TEXAS INSTRUMENTS bq27541-V200 Technical data

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BatteryPack

PACK-

PROTECTION

PACK+

SDA

SCL

bq27541-V200

LDO

REG25

REGIN

Vcc

SRP

SRN

BAT

Vss

SHDQ

bq27541-V200

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Single Cell Li-Ion Battery Fuel Gauge for Battery Pack Integration

Check for Samples: bq27541-V200

FEATURES

• Battery Fuel Gauge for 1-Series Li-Ion Applications

• Microcontroller Peripheral Provides: – Accurate Battery Fuel Gauging – Internal Temperature Sensor for System

Temperature Reporting – SHA-1/HMAC Authentication – Lifetime Data Logging – 96 Bytes of Non-Volatile Scratch Pad

FLASH

• Battery Fuel Gauging Based on Patented Impedance Track™ Technology

– Models Battery Discharge Curve for

Accurate Time-To-Empty Predictions

– Automatically Adjusts for Battery Aging,

Battery Self-Discharge, and Temperature/Rate Inefficiencies

– Low-Value Sense Resistor (5mΩ to 20mΩ)

• HDQ and I2C™ Interface Formats for Communication With Host System

• Small 12-pin 2,5 mm × 4 mm SON Package

SLUSA11 –FEBRUARY 2010

APPLICATIONS

• Smartphones

• PDAs

• Digital Still and Video Cameras

• Handheld Terminals

• MP3 or Multimedia Players

DESCRIPTION

The Texas Instruments bq27541 Li-Ion battery fuel gauge is a microcontroller peripheral that provides fuel gauging for single-cell Li-Ion battery packs. The device requires little system microcontroller firmware development for accurate battery fuel gauging. The bq27541 resides within the battery pack or on the system’s main-board with an embedded battery (nonremovable).

The bq27541 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).

The bq27541 also features integrated support for secure battery pack authentication, using the SHA-1/HMAC authentication algorithm.

TYPICAL APPLICATION

2Impedance Track is a trademark of Texas Instruments.

C is a trademark of Phillips Corporation.

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

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 data sheet.

SRN

SRP

HDQ

SDA

SCL

REGIN

BAT

REG25

bq27541-V200

SLUSA11 –FEBRUARY 2010

This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.

ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.

DEVICE INFORMATION

AVAILABLE OPTIONS

PRODUCTION PACKAGE TA COMMUNICATION TAPE and REEL

bq27541DRZR-V200 3000 bq27541DRZT-V200 250

(1) bq27541-V200 is shipped in I2C mode

PART #

(1)

12-pin, 2,5-mm × 4-mm SON –40°C to 85°C I2C, HDQ

FORMAT QUANTITY

(1)

bq27541PIN DIAGRAMS

(TOP VIEW)

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PIN FUNCTIONS

PIN DESCRIPTION

NAME NO. TYPE

BAT 4 I Cell-voltage measurement input. ADC input. Decouple with 0.1mF capacitor. REG25 2 P 2.5V output voltage of the internal integrated LDO. Connect a minimum 0.47mF ceramic capacitor. REGIN 3 P The input voltage for the internal integrated LDO. Connect a 0.1mF ceramic capacitor. SCL 11 I Slave I2C serial communications clock input line for communication with system (Slave). Use with 10kΩ

SDA 10 I/O Slave I2C serial communications data line for communication with system (Slave). Open-drain I/O. Use

SE 1 O Shutdown Enable output. Push-pull output. HDQ 12 I/O HDQ serial communications line (Slave). Open-drain. SRN 8 IA Analog input pin connected to the internal coulomb counter where SRN is nearest the PACK- connection.

SRP 7 IA Analog input pin connected to the internal coulomb counter where SRP is nearest the CELL- connection.

TS 9 IA Pack thermistor voltage sense (use 103AT-type thermistor). ADC input Vcc 5 P Processor power input. The minimum 0.47mF capacitor connected to REG25 should be close to Vcc. Vss 6 P Device ground

(1) I/O = Digital input/output, IA = Analog input, P = Power connection

(1)

pull-up resistor (typical).

with 10kΩ pull-up resistor (typical).

Connect to 5-mΩ to 20-mΩ sense resistor.

Connect to 5-mΩ to 20-mΩ sense resistor

Product Folder Link(s): bq27541-V200

bq27541-V200

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SLUSA11 –FEBRUARY 2010

ELECTRICAL SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS

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

IOD

BAT

ESD kV

stg

(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-rated conditions for extended periods may affect device reliability.

Regulator input, REGIN –0.3 to 24 V Supply voltage range –0.3 to 2.75 V Open-drain I/O pins (SDA, SCL, HDQ) –0.3 to 6 V BAT input, (pin 4) –0.3 to 6 V Input voltage range to all others (pins 1, 7, 8, 9) –0.3 to VCC+ 0.3 V Human Body Model (HBM), BAT pin 1.5 Human Body Model (HBM), all pins 2 Functional temperature range –40 to 100 °C Storage temperature range –65 to 150 °C

(1)

VALUE UNIT

DISSIPATION RATINGS

PACKAGE

12-pin DRZ

(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) This data is based on using a 4-layer JEDEC high-K board with the exposed die pad connected to a Cu pad on the board. The board

pad is connected to the ground plane by a 2- × 2-via matrix.

(1)

TA≤ 40°C DERATING FACTOR R

qJA

POWER RATING TA≤ 40°C

(2)

482 mW 5.67 mW/°C 176°C/W

RECOMMENDED OPERATING CONDITIONS

TA= -40°C to 85°C; typical values at TA= 25°C and V

(SLP)

(FULLSLP)

(HIB)

OH(PP)

OH(OD)

(A1)

(A2)

(A3)

lkg

PUCD

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

Supply voltage, REGIN V

Normal operating mode current

(1)

Low-power operating mode current

Hibernate operating mode current Output voltage low (HDQ, SDA, SCL,

SE) Output high voltage (SE) IOH = –1 mA VCC–0.5 V

Output high voltage (HDQ, SDA, SCL) VCC–0.5 V Input voltage low (HDQ, SDA, SCL) –0.3 0.6 V

Input voltage high (HDQ, SDA, SCL) 1.2 6 V Input voltage range (TS) 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 Input leakage current (I/O pins) 0.3 mA Power-up communication delay 250 ms

(REGIN)

No operating restrictions 2.7 5.5 No FLASH writes 2.45 2.7 Fuel gauge in NORMAL mode.

LOAD

Fuel gauge in SLEEP mode.

(1)

LOAD

Fuel gauge in FULLSLEEP mode.

(1)

LOAD

Fuel gauge in HIBERNATE mode.

(1)

LOAD

IOL= 3 mA 0.4 V

External pull-up resistor connected to Vcc

= V

= 3.6 V (unless otherwise noted)

BAT

> Sleep Current

< Sleep Current

< Hibernate Current

MIN TYP MAX UNIT

131 mA

60 mA

21 mA

6 mA

Product Folder Link(s): bq27541-V200

bq27541-V200

SLUSA11 –FEBRUARY 2010

POWER-ON RESET

TA= –40°C to 85°C, C (unless otherwise noted)

IT+

HYS

Positive-going battery voltage input at V Power-on reset hysteresis 45 115 185 mV

2.5 V LDO REGULATOR

TA= –40°C to 85°C, C (unless otherwise noted)

PARAMETER TEST CONDITION MIN NOM MAX UNIT

ΔV

(REGTEMP)

ΔV

(REGLINE)

ΔV

(REGLOAD)

(2)

(1) LDO output current, I (2) Specified by design. Not production tested.

Regulator output voltage, REG25

Regulator dropout voltage TA= –40°C to 85°C mV

Regulator output change with temperature

Line regulation 2.7 V ≤ V

Load regulation mV

Short circuit current limit V

= 0.47mF, 2.45 V < V

(REG)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

(1)

= 0.47 mF, 2.45 V < V

(REG)

, is the sum of internal and external load currents.

OUT

(REGIN)

2.7 V ≤ V I

≤ 16mA

OUT

2.45 V ≤ V battery), I

2.7 V, I

OUT

2.45 V, I V

(REGIN)

= 16 mA

OUT

0.2 mA ≤ I 3 mA ≤ I

(REG25)

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= V

< 5.5 V; typical values at TA= 25°C and V

BAT

(REGIN)

= V

BAT

= 3.6 V

2.05 2.20 2.31 V

= V

(REGIN)

OUT

BAT

≤ 5.5 V,

< 2.7 V (low

≤ 3mA

< 5.5 V; typical values at TA= 25°C and V

2.42 2.48 2.57 V

TA= –40°C to 85°C

2.4 V

(REGIN)

= V

BAT

= 3.6 V

≤ 16 mA 280

≤ 3 mA 50

OUT

= 3.6 V,

(REGIN)

OUT

≤ 16 mA, V

OUT

≤ 5.5 V, I

≤ 3 mA, V

TA= –40°C to 85°C 0.3%

= 16 mA 11 25 mV

OUT

= 2.45 V 34 40

(REGIN)

= 2.7 V 31

(REGIN)

= 0 V TA= –40°C to 85°C 250 mA

INTERNAL TEMPERATURE SENSOR CHARACTERISTICS

TA= –40°C to 85°C, C (unless otherwise noted)

(TEMP)

Temperature sensor voltage gain –2.0 mV/°C

= 0.47mF, 2.45 V < V

(REG)

(REGIN)

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

HIGH FREQUENCY OSCILLATOR

TA= –40°C to 85°C, C (unless otherwise noted)

(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 VCC= 2.5 V, TA= 25°C. (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

= 0.47mF, 2.45 V < V

(REG)

(REGIN)

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

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%

(3)

= V

BAT

= 3.6 V

(REGIN)

2.5 5 ms

Product Folder Link(s): bq27541-V200

bq27541-V200

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SLUSA11 –FEBRUARY 2010

LOW FREQUENCY OSCILLATOR

TA= –40°C to 85°C, C (unless otherwise noted)

(LOSC)

(LEIO)

(LSXO)

(1) The frequency drift is included and measured from the trimmed frequency at VCC= 2.5 V, 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% of typical oscillator frequency.

Operating frequency 32.768 KHz

Frequency error

Start-up time

= 0.47mF, 2.45 V < V

(REG)

(REGIN)

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

(REGIN)

= V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

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%

(3)

INTEGRATING ADC (COULOMB COUNTER) CHARACTERISTICS

TA= –40°C to 85°C, C (unless otherwise noted)

IN(SR)

CONV(SR)

OS(SR)

IN(SR)

lkg(SR)

(1) Specified by design. Not production tested.

Input voltage range, V Conversion time Single conversion 1 s Resolution 14 15 bits Input offset 10 mV Integral nonlinearity error ±0.007 ±0.034 FSR Effective input resistance Input leakage current

= 0.47mF, 2.45 V < V

(REG)

(REGIN)

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

(REGIN)

= V

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

(SRN)

(1)

and V

(SRP)

VSR= V

(SRN)

– V

(SRP)

–0.125 0.125 V

2.5 MΩ

= 3.6 V

BAT

500 ms

= 3.6 V

BAT

0.3 mA

ADC (TEMPERATURE AND CELL VOLTAGE) CHARACTERISTICS

TA= –40°C to 85°C, C (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

IN(ADC)

CONV(ADC)

OS(ADC)

(ADC1)

(ADC2)

lkg(ADC)

(1) Specified by design. Not production tested.

Input voltage range –0.2 1 V Conversion time 125 ms Resolution 14 15 bits Input offset 1 mV Effective input resistance (TS) Effective input resistance (BAT)

Input leakage current

= 0.47mF, 2.45 V < V

(REG)

(1)

= V

(REGIN)

(1)

bq27541 not measuring cell voltage 8 MΩ

< 5.5 V; typical values at TA= 25°C and V

BAT

bq27541 measuring cell voltage 100 kΩ

DATA FLASH MEMORY CHARACTERISTICS

TA= –40°C to 85°C, C (unless otherwise noted)

WORDPROG

CCPROG

(1) Specified by design. Not production tested.

