BQ27741YZFR-G1 - Texas Instruments

Battery Pack

PACK–

PACK+

SDA

SCL

REG25

VPWR

HDQ

SRP

Vss

HDQ

SDA

SCL

PACKP

CHG

DSG

SRN

VBAT

–

Product

Folder

Sample &

Buy

Technical

Documents

Tools &

Software

Support &

Community

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

bq27741-G1 Single-Cell Li-Ion Battery Fuel Gauge with Integrated Protection

1 Features 3 Description

The Texas Instruments bq27741-G1 Li-Ion battery

1• Battery Fuel Gauge and Protector for 1-Series Li- fuel gauge is a microcontroller peripheral that

Ion Applications provides fuel gauging for single-cell Li-Ion battery

• Microcontroller Peripheral Provides: packs. The device requires little system

– Accurate Battery Fuel Gauging Supports up to microcontroller firmware development for accurate

battery fuel gauging. The fuel gauge resides within

14,500 mAh the battery pack or on the system’s main board with

– External and Internal Temperature Sensors for an embedded battery (non-removable). The fuel

Battery Temperature Reporting gauge provides hardware-based over- and

– Precision 16-Bit High-Side Coulomb Counter undervoltage, overcurrent in charge or discharge, and

with High-Side Low-Value Sense Resistor short-circuit protections.

(5 mΩto 20 mΩ)The fuel gauge uses the patented Impedance

– Lifetime and Current Data Logging Track™ algorithm for fuel gauging, and provides

information such as remaining battery capacity

– 64 Bytes of Non-Volatile Scratch Pad Flash (mAh), state-of-charge (%), run-time to empty

– SHA-1/HMAC Authentication (minimum), battery voltage (mV), and temperature

• Battery Fuel Gauging Based on Patented (°C), as well as recording vital parameters throughout

Impedance Track™ Technology the lifetime of the battery.

– Models Battery Discharge Curve for Accurate The device comes in a 15-ball BGA package

Time-To-Empty Predictions (2.776 mm × 1.96 mm) that is ideal for space-

– Automatically Adjusts for Aging, Self- constrained applications.

Discharge, and Temperature- and Rate- Device Information(1)

Induced Effects on Battery PART NUMBER PACKAGE BODY SIZE (NOM)

• Advanced Fuel Gauging Features bq27741-G1 YZF (15) 2.78 mm × 1.96 mm

– Internal Short Detection (1) For all available packages, see the orderable addendum at

– Tab Disconnection Detection the end of the data sheet.

• Safety and Protection:

– Over- and Undervoltage Protection with Low- Simplified Schematic

Power Mode

– Overcharging and Discharging Current

Protection

– Overtemperature Protection

– Short-Circuit Protection

– Low-Voltage Notification

– Voltage Doubler to Support High-Side

N-Channel FET Protection

• HDQ and I2C Interface Formats for

Communication with Host System

• Small 15-Ball NanoFree™ (BGA) Packaging

2 Applications

• Smartphones

• PDAs

• Digital Still and Video Cameras

• Handheld Terminals

• MP3 or Multimedia Players

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.

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Table of Contents

7.19 Data Flash Memory Characteristics........................ 9

1 Features.................................................................. 17.20 I2C-Compatible Interface Timing Characteristics.... 9

2 Applications ........................................................... 17.21 HDQ Communication Timing Characteristics ......... 9

3 Description............................................................. 17.22 Typical Characteristics.......................................... 11

4 Revision History..................................................... 28 Detailed Description............................................ 12

5 Device Comparison Table..................................... 38.1 Overview................................................................. 12

6 Pin Configuration and Functions......................... 38.2 Functional Block Diagram....................................... 12

7 Specifications......................................................... 48.3 Feature Description................................................. 13

7.1 Absolute Maximum Ratings ...................................... 48.4 Device Functional Modes........................................ 16

7.2 ESD Ratings.............................................................. 49 Application and Implementation ........................ 22

7.3 Recommended Operating Conditions....................... 59.1 Application Information .......................................... 22

7.4 Thermal Information.................................................. 59.2 Typical Applications ................................................ 22

7.5 Power-On Reset........................................................ 610 Power Supply Recommendations ..................... 29

7.6 2.5-V LDO Regulator ............................................... 610.1 Power Supply Decoupling..................................... 29

7.7 Charger Attachment and Removal Detection ........... 611 Layout................................................................... 29

7.8 Voltage Doubler ........................................................ 611.1 Layout Guidelines ................................................. 29

7.9 Overvoltage Protection (OVP) .................................. 611.2 Layout Example .................................................... 31

7.10 Undervoltage Protection (UVP)............................... 712 Device and Documentation Support................. 32

7.11 Overcurrent in Discharge (OCD)............................. 712.1 Device Support...................................................... 32

7.12 Overcurrent in Charge (OCC)................................. 712.2 Documentation Support ........................................ 32

7.13 Short-Circuit in Discharge (SCD)............................ 712.3 Community Resources.......................................... 32

7.14 Low-Voltage Charging............................................. 812.4 Trademarks........................................................... 32

7.15 Internal Temperature Sensor Characteristics......... 812.5 Electrostatic Discharge Caution............................ 32

7.16 Internal Clock Oscillators ........................................ 812.6 Glossary................................................................ 32

7.17 Integrating ADC (Coulomb Counter)

Characteristics ........................................................... 813 Mechanical, Packaging, and Orderable

7.18 ADC (Temperature and Cell Voltage) Information ........................................................... 32

Characteristics ........................................................... 8

4 Revision History

Changes from Revision B (April 2015) to Revision C Page

• Changed Pin Configuration and Functions ............................................................................................................................ 3

• Changed Absolute Maximum Ratings.................................................................................................................................... 4

• Changed Recommended Operating Conditions .................................................................................................................... 5

• Changed Functional Block Diagram..................................................................................................................................... 12

• Deleted UNDERTEMPERATURE FAULT Mode ................................................................................................................. 21

• Added Community Resources.............................................................................................................................................. 32

Product Folder Links: bq27741-G1

(TOP VIEW) (BOTTOM VIEW)

C3 B3

BOTTOM VIEW

SRP

CHG

DSG

SRN

VPWR

BAT

SDA PACKP

RC2

VSS

HDQ

SCL

REG25

ABCDE

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

5 Device Comparison Table

PRODUCTION FIRMWARE VERSION COMMUNICATION FORMAT

PART NO.(1)

bq27741YZFR-G1 1.08 I2C, HDQ(1)

bq27741YZFT-G1

(1) bq27741-G1 is shipped in the I2C mode.

6 Pin Configuration and Functions

YZF Package

15-Pin DSBGA

Pin Functions

PIN I/O(1) DESCRIPTION

NAME NO.

BAT C2 IA Cell-voltage measurement input. ADC input

CHG A2 O External high-side N-channel charge FET driver

DSG A3 O External high-side N-channel discharge FET driver

HDQ D2 IO HDQ serial communications line. Open-drain

PACKP B3 IA Pack voltage measurement input for protector operation

NC B2 IO Not used. Reserved for future GPIO. Recommended to connect to GND.

RC2 D3 IO General purpose IO. Push-pull output

REG25 E1 P Regulator output and bq27741-G1 processor power. Decouple with 1-µF ceramic capacitor to VSS.

SCL E3 IO Slave I2C serial communications clock input line for communication with system. Use with 10-kΩ

pullup resistor (typical).

SDA C3 IO Slave I2C serial communications data line for communication with system. Open-drain I/O. Use with

10-kΩpullup resistor (typical).

SRN B1 IA Analog input pin connected to the internal coulomb counter where SRN is nearest the CELL+

connection. Connect to sense resistor.

SRP A1 IA Analog input pin connected to the internal coulomb counter where SRP is nearest the PACK+

connection. Connect to sense resistor.

VPWR C1 P Power input. Decouple with 0.1-µF ceramic capacitor to VSS.

VSS D1 P Device ground

TS E2 IA Pack thermistor voltage sense (use 103AT-type thermistor). ADC input

(1) IO = Digital input-output, IA = Analog input, P = Power connection, O = Output

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Table 1. Default Configuration

OVERVOLTAGE UNDERVOLTAGE OVERCURRENT IN OVERCURRENT IN SHORT CIRCUIT IN

PROTECTION (VOVP) PROTECTION (VUVP) DISCHARGE (VOCD) CHARGE (VOCC) DISCHARGE (Vscd)

4.390 V 2.407 V 34.4 mV 20 mV 74.6 mV

OVERVOLTAGE UNDERVOLTAGE OVERCURRENT IN SHORT CIRCUIT IN

OVERCURRENT IN

PROTECTION DELAY PROTECTION DELAY DISCHARGE DELAY DISCHARGE DELAY

CHARGE DELAY (tOCC)

(tOVP) (tUVP) (tOCD) (tscd)

1 s 31.25 ms 31.25 ms 7.8125 ms 312.5 µs

7 Specifications

7.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)

MIN MAX UNIT

VVPWR Power input –0.3 5.5 V

VREG25 Supply voltage –0.3 2.75 V

PACKP input pin –0.3 5.5 V

VPACKP PACK+ input when external 2-kΩresistor is in series with PACKP input pin (see (1)) –0.3 28 V

VOUT Voltage output pins (DSG, CHG) –0.3 10 V

VIOD1 Push-pull IO pins (RC2) –0.3 2.75 V

VIOD2 Open-drain IO pins (SDA, SCL, HDQ, NC) –0.3 5.5 V

VBAT BAT input pin –0.3 5.5 V

VIInput voltage to all other pins (SRP, SRN) –0.3 5.5 V

VTS Input voltage for TS –0.3 2.75 V

TAOperating free-air temperature –40 85 °C

TFFunctional temperature –40 100 °C

TSTG Storage temperature –65 150 °C

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

7.2 ESD Ratings VALUE UNIT

Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000

V(ESD) Electrostatic discharge V

Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±500

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

7.3 Recommended Operating Conditions

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITION MIN NOM MAX UNIT

No operating restrictions 2.8 5

VVPWR Supply voltage V

No FLASH writes 2.45 2.8

External input capacitor for internal

CVPWR 0.1 µF

Nominal capacitor values specified.

