Texas Instruments bq27500 User Manual

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1 INTRODUCTION

HostSystem

SingleCellLi-Ion

BatteryPack

PACK-

PROTECTION

CHG DSG

Temp

Sense

Battery Good

Current

Sense

I2C

LDO

PACK+

Voltage

Sense Battery Low Warning

FETs

bq27500 /1

RID

Sense*

*bq27501Only

Power

Management

Controller

1.1 FEATURES 1.2 APPLICATIONS

• Battery Fuel Gauge for 1-Series Li-Ion

Applications

• Resides on System Main Board

– Works with Embedded or Removable

Battery Packs

• Two Varieties

– bq27500: Uses PACK+, PACK-, and T

Battery Terminals

– bq27501: Includes Battery Pack ID Resistor

(RID) Terminal

• Micro-Controller Peripheral 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-Volatile Scratch Pad

FLASH

• Battery Fuel Gauge Based on Patented

Impedance Track™ Technology – Models the Battery Discharge Curve for

Accurate Time-to-Empty Predictions – Automatically Adjusts for Battery Aging,

Battery Self Discharge, and

Temperature/Rate Inefficiencies – Low Value Sense Resistor (10m Ω or Less)

• I2C™ Interface for Connection to System

Micro-Controller Port

• 12-Pin 2,5 mm × 4,0 mm SON Package

bq27500 bq27501

System-Side Impedance Track™ Fuel Gauge

SLUS785 – SEPTEMBER 2007

• Smartphones

• PDAs

• Digital Still and Video Cameras

• Handheld Terminals

• MP3 or Multimedia Players

1.3 DESCRIPTION

The Texas Instruments bq27500/01 System-Side Li-Ion Battery Fuel Gauge is a micro-controller peripheral that provides fuel gauging for single cell Li-Ion battery packs. The device requires little system micro-controller firmware 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-time to 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.

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 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.

TYPICAL APPLICATION

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bq27500 bq27501 System-Side Impedance Track™ Fuel Gauge

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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.

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

3.4 INTERNAL TEMPERATURE SENSOR

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)

CHARACTERISTICS ................................. 5

3.8 ADC (TEMPERATURE AND CELL

MEASUREMENT) CHARACTERISTICS ............. 5

3.9 DATA FLASH MEMORY CHARACTERISTICS ...... 6

3.10 I2C-COMPATIBLE INTERFACE COMMUNICATION

TIMING CHARACTERISTICS ........................ 6

4 GENERAL DESCRIPTION .............................. 8

4.1 DATA COMMANDS .................................. 9

5.6 CHARGING AND CHARGE-TERMINATION

INDICATION ......................................... 26

6 APPLICATION-SPECIFIC INFORMATION .......... 31

6.1 BATTERY PROFILE STORAGE AND SELECTION 31

6.2 APPLICATION-SPECIFIC FLOW AND CONTROL . 31

7 COMMUNICATIONS .................................... 33

7.1 I

C INTERFACE ..................................... 33

8 REFERENCE SCHEMATICS .......................... 34

8.1 SCHEMATIC ........................................ 34

2 Contents Submit Documentation Feedback

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BAT

SRN

SRP

BAT_GD

SDA

SCL

BAT_LOW_

BI/TOUT

BAT

BAT_LOW_

BI/TOUT

SRN

SRP

BAT_GD

SDA

SCL

RID

bq27500

bq27501

bq27500 bq27501

System-Side Impedance Track™ Fuel Gauge

SLUS785 – SEPTEMBER 2007

2 DEVICE INFORMATION

2.1 AVAILABLE OPTIONS

PART NUMBER PACKAGE

bq27500DRZR 3000

bq27500DRZT 300 bq27501DRZR bq27501DRZT

(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

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

(2) (2)

(1)

SON

–40 ° C to 85 ° C I2C

2.2 PIN DIAGRAMS

COMMUNICATION TAPE and REEL

FORMAT QUANTITY

3000

300

2.3 TERMINAL FUNCTIONS

TERMINAL

PIN NO.

1 BAT_LOW BAT_LOW O

2 BI/TOUT BI/TOUT I/O 3 TS TS P Pack thermistor voltage sense (use 103AT-type thermistor). ADC input.

4 BAT BAT I Cell-voltage measurement input. ADC input. 5 V 6 V

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

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

NAME NAME

bq27500 bq27501

CC SS

(1)

I/O

Battery Low output indicator. Active high by default, though polarity can be configured through the [BATL_POL] in Operation Configuration Push-pull output.