Data retention Flash programming write-cycles Word programming time Flash-write supply current

= 0.47mF, 2.45 V < V

(REG)

(REGIN)

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

(1)

= V

(REGIN)

BAT

= 3.6 V

8 MΩ

0.3 mA

= V

(REGIN)

BAT

= 3.6 V

10 Years

20,000 Cycles

2 ms

5 10 mA

Product Folder Link(s): bq27541-V200

(B)

(BR)

(HW1)

(HW0)

(CYCH)

(DW1)

(DW0)

(CYCD)

Break

7-bitaddress

8-bitdata

(a) BreakandBreakRecovery

(d) Gauge TransmittedBit

(e) GaugetoHostResponse

1.2V

(RISE)

(b) HDQlinerisetime

1-bit R/W

(RSPS)

bq27541-V200

SLUSA11 –FEBRUARY 2010

HDQ COMMUNICATION TIMING CHARACTERISTICS

TA= –40°C to 85°C, C (unless otherwise noted)

(CYCH)

(CYCD)

(HW1)

(DW1)

(HW0)

(DW0)

(RSPS)

(B)

(BR)

(RISE)

= 0.47mF, 2.45 V < V

REG

REGIN

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Cycle time, host to bq27541 190 ms Cycle time, bq27541 to host 190 205 250 ms Host sends 1 to bq27541 0.5 50 ms bq27541 sends 1 to host 32 50 ms Host sends 0 to bq27541 86 145 ms bq27541 sends 0 to host 80 145 ms Response time, bq27541 to host 190 320 ms Break time 190 ms Break recovery time 40 ms HDQ line resing time to logic 1 (1.2V) 950 ns

REGIN

= V

BAT

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= 3.6 V

Figure 1. Timing Diagrams

Product Folder Link(s): bq27541-V200

SU(STA)

SCL

SDA

w(H)

w(L)

(BUF)

d(STA)

REPEATED

START

h(DAT)tsu(DAT)

su(STOP)

STOP START

bq27541-V200

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I2C-COMPATIBLE INTERFACE TIMING CHARACTERISTICS

TA= –40°C to 85°C, C (unless otherwise noted)

w(H)

w(L)

su(STA)

d(STA)

su(DAT)

h(DAT)

su(STOP)

BUF

SCL

SCL/SDA rise time 300 ns SCL/SDA fall time 300 ns SCL pulse width (high) 600 ns SCL pulse width (low) 1.3 ms Setup for repeated start 600 ns Start to first falling edge of SCL 600 ns Data setup time 1000 ns Data hold time 0 ns Setup time for stop 600 ns Bus free time between stop and start 66 ms Clock frequency 400 kHz

= 0.47mF, 2.45 V < V

REG

REGIN

= V

< 5.5 V; typical values at TA= 25°C and V

BAT

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SLUSA11 –FEBRUARY 2010

= V

REGIN

BAT

= 3.6 V

Figure 2. I2C-Compatible Interface Timing Diagrams

GENERAL DESCRIPTION

The bq27541 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 bq27541 control and status registers, as well as its data flash locations. Commands are sent from system to gauge using the bq27541’s serial communications engine, and can be executed during application development, pack manufacture, or end-equipment operation.

Cell information is stored in the bq27541 in non-volatile flash memory. Many of these data flash locations are accessible during application development. They cannot, generally, be accessed directly during end-equipment operation. Access to these locations is achieved by either use of the bq27541’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 bq27541 provides 96 bytes of user-programmable data flash memory, partitioned into three (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 Manufacturer Information Blocks. The key to the bq27541’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.

Product Folder Link(s): bq27541-V200

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SLUSA11 –FEBRUARY 2010

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The bq27541 measures charge/discharge activity by monitoring the voltage across a small-value series sense resistor (5 mΩ to 20 mΩ typ.) located between the CELL-and the battery’s PACK-terminal. When a cell is attached to the bq27541, cell impedance is computed, based on cell current, cell open-circuit voltage (OCV), and cell voltage under loading conditions.

The bq27541 external temperature sensing is optimized with the use of a high accuracy negative temperature coefficient (NTC) thermistor with R25 = 10kΩ ± 1% and B25/85 = 3435kΩ ± 1% (such as Semitec 103AT for measurement). The bq2741 can also be configured to use its internal temperature sensor. The bq27541 uses temperature to monitor the battery-pack environment, which is used for fuel gauging and cell protection functionality.

To minimize power consumption, the bq27541 has different power modes: NORMAL, SLEEP, FULLSLEEP, HIBERNATE, and PRESHUTDOWN. The bq27541 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 section Power Modes.

NOTE

FORMATTING CONVENTIONS IN THIS DOCUMENT:

Commands: italics with parentheses( ) and no breaking spaces. e.g. RemainingCapacity( ) Data Flash: italics, bold, and breaking spaces. e.g. Design Capacity Register bits and flags: italics with brackets[]. e.g. [TDA] Data flash bits: italics, bold, and brackets[]. e.g: [LED1] Modes and states: ALL CAPITALS. e.g. UNSEALED mode

do not delete this subsection

Product Folder Link(s): bq27541-V200

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SLUSA11 –FEBRUARY 2010

DATA COMMANDS

STANDARD DATA COMMANDS

The bq27541 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 1. Each protocol has specific means to access the data at each Command Code. DataRAM is updated and read by the gauge only once per second. Standard commands are accessible in NORMAL operation mode.

Table 1. Standard Commands

NAME COMMAND CODE UNITS SEALED

Control( ) CNTL 0x00 / 0x01 N/A R/W AtRate( ) AR 0x02 / 0x03 mA R/W AtRateTimeToEmpty( ) ARTTE 0x04 / 0x05 Minutes R Temperature( ) TEMP 0x06 / 0x07 0.1K R Voltage( ) VOLT 0x08 / 0x09 mV R Flags( ) FLAGS 0x0a / 0x0b N/A R NominalAvailableCapacity( ) NAC 0x0c / 0x0d mAh R FullAvailableCapacity( ) FAC 0x0e / 0x0f mAh R RemainingCapacity( ) RM 0x10 / 0x11 mAh R FullChargeCapacity( ) FCC 0x12 / 0x13 mAh R AverageCurrent( ) AI 0x14 / 0x15 mA R TimeToEmpty( ) TTE 0x16 / 0x17 Minutes R TimeToFull( ) TTF 0x18 / 0x19 Minutes R StandbyCurrent( ) SI 0x1a / 0x1b mA R StandbyTimeToEmpty( ) STTE 0x1c / 0x1d Minutes R MaxLoadCurrent( ) MLI 0x1e / 0x1f mA R MaxLoadTimeToEmpty( ) MLTTE 0x20 / 0x21 Minutes R AvailableEnergy( ) AE 0x22 / 0x23 10 mWhr R AveragePower( ) AP 0x24 / 0x25 10 mW R TTEatConstantPower( ) TTECP 0x26 / 0x27 Minutes R

Internal_Temp( ) INTTEMP 0x28 / 0x29 0.1°K R CycleCount( ) CC 0x2a / 0x2b Counts R StateOfCharge( ) SOC 0x2c / 0x2d % R StateOfHealth( ) SOH 0x2e / 0x2f % / num R PassedCharge( ) PCHG 0x34 / 0x35 mAh R DOD0( ) DOD0 0x36 / 0x37 HEX# R

ACCESS

Product Folder Link(s): bq27541-V200

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Control( ): 0x00/0x01

Issuing a Control( ) command requires a subsequent 2-byte subcommand. These additional bytes specify the particular control function desired. The Control( ) command allows the system to control specific features of the bq27541 during normal operation and additional features when the bq27541 is in different access modes, as described in Table 2.

Table 2. Control( ) Subcommands

CNTL FUNCTION CNTL DATA SEALED DESCRIPTION

CONTROL_STATUS 0x0000 Yes Reports the status of DF Checksum, Hibernate, IT, etc. DEVICE_TYPE 0x0001 Yes Reports the device type of 0x0541 (indicating bq27541) FW_VERSION 0x0002 Yes Reports the firmware version on the device type HW_VERSION 0x0003 Yes Reports the hardware version of the device type DF_CHECKSUM 0x0004 No Enables a data flash checksum to be generated and reports on a read RESET_DATA 0x0005 No Returns reset data Reserved 0x0006 No Not to be used PREV_MACWRITE 0x0007 No Returns previous MAC command code CHEM_ID 0x0008 Yes Reports the chemical identifier of the Impedance Track™ configuration DF_VERSION 0x000C Yes Reports the data flash version on the device SET_FULLSLEEP 0x0010 No Set the [FullSleep] bit in Control Status register to 1 SET_HIBERNATE 0x0011 Yes Forces CONTROL_STATUS [HIBERNATE] to 1 CLEAR_HIBERNATE 0x0012 Yes Forces CONTROL_STATUS [HIBERNATE] to 0 SET_SHUTDOWN 0x0013 Yes Enables the SE pin to change state CLEAR_SHUTDOWN 0x0014 Yes Disables the SE pin from changing state SET_HDQINTEN 0x0015 Yes Forces CONTROL_STATUS [HDQIntEn] to 1 CLEAR_HDQINTEN 0x0016 Yes Forces CONTROL_STATUS [HDQIntEn] to 0 SEALED 0x0020 No Places the bq27541 is SEALED access mode IT_ENABLE 0x0021 No Enables the Impedance Track™ algorithm CAL_MODE 0x0040 No Places the bq27541 in calibration mode RESET 0x0041 No Forces a full reset of the bq27541

ACCESS

Product Folder Link(s): bq27541-V200

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SLUSA11 –FEBRUARY 2010

CONTROL_STATUS: 0X0000

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

Table 3. CONTROL_STATUS Flags

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

High Byte SE FAS SS CSV CCA BCA – HDAIntEn

Low Byte SHUTDOWN HIBERNATE FULLSLEEP SLEEP LDMD RUP_DIS VOK QEN

SE = Status bit indicating the SE pin is active. True when set. Default is 0.

FAS = Status bit indicating the bq27541 is in FULL ACCESS SEALED state. Active when set.

SS = Status bit indicating the bq27541 is in the SEALED State. Active when set.

CSV = Status bit indicating a valid data flash checksum has been generated. Active when set.

CCA = Status bit indicating the bq27541 Coulomb Counter Calibration routine is active. Active when set.

BCA = Status bit indicating the bq27541 Board Calibration routine is active. Active when set.

HDQIntEn = Status bit indicating the HDQ interrupt function is active. True when set. Default is 0.

SHUTDOWN = Control bit indicating the fuel gauge can force its SE pin low to signal an external shutdown. True when set. Default is 0.

HIBERNATE = Status bit indicating a request for entry into HIBERNATE from SLEEP mode has been issued. True when set. Default is

FULLSLEEP =

SLEEP = Status bit indicating the bq27541 is in SLEEP mode. True when set

LDMD = Status bit indicating the bq27541 Impedance Track™ algorithm using constant-power mode. True when set. Default is 0

RUP_DIS = Status bit indicating the bq27541 Ra table updates are disabled. True when set.

VOK = Status bit indicating cell voltages are OK for Qmax updates. True when set. QEN = Status bit indicating the bq27541 Qmax updates are enabled. True when set.

0. Control bit when set will put the bq27541 into the lower power state of SLEEP mode. It is not possible to monitor this bit

Status bit indicating the bq27541 is in FULLSLEEP mode. True when set. The state can be detected by monitoring the power used by the bq27541 because any communication will automatically clear it

(constant-current mode).

Product Folder Link(s): bq27541-V200

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DEVICE_TYPE: 0X0001

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

FW_VERSION: 0X0002

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

HW_VERSION: 0X0003

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

DF_CHECKSUM: 0X0004

Instructs the fuel gauge to compute the checksum of the data flash memory. The checksum value is written and returned to addresses 0x00/0x01 (UNSEALED mode only). The checksum will not be calculated in SEALED mode; however, the checksum value can still be read.

RESET_DATA: 0X0005

Instructs the fuel gauge to return the reset data to addresses 0x00/0x01.

PREV_MACWRITE: 0X0007

Instructs the fuel gauge to return the previous command written to addresses 0x00/0x01. The value returned is limited to less than 0x0020.