LDO between VPWR and VSS Recommend a 5% ceramic X5R

External output capacitor for type capacitor located close to the

CREG25 internal LDO between REG25 and 0.47 1 µF

device.

VSS Fuel gauge in NORMAL mode.

Normal operating mode

ICC ILOAD >Sleep Current with charge 167 µA

current(1)(2) (VPWR) pumps on (FETs on)

Fuel gauge in SLEEP+ mode.

ISLP SLEEP mode current(1)(2) (VPWR) ILOAD <Sleep Current with charge 88 µA

pumps on (FETs on)

Fuel gauge in SLEEP mode.

FULLSLEEP mode current(1)(2)

IFULLSLP ILOAD <Sleep Current with charge 40 µA

(VPWR) pumps on (FETs on)

Fuel gauge in SHUTDOWN mode.

UVP tripped with fuel gauge and

protector turned off (FETs off) 0.1 0.2 µA

Shutdown mode current(1)(2)

ISHUTDOWN VVPWR = 2.5 V

(VPWR) TA= 25°C

TA= –40°C to 85°C 0.5 µA

Output voltage low (SCL, SDA,

VOL IOL = 1 mA 0.4 V

HDQ, NC, RC2)

Output voltage high (SDA, SCL, External pullup resistor connected

VOH(OD) VREG25 – 0.5 V

HDQ, NC, RC2) to VREG25

Input voltage low (SDA, SCL,

VIL –0.3 0.6 V

HDQ, NC)

Input voltage high (SDA, SCL,

VIH(OD) 1.2 5.5 V

HDQ, NC)

VA1 Input voltage range (TS) VSS – 0.125 2 V

VA2 Input voltage range (BAT) VSS – 0.125 5 V

VVPWR – VVPWR +

VA3 Input voltage range (SRP, SRN) V

0.125 0.125

Ilkg Input leakage current (I/O pins) 0.3 µA

tPUCD Power-up communication delay 250 ms

(1) All currents are specified as charge pump on (FETs on).

(2) All currents are continuous average over 5-second period.

7.4 Thermal Information bq27741-G1

THERMAL METRIC(1) YZF [DSBGA] UNIT

15 PINS

RθJA Junction-to-ambient thermal resistance 70

RθJC(top) Junction-to-case (top) thermal resistance 17

RθJB Junction-to-board thermal resistance 20 °C/W

ψJT Junction-to-top characterization parameter 1

ψJB Junction-to-board characterization parameter 18

RθJC(bot) Junction-to-case (bottom) thermal resistance N/A

(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

7.5 Power-On Reset

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VIT+ Increasing battery voltage input at VREG25 2.09 2.20 2.31 V

VHYS Power-on reset hysteresis 115 mV

7.6 2.5-V LDO Regulator(1)

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

2.8 V ≤VVPWR ≤4.5 V, 2.3 2.5 2.6 V

IOUT(1) ≤16 mA TA= –40°C to

VREG25 Regulator output voltage 2.45 V ≤VVPWR < 2.8 V (low 85°C

battery), 2.3 V

IOUT(1) ≤3 mA TA= –40°C to

ISHORT (2) Short-circuit current limit VREG25 = 0 V 250 mA

85°C

(1) LDO output current, IOUT, is the sum of internal and external load currents.

(2) Assured by characterization. Not production tested.

7.7 Charger Attachment and Removal Detection

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VCHGATT Voltage threshold for charger attachment detection 2.7 3 V

VCHGREM Voltage threshold for charger removal detection 0.5 1 V

7.8 Voltage Doubler

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

IL= 1 µA

VFETON CHG and DSG FETs on 2 × VVPWR – 0.4 2 × VVPWR – 0.2 2 × VVPWR V

TA= –40°C to 85°C

VFETOFF CHG and DSG FETs off TA= –40°C to 85°C 0.2 V

IL= 1 µA

VFETRIPPLE(1) CHG and DSG FETs on 0.1 VPP

TA= –40°C to 85°C

CL= 4 nF

FET gate rise time

tFETON TA= –40°C to 85°C 67 140 218 μs

(10% to 90%) No series resistance

CL= 4 nF

FET gate fall time

tFETOFF TA= –40°C to 85°C 10 30 60 μs

(90% to 10%) No series resistance

(1) Assured by characterization. Not production tested.

7.9 Overvoltage Protection (OVP)

TA= 25°C and CREG25 = 1.0 µF (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TA= 25°C VOVP – 0.006 VOVP VOVP + 0.006

TA= 0°C to 25°C VOVP – 0.023 VOVP VOVP + 0.020

OVP detection voltage

VOVP V

threshold TA= 25°C to 50°C VOVP – 0.018 VOVP VOVP + 0.014

TA= –40°C to 85°C VOVP – 0.053 VOVP VOVP + 0.035

TA= 25°C VOVPREL – 0.012 VOVP – 0.215 VOVPREL + 0.012

TA= 0°C to 25°C VOVPREL – 0.023 VOVP – 0.215 VOVPREL + 0.020

VOVPREL OVP release voltage V

TA= 25°C to 50°C VOVPREL – 0.018 VOVP – 0.215 VOVPREL + 0.014

TA= –40°C to 85°C VOVPREL – 0.053 VOVP – 0.215 VOVPREL + 0.035

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Overvoltage Protection (OVP) (continued)

TA= 25°C and CREG25 = 1.0 µF (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

tOVP OVP delay time TA= –40°C to 85°C tOVP – 5% tOVP tOVP + 5% s

7.10 Undervoltage Protection (UVP)

TA= 25°C and CREG25 = 1.0 µF (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TA= 25°C VUVP – 0.012 VUVP VUVP + 0.012

UVP detection voltage

VUVP TA= –5°C to 50°C VUVP – 0.020 VUVP VUVP + 0.020 V

threshold TA= –40°C to 85°C VUVP – 0.040 VUVP VUVP + 0.040

TA= 25°C VUVPREL – 0.012 VUVP + 0.105 VUVPREL + 0.012

VUVPREL UVP release voltage TA= –5°C to 50°C VUVPREL – 0.020 VUVP + 0.105 VUVPREL + 0.020 V

TA= –40°C to 85°C VUVPREL – 0.040 VUVP + 0.105 VUVPREL + 0.040

tUVP UVP delay time TA= –40°C to 85°C tUVP – 5% tUVP tUVP + 5% ms

7.11 Overcurrent in Discharge (OCD)

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TA= 25°C VOCD – 3 VOCD VOCD + 3

VSRN – VSRP

OCD detection voltage TA= –20°C to 60°C

VOCD VOCD – 3.785 VOCD VOCD + 3.785 mV

threshold VSRN – VSRP

TA= –40°C to 85°C VOCD – 4.16 VOCD VOCD + 4.16

VSRN – VSRP

tOCD OCD delay time TA= –40°C to 85°C tOCD – 5% tOCD tOCD + 5% ms

7.12 Overcurrent in Charge (OCC)

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TA= 25°C VOCC – 3 VOCC VOCC + 3

VSRP – VSRN

OCC detection voltage TA= –20°C to 60°C

VOCC VOCC – 3.49 VOCC VOCC + 3.49 mV

threshold VSRP – VSRN

TA= –40°C to 85°C VOCC – 3.86 VOCC VOCC + 3.86

VSRP – VSRN

tOCC OCC delay time TA= –40°C to 85°C tOCC – 5% tOCC tOCC + 5% ms

7.13 Short-Circuit in Discharge (SCD)

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TA= 25°C VSCD – 3 VSCD VSCD + 3

VSRN – VSRP

SCD detection voltage TA= –20°C to 60°C

VSCD VSCD – 4.5 VSCD VSCD + 4.5 mV

threshold VSRN – VSRP

TA= –40°C to 85°C VSCD – 4.9 VSCD VSCD + 4.9

VSRN – VSRP

tSCD SCD delay time TA= –40°C to 85°C tSCD – 10% tSCD tSCD + 10% µs

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

7.14 Low-Voltage Charging

TA= 25°C, CREG25 = 1.0 µF, and VVPWR = 3.6 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Voltage threshold for low-voltage charging

VLVDET TA= –40°C to 85°C 1.4 1.55 1.7 V

detection

7.15 Internal Temperature Sensor Characteristics

TA= –40°C to 85°C, 2.4 V < VREG25 < 2.6 V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

G(TEMP) Temperature sensor voltage gain –2 mV/°C

7.16 Internal Clock Oscillators

2.4 V < VREG25 < 2.6 V; typical values at TA= 25°C and VREG25 = 2.5 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

fOSC Operating frequency 8.389 MHz

f(LOSC) Operating frequency 32.768 kHz

7.17 Integrating ADC (Coulomb Counter) Characteristics

TA= –40°C to 85°C, 2.4 V < VREG25 < 2.6 V; typical values at TA= 25°C and VREG25 = 2.5 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VVPWR +

VSR_IN Input voltage range, VSRN and VSRP VSR = VSRN – VSRP VVPWR – 0.125 V

0.125

Conversion time Single conversion 1 s

tSR_CONV Resolution 14 15 bits

VSR_OS Input offset 10 μV

INL Integral nonlinearity error ±0.007% ±0.034% FSR

ZSR_IN Effective input resistance(1) 7 MΩ

ISR_LKG Input leakage current(1) 0.3 μA

(1) Assured by design. Not production tested.

