1 INTRODUCTION
1.1 FEATURES 1.2 APPLICATIONS
1.3 DESCRIPTION
HostSystem
Power
Management
Controller
I C
2
LDO
Battery
Low
Warning
bq27500
Battery
Good
Voltage
Sense
Temp
Sense
Current
Sense
PACK–
PACK+
T
Single-CellLi-Ion
BatteryPack
FETs CHG
DSG
Protection
IC
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
www.ti.com
SLUS880 – OCTOBER 2008
•Battery Fuel Gauge for 1-Series Li-Ion
•SmartphonesApplications
•PDAs•Resides on System Main Board
•Digital Still and Video Cameras– Works with Embedded or Removable
•Handheld TerminalsBattery Packs
•MP3 or Multimedia Players•Uses PACK+,PACK–, and TBattery Terminals•Microcontroller Peripheral Provides:– Accurate Battery Fuel Gauging– Internal Temperature Sensor for System
The Texas Instruments bq27500 system-side Li-IonTemperature Reporting
battery fuel gauge is a microcontroller peripheral that–Battery Low Interrupt Warning
provides fuel gauging for single-cell Li-Ion battery–Battery Insertion Indicator
packs. The device requires little system– 96 Bytes of Non-Volatile Scratch-Pad
microcontroller firmware development. The bq27500FLASH
resides on the system main board, and manages an•Battery Fuel Gauge Based on Patented
embedded battery (non-removable) or a removableImpedance Track™ Technology
battery pack.– Models the Battery Discharge Curve for
The bq27500 uses the patented Impedance Track™Accurate Time-to-Empty Predictions
algorithm for fuel gauging, and provides information– Automatically Adjusts for Battery Aging,
such as remaining battery capacity (mAh),Battery Self-Discharge, andTemperature/Rate Inefficiencies
state-of-charge (%), run-time to empty (min.), batteryvoltage (mV), and temperature ( °C).– Low-Value Sense Resistor (10 m Ωor Less)•I
2
C™ Interface for Connection to System
Battery fuel gauging with the bq27500 requires onlyMicrocontroller Port
PACK+ (P+), PACK– (P–), and Thermistor (T)•12-Pin 2,5-mm ×4-mm SON Package
connections to a removable battery pack orembedded battery.
TYPICAL APPLICATION
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of TexasInstruments semiconductor products and disclaimers thereto appears at the end of this document.Impedance Track is a trademark of Texas Instruments.I
2
C is a trademark of Philips Electronics.
PRODUCTION DATA information is current as of publication date.
Copyright © 2008, Texas Instruments IncorporatedProducts conform to specifications per the terms of the TexasInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.
Contents
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed inconductive foam during storage or handling to prevent electrostatic damage to the MOS gates.
1 INTRODUCTION .......................................... 14.2 DATA FLASH INTERFACE ......................... 161.1 FEATURES ........................................... 14.3 MANUFACTURER INFORMATION BLOCKS ...... 171.2 APPLICATIONS ...................................... 14.4 ACCESS MODES ................................... 171.3 DESCRIPTION ....................................... 14.5 SEALING/UNSEALING DATA FLASH .............. 172 DEVICE INFORMATION ................................. 34.6 DATA FLASH SUMMARY ........................... 182.1 AVAILABLE OPTIONS ............................... 35 FUNCTIONAL DESCRIPTION ........................ 202.2 DISSIPATION RATINGS ............................. 35.1 FUEL GAUGING .................................... 202.3 PIN DIAGRAMS ...................................... 35.2 IMPEDANCE TRACK™ VARIABLES ............... 203 ELECTRICAL SPECIFICATIONS ...................... 45.3 DETAILED DESCRIPTION OF DEDICATED PINS .233.1 ABSOLUTE MAXIMUM RATINGS ................... 45.4 TEMPERATURE MEASUREMENT ................. 243.2 RECOMMENDED OPERATING CONDITIONS ...... 45.5 OVERTEMPERATURE INDICATION ............... 245.6 CHARGING AND CHARGE-TERMINATION3.3 POWER-ON RESET .................................. 5