CHEM_ID: 0X0008

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

DF_VERSION: 0x000C

Instructs the gas gauge to return the data flash version to addresses 0x00/0x01

SET_FULLSLEEP: 0X0010

Instructs the gas gauge to set the FullSleep bit in Control Status register to 1. This will allow the gauge to enter the FULLSLEEP power mode after the transition to SLEEP power state is detected. In FullSleep mode less power is consumed by disabling an oscillator circuit used by the communication engines. For HDQ communication one host message will be dropped. For I2C communications the first I2C message will incur a 6–8 millisecond clock stretch while the oscillator is started and stabilized. A communication to the device in FULLSLEEP will force the part back to the SLEEP mode.

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.

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.

SET_SHUTDOWN: 0x0013

Sets the CONTROL_STATUS [SHUTDOWN] bit to 1, thereby enabling the SE pin to change state. The Impedance Track algorithm controls the setting of the SE pin, depending on whether the conditions are met for fuel gauge shutdown or not.

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CLEAR_SHUTDOWN: 0X0014

Disables the SE pin from changing state. The SE pin is left in a high-impedance state.

SET_HDQINTEN: 0x0015

Instructs the fuel gauge to set the CONTROL_STATUS [HDQIntEn] bit to 1. This will enable the HDQ Interrupt function. When the this subcommand is received, the bq27541 will detect any of the interrupt conditions and assert the interrupt at one second intervals until the CLEAR_HDQINTEN command is received or the count of HDQHostIntrTries has lapsed.

CLEAR_HDQINTEN: 0x0016

Instructs the fuel gauge to set the CONTROL_STATUS [HDQIntEn] bit to 0. This will disable the HDQ Interrupt function.

SEALED: 0X0020

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

IT ENABLE: 0X0021

This command forces the fuel gauge to begin the Impedance Track™ algorithm, sets the active UpdateStatuslocation to 0x01 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.

CAL MODE: 0X0040

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

RESET: 0X0041

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

AtRate( ): 0x02/0x03

The AtRate( ) read-/write-word function is the first half of a two-function command call-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, with negative values 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 AtRateTimeToEmpty( ) to return 65,535. Both the AtRate( ) and AtRateTimeToEmpty( ) commands should only be used in NORMAL mode.

AtRateTimeToEmpty( ): 0x04/0x05

This read-only 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 65,534. A value of 65,535 indicates AtRate( ) = 0. The fuel gauge updates AtRateTimeToEmpty( ) within 1 s 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.

Temperature( ): 0x06/0x07

This read-only function returns an unsigned integer value of the battery temperature in units of 0.1K measured by the fuel gauge.

Voltage( ): 0x08/0x09

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

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Flags( ): 0x0a/0x0b

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

Table 4. Flags Bit Definitions

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

High Byte OTC OTD – – CHG_INH XCHG FC CHG

Low Byte OCVTAKEN – – – – SOC1 SOCF DSG

OTC = Over-Temperature in Charge condition is detected. True when set. OTD = Over-Temperature in Discharge condition is detected. True when set.

CHG_INH = Charge Inhibit indicates the temperature is outside the range [Charge Inhibit Temp Low, Charge Inhibit Temp

XCHG = Charge Suspend Alert indicates the temperature is outside the range [Suspend Temperature Low, Suspend

CHG = (Fast) charging allowed. True when set.

OVERTAKEN = Cleared on entry to relax mode and set to 1 when OCV measurement is performed in relax

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.

High]. True when set.

Temperature High].

FC = Full-charged condition reached (RMFCC=1; Set FC_Set%=-1% when RMFCC=0). True when set

NominalAvailableCapacity( ): 0x0c/0x0d

This read-only command pair returns the uncompensated (less than C/20 load) battery capacity remaining. Units are mAh.

FullAvailableCapacity( ): 0x0e/0x0f

This read-only command pair returns the uncompensated (less than C/20 load) capacity of the battery when fully charged. Units are mAh. FullAvailableCapacity( ) is updated at regular intervals, as specified by the IT algorithm.

RemainingCapacity( ): 0x10/0x11

This read-only command pair returns the compensated battery capacity remaining. Units are mAh.

FullChargeCapacity( ): 0x12/13

This read-only command pair returns the compensated capacity of the battery when fully charged. Units are mAh. FullChargeCapacity( ) is updated at regular intervals, as specified by the IT algorithm.

AverageCurrent( ): 0x14/0x15

This read-only command pair returns a signed integer value that is the average current flow through the sense resistor. It is updated every 1 second. Units are mA.

TimeToEmpty( ): 0x16/0x17

This read-only function returns an unsigned integer value of the predicted remaining battery life at the present rate of discharge, in minutes. A value of 65,535 indicates battery is not being discharged.

TimeToFull( ): 0x18/0x19

This read-only function returns an unsigned integer value of predicted remaining time until the battery reaches full charge, in minutes, based upon AverageCurrent( ). The computation accounts for the taper current time extension from the linear TTF computation based on a fixed AverageCurrent( ) rate of charge accumulation. A value of 65,535 indicates the battery is not being charged.

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StandbyCurrent( ): 0x1a/0x1b

This read-only function returns a signed integer value of the measured standby current through the sense resistor. The StandbyCurrent( ) is an adaptive measurement. Initially it reports the standby current programmed in Initial Standby, and after spending some time in standby, reports the measured standby current.

The register value is updated every 1 second when the measured current is above the Deadband and is less than or equal to 2 x Initial Standby. The first and last values that meet this criteria are not averaged in, since they may not be stable values. To approximate a 1 minute time constant, each new StandbyCurrent( ) value is computed by taking approximate 93% weight of the last standby current and approximate 7% of the current measured average current.

StandbyTimeToEmpty( ): 0x1c/0x1d

This read-only function returns an unsigned integer value of the predicted remaining battery life at the standby rate of discharge, in minutes. The computation uses Nominal Available Capacity (NAC), the uncompensated remaining capacity, for this computation. A value of 65,535 indicates battery is not being discharged.

MaxLoadCurrent( ): 0x1e/0x1f

This read-only function returns a signed integer value, in units of mA, of the maximum load conditions. The MaxLoadCurrent( ) is an adaptive measurement which is initially reported as the maximum load current programmed in Initial Max Load Current. If the measured current is ever greater than Initial Max Load Current, then MaxLoadCurrent( ) updates to the new current. MaxLoadCurrent( ) is reduced to the average of the previous value and Initial Max Load Current whenever the battery is charged to full after a previous discharge to an SOC less than 50%. This prevents the reported value from maintaining an unusually high value.

MaxLoadTimeToEmpty( ): 0x20/0x21

This read-only function returns an unsigned integer value of the predicted remaining battery life at the maximum load current discharge rate, in minutes. A value of 65,535 indicates that the battery is not being discharged.

AvailableEnergy( ): 0x22/0x23

This read-only function returns an unsigned integer value of the predicted charge or energy remaining in the battery. The value is reported in units of mWh.

AveragePower( ): 0x24/0x25

This read-word function returns an unsigned integer value of the average power of the current discharge. It is negative during discharge and positive during charge. A value of 0 indicates that the battery is not being discharged. The value is reported in units of mW.

TimeToEmptyAtConstantPower( ): 0x26/0x27

This read-only function returns an unsigned integer value of the predicted remaining operating time if the battery is discharged at the AveragePower( ) value in minutes. A value of 65,535 indicates AveragePower( ) = 0. The fuel gauge automatically updates TimeToEmptyatContantPower( ) based on the AveragePower( ) value every 1s.

Internal_Temp( ): 0x28/0x29

This read-only function returns an unsigned integer value of the measured internal temperature of the device in units of 0.1K measured by the fuel gauge.

CycleCount( ): 0x2a/0x2b

This read-only function returns an unsigned integer value of the number of cycles the battery has experienced with a range of 0 to 65,535. One cycle occurs when accumulated discharge ≥ CC Threshold.

StateOfCharge( ): 0x2c/0x2d

This read-only function returns an unsigned integer value of the predicted remaining battery capacity expressed as a percentage of FullChargeCapacity( ), with a range of 0 to 100%.

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StateOfHealth( ): 0x2e/0x2f

0x2e SOH percentage: this read-only function returns an unsigned integer value, expressed as a percentage of the ration of predicted FCC(25°C, SOH current rate) over the DesignCapacity(). The FCC(25°C, SOH current rate) is the calculated full charge capacity at 25°C and the SOH current rate which is specified in the data flash (State of Health Load I). The range of the returned SOH percentage is 0x00 to 0x64, indicating 0 to 100% correspondingly.

0x2f SOH Status: this read-only function returns an unsigned integer value, indicating the status of the SOH percentage. The meanings of the returned value are:

• 0x00: SOH not valid (initialization)

• 0x01: Instant SOH value ready

• 0x02: Initial SOH value ready – Calculation based on uncompensated Qmax – Updated at first grid point update after cell insertion

• 0x03: SOH value ready – Utilize the updated Qmax update – Calculation based on compensated Qmax – Updated after complete charge and relax is complete

• 0x04-0xFF: Reserved

PassedCharge( ): 0x34/0x35

This signed integer indicates the amount of charge passed through the sense resistor since the last IT simulation in mAh.

DOD0( ): 0x36/0x37

This unsigned integer indicates the depth of discharge during the most recent OCV reading.

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EXTENDED DATA COMMANDS

Extended commands offer additional functionality beyond the standard set of commands. They are used in the same manner; however unlike standard commands, extended commands are not limited to 2-byte words. The number of commands bytes for a given extended command ranges in size from single to multiple bytes, as specified in Table 5. For details on the SEALED and UNSEALED states, see Section Access Modes.

Table 5. Extended Commands

NAME COMMAND CODE UNITS SEALED UNSEALED

ACCESS

Reserved RSVD 0x38…0x39 N/A R R PackConfig( ) PCR 0x3a / 0x3b HEX# R R

DesignCapacity( ) DCAP 0x3c / 0x3d mAh R R DataFlashClass( ) DataFlashBlock( ) BlockData( ) / Authenticate( ) BlockData( ) / AuthenticateCheckSum( ) BlockData( ) DFD 0x55…0x5f N/A R R/W BlockDataCheckSum( ) DFDCKS 0x60 N/A R/W R/W BlockDataControl( ) DFDCNTL 0x61 N/A N/A R/W DeviceNameLength( ) DNAMELEN 0x62 N/A R R DeviceName( ) DNAME 0x63...0x69 N/A R R

Reserved RSVD 0x6a...0x7f N/A R R

(1) SEALED and UNSEALED states are entered via commands to Control( ) 0x00/0x01 (2) In SEALED mode, data flash CANNOT be accessed through commands 0x3e and 0x3f. (3) The BlockData( ) command area shares functionality for accessing general data flash and for using Authentication. See section on

Authentication for more details.

(2) (2)

(3)

DFCLS 0x3e N/A N/A R/W DFBLK 0x3f N/A R/W R/W

A/DF 0x40…0x53 N/A R/W R/W

ACKS/DFD 0x54 N/A R/W R/W

(1) (2)

ACCESS

(1) (2)

PackConfig( ): 0x3a/0x3b

SEALED and UNSEALED Access: This command returns the value is stored in Pack Configuration and is expressed in hex value.

DesignCapacity( ): 0x3c/0x3d

SEALED and UNSEALED Access: This command returns the value is stored in Design Capacity and is expressed in mAh. This is intended to be the theoretical or nominal capacity of a new pack, but has no bearing on the operation of the fuel gauge functionality.

DataFlashClass( ): 0x3e

This command sets the data flash class to be accessed. The class to be accessed should be entered in hexadecimal.

SEALED Access: This command is not available in SEALED mode.

DataFlashBlock( ): 0x3f

UNSEALED Access: This command sets the data flash block to be accessed. When 0x00 is written to BlockDataControl( ), DataFlashBlock( ) holds the block number of the data flash to be read or written. Example: writing a 0x00 to DataFlashBlock( ) specifies access to the first 32 byte block and a 0x01 specifies access to the second 32 byte block, and so on.

SEALED Access: This command directs which data flash block will be accessed by the BlockData( ) command. Writing a 0x00 to DataFlashBlock( ) specifies the BlockData( ) command will transfer authentication data. Issuing a 0x01, 0x02 or 0x03 instructs the BlockData( ) command to transfer Manufacturer Info Block A, B, or C, respectively.

