Texas Instruments bq27500 User Manual
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1 INTRODUCTION

1.1 FEATURES

Battery Fuel Gauge for 1-SeriesLi-IonApplications

Resides on System Main Board

Works with Embedded or Removable Battery Packs

Two Varieties

bq27500: Uses PACK+,PACK-,andT Battery Terminals

bq27501: Includes Battery Pack ID Resistor (RID) Terminal

Micro-ControllerPeripheral Provides:

Accurate Battery Fuel Gauging

Internal Temperature Sensor for System Temperature Reporting

Battery Low Interrupt Warning

Battery Insertion Indicator

Battery ID Detection

96 bytes of Non-VolatileScratch Pad FLASH

Battery Fuel Gauge Based on Patented Impedance Track™ Technology

Models the Battery Discharge Curve for Accurate Time-to-EmptyPredictions

Automatically Adjusts for Battery Aging, Battery Self Discharge, and Temperature/Rate Inefficiencies

Low Value Sense Resistor (10mΩ or Less)

I2C™ Interface for Connection to SystemMicro-ControllerPort

12-Pin2,5 mm× 4,0 mm SON Package

bq27500

bq27501 System-SideImpedance Track™ Fuel Gauge

SLUS785 –SEPTEMBER2007

1.2APPLICATIONS

Smartphones

PDAs

Digital Still and Video Cameras

Handheld Terminals

MP3 or Multimedia Players

1.3DESCRIPTION

The Texas Instruments bq27500/01 System-SideLi-IonBattery Fuel Gauge is amicro-controllerperipheral that provides fuel gauging for single cellLi-Ionbattery packs. The device requires little systemmicro-controllerfirmware development. The bq27500/01 resides on the system’s main board, and manages an embedded battery(non-removable)or a removable battery pack.

The bq27500/01 uses the patented Impedance Track™ algorithm for fuel gauging, and provides information such as remaining battery capacity (mAh), state-of-charge(%),run-timeto empty (min.), battery voltage (mV), and temperature (°C).

Battery fuel gauging with the bq27500 requires only PACK+ (P+), PACK- (P-),and Thermistor (T) connections to a removable battery pack or embedded battery circuit. The bq27501 works with identification resistors in battery packs, to gauge batteries of different fundamental chemistries and/or significantly different rated capacities.

 

TYPICAL APPLICATION

 

 

 

 

Host System

 

 

 

 

 

LDO

 

 

 

 

 

 

 

 

Single Cell Li-Ion

 

 

 

 

Battery Pack

 

 

Voltage

PACK+

 

 

 

 

Sense

 

 

 

 

 

 

 

 

Battery

RID

 

 

PROTECTION

 

Low

RID

 

IC

 

Sense*

 

 

Warning

 

 

 

 

 

 

 

 

 

 

 

Power

I2C

Temp

 

 

 

Management

Sense

T

 

 

 

 

 

 

Controller

 

 

 

 

bq 27500/1

 

 

 

 

 

 

 

 

Battery

 

PACK-

FETs

CHG

 

Good

 

DSG

 

 

 

 

 

 

 

 

 

Current

 

 

 

 

 

Sense

 

 

 

* bq27501 Only

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this document.

Impedance Track is a trademark of Texas Instruments. I2C is a trademark of Philips Electronics.

UNLESS OTHERWISE NOTED this

document

contains

Copyright © 2007, Texas Instruments Incorporated

PRODUCTION DATA information current as of publication date.

 

Products conform to specifications per

the terms

of Texas

 

Instruments standard warranty. Production processing does not

 

necessarily include testing of all parameters.

 

 

bq27500

bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

These devices have limited built-inESD 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.

Contents

1

INTRODUCTION ..........................................

1

 

4.2

DATA FLASH INTERFACE .........................

16

 

1.1

FEATURES ...........................................

1

 

4.3

MANUFACTURER INFORMATION BLOCKS ......

17

 

1.2

APPLICATIONS ......................................

1

 

4.4

ACCESS MODES ...................................

17

 

1.3

DESCRIPTION .......................................

1

 

4.5

SEALING/UNSEALING DATA FLASH ..............

17

2

DEVICE INFORMATION .................................

