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bq27532-G1
SLUSBU6B – SEPTEMBER 2014 – REVISED JANUARY 2016
bq27532-G1 Battery Management Unit Impedance Track™ Fuel Gauge
for bq2425x Charger
1 Features
3
•
The bq27532-G1 system-side, Li-Ion battery
management unit is a microcontroller peripheral that
provides Impedance Track™ fuel gauging and
charging control for single-cell Li-Ion battery packs.
The fuel gauge requires little system microcontroller
firmware development. Together with bq2425x singlecell switch-mode charger, the fuel gauge manages an
embedded battery (non-removable) or a removable
battery pack.
1
•
•
•
•
•
•
•
•
2
Battery Fuel Gauge and Charger Controller for 1Cell Li-Ion Applications up to 14,500-mAh
Capacity
Resides on System Main Board
Battery Fuel Gauge Based on Patented
Impedance Track™ Technology
– Models the Battery Discharge Curve for
Accurate Remaining Capacity Predictions
– Automatically Adjusts for Battery Aging,
Battery Self-Discharge, and Temperature and
Rate Inefficiencies
– Low-value Sense Resistor (5 to 20 mΩ)
Battery Charger Controller With Customizable
Charge Profiles
– Configurable Charge Voltage and Current
Based on Temperature
– Optional State-of-Health (SoH) and Multi-Level
Based Charge Profiles
Host-free Autonomous Battery Management
System
– Reduced Software Overhead Allows for Easy
Portability Across Platforms and Shorter OEM
Design Cycles
– Higher Safety and Security
Runtime Improvements
– Longer Battery Runtime Leveraging
Impedance Track™ Technology
– Tighter Accuracy Controls for Charger
Termination
– Improved Recharge Thresholds
Intelligent Charging – Customized and Adaptive
Charging Profiles
– Charger Control Based on SoH
– Temperature Level Charging (TLC)
Stand-alone Battery Charger Controller for
bq2425x Single-Cell Switch-mode Battery Charger
400-kHz I2C™ Interface for Connection to System
Microcontroller Port
Applications
Description
The fuel gauge uses the patented Impedance Track
algorithm for fuel gauging, and provides information,
such as remaining battery capacity (mAh), state-ofcharge (%), runtime-to-empty (minimum), battery
voltage (mV), temperature (°C), and SoH (%).
Battery fuel gauging with the device requires only
PACK+ (P+), PACK– (P–), and thermistor (T)
connections to a removable battery pack or
embedded battery circuit. The 15-pin NanoFree™
(CSP) package has dimensions of 2.61 mm × 1.96
mm with 0.5-mm lead pitch. It is ideal for spaceconstrained applications.
Device Information(1)
PART NUMBER
PACKAGE
bq27532-G1
BODY SIZE (NOM)
CSP (15)
2.61 mm × 1.96 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
SW
BQ2425x
4.35V t 10.5V
SYSTEM LOAD
SYS
VIN
Charger
BAT
PGND
I2C
Single Cell Li-Ion Battery Pack
BQ27532-G1
SYSTEM LOAD
REGIN
CE
BAT
TS
BI/TOUT
P+
T
PROTECTION IC
I2C
VCC
Application
Processor
P-
FETs
SRP
SOCINT
•
•
•
•
Smartphones, Feature Phones, and Tablets
Digital Still and Video Cameras
Handheld Terminals
MP3 or Multimedia Players
VSS
SRN
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.
bq27532-G1
SLUSBU6B – SEPTEMBER 2014 – REVISED JANUARY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics: Supply Current.................
Digital Input and Output DC Electrical
Characteristics ...........................................................
6.7 Power-on Reset ........................................................
6.8 2.5-V LDO Regulator ................................................
6.9 Internal Clock Oscillators ..........................................
6.10 ADC (Temperature and Cell Measurement)
Characteristics ...........................................................
6.11 Integrating ADC (Coulomb Counter)
Characteristics ...........................................................
6.12 Data Flash Memory Characteristics........................
6.13 I2C-compatible Interface Communication Timing
Requirements.............................................................
6.14 Typical Characteristics ............................................ 8
7
Detailed Description .............................................. 9
7.1
7.2
7.3
7.4
7.5
8
Overview ................................................................... 9
Functional Block Diagram ....................................... 10
Feature Description................................................. 11
Device Functional Modes........................................ 12
Programming........................................................... 16
Application and Implementation ........................ 21
8.1 Application Information............................................ 21
8.2 Typical Application .................................................. 22
9
Power Supply Recommendations...................... 26
9.1 Power Supply Decoupling ....................................... 26
5
5
5
5
6
6
6
7
10 Layout................................................................... 27
10.1 Layout Guidelines ................................................. 27
10.2 Layout Example .................................................... 28
11 Device and Documentation Support ................. 29
11.1
11.2
11.3
11.4
11.5
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
29
29
29
29
29
12 Mechanical, Packaging, and Orderable
Information ........................................................... 29
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision A (October 2015) to Revision B
•
2
Page
Changed ESD Ratings .......................................................................................................................................................... 4
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SLUSBU6B – SEPTEMBER 2014 – REVISED JANUARY 2016
5 Pin Configuration and Functions
YZF Package
15-Pin CSP
(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
(BOTTOM VIEW)
xx
xx
Pin A1
Index Area
D
DIM
MIN
TYP
MAX
D
2580
2610
2640
E
1926
1956
1986
UNITS
m
Pin Functions
PIN
NAME
NUMBER
TYPE (1)
DESCRIPTION
BAT
E2
I
Cell-voltage measurement input. ADC input. TI recommends 4.8 V maximum for conversion accuracy.