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BlockData( ): 0x40…0x5f

This command range is used to transfer data for data flash class access. This command range is the 32-byte data block used to access Manufacturer Info Block A, B, or C. Manufacturer Info Block A is read only for the sealed access. UNSEALED access is read/write.

BlockDataChecksum( ): 0x60

The host system should write this value to inform the device that new data is ready for programming into the specified data flash class and block.”

UNSEALED Access: This byte contains the checksum on the 32 bytes of block data read or written to data flash. The least-significant byte of the sum of the data bytes written must be complemented ( [255 – x] , for x the least-significant byte) before being written to 0x60.

SEALED Access: This byte contains the checksum for the 32 bytes of block data written to Manufacturer Info Block A, B, or C. The least-significant byte of the sum of the data bytes written must be complemented ( [255 – x] , for x the least-significant byte) before being written to 0x60.

BlockDataControl( ): 0x61

UNSEALED Access: This command is used to control data flash access mode. Writing 0x00 to this command enables BlockData( ) to access general data flash. Writing a 0x01 to this command enables SEALED mode operation of DataFlashBlock( ).

SEALED Access: This command is not available in SEALED mode.

DeviceNameLength( ): 0x62

UNSEALED and SEALED Access: This byte contains the length of the Device Name.

DeviceName( ): 0x63…0x69

UNSEALED and SEALED Access: This block contains the device name that is programmed in Device Name.

Reserved – 0x6a – 0x7f

SERIAL NUMBER

The bq27541 serial number can be read in the unsealed mode with authentication data flash control and data flash block commands. The operation under unsealed mode is as the following steps:

1. write 0x02 to register 0x61

2. write 0x00 to register 0x3f

3. read the 8 byte serial number from registers 0x40 to 0x47

do not delete this para

DATA FLASH INTERFACE

ACCESSING THE DATA FLASH

The bq27541 data flash is a non-volatile memory that contains bq27541 initialization, default, cell status, calibration, configuration, and user information. The data flash can be accessed in several different ways, depending on what mode the bq27541 is operating in and what data is being accessed.

Commonly accessed data flash memory locations, frequently read by a system, are conveniently accessed through specific instructions, already described in Section Data Commands. These commands are available when the bq27541 is either in UNSEALED or SEALED modes.

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Most data flash locations, however, are only accessible in UNSEALED mode by use of the bq27541 evaluation software or by data flash block transfers. These locations should be optimized and/or fixed during the development and manufacture processes. They become part of a golden image file and can then be written to multiple battery packs. Once established, the values generally remain unchanged during end-equipment operation.

To access data flash locations individually, the block containing the desired data flash location(s) must be transferred to the command register locations, where they can be read to the system or changed directly. This is accomplished by sending the set-up command BlockDataControl( ) (0x61) with data 0x00. Up to 32 bytes of data can be read directly from the BlockData( ) (0x40…0x5f), externally altered, then rewritten to the BlockData( ) command space. Alternatively, specific locations can be read, altered, and rewritten if their corresponding offsets are used to index into the BlockData( ) command space. Finally, the data residing in the command space is transferred to data flash, once the correct checksum for the whole block is written to BlockDataChecksum( ) (0x60).

Occasionally, a data flash CLASS will be larger than the 32-byte block size. In this case, the DataFlashBlock( ) command is used to designate which 32-byte block the desired locations reside in. The correct command address is then given by 0x40 + offset modulo 32. For example, to access Terminate Voltage in the Gas Gauging class, DataFlashClass( ) is issued 80 (0x50) to set the class. Because the offset is 48, it must reside in the second 32-byte block. Hence, DataFlashBlock( ) is issued 0x01 to set the block offset, and the offset used to index into the BlockData( ) memory area is 0x40 + 48 modulo 32 = 0x40 + 16 = 0x40 + 0x10 = 0x50.

Reading and writing subclass data are block operations up to 32 bytes in length. If during a write the data length exceeds the maximum block size, then the data is ignored.

None of the data written to memory are bounded by the bq27541 — the values are not rejected by the fuel gauge. Writing an incorrect value may result in hardware failure due to firmware program interpretation of the invalid data. The written data is persistent, so a power-on reset does not resolve the fault.

MANUFACTURER INFORMATION BLOCKS

The bq27541 contains 96 bytes of user programmable data flash storage: Manufacturer Info Block A, Manufacturer Info Block B, Manufacturer Info Block C. The method for accessing these memory locations is slightly different, depending on whether the device is in UNSEALED or SEALED modes.

When in UNSEALED mode and when and 0x00 has been written to BlockDataControl( ), accessing the Manufacturer Info Blocks is identical to accessing general data flash locations. First, a DataFlashClass( ) command is used to set the subclass, then a DataFlashBlock( ) command sets the offset for the first data flash address within the subclass. The BlockData( ) command codes contain the referenced data flash data. When writing the data flash, a checksum is expected to be received by BlockDataChecksum( ). Only when the checksum is received and verified is the data actually written to data flash.

As an example, the data flash location for Manufacturer Info Block B is defined as having a Subclass = 58 and an Offset = 32 through 63 (32 byte block). The specification of Class = System Data is not needed to address Manufacturer Info Block B, but is used instead for grouping purposes when viewing data flash info in the bq27541 evaluation software.

When in SEALED mode or when 0x01 BlockDataControl( ) does not contain 0x00, data flash is no longer available in the manner used in UNSEALED mode. Rather than issuing subclass information, a designated Manufacturer Information Block is selected with the DataFlashBlock( ) command. Issuing a 0x01, 0x02, or 0x03 with this command causes the corresponding information block (A, B, or C, respectively) to be transferred to the command space 0x40…0x5f for editing or reading by the system. Upon successful writing of checksum information to BlockDataChecksum( ), the modified block is returned to data flash. Note: Manufacturer Info Block A is read-only when in SEALED mode.

ACCESS MODES

The bq27541 provides three security modes (FULL ACCESS, UNSEALED, and SEALED) that control data flash access permissions according to Table 6. Data Flash refers to those data flash locations, specified in Table 7, that are accessible to the user. Manufacture Information refers to the three 32-byte blocks.

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Table 6. Data Flash Access

SECURITY MODE DATA FLASH MANUFACTURER INFORMATION

FULL ACCESS R/W R/W

UNSEALED R/W R/W

SEALED None R (A); R/W (B,C)

Although FULL ACCESS and UNSEALED modes appear identical, only FULL ACCESS mode allows the bq27541 to write access-mode transition keys.

SEALING/UNSEALING DATA FLASH

The bq27541 implements a key-access scheme to transition between SELAED, UNSEALED, and FULL-ACCESS modes. Each transition requires that a unique set of two keys be sent to the bq27541 via the Control( ) control command. The keys must be sent consecutively, with no other data being written to the Control( ) register in between. Note that to avoid conflict, the keys must be different from the codes presented in the CNTL DATA column of Table 2 subcommands.

When in SEALED mode the [SS] bit of CONTROL_STATUS is set, but when the UNSEAL keys are correctly received by the bq27541, the [SS] bit is cleared. When the full-access keys are correctly received then the CONTROL_STATUS [FAS] bit is cleared.

Both Unseal Key and Full-Access Key have two words and are stored in data flash. The first word is Key 0 and the second word is Key 1. The order of the keys sent to bq27541 are Key 1 followed by Key 0. The order of the bytes for each key entered through the Control( ) command is the reverse of what is read from the part. For an example, if the Unseal Key is 0x56781234, key 1 is 0x1234 and key 0 is 0x5678. Then Control( ) should supply 0x3412 and 0x7856 to unseal the part. The Unseal key and the FULL-ACCESS key can only be updated when in FULL-ACCESS mode. .

DATA FLASH SUMMARY

Table 7 summarizes the data flash locations available to the user, including their default, minimum, and

maximum values.

Table 7. Data Flash Summary

Class Subclass Subclass Offset Name Data Min Value Max Value Default Value Units

Configuration 2 Safety 0 OT Chg I2 0 1200 550 0.1°C Configuration 2 Safety 2 OT Chg Time U1 0 60 2 s Configuration 2 Safety 3 OT Chg Recovery I2 0 1200 500 0.1°C Configuration 2 Safety 5 OT Dsg I2 0 1200 600 0.1°C Configuration 2 Safety 7 OT Dsg Time U1 0 60 2 s Configuration 2 Safety 8 OT Dsg Recovery I2 0 1200 550 0.1°C Configuration 32 Charge Inhibit Cfg 0 Chg Inhibit Temp Low I2 –400 1200 0 0.1°C Configuration 32 Charge Inhibit Cfg 2 Chg Inhibit Temp High I2 –400 1200 450 0.1°C Configuration 32 Charge Inhibit Cfg 4 Temp Hys I2 0 100 50 0.1°C Configuration 34 Charge 2 Charging Voltage I2 0 4600 4200 mV Configuration 34 Charge 4 Delta Temp I2 0 500 50 0.1°C Configuration 34 Charge 6 Suspend Low Temp I2 –400 1200 -50 0.1°C Configuration 34 Charge 8 Suspend High Temp I2 –400 1200 50 0.1°C Configuration 36 Charge Termination 2 Taper Current I2 0 1000 100 mA Configuration 36 Charge Termination 4 Min Taper Capacity I2 0 1000 25 0.01 mAh Configuration 36 Charge Termination 6 Taper Voltage I2 0 1000 100 mV Configuration 36 Charge Termination 8 Current Taper Window U1 0 60 40 s Configuration 36 Charge Termination 9 TCA Set % I1 –1 100 99 % Configuration 36 Charge Termination 10 TCA Clear % I1 –1 100 95 % Configuration 36 Charge Termination 11 FC Set % I1 –1 100 100 % Configuration 36 Charge Termination 12 FC Clear % I1 –1 100 98 %

ID Type

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Table 7. Data Flash Summary (continued)

Class Subclass Subclass Offset Name Data Min Value Max Value Default Value Units

Configuration 36 Charge Termination 13 DODatEOCDelta T I2 0 1000 100 0.1°C Configuration 48 Data 0 Rem Cap Alarm I2 0 700 100 mAh Configuration 48 Data 8 Initial Standby I1 –256 0 –10 mA Configuration 48 Data 9 Initial MaxLoad I2 –32767 0 –200 mA Configuration 48 Data 17 Cycle Count U2 0 65535 0 Count Configuration 48 Data 19 CC Threshold I2 100 32767 900 mAh Configuration 48 Data 23 Design Capacity I2 0 32767 1000 mAh Configuration 48 Data 25 Design Energy I2 0 32767 5400 mWh Configuration 48 Data 27 Device Name S8 x x bq27541 – Configuration 48 Data 27 State of Health Load I2 0 –400 –400 mA Configuration 49 Discharge 0 SOC1 Set Threshold U1 0 255 150 mAh Configuration 49 Discharge 1 SOC1 Clear Threshold U1 0 255 175 mAh Configuration 49 Discharge 2 SOCF Set Threshold U1 0 255 75 mAh Configuration 49 Discharge 3 SOCF Clear Threshold U1 0 255 100 mAh Configuration 56 Manufacturer Data 0 Pack Lot Code H2 0 FFFF 0 – Configuration 56 Manufacturer Data 2 PCB Lot Code H2 0 FFFF 0 – Configuration 56 Manufacturer Data 4 Firmware Version H2 0 FFFF 0 – Configuration 56 Manufacturer Data 6 Hardware Revision H2 0 FFFF 0 – Configuration 56 Manufacturer Data 8 Cell Revision H2 0 FFFF 0 – Configuration 56 Manufacturer Data 10 DF Config Version H2 0 FFFF 0 –

System Data 58 Manufacturer Info 0 - 31 Block A [0 - 31] H1 0 FF 0 – System Data 58 Manufacturer Info 32 - 63 Block B [0 - 31] H1 0 FF 0 – System Data 58 Manufacturer Info 64 - 95 Block C [0 - 31] H1 0 FF 0 –