7.18 ADC (Temperature and Cell Voltage) Characteristics

TA= –40°C to 85°C, 2.4 V < VREG25 < 2.6 V; typical values at TA= 25°C and VREG25 = 2.5 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Input voltage range (VBAT channel) VSS – 0.125 5 V

VADC_IN Input voltage range (other channels) VSS – 0.125 1 V

tADC_CONV Conversion time 125 ms

Resolution 14 15 bits

VADC_OS Input offset 1 mV

ZADC1 Effective input resistance (TS) (1) 55 MΩ

Not measuring cell voltage 55 MΩ

ZADC2 Effective input resistance (BAT)(1) Measuring cell voltage 100 kΩ

IADC_LKG Input leakage current(1) 0.3 μA

(1) Assured by design. Not production tested.

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

7.19 Data Flash Memory Characteristics

TA= –40°C to 85°C, 2.4 V < VREG25 < 2.6 V; typical values at TA= 25°C and VREG25 = 2.5 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Data retention(1) 10 years

tDR Flash programming write-cycles (1) 20,000 cycles

tWORDPROG Word programming time(1) 2 ms

ICCPROG Flash-write supply current(1) 5 10 mA

(1) Assured by design. Not production tested.

7.20 I2C-Compatible Interface Timing Characteristics

TA= –40°C to 85°C, 2.4 V < VREG25 < 2.6 V; typical values at TA= 25°C and VREG25 = 2.5 V (unless otherwise noted)

MIN TYP MAX UNIT

tRSCL or SDA rise time 300 ns

tFSCL or SDA fall time 300 ns

tw(H) SCL pulse width (high) 600 ns

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 100 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 Clock frequency 400 kHz

7.21 HDQ Communication Timing Characteristics

TA= –40°C to 85°C, 2.4 V < VREG25 < 2.6 V; typical values at TA= 25°C and VREG25 = 2.5 V (unless otherwise noted)

MIN TYP MAX UNIT

t(CYCH) Cycle time, host to fuel gauge 190 μs

t(CYCD) Cycle time, fuel gauge to host 190 205 250 μs

t(HW1) Host sends 1 to fuel gauge 0.5 50 μs

t(DW1) Fuel gauge sends 1 to host 32 50 μs

t(HW0) Host sends 0 to fuel gauge 86 145 μs

t(DW0) Fuel gauge sends 0 to host 80 145 μs

t(RSPS) Response time, fuel gauge to host 190 950 μs

t(B) Break time 190 μs

t(BR) Break recovery time 40 μs

t(RST) HDQ reset 1.8 2.2 s

t(RISE) HDQ line rise time to logic 1 (1.2 V) 950 ns

Turnaround time (time from the falling edge of the last transmitted bit of 8-bit

t(TRND) 210 μs

data and the falling edge of the next Break signal)

Product Folder Links: bq27741-G1

t(B) t(BR)

t(HW1)

t(HW0)

t(CYCH)

t(DW1)

t(DW0)

t(CYCD)

Break 7-bit address 8-bit data

(a) Break and Break Recovery

(e) Gauge to Host Response

1.2V

t(RISE)

(b) HDQ line rise time

1-bit

R/W

t(RSPS)

t(RST)

(f) HDQ Reset

f. HDQ Host to fuel gauge

e. Fuel gauge to Host response format

d. Fuel gauge to Host communication

c. HDQ Host to fuel gauge communication

b. Rise time of HDQ line

a. HDQ Breaking

tSU(STA)

SCL

SDA

tw(H) tw(L) tftrt(BUF)

td(STA)

REPEATED

START

th(DAT) tsu(DAT)

tftsu(STOP)

STOP START

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Figure 1. I2C-Compatible Interface Timing Diagrams

Figure 2. HDQ Timing Diagrams

Product Folder Links: bq27741-G1

280

285

290

295

300

305

310

315

320

325

330

335

340

345

350

±40 ±30 ±20 ±10 0 10 20 30 40 50 60 70 80

tSCD - Short-circuit Current in Discharge Delay Time (µs)

Temperature (C)

C001

6.80

7.00

7.20

7.40

7.60

7.80

8.00

8.20

8.40

8.60

8.80

9.00

±40 ±30 ±20 ±10 0 10 20 30 40 50 60 70 80

tOCC - Overcurrent in Charge Delay Time (ms)

Temperature (C)

C001

29.00

29.50

30.00

30.50

31.00

31.50

32.00

32.50

33.00

33.50

34.00

±40 ±30 ±20 ±10 0 10 20 30 40 50 60 70 80

tOCD - Overcurrent in Discharge Delay Time (ms)

Temperature (C)

C001

0.95

0.96

0.97

0.98

0.99

1.00

1.01

1.02

1.03

1.04

1.05

±40 ±30 ±20 ±10 0 10 20 30 40 50 60 70 80

tOVP - Overvoltage Delay Time (s)

Temperature (C)

C001

29.00

29.50

30.00

30.50

31.00

31.50

32.00

32.50

33.00

33.50

34.00

±40 ±30 ±20 ±10 0 10 20 30 40 50 60 70 80

tUVP - Undervoltage Delay Time (ms)

Temperature (C)

C001

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

7.22 Typical Characteristics

Figure 3. Overvoltage Delay Time Figure 4. Undervoltage Delay Time

Figure 5. Overcurrent in Charge Delay Time Figure 6. Overcurrent in Discharge Delay Time

Figure 7. Short-Circuit Current in Discharge Delay Time

Product Folder Links: bq27741-G1

VPWR

BAT

REG25

SRN

SRP

PACKP

CHG

NC DSG

RC2 SDA

VSS SCL

HDQ

MUX

–

VOVP

Data

FLASH

LDO

Data

SRAM

ADC

Protector

FSM

OVP

Delay

+UVP

Delay

–

VUVP

OCD

Delay

–VOCD

SCD

Delay

–VSCD

–

VOCC

OCC

Delay

2.5 V

5 kΩ

Internal

Temp

Sensor

Wake

Comparator

Instruction

FLASH

Instruction

ROM

CHG Drive

DSG Drive

VPWR

I2C Engine

CPU

88HDQ

Engine

HFO LFO

–

0.3 V

GP Timer

and

PWM

I/O

Controller

Wake

and

Watchdog

Timer

360 kΩ

20 kΩ

VPWR

HFO

HFO/128

HFO /4

POR

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

8 Detailed Description

8.1 Overview

The bq27741-G1 fuel gauge accurately predicts the battery capacity and other operational characteristics of a

single Li-based rechargeable cell. It can be interrogated by a system processor to provide cell information, such

as state-of-charge (SOC), time-to-empty (TTE), and time-to-full (TTF).

8.2 Functional Block Diagram

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

8.3 Feature Description

NOTE

Formatting Conventions in This Document:

Commands:italics with parentheses and no breaking spaces, for example,

RemainingCapacity().

Data Flash:italics,bold, and breaking spaces, for example, Design Capacity.

Data Flash Bits:italic and bold, for example, [XYZ1]

Modes and states: ALL CAPITALS, for example, UNSEALED mode.

8.3.1 Configuration

Cell information is stored in the fuel gauge 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 these locations, use individual commands, a sequence of data-flash-access commands, or

the Battery Management Studio (bqStudio) Software. To access a desired data flash location, the correct data

flash subclass and offset must be known. For more information on the data flash, see the bq27741-G1 Pack-Side

Impedance Track™ Battery Fuel Gauge With Integrated Protector and LDO User's Guide (SLUUAA3).

The fuel gauge provides 96 bytes of user-programmable data flash memory, partitioned into two 64-byte blocks:

Manufacturer Info Block A and Manufacturer Info Block B. This data space is accessed through a data flash

interface.

8.3.2 Fuel Gauging

The key to the 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.

See the Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm Application Note

(SLUA364) for further details.

8.3.3 Wake-Up Comparator

The wake-up comparator indicates a change in cell current while the fuel gauge is in SLEEP mode. The wake

comparator threshold can be configured in firmware and set to the thresholds in Table 2. An internal event is

generated when the threshold is breached in either charge or discharge directions.