3

 

4.6

DATA FLASH SUMMARY...........................

18

 

2.1

AVAILABLE OPTIONS ...............................

3

5

FUNCTIONAL DESCRIPTION ........................

20

 

2.2

PIN DIAGRAMS ......................................

3

 

5.1

FUEL GAUGING ....................................

20

 

2.3

TERMINAL FUNCTIONS .............................

3

 

5.2

IMPEDANCE TRACK™ VARIABLES ...............

21

3

ELECTRICAL SPECIFICATIONS ......................

4

 

5.3

DETAILED DESCRIPTION OF DEDICATED PINS.

23

 

3.1

ABSOLUTE MAXIMUM RATINGS ...................

4

 

5.4

TEMPERATURE MEASUREMENT .................

26

 

3.2

RECOMMENDED OPERATING CONDITIONS......

4

 

5.5

OVERTEMPERATURE INDICATION ...............

26

 

3.3

POWER-ON RESET..................................

4

 

5.6

CHARGING AND CHARGE-TERMINATION

 

 

3.4

INTERNAL TEMPERATURE SENSOR

 

 

 

INDICATION.........................................

26

 

 

CHARACTERISTICS .................................

5

 

5.7

POWER MODES....................................

27

 

3.5

HIGH FREQUENCY OSCILLATOR ..................

5

 

5.8

POWER CONTROL .................................

29

 

3.6

LOW FREQUENCY OSCILLATOR...................

5

 

5.9

AUTOCALIBRATION................................

30

 

3.7

INTEGRATING ADC (COULOMB COUNTER)

 

6

APPLICATION-SPECIFICINFORMATION..........

31

 

 

CHARACTERISTICS .................................

5

 

6.1

BATTERY PROFILE STORAGE AND SELECTION

31

 

3.8

ADC (TEMPERATURE AND CELL

 

 

6.2

APPLICATION-SPECIFICFLOW AND CONTROL. 31

 

 

MEASUREMENT) CHARACTERISTICS

5

 

 

 

7

COMMUNICATIONS

33

 

3.9

DATA FLASH MEMORY CHARACTERISTICS

6

 

 

7.1

I2C INTERFACE

33

 

3.10

2

 

 

 

I C-COMPATIBLEINTERFACE COMMUNICATION

 

8

REFERENCE SCHEMATICS

34

 

 

TIMING CHARACTERISTICS ........................

6

4

GENERAL DESCRIPTION ..............................

8

 

8.1

SCHEMATIC ........................................

34

 

4.1

DATA COMMANDS ..................................

9

 

 

 

 

2

Contents

Submit Documentation Feedback

bq27500 bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

 

 

 

 

 

SLUS785 –SEPTEMBER2007

2

DEVICE INFORMATION

 

 

 

2.1

AVAILABLE OPTIONS

 

 

 

PART NUMBER

PACKAGE (1)

T

COMMUNICATION

TAPE and REEL

 

 

 

A

FORMAT

QUANTITY

bq27500DRZR

 

 

 

3000

bq27500DRZT

12-pin,2,5 mm x 4,0 mm

–40°Cto 85°C

I2C

300

bq27501DRZR(2)

3000

SON

 

 

bq27501DRZT(2)

 

 

 

300

(1)For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com.

(2)Product Preview

2.2 PIN DIAGRAMS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BAT_LOW

 

 

1

 

 

12

 

 

BAT_GD

BAT_LOW

 

 

1

 

 

12

 

 

BAT_GD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SCL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BI/TOUT

 

 

 

 

 

 

 

 

SCL

BI/TOUT

 

 

2

 

 

11

 

 

 

 

2

 

 

11

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SDA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SDA

 

 

 

3

 

 

10

 

 

TS

 

 

3

 

 

10

 

 

TS

 

 

bq27501

 

 

 

 

 

 

bq27500

 

 

 

 

 

 

 

 

 

 

 

 

 

RID

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NC

 

 

4

9

 

 

BAT

 

4

 

9

 

 

BAT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SRN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SRN

 

 

 

5

 

 

8

 

 

VCC

 

5

 

 

8

 

 

VCC

 

 

 

 

 

 

 

 

 

 

 

SRP

 

 

 

 

 

 

 

 

SRP

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VSS

 

 

 

 

 

 

 

 

VSS

 

 

6

 

 

7

 

 

 

 

6

 

 

7

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.3 TERMINAL FUNCTIONS

 

TERMINAL

 

 

 

PIN NO.