LT Data 59 Lifetime Data 0 Lifetime Max Temp I2 0 1400 300 0.1°C LT Data 59 Lifetime Data 2 Lifetime Min Temp I2 –600 1400 200 0.1°C LT Data 59 Lifetime Data 4 Lifetime Max Pack Voltage I2 0 32767 3200 mV LT Data 59 Lifetime Data 6 Lifetime Min Pack Voltage I2 0 32767 4200 mV LT Data 59 Lifetime Data 8 Lifetime Max Chg Current I2 –32767 32767 0 mA LT Data 59 Lifetime Data 10 Lifetime Max Dsg Current I2 –32767 32767 0 mA LT Data 60 Lifetime Temp Samples 0 LT Flash Cnt I2 0 32767 0 Count

Configuration 64 Registers 0 Pack Configuration H2 0 FFFF x0177 –

LT Data 66 Lifetime Resolution 0 LT Temp Res U1 0 255 10 0.1°C LT Data 66 Lifetime Resolution 1 LT V Res U1 0 255 25 mV LT Data 66 Lifetime Resolution 2 LT Cur Res U1 0 255 100 mA LT Data 66 Lifetime Resolution 11 LT Update Time U2 0 65535 60 s

Configuration 68 Power 0 Flash Update OK Voltage I2 0 4200 2800 mV Configuration 68 Power 2 Sleep Current I2 0 100 8 mA Configuration 68 Power 11 Hibernate I U2 0 700 3 mA Configuration 68 Power 13 Hibernate V U2 2400 3000 2550 mV Configuration 68 Power 15 FS Wait U1 0 255 0 s Gas Gauging 80 IT Cfg 0 Load Select U1 0 255 1 – Gas Gauging 80 IT Cfg 1 Load Mode U1 0 255 0 – Gas Gauging 80 IT Cfg 21 Max Res Factor U1 0 255 15 num Gas Gauging 80 IT Cfg 22 Min Res Factor U1 0 255 5 num Gas Gauging 80 IT Cfg 25 Ra Filter U2 0 1000 500 500 Gas Gauging 80 IT Cfg 50 Terminate Voltage I2 2800 3700 3000 mV Gas Gauging 80 IT Cfg 53 Res Relax Time U2 0 65535 200 sec Gas Gauging 80 IT Cfg 57 User Rate-mA I2 2000 9000 0 mA Gas Gauging 80 IT Cfg 59 User Rate-mW I2 3000 14000 0 cW Gas Gauging 80 IT Cfg 61 Reserve Cap-mAh I2 0 9000 0 mAh Gas Gauging 80 IT Cfg 63 Reserve Cap-mWh I2 0 14000 0 cWh Gas Gauging 80 IT Cfg 67 Max Scale Back Grid U1 0 15 4 num Gas Gauging 80 IT Cfg 68 Max Delta V U2 0 65535 200 mV Gas Gauging 80 IT Cfg 70 Min Delta V U2 0 65535 0 mV Gas Gauging 80 IT Cfg 76 Qmax Max Delta % U1 0 10 5 mAhr

ID Type

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Table 7. Data Flash Summary (continued)

Class Subclass Subclass Offset Name Data Min Value Max Value Default Value Units

Gas Gauging 80 IT Cfg 77 DeltaV Max Delta U2 0 65535 10 mV Gas Gauging 80 IT Cfg 78 Max Sim Rate U1 0 255 2 C/rate Gas Gauging 80 IT Cfg 79 Min Sim Rate U1 0 255 20 C/rate Gas Gauging 80 IT Cfg 80 Ra Max Delta U2 0 65535 44 mOhm Gas Gauging 81 Current Thresholds 0 Dsg Current Threshold I2 0 2000 60 mA Gas Gauging 81 Current Thresholds 2 Chg Current Threshold I2 0 2000 75 mA Gas Gauging 81 Current Thresholds 4 Quit Current I2 0 1000 40 mA Gas Gauging 81 Current Thresholds 6 Dsg Relax Time U2 0 8191 60 s Gas Gauging 81 Current Thresholds 8 Chg Relax Time U1 0 255 60 s

Gas Gaigomg 81 Current Thresholds 9 Quit Relax Time U1 0 63 1 s

Gas Gauging 81 Current Thresholds 10 Max IR Correct U2 0 1000 400 mV Gas Gauging 82 State 0 Qmax Cell 0 I2 0 32767 1000 mAh Gas Gauging 82 State 2 Cycle Count U2 0 65535 0 Count Gas Gauging 82 State 4 Update Status H1 0 6 0 num Gas Gauging 82 State 5 V at Chg Term I2 0 5000 4200 mV Gas Gauging 82 State 7 Avg I Last Run I2 –32768 32767 –299 mA Gas Gauging 82 State 9 Avg P Last Run I2 –32768 32767 –1131 mA Gas Gauging 82 State 11 Delta Voltage I2 –32768 32767 2 mV Gas Gauging 82 State 15 T Rise I2 0 32767 0 num Gas Gauging 82 State 17 T Time Constant I2 0 32767 32767 num

OCV Table 83 OCV Table 0 Chem ID H2 0 FFFF 0107 num

Ra Tables 88 Data 0-31 Cell0 R_a Table SeeNote 1

Ra Tables 89 Data 0-31 xCell0 R_a Table See Note 1 Calibration 104 Data 0 CC Gain (Note 4) F4 1.00E-01 4.00E+01 0.47095 num Calibration 104 Data 4 CC Delta Note 4) F4 2.98E+04 1.19E+06 5.595e5 num Calibration 104 Data 8 CC Offset (Note 4) U2 –32768 32768 –1200 num Calibration 104 Data 10 Board Offset (Note 4) I1 –128 127 0 num Calibration 104 Data 11 Int Temp Offset I1 –128 127 0 0.1°C Calibration 104 Data 12 Ext Temp Offset I1 –128 127 0 0.1°C Calibration 104 Data 13 Pack V Offset I1 –128 127 0 mV Calibration 107 Current 1 Deadband U1 0 255 5 mA

Security 112 Codes 0 Sealed to Unsealed H4 0 ffffffff 36720414 – Security 112 Codes 4 Unsealed to Full H4 0 ffffffff ffffffff – Security 112 Codes 8 Authen Key3 H4 0 ffffffff 1234567 – Security 112 Codes 12 Authen Key2 H4 0 ffffffff 89ABCDEF – Security 112 Codes 16 Authen Key1 H4 0 ffffffff FEDCBA98 – Security 112 Codes 20 Authen Key0 H4 0 ffffffff 76543210 –

1. Encoded battery profile information created by bqEasy software.

2. Part number and/or part specific

3. Not IEEE floating point

4. Display as Data Flash value; value displayed in EVSW is different. See Table 8 for conversion table.

ID Type

Table 8. Data Flash to EVSW Conversion

Class SubClass Offset Name Flash to EVSW

SubClass Data Data Flash EVSW EVSW

ID Type Default Default Unit

Gas Gauging 80 IT Cfg 59 User Rate-mW I2 0 cW 0 mW DF × 10 Gas Gauging 80 IT Cfg 63 Reserve Cap-mWh I2 0 cWh 0 mWh DF × 10

Calibration 104 Data 0 CC Gain F4 0.47095 Num 10.124 mΩ 4.768/DF Calibration 104 Data 4 CC Delta F4 5.595e5 Num 10.147 mΩ 5677445/DF Calibration 104 Data 8 CC Offset I2 –1200 Num –0.576 mV DF × 0.00048 Calibration 104 Data 10 Board Offset I1 0 Num 0 µV DF × 16/0.48

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Data Data Flash (DF)

Unit Conversion

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FUNCTIONAL DESCRIPTION

FUEL GAUGING

The bq27541 measures the cell voltage, temperature, and current to determine battery SOC. The bq27541 monitors charge and discharge activity by sensing the voltage across a small-value resistor (5 mΩ to 20 mΩ typ.) between the SRP and SRN pins and in series with the cell. By integrating charge passing through the battery, the battery’s SOC is adjusted during battery charge or discharge.

The total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. When an application load is applied, the impedance of the cell is measured by comparing the OCV obtained from a predefined function for present SOC with the measured voltage under load. Measurements of OCV and charge integration determine chemical state of charge and chemical capacity (Qmax). The initial Qmax values are taken from a cell manufacturers' data sheet multiplied by the number of parallel cells. It is also used for the value in Design Capacity. The bq27541 acquires and updates the battery-impedance profile during normal battery usage. It uses this profile, along with SOC and the Qmax value, to determine FullChargeCapacity( ) and StateOfCharge( ), specifically for the present load and temperature. FullChargeCapacity( ) is reported as capacity available from a fully charged battery under the present load and temperature until Voltage( ) reaches the Terminate Voltage. NominalAvailableCapacity( ) and

FullAvailableCapacity( ) are the uncompensated (no or light load) versions of RemainingCapacity( ) and FullChargeCapacity( ) respectively.

The bq27541 has two flags accessed by the Flags( ) function that warns when the battery’s SOC has fallen to critical levels. When RemainingCapacity( ) falls below the first capacity threshold, specified in SOC1 Set Threshold, the [SOC1] (State of Charge Initial) flag is set. The flag is cleared once RemainingCapacity( ) rises above SOC1 Set Threshold. All units are in mAh.

When RemainingCapacity( ) falls below the second capacity threshold, SOCF Set Threshold, the [SOCF] (State of Charge Final) flag is set, serving as a final discharge warning. If SOCF Set Threshold = –1, the flag is inoperative during discharge. Similarly, when RemainingCapacity( ) rises above SOCF Clear Threshold and the [SOCF] flag has already been set, the [SOCF] flag is cleared. All units are in mAh.

IMPEDANCE TRACK™ VARIABLES

The bq27541 has several data flash variables that permit the user to customize the Impedance Track™ algorithm for optimized performance. These variables are dependent upon the power characteristics of the application as well as the cell itself.

Load Mode

Load Mode is used to select either the constant-current or constant-power model for the Impedance Track™ algorithm as used in Load Select (see Load Select). When Load Mode is 0, the Constant Current Model is used (default). When 1, the Constant Power Model is used. The [LDMD] bit of CONTROL_STATUS reflects the status of Load Mode.

Load Select

Load Select defines the type of power or current model to be used to compute load-compensated capacity in the Impedance Track™ algorithm. If Load Mode = 0 (Constant Current), then the options presented in Table 9.

Table 9. Constant-Current Model Used when Load Mode = 0

LoadSelect Value Current Model Used

0 Average discharge current from previous cycle: There is an internal register that records the average discharge current through each

1(default) Present average discharge current: This is the average discharge current from the beginning of this discharge cycle until present time.

2 Average current: based off the AverageCurrent( ) 3 Current: based off of a low-pass-filtered version of AverageCurrent( ) (t = 14s) 4 Design capacity / 5: C Rate based off of Design Capacity /5 or a C / 5 rate in mA. 5 AtRate (mA): Use whatever current is in AtRate( ) 6 User_Rate-mA: Use the value in User_Rate( ). This gives a completely user-configurable method.

entire discharge cycle. The previous average is stored in this register.

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If Load Mode = 1 (Constant Power) then the following options are available:

Table 10. Constant-Power Model Used When Load Mode = 0

LoadSelect Value Power Model Used

0 (default) Average discharge power from previous cycle: There is an internal register that records the average discharge power through each

1 Present average discharge power: This is the average discharge power from the beginning of this discharge cycle until present time. 2 Average current × voltage: based off the AverageCurrent( ) and Voltage( ). 3 Current × voltage: based off of a low-pass-filtered version of AverageCurrent( ) (t = 14s) and Voltage( ) 4 Design energy / 5: C Rate based off of Design Energy /5 or a C / 5 rate in mA . 5 AtRate (10 mW): Use whatever value is in AtRate( ). 6 User_Rate-10mW: Use the value in. User_Rate( ) mW. This gives a completely user- configurable method.

entire discharge cycle. The previous average is stored in this register.

Reserve Cap-mAh

Reserve Cap-mAh determines how much actual remaining capacity exists after reaching 0 RemainingCapacity( ), before Terminate Voltage is reached. A no-load rate of compensation is applied to this

reserve capacity.