BI/TOUT
E3
IO
Battery-insertion detection input. Power pin for pack thermistor network. Thermistor-multiplexer control pin. Use with
pullup resistor > 1 MΩ (1.8 MΩ typical).
BSCL
B2
O
Battery charger clock output line for chipset communication. Use without external pullup resistor. Push-pull output.
BSDA
C3
IO
Battery charger data line for chipset communication. Use without external pullup resistor. Push-pull output.
CE
D2
I
Chip enable. Internal LDO is disconnected from REGIN when driven low.
Note: CE has an internal ESD protection diode connected to REGIN. TI recommends maintaining VCE ≤ VREGIN under
all conditions.
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). Open-drain IO. Use with
10-kΩ pullup resistor (typical).
SDA
B3
IO
Slave I2C serial communications data line for communication with system (master). Open-drain IO. Use with 10-kΩ
pullup resistor (typical).
SOC_INT
A2
IO
SOC state interrupts output. Generates a pulse as described in bq27532-G1 Technical Reference Manual, SLUUB04.
Open-drain output.
SRN
B1
AI
Analog input pin connected to the internal coulomb counter where SRN is nearest the VSS connection. Connect to 5to 20-mΩ sense resistor.
SRP
A1
AI
Analog input pin connected to the internal coulomb counter where SRP is nearest the PACK– connection. Connect to
5- to 20-mΩ sense resistor.
TS
D3
AI
Pack thermistor voltage sense (use 103AT-type thermistor). ADC input.
VCC
D1
P
Regulator output and bq27532-G1 device power. Decouple with 1-μF ceramic capacitor to VSS. Pin is not intended to
power additional external loads.
VSS
C1, C2
P
Device ground
(1)
IO = Digital input-output, AI = Analog input, P = Power connection
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
VREGIN
Regulator input
MIN
MAX
UNIT
–0.3
5.5
V
–0.3
6
(2)
V
VCE
CE input pin
–0.3
VREGIN + 0.3
V
VCC
Supply voltage
–0.3
2.75
V
VIOD
Open-drain IO pins (SDA, SCL, SOC_INT)
–0.3
5.5
V
VBAT
BAT input pin
–0.3
5.5
V
–0.3
6
VI
Input voltage to all other pins
(BI/TOUT, TS, SRP, SRN, BSCL, BSDA)
–0.3
TA
Operating free-air temperature
Tstg
Storage temperature
(1)
(2)
(2)
V
VCC + 0.3
V
–40
85
°C
–65
150
°C
Stresses beyond those listed as 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 as recommended operating conditions is
not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
Condition not to exceed 100 hours at 25°C lifetime.
6.2 ESD Ratings
VALUE
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001, BAT pin
Electrostatic
discharge
V(ESD)
(1)
(2)
(1)
UNIT
±1500
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001, All other pins (1)
±2000
Charged device model(CDM), per JEDEC specification JESD22-C101 (2)
±250
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.
6.3 Recommended Operating Conditions
TA = –40°C to 85°C, 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
tPUCD
Power-up communication delay
No flash 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
0.47
UNIT
V
0.1
μF
1
μF
250
ms
6.4 Thermal Information
bq27532-G1
THERMAL METRIC
(1)
YZF (CSP)
UNIT
15 PINS
RθJA
Junction-to-ambient thermal resistance
70
°C/W
RJC(top)
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
RθJC(bottom)
Junction-to-case (bottom) thermal resistance
n/a
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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SLUSBU6B – SEPTEMBER 2014 – REVISED JANUARY 2016
6.5 Electrical Characteristics: Supply Current
TA = 25°C and VREGIN = VBAT = 3.6 V (unless otherwise noted)
PARAMETER
(1)
ICC
ISLP+
(1)
TEST CONDITIONS
TYP
MAX
UNIT
Normal operating-mode current
Fuel gauge in NORMAL mode
ILOAD > Sleep current
118
μA
Sleep+ operating-mode current
Fuel gauge in SLEEP+ mode
ILOAD < Sleep current
62
μA
23
μA
8
μA
ISLP
(1)
Low-power storage-mode current
Fuel gauge in SLEEP mode
ILOAD < Sleep current
IHIB
(1)
Hibernate operating-mode current
Fuel gauge in HIBERNATE mode
ILOAD < Hibernate current
(1)
MIN
Specified by design. Not production tested. Actual supply current consumption will vary slightly depending on firmware operation and
dataflash configuration.