NAME

NAME

I/O(1)

DESCRIPTION

bq27500

bq27501

 

 

 

 

 

1

BAT_LOW

BAT_LOW

O

2

BI/TOUT

BI/TOUT

I/O

3

TS

TS

P

4

BAT

BAT

I

5

VCC

VCC

P

6

VSS

VSS

P

7

SRP

SRP

IA

8

SRN

SRN

IA

9

NC

RID

–,I

10

SDA

SDA

I/O

11

SCL

SCL

I

12

BAT_GD

BAT_GD

O

Battery Low output indicator. Activehigh by default, though polarity can be configured through the [BATL_POL] inOperation Configuration Push-pulloutput.

Battery-insertiondetection input. Power pin for pack thermistor network. Thermistor multiplexer control pin.Open-drainI/O. use withpull-upresistor > 1MΩ (1.8MΩ typical)

Pack thermistor voltage sense (use103AT-typethermistor). ADC input.

Cell-voltagemeasurement input. ADC input.

Processor power input. Decouple with 0.1μF capacitor, minimum.

Device ground.

Analog input pin connected to the internal coulomb-counterwhere SRP is nearest the CELLconnection. Connect to5-20mΩ sense resistor.

Analog input pin connected to the internal coulomb-counterwhere SRN is nearest the PACKconnection. Connect to5-20mΩ sense resistor.

No connection (bq27500). Resistor ID input (bq27501). Analog input with current sourcing capabilities.

Slave I2C serial communications data line for communication with system (Master).Open-drainI/O. Use with 10kΩ pull-upresistor (typical).

Slave I2C serial communications clock input line for communication with system (Master).Open-drainI/O. Use with 10kΩ pull-upresistor (typical).

Battery Good indicator. Active low by default, though polarity can be configured through the [BATG_POL] ofOperation Configuration.Open-drainoutput.

(1)I/O = Digital Input/Output, IA = Analog Input, P = Power Connection

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DEVICE INFORMATION

3

bq27500

bq27501

System-SideImpedance Track™ Fuel Gauge

SLUS785 –SEPTEMBER2007

 

www.ti.com

 

 

3 ELECTRICAL SPECIFICATIONS

 

 

3.1

ABSOLUTE MAXIMUM RATINGS

 

 

over operating free-airtemperature range (unless otherwise noted)(1)

 

 

 

PARAMETER

VALUE

UNIT

VCC

Supply voltage range

–0.3to 2.75

V

VIOD

Open-drainI/O pins (BI_TOUT, SDA, SDL, BAT_GD)

–0.3to 6

V

VBAT

BAT input pin

–0.3to +6

 

VI

Input voltage range to all other pins (TS, SRP, SRN, RID [bq27501 only], NC

–0.3to VCC + 0.3

V

 

[bq27500 only])

 

 

ESD

Human Body Model (HMB)

1

kV

2

kV

 

 

TF

Functional temperature range

–40to 100

°C

TSTG

Storage temperature range

–65to 150

°C

(1)Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-ratedconditions for extended periods may affect device reliability.

3.2RECOMMENDED OPERATING CONDITIONS

TA = 25°C, VCC = 2.5 V (unless otherwise noted)

 

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

VCC

Supply Voltage

 

2.4

2.5

2.6

V

ICC

Normal operating mode current(1)

 

 

95

 

μA

ISLP

Low-powerstorage mode current(2)

 

 

15

 

μA

ICC

Hibernate operating mode current(3)

 

 

2

 

μA

VOL

Output voltage low (SDA, BAT_LOW, BI/TOUT)

IOL = 0.5 mA

 

 

0.4

V

VOH(PP)

Output high voltage (BAT_LOW)

IOH =–1mA

VCC–0.5

 

 

V

VOH(OD)

Output high voltage (SDA, SCL, BI/TOUT)

External pull-upresistor

VCC–0.5

 

 

V

connected to VCC

 