Table 2. IWAKE Threshold Settings(1)

RSNS1 RSNS0 IWAKE Vth(SRP-SRN)

0 0 0 Disabled

0 0 1 Disabled

0 1 0 1 mV or –1 mV

0 1 1 2.2 mV or –2.2 mV

1 0 0 2.2 mV or –2.2 mV

1 0 1 4.6 mV or –4.6 mV

1 1 0 4.6 mV or –4.6 mV

1 1 1 9.8 mV or –9.8 mV

(1) The actual resistance value versus the setting of the sense resistor is not important—only the actual voltage threshold is important when

calculating the configuration. The voltage thresholds are typical values under room temperature.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

8.3.4 Battery Parameter Measurements

8.3.4.1 Charge and Discharge Counting

The integrating delta-sigma ADC gauges the charge or discharge flow of the battery by measuring the voltage

drop across a small-value sense resistor between the SRP and SRN pins. The integrating ADC measures bipolar

signals and detects charge activity when VSR = VSRP – VSRN is positive and discharge activity when VSR = VSRP –

VSRN is negative. The fuel gauge continuously integrates the signal over time using an internal counter.

8.3.4.2 Voltage

The fuel gauge updates cell voltages at 1-second intervals when in NORMAL mode. The internal ADC of the fuel

gauge measures the voltage, and scales and calibrates it appropriately. Voltage measurement is automatically

compensated based on temperature. This data is also used to calculate the impedance of the cell for Impedance

Track fuel gauging.

8.3.4.3 Current

The fuel gauge uses the SRP and SRN inputs to measure and calculate the battery charge and discharge

current using a 5-mΩto 20-mΩtypical sense resistor.

8.3.4.4 Auto-Calibration

The bq27741-G1 device provides an auto-calibration feature to cancel the voltage offset error across SRN and

SRP for maximum charge measurement accuracy, and performs auto-calibration before entering the SLEEP

mode.

8.3.4.5 Temperature

The fuel gauge 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 = 3435 kΩ± 1% (such as Semitec 103AT for

measurement). The fuel gauge can also be configured to use its internal temperature sensor. The fuel gauge

uses temperature to monitor the battery-pack environment, which is used for fuel gauging and cell protection

functionality.

8.3.5 Communications

8.3.5.1 HDQ Single-Pin Serial Interface

The HDQ interface is an asynchronous return-to-one protocol where a processor sends the command code to

the fuel gauge. With HDQ, the least significant bit (LSB) of a data byte (command) or word (data) is transmitted

first. The DATA signal on pin 12 is open-drain and requires an external pullup resistor. The 8-bit command code

consists of two fields: the 7-bit HDQ command code (bits 0 through 6) and the 1-bit RW field (MSB bit 7). The

RW field directs the fuel gauge to either one of the following:

• Store the next 8 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.

HDQ serial communication is normally initiated by the host processor sending a break command to the fuel

gauge. 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 then is returned to its normal ready logic high state for a time t(BR). The fuel gauge is now ready to receive

information from the host processor.

The fuel gauge is shipped in the I2C mode. TI provides tools to enable the HDQ peripheral.

Product Folder Links: bq27741-G1

DATA[7:0]

ACMD[7:0]

S 0ADDR[6:0] AP

A AS 0ADDR[6:0] CMD[7:0] Sr 1ADDR[6:0] A DATA[7:0]

DATA[7:0] PN

AAPCMD[7:0] DATA[7:0] A

A AS 0ADDR[6:0] CMD[7:0] Sr 1ADDR[6:0] A DATA[7:0] A DATA[7:0]

S 0ADDR[6:0] S1

ADDR[6:0] A

. . .

(a) (b)

( c)

(d)

Host Generated GG Generated

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

8.3.5.2 HDQ Host Interruption

The default fuel gauge behaves as an HDQ slave-only device. If the HDQ interrupt function is enabled, the fuel

gauge is capable of mastering and also communicating to a HDQ device. There is no mechanism for negotiating

which 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 fuel gauge mastering an HDQ message. This message is a fixed

message that signals the interrupt condition. The message itself is 0x80 (slave write to register 0x00) with no

data byte being sent as the command is not intended to convey any status of the interrupt condition. The HDQ

interrupt function is not public and is only enabled by command.

When the SET_HDQINTEN subcommand is received, the fuel gauge detects any of the interrupt conditions and

asserts the interrupt at 1-s intervals until either:

• The CLEAR_HDQINTEN subcommand is received, or

• The number of tries for interrupting the host has exceeded a predetermined limit. After the interrupt event,

interrupts are automatically disabled. To re-enable interrupts, SET_HDQINTEN needs to be sent.

8.3.5.2.1 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.

8.3.5.2.2 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. (See details in HDQ Host Interruption.)

8.3.5.3 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 write or read, respectively.

Figure 8. Supported I2C Formats

(a) 1-byte write

(b) Quick read

(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 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).

Attempt to write a read-only address (NACK after data sent by master):

Product Folder Links: bq27741-G1

A AS

xxxxxxxx

ADDR[6:0]

xxxxxxxxx

CMD[7:0]

xxx

xxxxxxxx

ADDR[6:0] A DATA[7:0]

xxx

A DATA[7:0]

xxx

A AS A

xxxxxxxx

ADDR[6:0]

xxxxxxxxx

CMD[7:0]

xxxxxxxxx

DATA[7:0]

xxxxxxxxx

DATA[7:0] A 66Ps

A AS

xxxxxxxx

ADDR[6:0]

xxxxxxxxx

CMD[7:0]

xxx

xxxxxxx

ADDR[6:0] A DATA[7:0]

xxx

A DATA[7:0]

DATA[7:0]

A DATA[7:0]

xxx

Waiting time between control subcommand and reading results

Waiting time between continuous reading results

66Ps

A CMD[7:0]

ADDR[6:0] ASr DATA[7:0]

1ADDR[6:0] AA DATA[7:0] PN

Address

0x7F

Data from

addr 0x74

Data from

addr 0x00

DATA[7:0] A

ACMD[7:0] N

ADDR[6:0] DATA[7:0]

. . .

A P

CMD[7:0] N

S 0ADDR[6:0] P

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Attempt to read an address above 0x7F (NACK command):

Attempt at incremental writes (NACK all extra data bytes sent):

Incremental read at the maximum allowed read address:

The I2C engine releases both SDA and SCL if the I2C bus is held low for t(BUSERR). If the 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.

8.3.5.3.1 I2C Time Out

The I2C engine releases both SDA and SCL lines if the I2C bus is held low for about 2 seconds. If the fuel gauge

was holding the lines, releasing them frees the master to drive the lines.

8.3.5.3.2 I2C Command Waiting Time

To ensure the correct results of a command with the 400-kHz I2C operation, a proper waiting time must be added

between issuing a command and reading the results. For subcommands, the following diagram shows the

waiting time required between issuing the control command and reading the status with the exception of the

checksum command. A 100-ms waiting time is required between the checksum command and reading the 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 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.

Figure 9. I2C Command Waiting Time

The I2C clock stretch could happen in a typical application. A maximum 80-ms clock stretch could be observed

during the flash updates. There is up to a 270-ms clock stretch after the OCV command is issued.

8.4 Device Functional Modes

To minimize power consumption, the fuel gauge has three power modes: NORMAL, SLEEP, and FULLSLEEP.

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.

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Device Functional Modes (continued)

8.4.1 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 fuel gauge consumes the most power in NORMAL mode, the Impedance Track algorithm minimizes

the time the fuel gauge remains in this mode.

8.4.2 SLEEP Mode

SLEEP mode performs AverageCurrent(),Voltage(), and Temperature() less frequently, which results in reduced

power consumption. 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 has been qualified, but prior to entering it, the fuel gauge performs an ADC autocalibration to minimize

offset.

During the 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 if any entry condition is broken, specifically when either:

•AverageCurrent() rises above Sleep Current, or

• A current in excess of IWAKE through RSENSE is detected.

8.4.3 FULLSLEEP Mode

FULLSLEEP mode turns off the high-frequency oscillator and performs AverageCurrent(),Voltage(), and

Temperature() less frequently, which results in power consumption that is lower than that of the SLEEP mode.

FULLSLEEP mode can be enabled by two methods:

• Setting the [FULLSLEEP] bit in the Control Status register using the FULL_SLEEP subcommand and Full

Sleep Wait Time (FS Wait) in data flash is set as 0.

• Setting the Full Sleep Wait Time (FS Wait) in data flash to a number larger than 0. This method is disabled

when the FS Wait is set as 0.

FULLSLEEP mode is entered automatically when it is enabled by one of the methods above. When the first

method is used, the gauge enters the FULLSLEEP mode when the fuel gauge is in SLEEP mode. When the

second method is used, the FULLSLEEP mode is entered when the fuel gauge is in SLEEP mode and the timer

counts down to 0.

The fuel gauge exits the FULLSLEEP mode when there is any communication activity. Therefore, the execution

of SET_FULLSLEEP sets the [FULLSLEEP] bit. The FULLSLEEP mode can be verified by measuring the

current consumption of the gauge.