6.6 Digital Input and Output DC Electrical 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
VOL
Output voltage, low (SCL, SDA,
SOC_INT, BSDA, BSCL)
IOL = 3 mA
VOH(PP)
Output voltage, high (BSDA, BSCL)
IOH = –1 mA
VCC – 0.5
VOH(OD)
Output voltage, high (SDA, SCL,
SOC_INT)
External pullup resistor connected to
VCC
VCC – 0.5
Input voltage, low (SDA, SCL)
VIL
Input voltage, low (BI/TOUT)
Input voltage, high (SDA, SCL)
VIH
Input voltage, low (CE)
VIH(CE)
Input voltage, high (CE)
(1)
(1)
MAX
UNIT
0.4
V
V
–0.3
0.6
–0.3
0.6
V
1.2
Input voltage, high (BI/TOUT)
VIL(CE)
Ilkg
BAT INSERT CHECK MODE active
TYP
BAT INSERT CHECK MODE active
VREGIN = 2.8 to 4.5 V
1.2
V
VCC + 0.3
0.8
V
2.65
Input leakage current (IO pins)
μA
0.3
Specified by design. Not production tested.
6.7 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 battery voltage input at VCC
VHYS
Power-on reset hysteresis
MIN
TYP
MAX
2.05
2.15
2.20
UNIT
V
115
mV
6.8 2.5-V LDO Regulator
TA = –40°C to 85°C, CLDO25 = 1 μF, VREGIN = 3.6 V (unless otherwise noted)
PARAMETER
VREG25
(1)
Regulator output voltage (VCC)
TEST CONDITIONS
MIN
NOM
MAX
2.8 V ≤ VREGIN ≤ 4.5 V, IOUT ≤ 16 mA (1)
2.3
2.5
2.6
2.45 V ≤ VREGIN < 2.8 V (low battery),
IOUT ≤ 3 mA
2.3
UNIT
V
V
LDO output current, IOUT, is the total load current. LDO regulator should be used to power internal fuel gauge only.
6.9 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
MIN
TYP
MAX
UNIT
fOSC
High-frequency oscillator
8.389
MHz
fLOSC
Low-frequency oscillator
32.768
kHz
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6.10 ADC (Temperature and Cell Measurement) Characteristics
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; typical values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VADC1
Input voltage range (TS)
VSS – 0.125
2
V
VADC2
Input voltage range (BAT)
VSS – 0.125
5
V
VIN(ADC)
Input voltage range
0.05
1
GTEMP
Internal temperature sensor voltage
gain
tADC_CONV
Conversion time
–2
Resolution
VOS(ADC)
14
Input offset
(1)
Effective input resistance (TS)
ZADC2
(1)
Effective input resistance (BAT)
(1)
Ilkg(ADC)
(1)
125
ms
15
bits
1
ZADC1
mV
8
Device not measuring cell voltage
MΩ
8
Device measuring cell voltage
V
mV/°C
MΩ
100
kΩ
Input leakage current
0.3
μA
Specified by design. Not tested in production.
6.11 Integrating ADC (Coulomb Counter) Characteristics
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; typical values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
VSR
Input voltage range,
V(SRP) and V(SRN)
VSR = V(SRP) – V(SRN)
tSR_CONV
Conversion time
Single conversion
Resolution
Input offset
INL
Integral nonlinearity error
Ilkg(SR)
(1)
(1)
MAX
UNIT
0.125
V
1
s
15
bits
±0.034%
FSR
μV
10
±0.007%
Effective input resistance
(1)
TYP
14
VOS(SR)
ZIN(SR)
MIN
–0.125
2.5
MΩ
Input leakage current
0.3
μA
Specified by design. Not tested in production.
6.12 Data Flash Memory Characteristics
TA = –40°C to 85°C, 2.4 V < VCC < 2.6 V; typical values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)
PARAMETER
tDR
(1)
MIN
Data retention
Flash-programming write cycles (1)
tWORDPROG
(1)
ICCPROG
(1)
tDFERASE
tIFERASE
(1)
tPGERASE
(1)
6
(1)
(1)
TYP
MAX
UNIT
10
Years
20,000
Cycles
Word programming time
Flash-write supply current
5
2
ms
10
mA
Data flash master erase time
200
ms
Instruction flash master erase time
200
ms
20
ms
Flash page erase time
Specified by design. Not production tested
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6.13 I2C-compatible Interface Communication Timing Requirements
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)
MIN
TYP
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
0
ns
tsu(STOP)
Setup time for stop
t(BUF)
Bus free time between stop and start
fSCL
Clock frequency
(1)
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).
Figure 1. I2C-Compatible Interface Timing Diagrams
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6.14 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)
-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
8
100
D002
3
2
1
0
-1
-2
-3
-4
-5
-30
-20
D003
Figure 4. Low-Frequency Oscillator Frequency vs.
Temperature
80
Figure 3. High-Frequency Oscillator Frequency vs.
Temperature
Reported Temperature Error (qC)
fLOSC - Low Frequency Oscillator (kHz)
Figure 2. Regulator Output Voltage vs. Temperature
60
-10
0
10
20
30
Temperature (qC)
40
50
60
D004
Figure 5. Reported Internal Temperature Measurement vs.
Temperature
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7 Detailed Description
7.1 Overview
The fuel gauge 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
remaining capacity and state-of-charge (SOC) as well as SOC interrupt signal to the host.
The fuel gauge can control a bq2425x Charger IC without the intervention from an application system processor.
Using the bq27532-G1 and bq2425x chipset, batteries can be charged with the typical constant-current,
constant-voltage (CCCV) profile or charged using a Multi-Level Charging (MLC) algorithm.
