periodically during temperature sensing windows.
11.1.3 High-Current and Low-Current Path Separation
NOTE
For best possible noise performance, it is important to separate the low-current and highcurrent loops to different areas of the board layout.
The fuel gauge and all support components should be situated on one side of the boards and tap off of the highcurrent loop (for measurement purposes) at the sense resistor. Routing the low-current ground around instead of
under high-current traces will further help to improve noise rejection.
30
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
bq27546-G1
www.ti.com
SLUSC53B – MAY 2015 – REVISED MAY 2018
11.2 Layout Example
PACK+
SCL
Use copper
pours for battery
power path to
minimize IR
losses
R10
R7
SDA
R8
R4
SE
C1
R THERM
Kelvin connect the
BAT sense line
right at positive
battery terminal
REGIN
BAT
C2
NC
VSS
VSS
SDA
TS
SRN
SCL
SRP
Vcc
SE
HDQ
CE
C3
NC
HDQ
R6
R9
PACK –
10 mΩ 1%
Via connects to Power Ground
Kelvin connect SRP
and SRN
connections right at
Rsense terminals
Star ground right at PACK –
for ESD return path
Figure 15. Layout Example
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
31
bq27546-G1
SLUSC53B – MAY 2015 – REVISED MAY 2018
www.ti.com
12 Device and Documentation Support
12.1 Documentation Support
12.1.1 Related Documentation
For more information, see bq27546-G1 Technical Reference Manual (SLUUB74).
12.2 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.
12.3 Trademarks
Impedance Track, Nano-Free, E2E are trademarks of Texas Instruments.
I2C is a trademark of NXP Semiconductors, N.V.
All other trademarks are the property of their respective owners.
12.4 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
12.5 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.
32
Submit Documentation Feedback
Copyright © 2015–2018, Texas Instruments Incorporated
Product Folder Links: bq27546-G1
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)
BQ27546YZFR-G1
ACTIVE
DSBGA
YZF
15
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27546
BQ27546YZFT-G1
ACTIVE
DSBGA
YZF
15
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27546
(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
工商网监
湘ICP备2023018690号