INDICATION ......................................... 253.4 INTERNAL TEMPERATURE SENSORCHARACTERISTICS ................................. 55.7 POWER MODES .................................... 253.5 HIGH-FREQUENCY OSCILLATOR .................. 55.8 POWER CONTROL ................................. 283.6 LOW-FREQUENCY OSCILLATOR .................. 55.9 AUTOCALIBRATION ................................ 283.7 INTEGRATING ADC (COULOMB COUNTER)
6 APPLICATION-SPECIFIC INFORMATION .......... 29CHARACTERISTICS ................................. 6
6.1 BATTERY PROFILE STORAGE AND SELECTION 293.8 ADC (TEMPERATURE AND CELL
6.2 APPLICATION-SPECIFIC FLOW AND CONTROL .29MEASUREMENT) CHARACTERISTICS ............. 6
7 COMMUNICATIONS3.9 DATA FLASH MEMORY CHARACTERISTICS ...... 6
............................................................. 303.10 I
2
C-COMPATIBLE INTERFACE COMMUNICATION
7.1 I
2
C INTERFACE ..................................... 30TIMING CHARACTERISTICS ........................ 7
7.2 I
2
C TIME OUT ....................................... 304 GENERAL DESCRIPTION .............................. 8
8 REFERENCE SCHEMATICS .......................... 314.1 DATA COMMANDS .................................. 9
8.1 SCHEMATIC ........................................ 31
2Contents Submit Documentation Feedback
2 DEVICE INFORMATION
2.1 AVAILABLE OPTIONS
2.2 DISSIPATION RATINGS
2.3 PIN DIAGRAMS
1
2
3
4
5
6
12
11
10
9
8
7
BAT_LOW
BI/TOUT
TS
BAT
VCC
VSS
BAT_GD
SCL
DAL
NC
SRN
SRP
bq27500
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
www.ti.com
SLUS880 – OCTOBER 2008
TAPE andFIRMWARE COMMUNICATIONPART NUMBER PACKAGE
(2)
T
A
REELVERSION
(1)
FORMAT
QUANTITY
bq27500DRZR-V120 300012-pin, 2,5-mm ×4-mm1.20 –40 °C to 85 °C I
2
CSONbq27500DRZT-V120 250
(1) Ordering the device with the latest firmware version is recommended. To check the fiirmware revision and Errata list see SLUZ015(2) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TIwebsite at www.ti.com .
T
A
≤40 °C DERATING FACTORPACKAGE R
θJAPOWER RATING T
A
> 40 °C
12-pin DRZ
(1)
482 mW 5.67 mW/ °C 176 °C/W
(1) This data is based on using a four-layer JEDEC high-K board with the exposed die pad connected to a Cu pad on the board. The boardpad is connected to the ground plane by a 2- ×2-via matrix.
DRZ PACKAGE
(TOP VIEW)
Figure 2-1.
Table 2-1. PIN FUNCTIONS
PIN
TYPE
(1)
DESCRIPTIONNAME NO.
BAT 4 I Cell-voltage measurement input. ADC input. Decouple with 0.1 µF capacitor.Battery-good indicator. Active- low by default, though polarity can be configured throughBAT_GD 12 O
the [BATG_POL] of Operation Configuration. Open-drain outputBattery-low output indicator. Active- high by default, though polarity can be configuredBAT_LOW 1 O
through the [BATL_POL] in Operation Configuration. Push-pull outputBattery-insertion detection input. Power pin for pack thermistor network. ThermistorBI/TOUT 2 I/O
multiplexer control pin. Open-drain I/O. Use with pullup resistor > 1 M Ω(1.8 M Ωtypical).NC 9 – No connection
Slave I
2
C serial communications clock input line for communication with system (master).SCL 11 I
Open-drain I/O. Use with 10-k Ωpullup resistor (typical).