Reserve Cap-mWh

Reserve Cap-mWh determines how much actual remaining capacity exists after reaching 0 AvailableEnergy( ), before Terminate Voltage is reached. A no-load rate of compensation is applied to this reserve capacity.

Dsg Current Threshold

This register is used as a threshold by many functions in the bq27541 to determine if actual discharge current is flowing into or out of the cell. The default for this register should be sufficient for most applications. This threshold should be set low enough to be below any normal application load current but high enough to prevent noise or drift from affecting the measurement.

Chg Current Threshold

This register is used as a threshold by many functions in the bq27541 to determine if actual charge current is flowing into or out of the cell. The default for this register should be sufficient for most applications. This threshold should be set low enough to be below any normal charge current but high enough to prevent noise or drift from affecting the measurement.

Quit Current, Dsg Relax Time, Chg Relax Time, and Quit Relax Time

The Quit Current is used as part of the Impedance Track™ algorithm to determine when the bq27541 enters relaxation mode from a current flowing mode in either the charge direction or the discharge direction. The value of Quit Current is set to a default value that should be above the standby current of the system.

Either of the following criteria must be met to enter relaxation mode:

1. | AverageCurrent( ) | < | Quit Current | for Dsg Relax Time.

2. | AverageCurrent( ) | < | Quit Current | for Chg Relax Time.

After about 6 minutes in relaxation mode, the bq27541 attempts to take accurate OCV readings. An additional requirement of dV/dt < 4 µV/sec is required for the bq27541 to perform Qmax updates. These updates are used in the Impedance Track™ algorithms. It is critical that the battery voltage be relaxed during OCV readings to and that the current is not be higher than C/20 when attempting to go into relaxation mode.

Quit Relax Time specifies the minimum time required for AverageCurrent( ) to remain above the QuitCurrent threshold before exiting relaxation mode.

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Qmax

Qmax contains the maximum chemical capacity of the active cell profiles, and is determined by comparing states of charge before and after applying the load with the amount of charge passed. They also correspond to capacity at low rate of discharge, such as C/20 rate. For high accuracy, this value is periodically updated by the bq27541 during operation. Based on the battery cell capacity information, the initial value of chemical capacity should be entered in Qmax field. The Impedance Track™ algorithm will update this value and maintain it in the Pack profile.

Update Status

Bit 0 (0x01) of the Update Status register indicates that the bq27541 has learned new Qmax parameters and is accurate. The remaining bits are reserved. Bits 0 is a status bit set by the bq27541. Bit 0 should never be modified except when creating a golden image file as explained in the application note Preparing Optimized Default Flash Constants for specific Battery Types (SLUA334.pdf). Bit 0 is updated as needed by the bq27541.

Avg I Last Run

The bq27500 logs the current averaged from the beginning to the end of each discharge cycle. It stores this average current from the previous discharge cycle in this register. This register should never need to be modified. It is only updated by the bq27541 when required.

Avg P Last Run

The bq27541 logs the power averaged from the beginning to the end of each discharge cycle. It stores this average power from the previous discharge cycle in this register. To get a correct average power reading the bq27541 continuously multiplies instantaneous current times Voltage( ) to get power. It then logs this data to derive the average power. This register should never need to be modified. It is only updated by the bq27541 when required.

Delta Voltage

The bq27541 stores the maximum difference of Voltage( ) during short load spikes and normal load, so the Impedance Track™ algorithm can calculate remaining capacity for pulsed loads. It is not recommended to change this value.

Ra Tables and Ra Filtering Related Parameters

These tables contain encoded data and are automatically updated during device operation. In bq27541, during the update of Ra values a filtering process is performed to eliminate unexpected fluctuations in the updated Ra values. The DF parameters RaFilter, RaMaxDelta, MaxResfactor and MinResfactor control the Filtering process of Ra values. RaMaxDelta Limits the change in Ra values to an absolute magnitude. MinResFactor and MaxResFactor parameters are cumulative filters which limit the change in Ra values to a scale on a per discharge cycle basis. These values are Data Flash configurable. No further user changes should be made to Ra values except for reading/writing the values from a prelearned pack (part of the process for creating golden image files).

MaxScaleBackGrid

MaxScaleBackGrid Parameter Limits the resistance grid point after which back scaling will not be performed. This variable ensures that the resistance values in the lower resistance grid points remain accurate while the battery is at a higher DoD state.

Max DeltaV, Min DeltaV

Maximal / Minimal value allowed for delta V, which will be subtracted from simulated voltage during remaining capacity simulation.

Qmax Max Delta %

Maximal change of Qmax during one update, as percentage to Design Capacity. If the gauges attempts to change Qmax exceeds this limit, changed value will be capped to old value ± DesignCapacity*QmaxMaxDelta / 100

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DeltaV Max Delta

Maximal change of Delta V value. If attempted change of the value exceeds this limit, change value will be capped to old value ±DeltaV Max Delta

Lifetime Data Logging Parameters

The bq27541 implements Lifetime Data logging function to help development and diagnosis with fuel gauge. Note that IT_ENABLE needs to be enabled (Command 0x0021) for lifetime data logging functions to be active. bq275451 logs the following data in the Data Flash Registers:

Max Temp: Maximum Temperature Observed Min Temp: Minimum Temperature Observed Max Voltage: Maximum Battery Voltage Observed Min Voltage: Minimum Battery Voltage Observed Max Chg Current: Maximum Charge Current Observed

Max Dsg Current: Maximum Discharge Current Observed LT Flash Cnt The Lifetime Data parameters and recording are controlled by the following registers:

LT Temp Resolution

LT Voltage Resolution

LT Current Resolution

LT Update Time The Lifetime Data Logging can be started by setting the IT_ENABLE bit and setting the Update Time register to a

non-zero value. Once the Lifetime Data Logging function is enabled, the measured values are compared to what is already

stored in the Data Flash. If the measured value is higher than the maximum or lower than the minimum value stored in the Data Flash by more than the "Resolution" set for at least one parameter, the entire Data Flash Lifetime Registers are updated after at least LTUpdateTime.

LTUpdateTime sets the minimum update time between DF writes. When a new max/min is detected, a LT Update window of [update time] second is enabled and the DF writes occur at the end of this window. Any additional max/min value detected within this window will also be updated. The first new max/min value detected after this window will trigger the next LT Update window.

Internal to bq27541, there exists a RAM max/min table in addition to the DF max/min table. The RAM table is updated independent of the resolution parameters. The DF table is updated only if at least one of the RAM parameters exceeds the DF value by more than resolution associated with it. When DF is updated, the entire RAM table is written to DF. Consequently, it is possible to see a new max/min value for a certain parameter even if the value of this parameter never exceeds the maximum or minimum value stored in the Data Flash for this parameter value by the resolution amount.

The Life Time Data Logging of one or more parameters can be reset or restarted by writing new default (or starting) values to the corresponding Data Flash registers through sealed or unsealed access as described below. However, when using unsealed access, new values will only take effect after device reset

The logged data can be accessed as R/W in unsealed mode from Lifetime Data SubClass (SubClass ID=59) of Data Flash. Lifetime data may be accessed (R/W) when sealed using a process identical Manufacturer Info Block B and C. The DataFlashBlock command code is 4. Note only the first 32 bytes of lifetime data (not resolution parameters) can be R/W when sealed. See Manufacturers Info Block section for sealed access. The logging settings such as Temperature Resolution, Voltage Resolution, Current Resolution, and Update Time can be configured only in unsealed mode by writing to the Lifetime Resolution Subclass (SubClassID=66) of the Data Flash. (need to clean up parameters)

The Lifetime resolution registers contain the parameters which set the limits related to how much a data parameter must exceed the previously logged Max/Min value to be updated in the lifetime log. For example, V must exceed MaxV by more than Voltage Resolution to update MaxV in the Data Flash.

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DETAILED PIN DESCRIPTIONS

System Shutdown Enable (SE Pin)

By using SE pin, the fuel gauge can be made to power-off through an external circuit. This feature is useful to shutdown the fuel gauge in a deeply discharged battery to protect the battery.

The following bits are used to configure and control SE pin:

• Two Control Status bits signals the operation of the SE pin:

– SE – bit 15 – Status bit indicating the SE pin is active. Default is 0 – SHUTDOWN – bit 7 – Indicates the shutdown feature is enabled. Default is 0 (disabled)

• Two Control Subcommands enable or disable shutdown functionality:

– SET_SHUTDOWN (0x0013) – enables SE pin functionality (sets SHUTDOWN status bit) – CLEAR_SHUTDOWN (0x0014) – disables SE pin functionality (clears SHUTDOWN status bit)

• Two Data Flash bits in pack configuration register control the operation of the SE pin:

– SE_PU – low byte bit 3 – Pull-up enable for SE pin when SE pin state is 1 – SE_POL – low byte bit 2 – Polarity for SE pin when shutdown is enabled.

By default the SE pin is in normal state for all modes of operation. By sending SET_SHUTDOWN subcommand or setting [SE_EN] bit in Pack Configuration Register, the [SHUTDOWN] bit is set and enables shutdown feature. When this feature is enabled, the SE pin can be in normal state or shutdown state. The shutdown state can only be entered in HIBERNATE mode, all other modes will default SE pin to normal state. Table 10 shows the SE pin state for different states.

Note, the bq27541 SE pin will be high impedance at POR, the SE_POL does not affect the state of SE pin at POR. Also SE_PU configuration change will only take effect after POR.

Table 11. SE Pin State

SE_PU BIT SE_POL BIT SE PIN SE PIN STATE

0 0 High Impedance 0 0 1 0 High Impedance 1 0 1 0 1 1 0 1

IN NORMAL OPERATION TO SHUTDOWN THE GAUGE

The Pack Configuration Register

Some bq27541 pins are configured via the Pack Configuration data flash register, as indicated in Table 12. This register is programmed/read via the methods described in Section 1.2.1: Accessing the Data Flash. The register is located at subclass =64, offset = 0.

Table 12. Pack Configuration Bit Definition

bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0

High Byte RESCAP – – – GNDSEL IWAKE RSNS1 RSNS0

Low Byte – RESFACTSTEP SLEEP RMFCC SE_PU SE_POL SE_EN TEMPS

RESCAP = No-load rate of compensation is applied to the reserve capacity calculation. True when set. Default is 0. GNDSEL = The ADC ground select control. The Vss (Pin 6) is selected as ground reference when the bit is clear. Pin 7 is

IWAKE/RSNS1/RSNS0 = These bits configure the current wake function (see Table 13). Default is 0/0/1.

ResFactStep = Enables Ra step up/down to Max/Min Res Factor before disabling Ra updates. Default is 1

SLEEP = The fuel gauge can enter sleep, if operating conditions allow. True when set. Default is 1.

RMFCC = RM is updated with the value from FCC, on valid charge termination. True when set. Default is 1.

SE_PU = Pull-up enable for SE pin. True when set (push-pull). Default is 0.

SE_POL = Polarity bit for SE pin. SE is active low when clear (makes SE low when gauge is ready for shutdown).

selected when the bit is set. Default is 0.

Default is 1 (makes SE high when gauge is ready for shutdown).

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SE_EN = if set the SE pin is asserted when entering hibernate due to V and negated when waking from hibernate.

Default is 1

TEMPS = Selects external thermistor for Temperature( ) measurements. True when set. Default is 1.

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TEMPERATURE MEASUREMENT AND THE TS INPUT

The bq27541 measures battery temperature via the TS input, in order to supply battery temperature status information to the fuel gauging algorithm and charger-control sections of the gauge. Alternatively, the gauge can also measure internal temperature via its on-chip temperature sensor, but only if the [TEMPS] bit of Pack Configuration register is cleared.

Regardless of which sensor is used for measurement, a system processor can request the current battery temperature by calling the Temperature( ) function (see Section Standard Data Commands, for specific information).

The thermistor circuit requires the use of an external 10Kohm thermistor with negative temperature coefficients, such as Semetic 103AT-type thermistor that connects between the Vcc and TS pins. Additional circuit information for connecting this thermistor to the bq27541 is shown in Reference Schematic.