The fuel gauge can also be configured to suggest charge voltage and current values to the system so that the
host can control a charger that is not part of the bq2425x charger family.
NOTE
Formatting conventions 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: brackets and italics, for example, [TDA]
Data flash bits: brackets, italics and bold, for example, [LED1]
Modes and states: ALL CAPITALS, for example, UNSEALED mode
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7.2 Functional Block Diagram
REGIN
LDO
POR
2.5 V
VCC
HFO
BAT
CC
HFO
SRN
LFO
HFO/128
4R
HFO/128
SRP
MUX
ADC
R
Wake
Comparator
TS
Internal
Temp
Sensor
BI/TOUT
HFO/4
SDA
SOCINT
22
I2C Slave
Engine
Instruction
ROM
22
CPU
VSS
SCL
I/O
Controller
Instruction
FLASH
BSDA
8
Wake
and
Watchdog
Timer
10
GP Timer
and
PWM
8
I2C Master
Engine
BSCL
Data
SRAM
Data
FLASH
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7.3 Feature Description
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 flash locations. Commands are sent from system to gauge using the I2C serial communications engine,
and can be executed during application development, pack manufacture, or end-equipment operation.
Cell information is stored 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. Access
to these locations is achieved by either use of the companion evaluation software, through individual commands,
or through a sequence of data-flash-access commands. To access a desired data flash location, the correct data
flash subclass and offset must be known.
The key to the high-accuracy gas gauging prediction is the TI proprietary Impedance Track™ algorithm. This
algorithm uses cell measurements, characteristics, and properties to create SOC predictions that can achieve
less than 1% error across a wide variety of operating conditions and over the lifetime of the battery.
The fuel gauge measures the charging and discharging of the battery by monitoring the voltage across a smallvalue series sense resistor (5 to 20 mΩ, typical) located between the system VSS and the battery 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 external temperature sensing is optimized with the use of a high-accuracy negative temperature coefficient
(NTC) thermistor with R25 = 10.0 kΩ ±1%, B25/85 = 3435 K ± 1% (such as Semitec NTC 103AT). The fuel
gauge can also be configured to use its internal temperature sensor. When an external thermistor is used, a
18.2-kΩ pullup resistor between the BI/TOUT and TS pins is also required. The fuel gauge uses temperature to
monitor the battery-pack environment, which is used for fuel gauging and cell protection functionality.
To minimize power consumption, the fuel gauge has different power modes: NORMAL, SLEEP, SLEEP+,
HIBERNATE, and BAT INSERT CHECK. 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.
For complete operational details, see bq27532-G1 Technical Reference Manual, SLUUB04.
7.3.1 Functional Description
The fuel gauge measures the cell voltage, temperature, and current to determine battery SOC. The fuel gauge
monitors the charging and discharging of the battery by sensing the voltage across a small-value resistor (5 mΩ
to 20 mΩ, typical) between the SRP and SRN 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 a cell manufacturers' 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 battery-impedance profile
during normal battery usage. It uses this profile, along with SOC and the Qmax value, to determine
FullChargeCapacity( ) and StateOfCharge( ), specifically for the present load and temperature.
FullChargeCapacity( ) is reported as capacity available from a fully-charged battery under the present load and
temperature until Voltage( ) reaches the Terminate Voltage. NominalAvailableCapacity( ) and
FullAvailableCapacity( ) are the uncompensated (no or light load) versions of RemainingCapacity( ) and
FullChargeCapacity( ), respectively.
The fuel gauge has two flags accessed by the Flags( ) function that warn when the battery SOC has fallen to
critical levels. When RemainingCapacity( ) falls below the first capacity threshold as specified in SOC1 Set
Threshold, the [SOC1] (State of Charge Initial) flag is set. The flag is cleared once RemainingCapacity( ) rises
above SOC1 Clear Threshold.
When the voltage is discharged to Terminate Voltage, the SOC will be set to 0.
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7.4 Device Functional Modes
7.4.1 Power Modes
The fuel gauge has different power modes:
1. BAT INSERT CHECK: The BAT INSERT CHECK mode is a powered-up, but low-power halted, state where
the fuel gauge resides when no battery is inserted into the system.
2. NORMAL: In NORMAL mode, the fuel gauge is fully powered and can execute any allowable task.
3. SLEEP: In SLEEP mode, the fuel gauge turns off the high-frequency oscillator and exists in a reducedpower
state, periodically taking measurements and performing calculations.
4. SLEEP+: In SLEEP+ mode, both low-frequency and high-frequency oscillators are active. Although the
SLEEP+ mode has higher current consumption than the SLEEP mode, it is also a reduced power mode.
5. HIBERNATE: In HIBERNATE mode, the fuel gauge is in a low power state, but can be woken up by
communication or certain I/O activity.
The relationship between these modes is shown in Figure 6.
7.4.2 BAT INSERT CHECK Mode
This mode is a halted-CPU state that occurs when an adapter, or other power source, is present to power the
fuel gauge (and system), yet no battery has been detected. When battery insertion is detected, a series of
initialization activities begin, which include: OCV measurement, setting the Flags() [BAT_DET] bit, and selecting
the appropriate battery profiles.
Some commands, issued by a system processor, can be processed while the fuel gauge is halted in this mode.
The gauge wakes up to process the command, then returns to the halted state awaiting battery insertion.