During FULLSLEEP 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 if any entry condition is broken, specifically when either:

•AverageCurrent() rises above Sleep Current, or

• A current in excess of IWAKE through RSENSE is detected.

While in FULLSLEEP mode, the fuel gauge can suspend serial communications by as much as 4 ms by holding

the comm line(s) low. This delay is necessary to correctly process host communication, because the fuel gauge

processor is mostly halted in SLEEP mode.

8.4.4 Battery Protector Description

The battery protector controls two external high-side N-channel FETs in a back-to-back configuration for battery

protection. The protector uses two voltage doublers to drive the CHG and DSG FETs on.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Device Functional Modes (continued)

8.4.4.1 High-Side N-Channel FET Charge and Discharge FET Drive

The CHG or DSG FET is turned on by pulling the FET gate input up to VFETON. The FETs are turned off by

pulling the FET gate input down to VSS. These FETs are automatically turned off by the protector based on the

detected protection faults, or when commanded to turn off via the FETTest(0x74/0x75) extended command.

Once the protection fault(s) is cleared, the FETs may be turned on again.

8.4.4.2 Operating Modes

The battery protector has several operating modes:

• Virtual SHUTDOWN mode

– ANALOG SHUTDOWN

– Low voltage charging

• UVP fault (POR state)

• NORMAL mode

• SHUTDOWN WAIT

• OCD or SCD FAULT mode

• OCC FAULT mode

• OVP FAULT mode

The relationships among these modes are shown in Figure 10.

Product Folder Links: bq27741-G1

VPWR

< V

OVPREL

AND

Fault recovery:

Charger removed

Fault recovery:

load removed

SRN

V–

SRP

) > V

OCD

SRN

V–

SRP

) > V

SCD

VPWR

> V

OVP

SRP

V–

SRN

) > V

OCC

Fault recovery:

Charger removed POR

OCD/SCD Fault

CHG FET on

DSG FET off

Fuel Gauge on

LDO on

OCC Fault

CHG FET off

DSG FET on

Fuel Gauge on

LDO on

OVP Fault

CHG FET off

DSG FET on

Fuel Gauge on

LDO on

Analog Shutdown

CHG FET off

DSG FET off

Fuel Gauge off

LDO is off

Low Voltage Charging

CHG FET control shorted to

PACKP pin

DSG FET off

Protection off

Fuel Gauge off

LDO is off

Normal

Fuel Gauge in

Normal, SLEEP,

FULLSLEEP Modes

CHG FET on

DSG FET on

Fuel Gauge on

LDO is on

Charger attached

AND

VPWR

LVDET

Virtual Shutdown

UVP Fault

(POR State)

CHG FET on

DSG FET off

Fuel Gauge on

LDO is on

VPWR

> V

UVPREL

VVPWR < VUVP

Charger removed

Shutdown Wait

CHG FET off

DSG FET off

Fuel Gauge on

LDO is on

Shutdown bit

cleared

Charger removed

FW(ROM) turns

FETs off briefly

Shutdown Bit

set

(Force UVP set)

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Device Functional Modes (continued)

Figure 10. Operating Modes

8.4.4.2.1 VIRTUAL SHUTDOWN Mode

In this mode, the fuel gauge is not functional and only certain portions of analog circuitry are running to allow

device wakeup from shutdown and low voltage charging.

8.4.4.2.1.1 ANALOG SHUTDOWN Mode

In this mode, the fuel gauge is not functional. Once the charger is connected, the fuel gauge determines if low

voltage charging is allowed and then transitions to low voltage charging.

8.4.4.2.1.2 LOW-VOLTAGE CHARGING Mode

In this mode, the fuel gauge closes the CHG FET by shorting the gate to the PACKP pin. Low voltage charging

continues until the cell voltage (VVPWR) rises above the POR threshold.

8.4.4.2.2 UNDERVOLTAGE FAULT Mode

In this mode, the voltage on VPWR pin is below VUVP and the charger is connected. As soon as the charger

disconnects, the fuel gauge transitions into ANALOG SHUTDOWN mode to save power.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Device Functional Modes (continued)

The fuel gauge can enter this mode from LOW VOLTAGE CHARGING mode when the battery pack is being

charged from a deeply discharged state or from NORMAL mode when the battery pack is being discharged

below the allowed voltage.

When the battery pack is charged above VUVPREL, the fuel gauge transitions to NORMAL mode.

8.4.4.2.3 NORMAL Mode

In this mode, the protector is fully powered and operational. Both CHG and DSG FETs are closed, while further

operation is determined by the firmware. The protector is continuously checking for all faults.

The CHG or DSG FET may be commanded to be opened via the protector register by the firmware, but it does

not affect protector operation or change the mode of operation.

Firmware can also command the fuel gauge to go into SHUTDOWN mode based on the command from the host.

In this case, firmware sets the shutdown bit to indicate intent to go into SHUTDOWN mode. The fuel gauge then

transitions to SHUTDOWN WAIT mode.

8.4.4.2.4 SHUTDOWN WAIT Mode

In this mode, the shutdown bit was set by the firmware and the fuel gauge initiated the shutdown sequence.

The shutdown sequence is as follows:

1. Open both CHG and DSG FETs.

2. Determine if any faults are set. If any faults are set, then go back to NORMAL mode.

3. Wait for charger removal. Once the charger is removed, turn off the LDO, which puts the fuel gauge into

ANALOG SHUTDOWN mode.

8.4.4.2.5 OVERCURRENT IN DISCHARGE (OCD) and SHORT-CIRCUIT IN DISCHARGE (SCD) FAULT Mode

In this mode, a short-circuit in discharge (SCD) or overcurrent in discharge (OCD) protection fault is detected

when the voltage across the sense resistor continuously exceeds the configured VOCD or VSCD thresholds for

longer than the configured delay.

The fuel gauge enables the fault removal detection circuitry, which monitors load removal. A special high

resistance load is switched on to monitor load presence. The OCD/SCD fault is cleared when the load is

removed, which causes the fuel gauge to transition into NORMAL mode.

8.4.4.2.6 OVERCURRENT IN CHARGE (OCC) FAULT Mode

In this mode, an overcurrent in charge (OCC) protection fault is detected when the voltage across the sense

resistor continuously exceeds the configured VOCC for longer than the configured delay.

The fuel gauge enables the fault removal detection circuitry, which monitors the charger removal. The OCC fault

is cleared once the charger voltage drops below the cell voltage by more than 300 mV, which causes the fuel

gauge to transition to NORMAL mode.

8.4.4.2.7 OVERVOLTAGE PROTECTION (OVP) FAULT Mode

In this mode, an OVERVOLTAGE PROTECTION (OVP) fault mode is entered when the voltage on VPWR pin

continuously exceeds the configured VOVP threshold for longer than the configured delay.

The fuel gauge enables the fault removal detection circuitry, which monitors the charger removal. The OVP fault

is cleared once the charger voltage drops below the cell voltage by more than 300 mV and the cell voltage drops

below VOVPREL, which causes the fuel gauge to transition to NORMAL mode.

8.4.4.3 Firmware Control of Protector

The firmware has control to open the CHG FET or DSG FET independently by overriding hardware control.

However, it has no control to close the CHG FET or DSG FET and can only disable the FET override.

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Device Functional Modes (continued)

8.4.5 OVERTEMPERATURE FAULT Mode

Overtemperature protection is implemented in firmware. Gauging firmware monitors temperature every second

and opens the CHG and DSG FETs if Temperature() >OT Prot Threshold for OT Prot Delay. The CHG and DSG

FETs override will be released when Temperature() <OT Prot Recover.

Product Folder Links: bq27741-G1

VPWR

BAT[RC3]

REG25

RC2

VSS

SRN

SRP

PACKP

CHG

DSG

SDA

SCL

HDQ

S2A

S1A

R2 5 mΩ

UPA2375T1P

1 k

R13

2 k

0.1 Fµ

100

R7 R10

100 100

PACK+

I2C_SDA

I2C_CLK

PACK–

TB2

R16

TB1

CELL+

CELL–

0.1 Fµ

1 Fµ

.47 Fµ

Ext Therm

RT1

10 k

200

0.1 Fµ

R11 R12

0.1 Fµ

200

0.1 Fµ C10 0.1 Fµ

C11

C12

0.1 Fµ

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

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 bq27741-G1 device is a single-cell fuel gauge with integrated Li-Ion protection circuitry for highly accurate

detection of overvoltage, undervoltage, overcurrent in charge, overcurrent in discharge, and short-circuit in

discharge fault conditions. If the detected fault continues to be present for a specific delay time (pre-configured in

the device), the protection front-end will disable the applicable charge pump circuit, resulting in opening of the

FET until the provoking safety condition resolves. The integrated 16-bit delta-sigma converters provide accurate,

high precision measurements for voltage, current, and temperature in order to accomplish effective battery

monitoring, protection, and gauging. To allow for optimal performance in the end application, special

considerations must be taken to ensure minimization of measurement error through proper printed circuit board

(PCB) layout and correct configuration of battery characteristics in the fuel gauge data flash. Such requirements

are detailed in Design Requirements.