OVER-TEMPERATURE INDICATION

Over-Temperature: Charge

If during charging, Temperature( ) reaches the threshold of OT Chg for a period of OT Chg Time and AverageCurrent( ) > Chg Current Threshold, then the [OTC] bit of Flags( ) is set. When Temperature( ) falls to

OT Chg Recovery, the [OTC] of Flags( ) is reset. If OT Chg Time = 0, the feature is completely disabled.

Over-Temperature: Discharge

If during discharging, Temperature( ) reaches the threshold of OT Dsg for a period of OT Dsg Time, and AverageCurrent( ) ≤ -Dsg Current Threshold, then the [OTD] bit of Flags( ) is set. When Temperature( ) falls to

OT Dsg Recovery, the [OTD] bit of Flags( ) is reset. If OT Dsg Time = 0, the feature is completely disabled.

CHARGING AND CHARGE TERMINATION INDICATION

Detection Charge Termination

For proper bq27541 operation, the cell charging voltage must be specified by the user. The default value for this variable is in the data flash Charging Voltage.

The bq27541 detects charge termination when (1) during 2 consecutive periods of Current Taper Window, the AverageCurrent( ) is < Taper Current, (2) during the same periods, the accumulated change in capacity >

0.25mAh / Current Taper Window, and (3) Voltage( ) > Charging Voltage – Taper Voltage. When this occurs, the [CHG] bit of Flags( ) is cleared. Also, if the [RMFCC] bit of Pack Configuration is set, and RemainingCapacity( ) is set equal to FullChargeCapacity( ). When TCA_Set is set to -1, it disables the use of the charger alarm threshold. In that case, TerminateCharge is set when the taper condition is detected. When FC_Set is set to -1, it disables the use of the full charge detection threshold. In that case, FullCharge is not set until the taper condition is met.

Charge Inhibit and Suspend

The bq27541 can indicate when battery temperature has fallen below or risen above predefined thresholds (Charge Inhibit Temp Low and Charge Inhibit Temp High, respectively). In this mode, the [CHG_INH] of Flags( ) is made high to indicate this condition, and is returned to its low state, once battery temperature returns to the range [Charge Inhibit Temp Low + Temp Hys, Charge Inhibit Temp High – Temp Hys].

When the battery temperature has fallen below or risen above predefined thresholds Suspend Temperature Low or Suspend Temperature High, respectively. In this mode, the [XCHG] of Flags( ) is made high to indicate this condition, and is returned to its low state, once battery temperature returns to the range [Charge Inhibit Temp Low + Temp Hys, Charge Inhibit Temp High – Temp Hys].

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Exit From SLEEP

Pack Configuration [SLEEP] = 0

| AverageCurrent( ) | > Sleep Current

Current is Detected above I

WAKE

Exit From SLEEP

(Host has set Control Status

[HIBERNATE] = 1

CELL

< Hibernate Voltage

Fuelgauginganddata

updated every 1s

NORMAL

Fuel gauging and data

updated every 20 seconds

SLEEP

Disableallbq27541

subcircuits except GPIO.

HIBERNATE

Entry to SLEEP

Pack Configuration [SLEEP] = 1

AND

| AverageCurrent( ) |≤ Sleep Current

Wakeup From HIBERNATE

Communication Activity

AND

Comm address is NOT for bq27541

Exit From HIBERNATE

CELL

< POR threshold

POR

Exit From WAIT_HIBERNATE

Cell relaxed

AND

| AverageCurrent() | < Hibernate

Current

Cell relaxed

AND

CELL

< Hibernate Voltage

System Shutdown

Exit From WAIT_HIBERNATE

Host must set Control Status

[HIBERNATE] = 0

AND

CELL

> Hibernate Voltage

Exit From HIBERNATE

Communication Activity

bq27541 clears Control Status

[HIBERNATE] = 0

Recommend Host also set Control

Status [HIBERNATE] = 0

WAIT_HIBERNATE

Fuel gauging and data

updated every 20 seconds

In low power state of SLEEP

mode. Gas gauging and data

updated every 20 seconds

FULLSLEEP

System Sleep

FULLSLEEP Count Down

WAITFULLSLEEP

Entry to FULLSLEEP

Host must set Control Status

[FULLSLEEP] = 1

Exit From WAITFULLSLEEP

Any Communication Cmd

Entry to WAITFULLSLEEP

Full Sleep Wait Time > 0

Entry to FULLSLEEP

Count <1

FULLSLEEP

Exit From

Any

Communication

Cmd

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The charging should not start when the temperature is below the Charge Inhibit Temp Low or above the

Charge Inhibit Temp High. The charging can continue if the charging starts inside the window [Charge Inhibit Temp Low, Charge Inhibit Temp High] until the temperature is either below Suspend Temperature Low or above the Suspend Temperature High. Therefore, the window [Charge Inhibit Temp Low, Charge Inhibit Temp High] must be inside the window of [Suspend Temperature Low, Suspend Temperature High].

POWER MODES

The bq27500 has three power modes: NORMAL, SLEEP, and HIBERNATE. In NORMAL mode, the bq27541 is fully powered and can execute any allowable task. In SLEEP mode the fuel gauge exists in a reduced-power state, periodically taking measurements and performing calculations. Finally, in HIBERNATE mode, the fuel gauge is in a very low power state, but can be awaken by communication or certain I/O activity.

The relationship between these modes is shown in Figure 3. Details are described in the sections that follow.

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.

Figure 3. Power Mode Diagram

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Because the gauge consumes the most power in NORMAL mode, the Impedance Track™ algorithm minimizes the time the fuel gauge remains in this mode.

SLEEP MODE

SLEEP mode is entered automatically if the feature is enabled (Pack Configuration [SLEEP]) = 1) and AverageCurrent( ) is below the programmable level Sleep Current. Once entry into SLEEP mode has been qualified, but prior to entering it, the bq27541 performs an ADC autocalibration to minimize offset.

While in SLEEP mode, the fuel gauge can suspend serial communications as much as 4ms by holding the comm line(s) low. This delay is necessary to correctly process host communication, since the fuel gauge processor is mostly halted in SLEEP mode.

During the SLEEP mode, the bq27541 periodically takes data measurements and updates its data set. However, a majority of its time is spent in an idle condition.

The bq27541 exits SLEEP if any entry condition is broken, specifically when (1) AverageCurrent( ) rises above Sleep Current, or (2) a current in excess of I

WAKE

through R

SENSE

is detected.

FULLSLEEP MODE

FULLSLEEP mode is entered automatically if the feature is enabled by setting the Pack Configuration [FULLSLEEP] bit in the Control Status register when the bq27541 is in SLEEP mode. The gauge exits the

FULLSLEEP mode when there is any communication activity. Therefore, the execution of SET_FULLSLEEP sets [FULLSLEEP] bit, but EVSW might still display the bit clear. The FULLSLEEP mode can be verified by measuring the current consumption of the gauge. In this mode, the high frequency oscialliator is turned off. The power consumption is further reduced in this mode compared to the SLEEP mode.

FULLSLEEP mode can also be entered by setting the Full Sleep Wait Time to be a number larger than 0. The FULLSLEEP will be entered when the timer counts down to 0. This feature is disabled when the data flash is set as 0.

During FULLSLEEP mode, the bq27541 periodically takes data measurements and updates its data set. However, a majority of its time is spent in an idle condition.

The bq27541 exits SLEEP if any entry condition is broken, specifically when (1) AverageCurrent( ) rises above Sleep Current, or (2) a current in excess of IWAKE through RSENSE is detected.

While in FULLSLEEP mode, the fuel gauge can suspend serial communications as much as 4ms by holding the comm line(s) low. This delay is necessary correctly process host communication, since the fuel gauge processor is mostly halted in SLEEP mode.

HIBERNATE MODE

HIBERNATE mode should be used when the host system needs to enter a very low-power state, and minimal gauge power consumption is required. This mode is ideal when the host is set to its own HIBERNATE, SHUTDOWN, or OFF modes. The fuel gauge can enter HIBERNATE due to either low cell voltage or low load current.

• HIBERNATE due to the load current. If the fuel gauge enters the HIBERNATE mode due to the load current,

the [HIBERNATE] bit of the CONTROL_STATUS register must be set. The gauge waits to enter HIBERNATE mode until it has taken a valid OCV measurement and the magnitude of the average cell current has fallen below Hibernate Current.

• HIBERNATE due to the cell voltage. When the cell voltage drops below the Hibernate Voltage and a valid

OCV measurement has been taken, the fuel gauge enters HIBERNATE mode. The [HIBERNATE] bit of the CONTROL register has no impact for the fuel gauge to enter the HIBERNATE mode. If the [SHUTDOWN] bit of CONTROL _STATUS is also set, the SE pin will be released in the state shown by Table 11; thereby, allowing an optional external circuit to remove power from the gauge LDO.

The gauge will remain in HIBERNATE mode until any communication activity appears on the communication lines Upon exiting HIBERNATE mode, the [HIBERNATE] bit of CONTROL_STATUS is cleared. Since any communication activity wakes up the gauge from HIBERNATE mode, the host is required to set the [HIBERNATE] bit of the CONTROL_STATUS register to allow gauge to re-enter HIBERNATE mode.

Because the fuel gauge is dormant in HIBERNATE mode, the battery should not be charged or discharged in this

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mode, because any changes in battery charge status will not be measured. If necessary, the host equipment can draw a small current (generally infrequent and less than 1mA, for purposes of low-level monitoring and updating); however, the corresponding charge drawn from the battery will not be logged by the gauge. Once the gauge exits to NORMAL mode, the IT algorithm will take about 3 seconds to re-establish the correct battery capacity and measurements, regardless of the total charge drawn in HIBERNATE mode. During this period of re-establishment, the gauge reports previously calculated values prior to entering HIBERNATE mode. The host can identify exit from HIBERNATE mode by checking if Voltage() < Hibernate Voltage or [HIBERNATE] bit is cleared by the gauge.

If a charger is attached, the host should immediately take the fuel gauge out of HIBERNATE mode before beginning to charge the battery. Charging the battery in HIBERNATE mode will result in a notable gauging error that will take several hours to correct.

POWER CONTROL

Reset Functions

When the bq27541 detects a software reset ([RESET] bit of Control( ) initiated), it determines the type of reset and increments the corresponding counter. This information is accessible by issuing the command Control( ) function with the RESET_DATA subcommand.

Wake-Up Comparator

The wake up comparator is used to indicate a change in cell current while the bq27541 is in SLEEP modes. Pack Configuration uses bits [RSNS1-RSNS0] to set the sense resistor selection. Operation Configuration also uses the [IWAKE] bit to select one of two possible voltage threshold ranges for the given sense resistor selection. An internal interrupt is generated when the threshold is breached in either charge or discharge directions. Setting both [RSNS1] and [RSNS0] to 0 disables this feature.

Table 13. I

RSNS1 RSNS0 IWAKE Vth(SRP-SRN)

0 0 0 Disabled 0 0 1 Disabled 0 1 0 +1.0 mV or –1.0 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 vs the setting of the sense resistor is not important just the actual voltage

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

Threshold Settings

WAKE

(1)

Flash Updates

Data Flash can only be updated if Voltage( ) ≥ Flash Update OK Voltage. Flash programming current can cause an increase in LDO dropout. The value of Flash Update OK Voltage should be selected such that the bq27541 Vcc voltage does not fall below its minimum of 2.4V during Flash write operations.

AUTOCALIBRATION

The bq27541 provides an autocalibration feature that will measure the voltage offset error across SRP and SRN from time-to-time as operating conditions change. It subtracts the resulting offset error from normal sense resistor voltage, VSR, for maximum measurement accuracy.

Autocalibration of the ADC begins on entry to SLEEP mode, except if Temperature( ) is ≤ 5°C or Temperature( ) ≥ 45°C.

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The fuel gauge also performs a single offset when (1) the condition of AverageCurrent( ) ≤≤ 100mA and (2) {voltage change since last offset calibration ≥ 256mV} or {temperature change since last offset calibration is greater than 80°C for ≥ 60s}.

Capacity and current measurements will continue at the last measured rate during the offset calibration when these measurements cannot be performed. If the battery voltage drops more than 32mV during the offset calibration, the load current has likely increased considerably; hence, the offset calibration will be aborted.