 

 

 

 

 

 

 

VIL

Input voltage low (SDA, SCL)

 

–0.3

 

0.8

V

VIH(OD)

Input voltage high (SDA, SCL, BI/TOUT)

 

2

 

6

 

 

 

CIN

Input capacitance

 

 

5

 

pF

VA1

Input voltage range (TS, RID [bq27501 only])

 

VSS–0.125

 

2

V

VA2

Input voltage range (BAT)

 

VSS–0.125

 

5

V

VA3

Input voltage range (SRP, SRN)

 

VSS–0.125

 

0.125

V

tPUCD

Power up communication delay

 

 

250

 

ms

TA

Operating free-airtemperature range

 

–40

 

85

°C

(1)High level of system activity.

(2)Low level of system activity.

(3)Fuel gauge algorithm power inactive. Only able to receive I2C communication.

3.3POWER-ONRESET

TA =–40°Cto 85°C, Typical Values at TA = 25°C and VBAT = 3.6 V (unless otherwise noted)

 

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

VIT+

Positive-goingbattery voltage input at VCC

 

2.09

2.20

2.31

V

VHYS

 

 

45

115

185

mV

4

ELECTRICAL SPECIFICATIONS

Submit Documentation Feedback

bq27500 bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

3.4INTERNAL TEMPERATURE SENSOR CHARACTERISTICS

TA =–40°Cto 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)

 

PARAMETER

TEST CONDITIONS

MIN TYP

MAX

UNIT

GTEMP

Temperature sensor voltage gain

 

–2.0

 

mV/°C

3.5HIGH FREQUENCY OSCILLATOR

TA =–40°Cto 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

fOSC

Operating frequency

 

 

2.097

 

MHz

 

 

TA = 0°C to 60°C

–2.0%

0.38%

2.0%

 

f

Frequency error (1) (2)

T = –20°Cto 70°C

–3.0%

0.38%

3.0%

 

EIO

 

A

 

 

 

 

 

 

TA =–40°Cto 85°C

–4.5%

0.38%

4.5%

 

t

Start-uptime(3)

 

 

2.5

5

ms

SXO

 

 

 

 

 

 

(1)The frequency error is measured from 2.097 MHz.

(2)The frequency drift is included and measured from the trimmed frequency at VCC = 2.5V, TA = 25°C.

(3)The startup time is defined as the time it takes for the oscillator output frequency to be ±3%.

3.6LOW FREQUENCY OSCILLATOR

TA =–40°Cto 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

fLOSC

Operating frequency

 

 

32.768

 

kHz

 

 

TA = 0°C to 60°C

–1.5%

0.25%

1.5%

 

f

Frequency error (1) (2)

T = –20°Cto 70°C

–2.5%

0.25%

2.5%

 

LEIO

 

A

 

 

 

 

 

 

TA =–40°Cto 85°C

–4.0%

0.25%

4.0%

 

tLSXO

Start-uptime(3)

 

 

 

500

μs

(1)The frequency drift is included and measured from the trimmed frequency at VCC = 2.5V, TA = 25°C.

(2)The frequency error is measured from 32.768 kHz.

(3)The startup time is defined as the time it takes for the oscillator output frequency to be ±3%.

3.7INTEGRATING ADC (COULOMB COUNTER) CHARACTERISTICS

TA =–40°Cto 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

VSR_IN

Input voltage range, V(SRN) and V(SRP)

VSR= V(SRN)– V(SRP)

–0.125

0.125

V

tSR_CONV

Conversion time

Single conversion

1

 

s

 

Resolution

 

14

15

bits

VSR_OS

Input offset

Before calibration

1

 

mV

After calibration

10

 

μV

 

 

 

INL

Integral nonlinearity error

 

±0.007

±0.034

% FSR

Z

Effective input resistance(1)

 

2.5

 

MΩ

SR_IN

 

 

 

 

 

ISR_LKG

Input leakage current(1)

 

 

0.3

μA

(1)Specified by design. Not tested in production.