7.4.3 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, 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.
7.4.4 SLEEP Mode
SLEEP mode is entered automatically if the feature is enabled (Op Config [SLEEP] = 1) and AverageCurrent() is
below the programmable level Sleep Current. Once entry into SLEEP mode has been qualified, but prior to
entering it, the fuel gauge performs a coulomb counter autocalibration to minimize offset.
During SLEEP mode, the fuel gauge periodically takes data measurements and updates its data set. However, a
majority of its time is spent in an idle condition.
The fuel gauge exits SLEEP mode 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.
In the event that a battery is removed from the system while a charger is present (and powering the gauge),
Impedance Track™ updates are not necessary. Hence, the fuel gauge enters a state that checks for battery
insertion and does not continue executing the Impedance Track™ algorithm.
7.4.5 SLEEP+ Mode
Compared to the SLEEP mode, SLEEP+ mode has the high-frequency oscillator in operation. The
communication delay could be eliminated. The SLEEP+ mode is entered automatically if the feature is enabled
(CONTROL_STATUS [SNOOZE] = 1) and AverageCurrent() is below the programmable level Sleep Current.
During SLEEP+ mode, the fuel gauge periodically takes data measurements and updates its data set. However,
a majority of its time is spent in an idle condition.
The fuel gauge exits SLEEP+ mode if any entry condition is broken, specifically when:
12
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Device Functional Modes (continued)
1. Any communication activity with the gauge, or
2. AverageCurrent() rises above Sleep Current, or
3. A current in excess of IWAKE through RSENSE is detected.
7.4.6 HIBERNATE Mode
HIBERNATE mode should be used when the system equipment needs to enter a low-power state, and minimal
gauge power consumption is required. This mode is ideal when system equipment is set to its own HIBERNATE,
SHUTDOWN, or OFF mode.
Before the fuel gauge can enter HIBERNATE mode, the system must set the CONTROL_STATUS
[HIBERNATE] bit. 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 and a valid OCV measurement has been
taken. The gauge remains in HIBERNATE mode until the system issues a direct I2C command to the gauge or a
POR occurs. Any I2C communication that is not directed to the gauge does not wake the gauge.
It is the responsibility of the system to wake the fuel gauge after it has gone into HIBERNATE mode. After
waking, the gauge can proceed with the initialization of the battery information (OCV, profile selection, and so
forth).
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Device Functional Modes (continued)
Exit From HIBERNATE
Battery Removed
POR
BAT INSERT CHECK
Exit From HIBERNATE
Communication Activity
AND Comm address is for fuel gauge
Fuel gauge clears CONTROL_STATUS
[HIBERNATE] = 0
Recommend Host also set
CONTROL_STATUS
[HIBERNATE] = 0
Check for battery insertion
from HALT state.
No gauging
Entry To NORMAL
Flags [BAT_DET] = 1
Exit From NORMAL
Flags [BAT_DET] = 0
NORMAL
Entry To SLEEP+
Operation Configuration [SLEEP] = 1
AND
CONTROL_STAUS [SNOOZE] = 1]
AND
Ι AverageCurrent ( ) Ι < Sleep Current
Flags [BAT_DET] = 0
Fuel gauging and data
updated every second
Exit From SLEEP
Flags [BAT_DET] = 0
Exit From SLEEP
Ι AverageCurrent ( ) Ι > Sleep Current
OR
Current is detected above Ι WAKE
Exit From SLEEP+
Any communication to the gauge
OR
Ι AverageCurrent ( ) Ι > Sleep Current
OR
Current is detected above Ι WAKE
SLEEP+
Entry To SLEEP+
Operation Configuration [SLEEP] = 1
Fuel gauging and data
updated every 20 seconds.
Both LFO and HFO are ON.
AND
Ι AverageCurrent ( ) Ι < Sleep Current
AND
CONTROL_STAUS [SNOOZE] = 0
Entry to SLEEP+
CONTROL_STATUS [SNOOZE] = 1
Entry to SLEEP
CONTROL_STATUS [SNOOZE] = 0
SLEEP
Fuel gauging and data
updated every 20 seconds.
(LFO ON and HFO OFF)
Exit From WAIT_HIBERNATE
Host must set CONTROL_STATUS
[HIBERNATE] = 0
AND
VCELL < Hibernate Voltage
To WAIT_HIBERNATE
System Sleep
Exit From SLEEP
Host has set CONTROL_STATUS
[HIBERNATE] = 1
OR
VCELL < Hibernate Voltage
Figure 6. Power Mode Diagram—System Sleep
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Device Functional Modes (continued)
POR
Exit From HIBERNATE
Battery Removed
Exit From HIBERNATE
Communication Activity
AND Comm address is for fuel gauge
Fuel gauge clears CONTROL_STATUS
[HIBERNATE] = 0
Recommend Host also set
CONTROL_STATUS
[HIBERNATE] = 0
Exit From SLEEP
Flags [BAT_DET] = 0
BAT INSERT CHECK
Check for battery insertion
from HALT state.
No gauging
Entry To NORMAL
Flags [BAT_DET] = 1
Flags [BAT_DET] = 0
Exit From NORMAL
Flags [BAT_DET] = 0
NORMAL
Fuel gauging and data
updated every second.