9.2 Typical Applications

9.2.1 Pack-Side, Single-Cell Li-Ion Fuel Gauge and Protector

Figure 11. Typical Application Schematic, I2C Mode

Product Folder Links: bq27741-G1

VPWR

BAT[RC3]

REG25

RC2

VSS

SRN

SRP

PACKP

CHG

DSG

SDA

SCL

HDQ

S2A

S1A

R2 5 mΩ

UPA2375T1P

1 k

R13

2 k

0.1 Fµ

PACK+/Load+

HDQ

PACK /Load––

TB3

R16

TB1

CELL+

CELL–

0.1 Fµ

1 Fµ

.47 Fµ

Ext Therm

RT1

10 k

200

0.1 Fµ

R11 R12

0.1 Fµ

200

0.1 Fµ C10 0.1 Fµ

C11

C12

0.1 Fµ

1.8-V pullup. HDQ requires pack-side pullup.

R10

100

4.7 k

R17

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Typical Applications (continued)

Figure 12. Typical Application Schematic, HDQ Mode

9.2.1.1 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 packs 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 production packs, assuming identical pack design and Li-Ion cell origin (chemistry,

lot, and so on). Calibration data can be included as part of this golden file to cut down on battery pack production

time. If using this method, it is recommended to average the calibration data from a large sample size and use

these in the golden file.

NOTE

It is recommended to calibrate all packs individually as this will lead to the highest

performance and lowest measurement error in the end application on a per-pack basis. In

addition, the integrated protection functionality should be correctly configured to ensure

activation based on the fault protection needs of the target pack design, or else accidental

trip could be possible if using defaults.

Table 3 shows the items that should be configured to achieve reliable protection and accurate gauging with

minimal initial configuration.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Typical Applications (continued)

Table 3. Key Data Flash Parameters for Configuration

NAME DEFAULT UNIT RECOMMENDED SETTING

Set based on the nominal pack capacity as shown in the cell manufacturer's data

Design Capacity 1000 mAh sheet. If multiple parallel cells are used, should be set to N × Cell Capacity.

Set based on the nominal pack energy (nominal cell voltage × nominal cell

Design Energy 3800 mWh capacity) as shown in the cell manufacturer's data sheet. If multiple parallel cells

are used, should be set to N × Cell Energy.

Set to 10 to convert all power values to cWh or to 1 for mWh. Design Energy is

Design Energy Scale 1 — divided by this value.

Set to desired runtime remaining (in seconds/3600) × typical applied load

Reserve Capacity 0 mAh between reporting 0% SOC and reaching Terminate Voltage, if needed.

Design Voltage 3800 mV Set to nominal cell voltage per manufacturer data sheet.

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

Device Chemistry 0354 hex 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).

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.

Set to initial configured value for Design Capacity. The gauge will update this

Qmax Cell 0 1000 mAh parameter automatically after the optimization cycle and for every regular Qmax

update thereafter.

Set to nominal cell voltage for a fully charged cell. The gauge will update this

V at Chg Term 4350 mV parameter automatically each time full charge termination is detected.

Set to empty point reference of battery based on system needs. Typical is

Terminate Voltage 3000 mV between 3000 and 3200 mV.

Ra Max Delta 43 mΩSet to 15% of Cell0 R_a 4 resistance after an optimization cycle is completed.

Set based on nominal charge voltage for the battery in normal conditions (25°C,

Charging Voltage 4350 mV and so on). Used as the reference point for offsetting by Taper Voltage for full

charge termination detection.

Set to the nominal taper current of the charger + taper current tolerance to ensure

Taper Current 100 mA that the gauge will reliably detect charge termination.

Sets the voltage window for qualifying full charge termination. Can be set tighter

Taper Voltage 100 mV to avoid or wider to ensure possibility of reporting 100% SOC in outer JEITA

temperature ranges that use derated charging voltage.

Sets threshold for gauge detecting battery discharge. Should be set lower than

Dsg Current Threshold 60 mA minimal system load expected in the application and higher than Quit Current.

Sets the threshold for detecting battery charge. Can be set higher or lower

Chg Current Threshold 75 mA depending on typical trickle charge current used. Also should be set higher than

Quit Current.

Sets threshold for gauge detecting battery relaxation. Can be set higher or lower

Quit Current 40 mA depending on typical standby current and exhibited in the end system.

Current profile used in capacity simulations at onset of discharge or at all times if

Avg I Last Run –299 mA Load Select = 0. Should be set to nominal system load. Is automatically updated

by the gauge every cycle.

Power profile used in capacity simulations at onset of discharge or at all times if

Avg P Last Run –1131 mW Load Select = 0. Should be set to nominal system power. Is automatically

updated by the gauge every cycle.

Sets the threshold at which the fuel gauge enters SLEEP mode. Take care in

Sleep Current 15 mA setting above typical standby currents else entry to SLEEP may be

unintentionally blocked.

If auto-shutdown of fuel gauge is required prior to protect against accidental

discharge to undervoltage condition, set this to desired voltage threshold for

Shutdown V 0 mV completely powering down the fuel gauge. Recovery occurs when a charger is

connected.

Set to desired temperature at which charging is prohibited to prevent cell damage

OT Chg 55 °C due to excessive ambient temperature.

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Typical Applications (continued)

Table 3. Key Data Flash Parameters for Configuration (continued)

NAME DEFAULT UNIT RECOMMENDED SETTING

Set to desired time before CHG FET is disabled based on overtemperature.

OT Chg Time 5 s Since temperature changes much more slowly than other fault conditions, the

default setting is sufficient for most application.

OT Chg Recovery 50 °C Set to the temperature threshold at which charging is no longer prohibited.

Set to desired temperature at which discharging is prohibited to prevent cell

OT Dsg 60 °C damage due to excessive ambient temperature.

Set to desired time before DSG FET is disabled based on overtemperature. Since

OT Dsg Time 5 s temperature changes much more slowly than other fault conditions, the default

setting is sufficient for most application.

OT Dsg Recovery 55 °C Set to the temperature threshold at which cell discharging is no longer prohibited.

Calibrate this parameter using TI-supplied bqStudio software and calibration

CC Gain 5 mΩprocedure in the TRM. Determines conversion of coulomb counter measured

sense resistor voltage to current.

Calibrate this parameter using TI-supplied bqStudio software and calibration

CC Delta 5.074 mΩprocedure in the TRM. Determines conversion of coulomb counter measured

sense resistor voltage to passed charge.

Calibrate this parameter using TI-supplied bqStudio software and calibration

CC Offset 6.874 mA procedure in the TRM. Determines native offset of coulomb counter hardware

that should be removed from conversions.

Calibrate this parameter using TI-supplied bqStudio software and calibration

Board Offset 0.66 µA procedure in the TRM. Determines native offset of the printed circuit board

parasitics that should be removed from conversions.

Calibrate this parameter using TI-supplied bqStudio software and calibration

procedure in the TRM. Determines voltage offset between cell tab and ADC input

Pack V Offset 0 mV node to incorporate back into or remove from measurement, depending on

polarity.

9.2.1.2 Detailed Design Procedure

9.2.1.2.1 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 is 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.

The series resistor between the battery and the BAT input is used to limit current that could be conducted

through the chip-scale package's solder bumps in the event of an accidental short during the board assembly

process. The resistor is not likely to survive a sustained short condition (depends on power rating); however, it

damages the much cheaper resistor component over suffering damage to the fuel gauge die itself.

9.2.1.2.2 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 in order to best minimize impedance

mismatch-induced measurement errors. The single-ended ceramic capacitors should be tied to the battery

voltage node (preferably to a large copper pour connected to the SRN side of the sense resistor) in order to

further improve common-mode noise rejection. The series resistors between the CC inputs and the sense

resistor should be at least 200 Ωin order to mitigate SCR-induced latch-up due to possible ESD events.

9.2.1.2.3 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, 50-ppm drift

sense resistor with a 1-W power rating.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

9.2.1.2.4 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 most thermistors are handled and manually soldered to the

PCB as a separate step in the factory production flow. It should be placed as close as possible to the respective

input pin for optimal filtering performance.

9.2.1.2.5 Thermistor Selection

The fuel gauge temperature sensing circuitry is designed to work with a negative temperature coefficient-type

(NTC) thermistor with a characteristic 10-kΩresistance 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.

9.2.1.2.6 VPWR Power Supply Input Filtering

A ceramic capacitor is placed at the input to the fuel gauge's internal LDO in order 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 device's internal supply rails.

9.2.1.2.7 REG25 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 device.

9.2.1.2.8 Communication Interface Lines

A protection network composed of resistors and zener diodes is recommended on each of the serial

communication inputs to protect the fuel gauge from serious ESD transients. The Zener should be selected to

break down at a voltage larger than the typical pullup voltage for these lines but less than the internal diode

clamp breakdown voltage of the device inputs (approximately 6 V). A zener voltage of 5.6 V is typically

recommended. The series resistors are used to limit the current into the Zener diode and prevent component

destruction due to thermal strain once it goes into breakdown. 100 Ωis typically recommended for these

resistance values.