Battery-insertion detection input. Power pin for pack thermistor network. Thermistor multiplexer control pin. Open-drain I/O. use with pull-up resistor > 1M Ω (1.8M Ω typical)

P Processor power input. Decouple with 0.1 μ F capacitor, minimum. P Device ground.

Analog input pin connected to the internal coulomb-counter where SRP is nearest the CELL- connection. Connect to 5-20m Ω sense resistor.

Analog input pin connected to the internal coulomb-counter where SRN is nearest the PACK- connection. Connect to 5-20m Ω 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-drain I/O. Use with 10k Ω pull-up resistor (typical).

Slave I2C serial communications clock input line for communication with system ( Master). Open-drain I/O. Use with 10k Ω pull-up resistor (typical).

Battery Good indicator. Active low by default, though polarity can be configured through the [BATG_POL] of Operation Configuration. Open-drain output.

DESCRIPTION

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3 ELECTRICAL SPECIFICATIONS

3.1 ABSOLUTE MAXIMUM RATINGS

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

PARAMETER VALUE UNIT

V V V V

ESD Human Body Model (HMB)

T T

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

Supply voltage range –0.3 to 2.75 V

Open-drain I/O pins (BI_TOUT, SDA, SDL, BAT_GD) –0.3 to 6 V

IOD

BAT input pin –0.3 to +6

BAT

Input voltage range to all other pins (TS, SRP, SRN, RID [bq27501 only], NC –0.3 to V

[bq27500 only])

Functional temperature range –40 to 100 ° C

Storage temperature range –65 to 150 ° C

STG

only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(1)

+ 0.3 V

1 kV 2 kV

3.2 RECOMMENDED OPERATING CONDITIONS

TA= 25 ° C, V

SLP

OH(PP)

OH(OD)

IH(OD)

PUCD

(1) High level of system activity. (2) Low level of system activity. (3) Fuel gauge algorithm power inactive. Only able to receive I2C communication.

= 2.5 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Supply Voltage 2.4 2.5 2.6 V Normal operating mode current Low-power storage mode current Hibernate operating mode current Output voltage low (SDA, BAT_LOW, BI/TOUT) IOL= 0.5 mA 0.4 V Output high voltage (BAT_LOW) IOH= –1 mA VCC–0.5 V

Output high voltage (SDA, SCL, BI/TOUT) VCC–0.5 V Input voltage low (SDA, SCL) –0.3 0.8

Input voltage high (SDA, SCL, BI/TOUT) 2 6 Input capacitance 5 pF Input voltage range (TS, RID [bq27501 only]) VSS–0.125 2 V Input voltage range (BAT) VSS–0.125 5 V Input voltage range (SRP, SRN) VSS–0.125 0.125 V Power up communication delay 250 ms Operating free-air temperature range –40 85 ° C

(1)

(2)

(3)

95 μ A 15 μ A

2 μ A

External pull-up resistor connected to V

3.3 POWER-ON RESET

TA= –40 ° C to 85 ° C, Typical Values at TA= 25 ° C and V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

IT+

HYS

Positive-going battery voltage input at V

ELECTRICAL SPECIFICATIONS4 Submit Documentation Feedback

= 3.6 V (unless otherwise noted)

BAT

2.09 2.20 2.31 V 45 115 185 mV

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System-Side Impedance Track™ Fuel Gauge

3.4 INTERNAL TEMPERATURE SENSOR CHARACTERISTICS

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

TEMP

Temperature sensor voltage gain –2.0 mV/ ° C

3.5 HIGH FREQUENCY OSCILLATOR

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

OSC

EIO

SXO

(1) The frequency error is measured from 2.097 MHz. (2) The frequency drift is included and measured from the trimmed frequency at V (3) The startup time is defined as the time it takes for the oscillator output frequency to be ± 3%.

Operating frequency 2.097 MHz

Frequency error

Start-up time

(3)

< 2.6 V; Typical Values at TA= 25 ° C and V

TA= 0 ° C to 60 ° C –2.0% 0.38% 2.0%

(1) (2)

TA= –20 ° C to 70 ° C –3.0% 0.38% 3.0% TA= –40 ° C to 85 ° C –4.5% 0.38% 4.5%

= 2.5V, TA= 25 ° C.

bq27500 bq27501

SLUS785 – SEPTEMBER 2007

= 2.5 V (unless otherwise noted)

2.5 5 ms

3.6 LOW FREQUENCY OSCILLATOR

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

LOSC

LEIO

LSXO

(1) The frequency drift is included and measured from the trimmed frequency at V (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%.