HIBERNATE
Wakeup From HIBERNATE
Communication Activity
AND
Comm address is not for
fuel gauge.
Disable all fuel gauge
subcircuits.
Exit From WAIT_HIBERNATE
Host must set CONTROL_STATUS
[HIBERNATE] = 0
AND
VCELL < Hibernate Voltage
To SLEEP
WAIT_HIBERNATE
Exit From WAIT_HIBERNATE
Cell relaxed
AND
Ι AverageCurrent () Ι < Hibernate
Current
OR
Cell relaxed
AND
VCELL < Hibernate Voltage
Fuel gauging and data
updated every 20 seconds.
Exit From SLEEP
Host has set CONTROL_STATUS
[HIBERNATE] = 1
OR
VCELL < Hibernate Voltage
System Shutdown
Figure 7. Power Mode Diagram—System Shutdown
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7.5 Programming
7.5.1 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. 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 details are found in the bq27532-G1
Technical Reference Manual, SLUUB04.
Table 1. Standard Commands
NAME
COMMAND CODE
UNIT
SEALED
ACCESS
UNSEALED
ACCESS
Control( )
0x00 and 0x01
NA
RW
RW
AtRate( )
0x02 and 0x03
mA
RW
RW
AtRateTimeToEmpty( )
0x04 and 0x05
Minutes
R
RW
Temperature( )
0x06 and 0x07
0.1 K
RW
RW
Voltage( )
0x08 and 0x09
mV
R
RW
Flags( )
0x0A and 0x0B
Hex
R
RW
NominalAvailableCapacity( )
0x0C and 0x0D
mAh
R
RW
FullAvailableCapacity( )
0x0E and 0x0F
mAh
R
RW
RemainingCapacity( )
0x10 and 0x11
mAh
R
RW
FullChargeCapacity( )
0x12 and 0x13
mAh
R
RW
AverageCurrent( )
0x14 and 0x15
mA
R
RW
InternalTemperature( )
0x16 and 0x17
0.1 K
R
RW
ResScale( )
0x18 and 0x19
Num
R
RW
ChargingLevel( )
0x1A and 0x1B
Num
R
RW
StateOfHealth( )
0x1C and 0x1D
% / num
R
RW
CycleCount( )
0x1E and 0x1F
Counters
R
R
StateOfCharge( )
0x20 and 0x21
%
R
R
InstantaneousCurrentReading( )
0x22 and 0x23
mA
R
RW
FineQPass( )
0x24 and 0x25
mAh
R
RW
FineQPassFract( )
0x26 and 0x27
num
R
RW
ProgChargingCurrent( )
0x28 and 0x29
mA
R
RW
ProgChargingVoltage( )
0x2A and 0x2B
mV
R
RW
LevelTaperCurrent( )
0x2C and 0x2D
mA
R
RW
CalcChargingCurrent( )
0x2E and 0x2F
mA
R
RW
CalcChargingVoltage( )
0x30 and 0x31
mV
R
RW
ChargerStatus( )
0x32
Hex
R
RW
ChargReg0( )
0x33
Hex
RW
RW
ChargReg1( )
0x34
Hex
RW
RW
ChargReg2( )
0x35
Hex
RW
RW
ChargReg3( )
0x36
Hex
RW
RW
ChargReg4( )
0x37
Hex
RW
RW
ChargReg5( )
0x38
Hex
RW
RW
ChargReg6( )
0x39
Hex
RW
RW
RemainingCapacityUnfiltered( )
0x6C and 0x6D
mAh
R
RW
RemainingCapacityFiltered( )
0x6E and 0x6F
mAh
R
RW
FullChargeCapacityUnfiltered( )
0x70 and 0x71
mAh
R
RW
FullChargeCapacityFiltered( )
0x72 and 0x73
mAh
R
RW
TrueSOC( )
0x74 and 0x75
%
R
RW
MaxCurrent( )
0x76 and 0x77
mA
R
RW
16
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7.5.2
SLUSBU6B – SEPTEMBER 2014 – REVISED JANUARY 2016
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
fuel gauge during normal operation and additional features when the fuel gauge is in different access modes, as
described in Device Functional Modes. Additional details are found in the bq27532-G1 Technical Reference
Manual, SLUUB04.
Table 2. Control( ) Subcommands
CONTROL
DATA
SEALED
ACCESS
CONTROL_STATUS
0x0000
Yes
Reports the status of HIBERNATE, IT, and so on
DEVICE_TYPE
0x0001
Yes
Reports the device type (for example, 0x0532 for bq27532-G1)
FW_VERSION
0x0002
Yes
Reports the firmware version on the device type
HW_VERSION
0x0003
Yes
Reports the hardware version of the device type
MLC_ENABLE
0x0004
Yes
Charge profile is based on MaxLife profile
MLC_DISABLE
0x0005
Yes
Charge profile is solely based on charge temperature tables and, if enabled, State
of Health
CLEAR_IMAX_INT
0x0006
Yes
Clears the IMAX status bit and the interrupt signal from SOC_INT pin.