9.2.1.2.9 PACKP Voltage Sense Input

Inclusion of a 2-kΩseries resistor on the PACKP input allows it to tolerate a charger overvoltage event up to

28 V without device damage. The resistor also protects the device in the event of a reverse polarity charger

input, since the substrate diode will be forward biased and attempt to conduct charger current through the fuel

gauge (as well as the high FETs). An external reverse charger input FET clamp can be added to short the DSG

FET gate to its source terminal, forcing the conduction channel off when negative voltage is present at PACK+

input to the battery pack and preventing large battery discharge currents. A ceramic capacitor connected at the

PACKP pin helps to filter voltage into the comparator sense lines used for checking charger and load presence.

In addition, in the LOW VOLTAGE CHARGING state, the minimal circuit elements that are operational are

powered from this input pin and require a stable supply.

9.2.1.2.10 CHG and DSG Charge Pump Voltage Outputs

The series resistors used at the DSG and CHG output pins serve to protect them from damaging ESD events or

breakdown conditions, allowing the resistors to be damaged in place of the fuel gauge itself. An added bonus is

that they also help to limit in-rush currents due to use of FETs with large gate capacitance, allowing a smooth

ramp of power-path connection turn-on to the system.

Product Folder Links: bq27741-G1

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

9.2.1.2.11 N-Channel FET Selection

The selection of N-channel FETs for a single-cell battery pack design depends on a variety of factors including

package type, size, and device cost as well as performance metrics such as drain-to-source resistance

(rDS(on)), gate capacitance, maximum current and power handling, and similar. At a minimum, it is

recommended that the selected FETs have a drain-to-source voltage (VDS) and gate-to-source (VGS) voltage

tolerance of 12 V. Some FETs are designed to handle as much as 24 V between the drain and source terminals

and this would provide an increased safety margin for the pack design. Additionally, the DC current rating should

be high enough to safely handle sustained current in charge or discharge direction just below the maximum

threshold tolerances of the configured OCC and OCD protections and the lowest possible sense resistance value

based on tolerance and TCR considerations, or vice-versa. This ensures that there is sufficient power dissipation

margin given a worst-case scenario for the fault detections. In addition, striving for minimal FET resistance at the

expected gate bias as well as lowest gate capacitance will help reduce conduction losses and increase power

efficiency as well as achieve faster turn-on and turn-off times for the FETs. Many of these FETs are now offered

as dual, back-to-back N-channel FETs in wafer-chip scale (WCSP) packaging, decreasing both BOM count and

shrinking necessary board real estate to accommodate the components. Finally, refer to the safe operating area

(SOA) curves of the target FETs to ensure that the boundaries are never violated based on all possible load

conditions in the end application. The CSD83325L is an excellent example of a FET solution that meets all of the

aforementioned criteria, offering rDS(on) of 10.3 mΩand VDS of 12 V with back-to-back N-channel FETs in a

chip-scale package, a perfect fit for battery pack designs.

9.2.1.2.12 Additional ESD Protection Components

The additional capacitors placed across the CHG and DSF FET source pins as well as between PACK+ and

ground help to bolster and greatly improve the ESD robustness of the pack design. The former components

shunt damaging transients around the FETs and the latter components attempt to bypass such pulses to PACK–

before they couple further into the battery pack PCB. Two series capacitors are used for each of these protection

areas to prevent a battery short in the event of a single capacitor failure.

Product Folder Links: bq27741-G1

2V / div

5V / div

20ms / div

2V / div

5V / div

20ms / div

500ms / div

2V / div

5V / div

2V / div

5V / div

50ms / div

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

9.2.1.3 Application Curves

Figure 13. Overvoltage Protection Set and Clear Figure 14. Undervoltage Protection Set and Clear

Figure 15. Overcurrent in Charge Protection Set and Clear Figure 16. Overcurrent in Discharge Protection Set and

Clear

Product Folder Links: bq27741-G1

100µs / div

2V / div

5V / div

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

Figure 17. Short-Circuit in Discharge Protection Set and Clear

10 Power Supply Recommendations

10.1 Power Supply Decoupling

The VPWR input pin and the REG25 output pin require low equivalent series resistance (ESR) ceramic

capacitors placed as closely as possible to the respective pins to optimize ripple rejection and to provide a stable

and dependable power rail that is resilient to line transients. A 0.1-μF capacitor at the VPWR and a 1-μF

capacitor at REG25 suffice for satisfactory device performance.

11 Layout

11.1 Layout Guidelines

11.1.1 Li-Ion Cell Connections

For the highest voltage measurement accuracy, it is important to connect the BAT pin directly to the battery

terminal PCB pad. This avoids measurement errors caused by IR drops when high charge or discharge currents

are flowing. Connecting directly at the positive battery terminal with a Kelvin connection ensures the elimination

of parasitic resistance between the point of measurement and the actual battery terminal. Likewise, the low

current ground return for the fuel gauge and all related passive components should be star-connected precisely

at the negative battery terminal. This technique minimizes measurement error due to current-induced ground

offsets and also improves noise performance through prevention of ground bounce that could occur with high

current and low current returns intersecting ahead of the battery ground. The bypass capacitor for this sense line

needs to be placed as close as possible to the BAT input pin.

11.1.2 Sense Resistor Connections

Kelvin connections at the sense resistor are 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 high

current trace path in order 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 an additional measurement offset may 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 inputs pins.

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

Layout Guidelines (continued)

11.1.3 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.

11.1.4 FET Connections

The battery current transmission path through the FETs should be routed with large copper pours to provide the

lowest resistance path possible to the system. Depending on package type, thermal vias can be placed in the

package land pattern's thermal pad to reduce thermal impedance and improve heat dissipation from the package

to the board, protecting the FETs during high system loading conditions. In addition, it is preferable to locate the

FETs and other heat generating components away from the low power pack electronics to reduce the chance of

temperature drift and associated impacts to data converter measurements. In the event of FET overheating,

keeping reasonable distance between the most critical components, such as the fuel gauge, and the FETs helps

to decrease the risk of thermal breakdown to the more fragile components.

11.1.5 ESD Component Connections

The ESD components included in the reference design that connect across the back-to-back FETs as well as

from PACK+ to ground require trace connections that are as wide and short as possible in order to minimize loop

inductance in their return path. This ensures impedance is lowest at the AC loop through the series capacitors

and makes this route most attractive for ESD transients such that they are conducted away from the vulnerable

low voltage, low power fuel gauge and passive components. The series resistors and Zener diodes connected to

the serial communications lines should be placed as close as possible to the battery pack connector to keep

large ESD currents confined to an area distant from the fuel gauge electronics. Further, all ESD components

referred to ground should be single-point connected to the PACK– terminal if possible. This reduces the

possibility of ESD coupling into other sensitive nodes well ahead of the PACK– ground return.

11.1.6 High Current and Low Current Path Separation

For best possible noise performance, it is 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

board 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 further helps to improve noise rejection. Finally, the

high current path should be confined to a small loop from the battery, through the FETs, into the PACK

connector, and back.

Product Folder Links: bq27741-G1

Via connects to Power Ground

Via connects between two layers

CVPWR

CBAT

CREG25 RESD1

RESD3

RESD2

RESD4

RTHERM

PACK+

SDA

SCL

PACK-

CESD1 CESD2

CESD3

CESD4

CHGSRP DSG

SRN PACK

BATVPWR SDA

HDQVSS RC2

TSREG25 SCL

CTHERM

CDIFF

CSRP

CSRN

RBAT

RSENSE

Star ground right at

negative battery

terminal for low current

return path

RSRN RSRP

Kelvin connect BAT

sense line right at

positive battery

terminal

Keep differential

traces length

matched

RVPWR

RDSG

Use short and wide

traces to minimize

inductance

Use short and wide

traces to minimize

inductance

RPACKP

RCHG

CPACKP

Use short and wide

traces to minimize

inductance

Use copper pours for

battery power path to

minimize IR losses

Star ground right at PACK-

for ESD return path

bq27741-G1

www.ti.com

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

11.2 Layout Example

Figure 18. bq27741-G1 Board Layout

Product Folder Links: bq27741-G1

bq27741-G1

SLUSBF2C –JULY 2013–REVISED AUGUST 2015

www.ti.com

12 Device and Documentation Support

12.1 Device Support

For the Battery Management Studio (bqStudio) Software, go to http://www.ti.com/tool/bqstudio.

12.2 Documentation Support

12.2.1 Related Documentation

For related documentation, see the following:

•bq27741-G1 Pack-Side Impedance Track™ Battery Fuel Gauge with Integrated Protector and LDO User's

Guide (SLUUAA3)

•bq27741 EVM Single Cell Impedance Track™ Technology Evaluation Module User's Guide (SLUUAH1)

12.3 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.

12.4 Trademarks

Impedance Track, NanoFree, E2E are trademarks of Texas Instruments.

All other trademarks are the property of their respective owners.

12.5 Electrostatic Discharge Caution

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

12.6 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.

Product Folder Links: bq27741-G1

PACKAGE OPTION ADDENDUM

www.ti.com 28-Jun-2016

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

BQ27741YZFR-G1 NRND DSBGA YZF 15 3000 Green (RoHS

& no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 85 BQ27741-G1

BQ27741YZFT-G1 NRND DSBGA YZF 15 250 Green (RoHS

& no Sb/Br) SNAGCU Level-1-260C-UNLIM -40 to 85 BQ27741-G1

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability

information and additional product content details.