Operating frequency 32.768 kHz

Frequency error

Start-up time

(3)

< 2.6 V; Typical Values at TA= 25 ° C and V

TA= 0 ° C to 60 ° C –1.5% 0.25% 1.5%

(1) (2)

TA= –20 ° C to 70 ° C –2.5% 0.25% 2.5% TA= –40 ° C to 85 ° C –4.0% 0.25% 4.0%

= 2.5 V (unless otherwise noted)

= 2.5V, TA= 25 ° C.

3.7 INTEGRATING ADC (COULOMB COUNTER) CHARACTERISTICS

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SR_IN

SR_CONV

SR_OS

INL Integral nonlinearity error ± 0.007 ± 0.034 % FSR Z

SR_IN

SR_LKG

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

Input voltage range, V Conversion time Single conversion 1 s Resolution 14 15 bits

Input offset

Effective input resistance Input leakage current

< 2.6 V; Typical Values at TA= 25 ° C and V

and V

(SRN)

(SRP)

= V

(SRN)

Before calibration 1 mV After calibration 10 μ V

(1)

= 2.5 V (unless otherwise noted)

– V

(SRP)

–0.125 0.125 V

2.5 M Ω

0.3 μ A

500 μ s

3.8 ADC (TEMPERATURE AND CELL MEASUREMENT) CHARACTERISTICS

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

ADC_IN

Submit Documentation Feedback ELECTRICAL SPECIFICATIONS 5

Input voltage range –0.2 1 V

< 2.6 V; Typical Values at TA= 25 ° C and V

= 2.5 V (unless otherwise noted)

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ADC (TEMPERATURE AND CELL MEASUREMENT) CHARACTERISTICS (continued)

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

ADC_CONV

Conversion time 125 ms Resolution 14 15 bits

ADC_OS

ADC1

ADC2

ADC_LKG

Input offset 1 mV Effective input resistance (TS, RID 8 M Ω

[bq27501 only])

Effective input resistance (BAT)

Input Leakage Current

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

3.9 DATA FLASH MEMORY CHARACTERISTICS

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

WORDPROG

CCPROG

(1) Specified by design. Not production tested

Data retention See Flash programming write-cycles See Word programming time See Flash-write supply current 5 10 mA

< 2.6 V; Typical Values at TA= 25 ° C and V

(1)

bq27500/1 not measuring cell voltage 8 M Ω bq27500/1 measuging cell voltage 100 k Ω

(1)

< 2.6 V; Typical Values at TA= 25 ° C and V

(1) (1) (1)

= 2.5 V (unless otherwise noted)

(1)

20,000 Cycles

0.3 μ A

Years

2 ms

3.10 I2C-COMPATIBLE INTERFACE COMMUNICATION TIMING CHARACTERISTICS

TA= –40 ° C to 85 ° C, 2.4 V < V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

w(H)

w(L)

su(STA)

d(STA)

su(DAT)

h(DAT)

su(STOP)

BUF

SCL

BUSERR

SCL/SDA rise time 1 μ s SCL/SDA fall time 300 ns SCL pulse width (high) 4 μ s SCL pulse width (low) 4.7 μ s Setup for repeated start 4.7 μ s Start to first falling edge of SCL 4 μ s Data setup time 250 ns

Data hold time ns

Setup time for stop 4 μ s Bus free time between stop and start 4.7 μ s Clock frequency 10 100 kHz Bus error timeout 17.3 21.2 s

< 2.6 V; Typical Values at TA= 25 ° C and V

Receive mode 0 Transmit mode 300

= 2.5 V (unless otherwise noted)

ELECTRICAL SPECIFICATIONS6 Submit Documentation Feedback

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Figure 3-1. I2C-Compatible Interface Timing Diagrams

bq27500 bq27501

System-Side Impedance Track™ Fuel Gauge

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Submit Documentation Feedback ELECTRICAL SPECIFICATIONS 7

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bq27500 bq27501 System-Side Impedance Track™ Fuel Gauge

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4 GENERAL DESCRIPTION

The bq27500/1 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).