3.8ADC (TEMPERATURE AND CELL MEASUREMENT) CHARACTERISTICS

TA =–40°Cto 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

VADC_IN

Input voltage range

 

–0.2

1

V

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ELECTRICAL SPECIFICATIONS

5

bq27500

bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

ADC (TEMPERATURE AND CELL MEASUREMENT) CHARACTERISTICS (continued)

TA =–40°Cto 85°C, 2.4 V < VCC < 2.6 V; Typical Values at TA = 25°C and VCC = 2.5 V (unless otherwise noted)

tADC_CONV

VADC_OS

ZADC1

PARAMETER

TEST CONDITIONS

MIN

TYP MAX

UNIT

Conversion time

 

 

125

ms

Resolution

 

14

15

bits

Input offset

 

 

1

mV

Effective input resistance (TS, RID

 

8

 

MΩ

[bq27501 only])

 

 

 

 

Z

Effective input resistance (BAT)(1)

bq27500/1 not measuring cell voltage

8

 

MΩ

 

 

 

 

ADC2

 

bq27500/1 measuging cell voltage

 

100

kΩ

 

 

 

IADC_LKG

Input Leakage Current(1)

 

 

0.3

μA

(1)Specified by design. Not tested in production.

3.9DATA FLASH MEMORY CHARACTERISTICS

TA =–40°Cto 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

t

Data retention

See (1)

10(1)

 

Years

ON

 

 

 

 

 

 

Flash programming write-cycles

See (1)

20,000

 

Cycles

t

Word programming time

See (1)

 

2

ms

WORDPROG

 

 

 

 

 

ICCPROG

Flash-writesupply current

 

5

10

mA

(1)Specified by design. Not production tested

3.10I2C-COMPATIBLEINTERFACE COMMUNICATION TIMING CHARACTERISTICS

TA =–40°Cto 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

tr

SCL/SDA rise time

 

 

1

μs

tf

SCL/SDA fall time

 

 

300

ns

tw(H)

SCL pulse width (high)

 

4

 

μs

tw(L)

SCL pulse width (low)

 

4.7

 

μs

tsu(STA)

Setup for repeated start

 

4.7

 

μs

td(STA)

Start to first falling edge of SCL

 

4

 

μs

tsu(DAT)

Data setup time

 

250

 

ns

th(DAT)

Data hold time

Receive mode

0

 

ns

Transmit mode

300

 

 

 

 

 

tsu(STOP)

Setup time for stop

 

4

 

μs

tBUF

Bus free time between stop and start

 

4.7

 

μs

fSCL

Clock frequency

 

10

100

kHz

tBUSERR

Bus error timeout

 

17.3

21.2

s

6

ELECTRICAL SPECIFICATIONS

Submit Documentation Feedback

bq27500 bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

Figure 3-1.I2C-CompatibleInterface Timing Diagrams

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ELECTRICAL SPECIFICATIONS

7

bq27500

bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

4 GENERAL DESCRIPTION

The bq27500/1 accurately predicts the battery capacity and other operational characteristics of a single Li-basedrechargeable cell. It can be interrogated by a system processor to provide cell information, such asState-of-Charge(SOC),Time-to-Empty(TTE) andTime-to-Full(TTF).

Information is accessed through a series of commands, called Standard Commands. Further capabilities are provided by the additionalExtended Commands set. Both sets of commands, indicated by the general formatCommand( ), are used to read and write information contained within the bq27500/1 control and status registers, as well as its data flash locations. Commands are sent from system to gauge using the bq27500/1’s I2C serial communications engine, and can be executed during application development, pack manufacture, orend-equipmentoperation.

Cell information is stored in the bq27500/1 in non-volatileflash memory. Many of these data flash locations are accessible during application development. They cannot be accessed directly duringend-equipmentoperation. Access to these locations is achieved by either use of the bq27500/1's companion evaluation software, through individual commands, or through a sequence ofdata-flash-accesscommands. To access a desired data flash location, the correct data flash subclass and offset must be known.

The bq27500/1 provides 96 bytes of user-programmabledata flash memory, partitioned into 332-byteblocks:Manufacturer Info Block A,Manufacturer Info Block B, andManufacturer Info Block C. This data space is accessed through a data flash interface. For specifics on accessing the data flash, seeSection 4.3 Manufacturer Information Blocks.