PREV_MACWRITE
0x0007
Yes
Returns previous MAC 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
CC_OFFSET
0x000A
No
Forces the device to measure the internal CC offset
CONTROL FUNCTION
DESCRIPTION
CC_OFFSET_SAVE
0x000B
No
Forces the device to store the internal CC offset
OCV_CMD
0x000C
Yes
Request the gauge to take a OCV measurement
BAT_INSERT
0x000D
Yes
Forces the BAT_DET bit set when the [BIE] bit is 0
BAT_REMOVE
0x000E
Yes
Forces the BAT_DET bit clear when the [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_SLEEP+
0x0013
Yes
Forces CONTROL_STATUS [SNOOZE] to 1
CLEAR_SLEEP+
0x0014
Yes
Forces CONTROL_STATUS [SNOOZE] to 0
ILIMIT_LOOP_ENABLE
0x0015
Yes
When the gauge is not connected to the charger through I2C, this command
indicates to the gauge that there is a charger input current limiting loop active.
Disables charge termination detection by the gauge.
ILIMIT_LOOP_DISABLE
0x0016
Yes
When the gauge is not connected to the charger through I2C, this command
indicates to the gauge that battery charge current is not limited. Allows charge
termination detection by the gauge.
SHIPMODE_ENABLE
0x0017
Yes
Commands the bq2425x to turn off BATFET after a delay time programmed in data
flash so that system load does not draw power from the battery
SHIPMODE_DISABLE
0x0018
Yes
Commands the bq2425x to disregard turning off BATFET before the delay time or
commands BATFET to turn on if a VIN had power during the SHIPMODE enabling
process
CHG_ENABLE
0x001A
Yes
Enable charger. Charge will continue as dictated by the gauge charging algorithm.
CHG_DISABLE
0x001B
Yes
Disable charger (Set CE bit of bq2425x)
GG_CHGRCTL_ENABLE
0x001C
Yes
Enables the gas gauge to control the charger while continuously resetting the
charger watchdog
GG_CHGRCTL_DISABLE
0x001D
Yes
The gas gauge stops resetting the charger watchdog
SMOOTH_SYNC
0x001E
Yes
Synchronizes RemainingCapacityFiltered( ) and FullChargeCapacityFiltered( ) with
RemainingCapacityUnfiltered( ) and FullChargeCapacityUnfiltered( )
DF_VERSION
0x001F
Yes
Returns the Data Flash Version
SEALED
0x0020
No
Places device in SEALED access mode
IT_ENABLE
0x0021
No
Enables the Impedance Track™ algorithm
RESET
0x0041
No
Forces a full reset of the bq27532-G1 device
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7.5.3 Charger Data Commands
The charger registers are mapped to a series of single-byte Charger Data Commands to enable system reading
and writing of battery charger registers. During charger power up, the registers are initialized to Charger Reset
State. The fuel gauge can change the values of these registers during the System Reset State.
Each of the bits in the Charger Data Commands can be read or write. Note that System Access can be different
from the read or write access as defined in bq2425x charger hardware. The fuel gauge may block write access to
the charger hardware when the bit function is controlled by the fuel gauge exclusively. For example, the
[VBATREGx] bits of Chrgr_Reg2 are controlled by the fuel gauge and cannot be modified by system.
The fuel gauge reads the corresponding registers of Chrgr_Reg0( ) and Chrgr_Reg2( ) every second to mirror
the charger status. Other registers in the bq2425x device are read when registers are modified by the fuel gauge.
Table 3. Charger Data Commands
COMMAND
CODE
NAME
ChargerStatus( )
bq2425x CHARGER
MEMORY LOCATION
SEALED
ACCESS
UNSEALED
ACCESS
REFRESH
RATE
CHGRSTAT
0x32
NA
R
R
Every second
Chrgr_Reg0( )
CHGR0
0x33
0x00
RW
RW
Every second
Chrgr_Reg1( )
CHGR1
0x34
0x01
RW
RW
Data change
Chrgr_Reg2( )
CHGR2
0x35
0x02
RW
RW
Every second
Chrgr_Reg3( )
CHGR3
0x36
0x03
RW
RW
Data change
Chrgr_Reg4( )
CHGR4
0x37
0x04
RW
RW
Every second
Chrgr_Reg5( )
CHGR5
0x38
0x05
RW
RW
Data change
Chrgr_Reg6( )
CHGR6
0x39
0x06
RW
RW
Data change
7.5.4 Communications
7.5.4.1 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]
(a) 1-byte write
S
ADDR[6:0]
0 A
1 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 8. I2C Interface
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).
18
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The following command sequences are not supported:
Attempt to write a read-only address (NACK after data sent by master):
Figure 9. Invalid Write
Attempt to read an address above 0x6B (NACK command):
Figure 10. Invalid Read
7.5.4.2 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.
7.5.4.3 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 to 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 11. I2C Command Waiting Time
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7.5.4.4 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 data flash are updated. The following table
summarizes the approximate clock stretch duration for various fuel gauge operating conditions.
Table 4. Approximate Clock Stretch Duration
GAUGING
MODE
APPROXIMATE
DURATION
OPERATING CONDITION / COMMENT
SLEEP
HIBERNATE
Clock stretch occurs at the beginning of all traffic as the device wakes up.
≤ 4 ms
INITIALIZATION
NORMAL
Clock stretch occurs within the packet for flow control (after a start bit, ACK or first data bit).
≤ 4 ms
Normal Ra table data flash updates.
24 ms
20
Data flash block writes.