TBD: The Pb-Free/Green conversion plan has not been defined.

Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that

lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.

Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between

the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.

Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight

in homogeneous material)

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish

value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

PACKAGE OPTION ADDENDUM

www.ti.com 28-Jun-2016

Addendum-Page 2

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type Package

Drawing Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm) B0

(mm) K0

(mm) P1

(mm) W

(mm) Pin1

Quadrant

BQ27741YZFR-G1 DSBGA YZF 15 3000 180.0 8.4 2.06 2.88 0.69 4.0 8.0 Q1

BQ27741YZFT-G1 DSBGA YZF 15 250 180.0 8.4 2.06 2.88 0.69 4.0 8.0 Q1

PACKAGE MATERIALS INFORMATION

www.ti.com 21-Aug-2015

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

BQ27741YZFR-G1 DSBGA YZF 15 3000 182.0 182.0 20.0

BQ27741YZFT-G1 DSBGA YZF 15 250 182.0 182.0 20.0

PACKAGE MATERIALS INFORMATION

www.ti.com 21-Aug-2015

Pack Materials-Page 2

www.ti.com

PACKAGE OUTLINE

0.625 MAX

0.35

0.15

15X 0.35

0.25

1 TYP

TYP

0.5

TYP

0.5 TYP

B E A

4219381/A 02/2017

DSBGA - 0.625 mm max heightYZF0015

DIE SIZE BALL GRID ARRAY

NOTES:

1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing

per ASME Y14.5M.

2. This drawing is subject to change without notice.

3. NanoFreeTM package configuration.

NanoFree Is a trademark of Texas Instruments.

BALL A1

CORNER

SEATING PLANE

BALL TYP 0.05 C

A13

0.015 C A B

SYMM

SCALE 6.500

www.ti.com

EXAMPLE BOARD LAYOUT

15X ( 0.245)

(0.5) TYP

( 0.245)

METAL 0.05 MAX

SOLDER MASK

OPENING

METAL UNDER

SOLDER MASK

( 0.245)

SOLDER MASK

OPENING

0.05 MIN

4219381/A 02/2017

DSBGA - 0.625 mm max heightYZF0015

DIE SIZE BALL GRID ARRAY

NOTES: (continued)

4. Final dimensions may vary due to manufacturing tolerance considerations and also routing constraints.

For more information, see Texas Instruments literature number SNVA009 (www.ti.com/lit/snva009).

SYMM

LAND PATTERN EXAMPLE

EXPOSED METAL SHOWN

SCALE:30X

NON-SOLDER MASK

DEFINED

(PREFERRED)

SOLDER MASK DETAILS

NOT TO SCALE

EXPOSED

METAL

SOLDER MASK

DEFINED

EXPOSED

METAL

www.ti.com

EXAMPLE STENCIL DESIGN

(0.5)

TYP

(0.5) TYP

15X ( 0.25) (R0.05) TYP

METAL

TYP

4219381/A 02/2017

DSBGA - 0.625 mm max heightYZF0015

DIE SIZE BALL GRID ARRAY

NOTES: (continued)

5. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release.

SYMM

SOLDER PASTE EXAMPLE

BASED ON 0.1 mm THICK STENCIL

SCALE:40X

IMPORTANT NOTICE

Texas Instruments Incorporated (TI) reserves the right to make corrections, enhancements, improvements and other changes to its

semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers

should obtain the latest relevant information before placing orders and should verify that such information is current and complete.

TI’s published terms of sale for semiconductor products (http://www.ti.com/sc/docs/stdterms.htm) apply to the sale of packaged integrated

circuit products that TI has qualified and released to market. Additional terms may apply to the use or sale of other types of TI products and

services.

Reproduction of significant portions of TI information in TI data sheets is permissible only if reproduction is without alteration and is

accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such reproduced

documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements

different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the

associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.

Buyers and others who are developing systems that incorporate TI products (collectively, “Designers”) understand and agree that Designers

remain responsible for using their independent analysis, evaluation and judgment in designing their applications and that Designers have

full and exclusive responsibility to assure the safety of Designers' applications and compliance of their applications (and of all TI products

used in or for Designers’ applications) with all applicable regulations, laws and other applicable requirements. Designer represents that, with

respect to their applications, Designer has all the necessary expertise to create and implement safeguards that (1) anticipate dangerous

consequences of failures, (2) monitor failures and their consequences, and (3) lessen the likelihood of failures that might cause harm and

take appropriate actions. Designer agrees that prior to using or distributing any applications that include TI products, Designer will

thoroughly test such applications and the functionality of such TI products as used in such applications.

TI’s provision of technical, application or other design advice, quality characterization, reliability data or other services or information,

including, but not limited to, reference designs and materials relating to evaluation modules, (collectively, “TI Resources”) are intended to

assist designers who are developing applications that incorporate TI products; by downloading, accessing or using TI Resources in any

way, Designer (individually or, if Designer is acting on behalf of a company, Designer’s company) agrees to use any particular TI Resource

solely for this purpose and subject to the terms of this Notice.

TI’s provision of TI Resources does not expand or otherwise alter TI’s applicable published warranties or warranty disclaimers for TI

products, and no additional obligations or liabilities arise from TI providing such TI Resources. TI reserves the right to make corrections,

enhancements, improvements and other changes to its TI Resources. TI has not conducted any testing other than that specifically

described in the published documentation for a particular TI Resource.

Designer is authorized to use, copy and modify any individual TI Resource only in connection with the development of applications that

include the TI product(s) identified in such TI Resource. NO OTHER LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE

TO ANY OTHER TI INTELLECTUAL PROPERTY RIGHT, AND NO LICENSE TO ANY TECHNOLOGY OR INTELLECTUAL PROPERTY

RIGHT OF TI OR ANY THIRD PARTY IS GRANTED HEREIN, including but not limited to any patent right, copyright, mask work right, or

other intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information

regarding or referencing third-party products or services does not constitute a license to use such products or services, or a warranty or

endorsement thereof. Use of TI Resources may require a license from a third party under the patents or other intellectual property of the

third party, or a license from TI under the patents or other intellectual property of TI.

TI RESOURCES ARE PROVIDED “AS IS” AND WITH ALL FAULTS. TI DISCLAIMS ALL OTHER WARRANTIES OR

REPRESENTATIONS, EXPRESS OR IMPLIED, REGARDING RESOURCES OR USE THEREOF, INCLUDING BUT NOT LIMITED TO

ACCURACY OR COMPLETENESS, TITLE, ANY EPIDEMIC FAILURE WARRANTY AND ANY IMPLIED WARRANTIES OF

MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF ANY THIRD PARTY INTELLECTUAL

PROPERTY RIGHTS. TI SHALL NOT BE LIABLE FOR AND SHALL NOT DEFEND OR INDEMNIFY DESIGNER AGAINST ANY CLAIM,

INCLUDING BUT NOT LIMITED TO ANY INFRINGEMENT CLAIM THAT RELATES TO OR IS BASED ON ANY COMBINATION OF

PRODUCTS EVEN IF DESCRIBED IN TI RESOURCES OR OTHERWISE. IN NO EVENT SHALL TI BE LIABLE FOR ANY ACTUAL,

DIRECT, SPECIAL, COLLATERAL, INDIRECT, PUNITIVE, INCIDENTAL, CONSEQUENTIAL OR EXEMPLARY DAMAGES IN

CONNECTION WITH OR ARISING OUT OF TI RESOURCES OR USE THEREOF, AND REGARDLESS OF WHETHER TI HAS BEEN

ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

Unless TI has explicitly designated an individual product as meeting the requirements of a particular industry standard (e.g., ISO/TS 16949

and ISO 26262), TI is not responsible for any failure to meet such industry standard requirements.

Where TI specifically promotes products as facilitating functional safety or as compliant with industry functional safety standards, such

products are intended to help enable customers to design and create their own applications that meet applicable functional safety standards

and requirements. Using products in an application does not by itself establish any safety features in the application. Designers must

ensure compliance with safety-related requirements and standards applicable to their applications. Designer may not use any TI products in

life-critical medical equipment unless authorized officers of the parties have executed a special contract specifically governing such use.

Life-critical medical equipment is medical equipment where failure of such equipment would cause serious bodily injury or death (e.g., life

support, pacemakers, defibrillators, heart pumps, neurostimulators, and implantables). Such equipment includes, without limitation, all

medical devices identified by the U.S. Food and Drug Administration as Class III devices and equivalent classifications outside the U.S.

TI may expressly designate certain products as completing a particular qualification (e.g., Q100, Military Grade, or Enhanced Product).

Designers agree that it has the necessary expertise to select the product with the appropriate qualification designation for their applications

and that proper product selection is at Designers’ own risk. Designers are solely responsible for compliance with all legal and regulatory

requirements in connection with such selection.

Designer will fully indemnify TI and its representatives against any damages, costs, losses, and/or liabilities arising out of Designer’s non-

compliance with the terms and provisions of this Notice.

Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265

Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

Texas Instruments:

BQ27741YZFR-G1 BQ27741YZFT-G1