The key to the bq27500/1’s high-accuracygas gauging prediction is Texas Instrument’s proprietary Impedance Track™ algorithm. This algorithm uses cell measurements, characteristics, and properties to createstate-of-chargepredictions that can achieve less than 1% error across a wide variety of operating conditions and over the lifetime of the battery.

The bq27500/1 measures charge/discharge activity by monitoring the voltage across a small-valueseries sense resistor (5 mΩ to 20 mΩ typ.) located between the system'sVss and the battery’s PACK– terminal. When a cell is attached to the bq27500/1, cell impedance is computed, based on cell current, cell Open Circuit Voltage (OCV), and cell voltage under loading conditions.

The bq27500/1 can use an NTC thermistor (default is Semitec 103AT) for temperature measurement, or can also be configured to use its internal temperature sensor. The bq27500/1 uses temperature to monitor the battery-packenvironment, which is used for fuel gauging and cell protection functionality.

To minimize power consumption, the bq27500/1 has several power modes: NORMAL, SLEEP, HIBERNATE, and BAT INSERT CHECK. The bq27500/1 passes automatically between these modes, depending upon the occurrence of specific events, though a system processor can initiate some of these modes directly. More details can be found in the Section 5.7 POWER MODES.

NOTE

FORMATTING CONVENTIONS IN THIS DOCUMENT:

Commands: italics with parentheses and no breaking spaces,e.g. RemainingCapacity( ).

Data Flash: italics,bold, andbreaking spaces, e.g.Design Capacity

Register Bits and Flags: brackets only, e.g. [TDA]

Data Flash Bits: italics andbold, e.g:[LED1]

Modes and states: ALL CAPITALS, e.g. UNSEALED mode.

8

GENERAL DESCRIPTION

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bq27500 bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

4.1 DATA COMMANDS

4.1.1STANDARD DATA COMMANDS

The bq27500/1 uses a series of 2-bytestandard commands to enable system reading and writing of battery information. Each standard command has an associatedcommand-codepair, as indicated inTable 4-1.Because each command consists of two bytes of data, two consecutive I2C transmissions must be executed both to initiate the command function, and to read or write the corresponding two bytes of data. Additional options for transferring data, such as spooling, are described inSection 7.1 I2C INTERFACE. Standard commands are accessible in NORMAL operation. Read/Write permissions depend on the active access mode, SEALED or UNSEALED (for details on the SEALED and UNSEALED states, seeSection 4.4 Access Modes).

Table 4-1.Standard Commands

NAME

 

COMMAND

UNITS

SEALED

UNSEALED

 

CODE

ACCESS

ACCESS

 

 

 

Control( )

CNTL

0x00 / 0x01

N/A

R/W

R/W

AtRate( )

AR

0x02 / 0x03

mA

R/W

R/W

AtRateTimeToEmpty( )

ARTTE

0x04 / 0x05

Minutes

R

R

Temperature( )

TEMP

0x06 / 0x07

0.1°K

R

R

Voltage( )

VOLT

0x08 / 0x09

mV

R

R

Flags( )

FLAGS

0x0a / 0x0b

N/A

R

R

NominalAvailableCapacity( )

NAC

0x0c / 0x0d

mAh

R

R

FullAvailableCapacity( )

FAC

0x0e / 0x0f

mAh

R

R

RemainingCapacity( )

RM

0x10 / 0x11

mAh

R

R

FullChargeCapacity( )

FCC

0x12 / 0x13

mAh

R

R

AverageCurrent( )

AI

0x14 / 0x15

mA

R

R

TimeToEmpty( )

TTE

0x16 / 0x17

Minutes

R

R

TimeToFull( )

TTF

0x18 / 0x19

Minutes

R

R

StandbyCurrent( )

SI

0x1a / 0x1b

mA

R

R

StandbyTimeToEmpty( )

STTE

0x1c / 0x1d

Minutes

R

R

MaxLoadCurrent( )

MLI

0x1e / 0x1f

mA

R

R

MaxLoadTimeToEmpty( )

MLTTE

0x20 / 0x21

Minutes

R

R

AvailableEnergy( )

AE

0x22 / 0x23

10mWhr

R

R

AveragePower( )