COMMUNICATIONS

AUTHENTICATION

The bq27541 can act as a SHA-1/HMAC authentication slave by using its internal engine. Sending a 160-bit SHA-1 challenge message to the bq27541 will cause the gauge to return a 160-bit digest, based upon the challenge message and a hidden, 128-bit plain-text authentication key. If this digest matches an identical one generated by a host or dedicated authentication master, and when operating on the same challenge message and using the same plain text keys, the authentication process is successful.

KEY PROGRAMMING (DATA FLASH KEY)

By default, the bq27541 contains a default plain-text authentication key of 0x0123456789ABCDEFFEDCBA9876543210. This default key is intended for development purposes. It should

be changed to a secret key and the part immediately sealed, before putting a pack into operation. Once written, a new plain-text key cannot be read again from the fuel gauge while in SEALED mode.

Once the bq27541 is UNSEALED, the authentication key can be changed from its default value by writing to the Authentication( ) Extended Data Command locations. A 0x00 is written to BlockDataControl( ) to enable the authentication data commands. The bq27541 is now prepared to receive the 16-byte plain-text key, which must begin at command location 0x40 and ending at 0x4f. Once written, the key is accepted when a successful checksum for the key has been written to AuthenticateChecksum( ). The gauge can then be SEALED again.

KEY PROGRAMMING (THE SECURE MEMORY KEY)

As the name suggests, the bq27541 secure-memory authentication key is stored in the secure memory of the bq27541. If a secure-memory key has been established, only this key can be used for authentication challenges (the programmable data flash key is not available). The selected key can only be established/programmed by special arrangements with TI, using the TI’s Secure B-to-B Protocol. The secure-memory key can never be changed or read from the bq27541.

EXECUTING AN AUTHENTICATION QUERY

To execute an authentication query in UNSEALED mode, a host must first write 0x01 to the BlockDataControl( ) command, to enable the authentication data commands. If in SEALED mode, 0x00 must be written to DataFlashBlock( ), instead.

Next, the host writes a 20-byte authentication challenge to the Authenticate( ) address locations (0x40 through 0x53). After a valid checksum for the challenge is written to AuthenticateChecksum( ), the bq27541 uses the challenge to perform it own the SHA-1/HMAC computation, in conjunction with its programmed keys. The resulting digest is written to AuthenticateData( ), overwriting the pre-existing challenge. The host may then read this response and compare it against the result created by its own parallel computation.

HDQ SINGLE-PIN SERIAL INTERFACE

The HDQ interface is an asynchronous return-to-one protocol where a processor sends the command code to the bq27541. With HDQ, the least significant bit (LSB) of a data byte (command) or word (data) is transmitted first. Note that the DATA signal on pin 12 is open-drain and requires an external pull-up resistor. The 8-bit command code consists of two fields: the 7-bit HDQ command code (bits 0–6) and the 1-bit R/W field (MSB bit 7). The R/W field directs the bq27541 either to

• Store the next 8 or 16 bits of data to a specified register or

• Output 8 bits of data from the specified register The HDQ peripheral can transmit and receive data as either an HDQ master or slave.

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HDQ serial communication is normally initiated by the host processor sending a break command to the bq27541. A break is detected when the DATA pin is driven to a logic-low state for a time t should then be returned to its normal ready high logic state for a time t

. The bq27541 is now ready to receive

(BR)

or greater. The DATA pin

(B)

information from the host processor. The bq27541 is shipped in the I2C mode. TI provides tools to enable the HDQ peripheral.

HDQ HOST INTERRUPTION FEATURE

The default bq27541 behaves as an HDQ slave only device. If the HDQ interrupt function is enabled, the bq27541 is capable of mastering and also communicating to a HDQ device. There is no mechanism for negotiating who 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 bq27541 mastering an HDQ "message". This message is a fixed message that will be used to signal the interrupt condition. The message itself is 0x80 (slave write to register 0x00) with no data byte being sent as the command is not intended to convey any status of the interrupt condition. The HDQ interrupt function is not public and needs to be enabled by command.

When the SET_HDQINTEN subcommand is received, the bq27541 will detect any of the interrupt conditions and assert the interrupt at one second intervals until the CLEAR_HDQINTEN command is received or the count of HDQHostIntrTries has lapsed.

The number of tries for interrupting the host will be determined the data flash parameter named Configuration.Register.HDQHostIntrTries.

Low Battery Capacity

This feature will work identically to SOC1. It will use the same data flash entries as SOC1 and will trigger interrupts as long as SOC1 = 1.

Temperature

This feature will work identically to Charge Inhibit. It will used the same DF entries as Charge Inhibit and will trigger interrupts as long as CHG_INH = 1.

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S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0] A P S ADDR[6:0] 1 A DATA[7:0] N P

ADDR[6:0]

0 A

CMD[7:0]

A Sr

ADDR[6:0] 1 A DATA[7:0]

N P

S ADDR[6:0] 0 A CMD[7:0]

A Sr

ADDR[6:0]

1 A

DATA[7:0]

...

DATA[7:0]

N P

(d)

(c)

(a) (b)

HostGenerated FuelGaugeGenerated

S ADDR[6:0] 0 A CMD[7:0] A DATA[7:0] A P

S ADDR[6:0] 0 A

CMD[7:0]

N P

ADDR[6:0]

0 A

CMD[7:0]

DATA[7:0]

...

S ADDR[6:0] 0 A CMD[7:0]

A Sr

ADDR[6:0]

1 A

DATA[7:0]

...

DATA[7:0]

N P

Address

0x7F

DataFrom

addr0x7F

DataFrom

addr0x00

bq27541-V200

SLUSA11 –FEBRUARY 2010

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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 4. Supported I2C formats: (a) 1-byte write, (b) quick read, (c) 1 byte-read, and (d) incremental read

(S = Start, Sr = Repeated Start, A = Acknowledge, N = No Acknowledge, and P = Stop).

The "quick read" returns data at the address indicated by the address pointer. The address pointer, a register internal to the I2C communication engine, increments whenever data is acknowledged by the bq27542 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):

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.

I2C Time Out

The I2C engine will release both SDA and SCL if the I2C bus is held low for about 2 seconds. If the bq27541 was holding the lines, releasing them will free for the master to drive the lines.

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A AS 0ADDR[6:0] CMD[7:0]

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

A AS A0 PADDR[6:0] CMD[7:0] DATA [7:0] DATA [7:0] A 66ms

A AS 0ADDR[6:0] CMD[7:0]

1ADDR[6:0] A DATA [7:0] A DATA[7:0] A

DATA[7:0] A DATA [7:0] PN

Waitingtimebetweencontrolsubcommandandreadingresults

Waitingtimebetweencontinuousreadingresults

66ms

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I2C Command Waiting Time

To make sure the correct results of a command with the 400KHz I2C operation, a proper waiting time should be added between issuing command and reading results. For subcommands, the following diagram shows the waiting time required between issuing the control command the reading the status with the exception of the checksum command. A 100ms waiting time is required between the checksum command and reading result. For read-write standard commands, a minimum of 2 seconds is required to get the result updated. For read-only standard commands, there is no waiting time required, but the host should not issue all standard commands more than two times per second. Otherwise, the gauge could result in a reset issue due to the expiration of the watchdog timer.

The I2C clock stretch could happen in a typical application. A maximum 80ms clock stretch could be observed during the flash updates. There is up to 270ms clock stretch after the OCV command is issued.

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REFERENCE SCHEMATIC

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PACKAGE OPTION ADDENDUM

www.ti.com 19-Apr-2010

PACKAGING INFORMATION

Orderable Device Status

(1)

Package

Type

Package

Drawing

Pins Package

Qty

Eco Plan

BQ27541DRZR-V200 ACTIVE SON DRZ 12 3000 Green (RoHS &

(2)

Lead/Ball Finish MSL Peak Temp

CU NIPDAU Level-2-260C-1 YEAR

(3)

no Sb/Br)

BQ27541DRZT-V200 ACTIVE SON DRZ 12 250 Green (RoHS &

CU NIPDAU Level-2-260C-1 YEAR

no Sb/Br)

(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.

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.

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.

Addendum-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com 20-Jul-2010

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type

BQ27541DRZR-V200 SON DRZ 12 3000 330.0 12.4 2.8 4.3 1.2 4.0 12.0 Q2

BQ27541DRZT-V200 SON DRZ 12 250 330.0 12.4 2.8 4.3 1.2 4.0 12.0 Q2

Package Drawing

Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm)B0(mm)K0(mm)P1(mm)W(mm)

Pin1

Quadrant

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com 20-Jul-2010

*All dimensions are nominal

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

BQ27541DRZR-V200 SON DRZ 12 3000 340.5 333.0 20.6 BQ27541DRZT-V200 SON DRZ 12 250 340.5 333.0 20.6

Pack Materials-Page 2

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TEXAS INSTRUMENTS bq27541-V200 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

DESCRIPTION

TYPICAL APPLICATION

DEVICE INFORMATION

AVAILABLE OPTIONS

DISSIPATION RATINGS

RECOMMENDED OPERATING CONDITIONS

POWER-ON RESET

2.5 V LDO REGULATOR

INTERNAL TEMPERATURE SENSOR CHARACTERISTICS

HIGH FREQUENCY OSCILLATOR

LOW FREQUENCY OSCILLATOR

INTEGRATING ADC (COULOMB COUNTER) CHARACTERISTICS

ADC (TEMPERATURE AND CELL VOLTAGE) CHARACTERISTICS

DATA FLASH MEMORY CHARACTERISTICS

HDQ COMMUNICATION TIMING CHARACTERISTICS

I2C-COMPATIBLE INTERFACE TIMING CHARACTERISTICS

GENERAL DESCRIPTION

DATA COMMANDS

STANDARD DATA COMMANDS

Control( ): 0x00/0x01

AtRate( ): 0x02/0x03

AtRateTimeToEmpty( ): 0x04/0x05

Temperature( ): 0x06/0x07

Voltage( ): 0x08/0x09

Flags( ): 0x0a/0x0b

NominalAvailableCapacity( ): 0x0c/0x0d

FullAvailableCapacity( ): 0x0e/0x0f

RemainingCapacity( ): 0x10/0x11

FullChargeCapacity( ): 0x12/13

AverageCurrent( ): 0x14/0x15

TimeToEmpty( ): 0x16/0x17

TimeToFull( ): 0x18/0x19

StandbyCurrent( ): 0x1a/0x1b

StandbyTimeToEmpty( ): 0x1c/0x1d

MaxLoadCurrent( ): 0x1e/0x1f

MaxLoadTimeToEmpty( ): 0x20/0x21

AvailableEnergy( ): 0x22/0x23

AveragePower( ): 0x24/0x25

TimeToEmptyAtConstantPower( ): 0x26/0x27

Internal_Temp( ): 0x28/0x29

CycleCount( ): 0x2a/0x2b

StateOfCharge( ): 0x2c/0x2d

StateOfHealth( ): 0x2e/0x2f

PassedCharge( ): 0x34/0x35

DOD0( ): 0x36/0x37

EXTENDED DATA COMMANDS

PackConfig( ): 0x3a/0x3b

DesignCapacity( ): 0x3c/0x3d

DataFlashClass( ): 0x3e

DataFlashBlock( ): 0x3f

BlockData( ): 0x40…0x5f

BlockDataChecksum( ): 0x60

BlockDataControl( ): 0x61

DeviceNameLength( ): 0x62

DeviceName( ): 0x63…0x69

Reserved – 0x6a – 0x7f

SERIAL NUMBER

DATA FLASH INTERFACE

ACCESSING THE DATA FLASH

MANUFACTURER INFORMATION BLOCKS

ACCESS MODES

SEALING/UNSEALING DATA FLASH

DATA FLASH SUMMARY

FUNCTIONAL DESCRIPTION

FUEL GAUGING

IMPEDANCE TRACK™ VARIABLES

Load Mode

Load Select

Reserve Cap-mAh

Reserve Cap-mWh

Dsg Current Threshold

Chg Current Threshold

Quit Current, Dsg Relax Time, Chg Relax Time, and Quit Relax Time

Qmax