Information is accessed through a series of commands, called Standard Commands. Further capabilities are provided by the additional Extended Commands set. Both sets of commands, indicated by the general format Command( ), are used to read and write information contained within the 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, or end-equipment operation.

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

The bq27500/1 provides 96 bytes of user-programmable data flash memory, partitioned into 3 32-byte blocks: Manufacturer Info Block A, Manufacturer Info Block B, and Manufacturer Info Block C. This data space is accessed through a data flash interface. For specifics on accessing the data flash, see

Section 4.3 Manufacturer Information Blocks.

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

The bq27500/1 measures charge/discharge activity by monitoring the voltage across a small-value series sense resistor (5 m Ω to 20 m Ω typ.) located between the system's Vss 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-pack environment, 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, and breaking spaces, e.g. Design Capacity Register Bits and Flags: brackets only, e.g. [TDA] Data Flash Bits: italics and bold, e.g: [LED1] Modes and states: ALL CAPITALS, e.g. UNSEALED mode.

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4.1 DATA COMMANDS

4.1.1 STANDARD DATA COMMANDS

The bq27500/1 uses a series of 2-byte standard commands to enable system reading and writing of battery information. Each standard command has an associated command-code pair, as indicated in

Table 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 in Section 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, see Section 4.4 Access Modes).

Table 4-1. Standard Commands

NAME UNITS

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

COMMAND SEALED UNSEALED

CODE ACCESS ACCESS

bq27500 bq27501

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4.1.1.1 Control( ): 0x00/0x01

Issuing a Control( ) command requires a subsequent two-byte sub-command. These additional bytes specify the particular control function desired. The Control( ) 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 in Table 4-2 .

Table 4-2. Control( ) Subcommands

CNTL FUNCTION DESCRIPTION

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 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

CNTL SEALED DATA ACCESS

Reports the chemical identifier of the Impedance Track™ configuration

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-power mode. True when set. Default is 0 (constant-current mode) 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.

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4.1.1.1.3 FW_VERSION: 0x0002

Instructs the fuel gauge to return the firmware version to addresses 0x00/0x01.

4.1.1.1.4 HW_VERSION: 0x0003

Instructs the fuel gauge to return the hardware version to addresses 0x00/0x01.

4.1.1.1.5 RESET_DATA: 0x0005

Instructs the fuel gauge to return the reset data to addresses 0x00/0x01, with the low-byte being the number of partial resets and the high-byte the number of full resets.

4.1.1.1.6 PREV_MACWRITE: 0x0007

Instructs the fuel gauge to return the previous command written to addresses 0x00/0x01.

4.1.1.1.7 CHEM ID: 0x0008

Instructs the fuel gauge to return the chemical identifier for the Impedance Track™ configuration to addresses 0x00/0x01.

4.1.1.1.8 BOARD_OFFSET: 0x0009

Instructs the fuel gauge to compute the coulomb counter offset with internal short and then without internal short applied across the SR inputs. During this activity, CONROL STATUS [BCA] is set. The difference between the two measurements is the Board Offset. The Board Offset is written to data flash and is also returned to addresses 0x00/0x01. The user must prevent any charge or discharge current from flowing during the process. This function is only available when the fuel gauge is UNSEALED. When SEALED, this command will only read back the Board Offset value stored in data flash.

4.1.1.1.9 CC_INT_OFFSET: 0x000A

Instructs the fuel gauge to compute the coulomb counter offset with internal short applied across the SR inputs. The offset value is written to data flash and is also returned to addresses 0x00/0x01. This function is only available when the fuel gauge is UNSEALED. When SEALED, this command will only read back the CC_INT_OFFSET value stored in data flash.

4.1.1.1.10 SET_HIBERNATE: 0x0011

Instructs the fuel gauge to force the CONTROL STATUS’ [HIBERNATE] bit to 1. This will allow the gauge to enter the HIBERNATE power mode after the transition to SLEEP power state is detected. The [HIBERNATE] bit is automatically cleared upon exiting from HIBERNATE mode.

4.1.1.1.11 CLEAR_HIBERNATE: 0x0012

Instructs the fuel gauge to force the CONTROL STATUS’ [HIBERNATE] bit to 0. This will prevent the gauge from entering the HIBERNATE power mode after the transition to SLEEP power state is detected. It can also be used to force the gauge out of HIBERNATE mode.