AP

0x24 / 0x25

10mW

R

R

TimeToEmptyAtConstantPower( )

TTECP

0x26 / 0x27

Minutes

R

R

Reserved

RSVD

0x28 / 0x29

N/A

R

R

CycleCount( )

CC

0x2a / 0x2b

Counts

R

R

StateOfCharge( )

SOC

0x2c / 0x2d

%

R

R

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GENERAL DESCRIPTION

9

bq27500

bq27501

System-SideImpedance Track™ Fuel Gauge

www.ti.com

SLUS785 –SEPTEMBER2007

4.1.1.1 Control( ): 0x00/0x01

Issuing a Control( ) command requires a subsequenttwo-bytesub-command.These additional bytes specify the particular control function desired. TheControl( ) command allows the system to control specific features of the bq27500 during normal operation and additional features when the bq27500/1 is in different access modes, as described inTable 4-2.

Table 4-2.Control( ) Subcommands

CNTL FUNCTION

CNTL

SEALED

DESCRIPTION

DATA

ACCESS

 

 

CONTROL STATUS

0x0000

Yes

Reports the status of DF Checksum, Hibernate, IT, etc.

DEVICE TYPE

0x0001

Yes

Reports the device type (eg: "bq27500")

FW VERSION

0x0002

Yes

Reports the firmware version on the device type

HW VERSION

0x0003

Yes

Reports the hardware version of the device type

Reserved

0x0004

No

Not to be used

RESET DATA

0x0005

No

Returns reset data

Reserved

0x0006

No

Not to be used

PREV_MACWRITE

0x0007

No

Returns previous MAC command code

CHEMID

0x0008

Yes

Reports the chemical identifier of the Impedance Track™

configuration

 

 

 

BOARD OFFSET

0x0009

No

Forces the device Board Offset to be measured and stored

CC INT OFFSET

0x000b

No

Forces the device to measure and store the internal CC offset

SET HIBERNATE

0x0011

Yes

Forces DF:Pack Configuration [HIBERNATE] to 1

CLEAR HIBERNATE

0x0012

Yes

Forces DF:Pack Configuration [HIBERNATE] to 0

SEALED

0x0020

No

Places the bq27500/1 in SEALED access mode

IT ENABLE

0x0021

No

Enables the Impedance Track™ algorithm

IFCHECKSUM

0x0022

No

Reports the instruction flash checksum

CALMODE

0x0040

No

Places the bq27500/1 in calibration mode

RESET

0x0041

No

Forces a full reset of the bq27500/1

4.1.1.1.1 CONTROL STATUS: 0X0000

Instructs the gas gauge to return status information to Control addresses 0x00/0x01. The status word includes the following information.

Table 4-3.CONTROL STATUS Bit Definitions

Flags( )

bit7

bit6

bit5

bit4

bit3

bit2

bit1

bit0

High Byte

FAS

SS

-

CCA

BCA

Low Byte

HIBERNATE

SLEEP

LDMD

RUP_DIS

VOK

QEN

FAS = Status bit indicating the bq27500/1 is in FULL ACCESS SEALED state. Active when set. SS = Status bit indicating the bq27500/1 is in SEALED State. Active when set.

CCA = Status bit indicating the bq27500/1 is Coulomb Counter Calibration routine is active. Active when set. BCA = Status bit indicating the bq27500/1 Board Calibration routine is active. Active when set.

HIBERNATE = Status bit indicating a request for entry into HIBERNATE from SLEEP mode. True when set. Default is 0. SLEEP = Status bit indicating the bq27500/1 is in SLEEP mode. True when set. Default is 0.

LDMD = Status bit indicating the bq27500/1 Impedance Track™ algorithm is using constant-powermode. True when set. Default is 0(constant-currentmode)

RUP_DIS = Status bit indicating the bq27500/1 Ra table updates are disabled. Updates disabled when set. VOK = Status bit indicating the bq27500/1 voltages are OK for QMAX. True when set.

QEN = Status bit indicating the bq27500/1 QMAX updates enabled. True when set.

4.1.1.1.2 DEVICE TYPE: 0x0001

Instructs the fuel gauge to return the device type to addresses 0x00/0x01.

10

GENERAL DESCRIPTION

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