72 ms
Restored data flash block write after loss of power.
116 ms
End of discharge Ra table data flash update.
144 ms
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8 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.
8.1 Application Information
The fuel gauge can control a bq2425x Charger IC without the intervention from an application system processor.
Using the bq27532-G1 and bq2425x chipset, batteries can be charged with the typical constant-current,
constant-voltage (CCCV) profile or charged using a Multi-Level Charging (MLC) algorithm.
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8.2 Typical Application
CPMID
1µF
PMID
VIN
IN
SW
LO
1.0PH
System Load
CIN
2.2µF
R1
CBOOT
33 nF
VDPM
bq24250
R2
BOOT
PGND
LDO
SYS
1 µF
22 F
STAT
GPIO1
EN1
GPIO2
EN2
BAT
1 F
LDO
/CE
R3
VGPIO
TS
INT
Host
GPIO3
SCL
SCL
SDA
SDA
ILIM
ISET
Optional
BAT
0.1µF
bq27532-G1
Optional for nonremovable pack
VCC
1µF
BSDA
1.8MŸ
BSCL
BI/TOUT
0.033µF
18.2kŸ
SOC_INT
SCL
1kŸ
TEMP
TS
0.1µF
SDA
PACK+
+
RNTC
PACK-
SRP
0.1µF
0.01
SRN
CE
Optional
REGIN
VSS
0.1µF
VSS
Figure 12. Typical Application Schematic
22
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Typical Application (continued)
8.2.1 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" gas gauge (.fs) 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 GG file to cut down on
system production time. If going this route, 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 5, Key Data Flash Parameters
for Configuration, shows the items that should be configured to achieve reliable protection and accurate gauging
with minimal initial configuration.
Table 5. Key Data Flash Parameters for Configuration
NAME
DEFAULT
UNIT
RECOMMENDED SETTING
Set based on the nominal pack capacity as interpreted from cell manufacturer's
datasheet. If multiple parallel cells are used, should be set to N × Cell Capacity.
Design Capacity
1000
mAh
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 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 appropriate software tool (that is, bqStudio).
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, etc). 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.
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Typical Application (continued)
Table 5. 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 Tn
parameters.
CC Gain
10
mohms
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
mohms
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
8.2.2 Detailed Design Procedure
8.2.2.1 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.
24
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8.2.2.2 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.
8.2.2.3 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.
8.2.2.4 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.
8.2.2.5 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.
8.2.2.6 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.
8.2.2.7 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.
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8.2.3 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
100
D002
3
2
1
0
-1
-2
-3
-4
-5
-30
-20
D003
Figure 15. Low-Frequency Oscillator Frequency vs.
Temperature
80
Figure 14. High-Frequency Oscillator Frequency vs.
Temperature
Reported Temperature Error (qC)
fLOSC - Low Frequency Oscillator (kHz)
Figure 13. Regulator Output Voltage vs. Temperature
60
-10
0
10
20
30
Temperature (qC)
40
50
60
D004
Figure 16. Reported Internal Temperature Measurement
vs. Temperature
9 Power Supply Recommendations
9.1 Power Supply Decoupling
Both the REGIN input pin and the VCC output pin require low equivalent series resistance (ESR) ceramic
capacitors placed as closely 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.
26
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10 Layout
10.1 Layout Guidelines
10.1.1 Sense Resistor Connections
Kelvin connections at the sense resistor are just as critical as those for the battery terminals themselves. The
differential traces should be connected at the inside of the sense resistor pads and not anywhere along the highcurrent 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 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.
10.1.2 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.
10.1.3 High-Current and Low-Current Path Separation
For best possible noise performance, it is extremely important to separate the low-current and high-current 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 high-current 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.
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10.2 Layout Example
Battery power
connection to
system
Use copper
pours for battery
power path to
minimize IR
losses
SCL
To system host
processor
SDA
BSDA
BATTERY PACK
CONNECTOR
To charger slave
BSCL
C1
PACK+
Kelvin connect the
BAT sense line right
at positive terminal to
battery pack
REGIN
BAT
C2
BI/TOUT
CE
Vcc
BSDA
VSS
VSS
SDA
BSCL
SRN
SCL
SOC_INT
SRP
C3
THERM
TS
INT
Ground return to
system
PACK –
10 mΩ 1%
Via connects to Power Ground
Kelvin connect SRP
and SRN
connections right at
Rsense terminals
Figure 17. bq27532-G1 Layout Schematic
28
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
For related documentation, see the following:
1. bq27532-G1 Technical Reference Manual User's Guide (SLUUB04)
2. bq27532EVM with bq27532 Battery Management Unit Impedance Track™ Fuel Gauge and bq24250 2.0-A,
Switch-Mode Battery Charger for Single-Cell Applications User's Guide (SLUUB58)
11.2 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.
11.3 Trademarks
Impedance Track, NanoFree, E2E are trademarks of Texas Instruments.
I2C is a trademark of NXP Semiconductors.
All other trademarks are the property of their respective owners.
11.4 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.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 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.
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PACKAGE OPTION ADDENDUM
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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)
BQ27532YZFR-G1
ACTIVE
DSBGA
YZF
15
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27532
BQ27532YZFT-G1
ACTIVE
DSBGA
YZF
15
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
-40 to 85
BQ27532
(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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