4.1.1.1.12 SEALED: 0x0020

Instructs the fuel gauge to transition from UNSEALED state to SEALED state. The fuel gauge should always be set to SEALED state for use in end equipment.

4.1.1.1.13 IT ENABLE: 0x0021

This command forces the fuel gauge to begin the Impedance Track™ algorithm, sets the active UpdateStatus n location to 0x04 and causes the [VOK] and [QEN] flags to be set in the CONTROL STATUS register. [VOK] is cleared if the voltages are not suitable for a Qmax update. Once set, [QEN] cannot be cleared. This command is only available when the fuel gauge is UNSEALED.

4.1.1.1.14 IF CHECKSUM: 0x0022

This command instructs the fuel gauge to compute the instruction flash checksum. When the checksum has been calculated and stored, then CONTROL STATUS [CVS] is set. In UNSEALED mode, the checksum value is returned to addresses 0x00/0x01. The checksum will not be calculated in SEALED mode; however, the checksum value can still be read.

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bq27500 bq27501 System-Side Impedance Track™ Fuel Gauge

SLUS785 – SEPTEMBER 2007

4.1.1.1.15 CAL MODE: 0x0040

This command instructs the fuel gauge to enter calibration mode. This command is only available when the fuel gauge is UNSEALED.

4.1.1.1.16 RESET: 0x0041

This command instructs the fuel gauge to perform a full reset. This command is only available when the fuel gauge is UNSEALED.

4.1.1.2 AtRate( ): 0x02/0x03

The AtRate( ) read-/write-word function is the first half of a two-function command-set used to set the AtRate value used in calculations made by the AtRateTimeToEmpty( ) function. The AtRate( ) units are in mA.

The AtRate( ) value is a signed integer, and both positive and negative values will be interpreted as a discharge current value. The AtRateTimeToEmpty( ) function returns the predicted operating time at the AtRate value of discharge. The default value for AtRate( ) is zero and will force AtRate( ) to return 65535. Both the AtRate( ) and AtRateTimeToEmpty( ) commands should only be used in NORMAL mode.

4.1.1.3 AtRateTimeToEmpty( ): 0x04/0x05

This read-word function returns an unsigned integer value of the predicted remaining operating time if the battery is discharged at the AtRate( ) value in minutes with a range of 0 to 65534. A value of 65535 indicates AtRate( ) = 0. The gas gauge updates AtRateTimeToEmpty( ) within 1s after the system sets the AtRate( ) value. The fuel gauge automatically updates AtRateTimeToEmpty( ) based on the AtRate( ) value every 1s. Both the AtRate( ) and AtRateTimeToEmpty( ) commands should only be used in NORMAL mode.

4.1.1.4 Temperature( ): 0x06/0x07

This read-word function returns an unsigned integer value of the temperature in units of 0.1 ° K measured by the gas gauge and has a range of 0 to 6553.5 ° K.

4.1.1.5 Voltage( ): 0x08/0x09

This read-word function returns an unsigned integer value of the measured cell-pack voltage in mV with a range of 0 to 6000 mV.

4.1.1.6 Flags( ): 0x0a/0x0b

This read-word function returns the contents of the gas-gauge status register, depicting the current operating status.

Table 4-4. Flags Bit Definitions

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

High Byte OTC OTD – – CHG_INH XCHG FC CHG

Low Byte CC_OFF – OCV_GD WAIT_ID BAT_DET SOC1 SOCF DSG

OTC = Overtemperature in Charge condition is detected. True when set. OTD = Overtemperature in Discharge condition is detected. True when set. CHG_INH = Charge Inhibit: unable to begin charging (temp outside the range [Charge Inhibit Temp Low, Charge Inhibit Temp High]). True when set. XCHG = Charge Suspend Alert (temp outside the range [Suspend Temp Low, Suspend Temp High]). True when set. FC = Fully Charged, set when Charge termination condition is met. True when set. CHG = (Fast)charging allowed. True when set. CC_OFF = bq27500/1 performing Coulomb Counter Offset measurement. True when set. OCV_GD = Good OCV measurement taken. True when set. WAIT_ID = Waiting to identify inserted battery. True when set. BAT_DET = Battery detected. True when set. SOC1 = State-of-Charge-Threshold 1 ( SOC1 Set) reached. True when set. SOCF = State-of-Charge-Threshold Final ( SOCF Set %) reached. True when set. DSG = Discharging detected. True when set.

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