(1) I = Digital input, O = Digital output, I/O = Digital input/output, IA = Analog input, P = Power connection
Submit Documentation Feedback DEVICE INFORMATION 3
3 ELECTRICAL SPECIFICATIONS
3.1 ABSOLUTE MAXIMUM RATINGS
3.2 RECOMMENDED OPERATING CONDITIONS
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
www.ti.com
Table 2-1. PIN FUNCTIONS (continued)
PIN
TYPE
(1)
DESCRIPTIONNAME NO.
Slave I
2
C serial communications data line for communication with system (master).SDA 10 I/O
Open-drain I/O. Use with 10-k Ωpullup resistor (typical).Analog input pin connected to the internal coulomb counter where SRN is nearest theSRN 8 IA
System V
SS
connection. Connect to 5-m Ωto 20-m Ωsense resistor.Analog input pin connected to the internal coulomb counter, where SRP is nearest theSRP 7 IA
PACK– connection. Connect to 5-m Ωto 20-m Ωsense resistor.TS 3 IA Pack thermistor voltage sense (require the use of NTC 103AT-type thermistor). ADC inputV
CC
5 P Processor power input. Decouple with 0.1- µF capacitor, minimum.Device ground. Electrically connected to the IC exposed thermal pad (do not use thermalV
SS
6 P
pad as primary ground. Connect thermal pad to Vss via a PCB trace).
over operating free-air temperature range (unless otherwise noted)
(1)
PARAMETER VALUE UNIT
V
CC
Supply voltage range –0.3 to 2.75 VV
IOD
Open-drain I/O pins (SDA, SDL, BAT_GD) –0.3 to 6 VV
BAT
BAT input pin –0.3 to 6V
I
Input voltage range to all other pins (BI/TOUT, TS, SRP, SRN, NC) –0.3 to V
CC
+ 0.3 VHuman-body model (HBM), BAT pin 1.5ESD kVHuman-body model (HBM), all other pins 2T
A
Operating free-air temperature range –40 to 85 °CT
F
Functional temperature range –40 to 100 °CT
stg
Storage temperature range –65 to 150 °C
(1) Stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device. These are stress ratingsonly, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operatingconditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
T
A
= -40 °C to 85 °C; Typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
CC
Supply voltage 2.4 2.5 2.6 VFuel gauge in NORMAL mode.I
CC
Normal operating-mode current 114 µAI
LOAD
>Sleep Current
Fuel gauge in SLEEP+ mode.I
SLP+
Sleep+ operating-mode current 58 µAI
LOAD
<Sleep Current
Fuel gauge in SLEEP mode.I
SLP
Low-power storage-mode current 19 µAI
LOAD
<Sleep Current
Fuel gauge in HIBERNATE mode.I
HIB
Hibernate operating-mode current 4 µAI
LOAD
<Hibernate Current
V
OL
Output voltage, low (SDA, BAT_LOW, I
OL
= 0.5 mA 0.4 VBI/TOUT)V
OH(PP)
Output voltage, high (BAT_LOW, BI/TOUT) I
OH
= –1 mA V
CC
– 0.5 VExternal pullup resistor connected toV
OH(OD)
Output voltage, high (SDA, SCL, BAT_GD) V
CC
– 0.5 VV
CC
ELECTRICAL SPECIFICATIONS4Submit Documentation Feedback
3.3 POWER-ON RESET
3.4 INTERNAL TEMPERATURE SENSOR CHARACTERISTICS
3.5 HIGH-FREQUENCY OSCILLATOR
3.6 LOW-FREQUENCY OSCILLATOR
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
www.ti.com
SLUS880 – OCTOBER 2008
RECOMMENDED OPERATING CONDITIONS (continued)
T
A
= -40 °C to 85 °C; Typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Input voltage (OD), low (SDA, SCL) –0.3 0.6V
IL
Input voltage, low (BI/TOUT) BAT INSERT CHECK MODE active –0.3 0.6
VInput voltage (OD), high (SDA, SCL) 1.2 6V
IH
V
CC
+Input voltage, high (BI/TOUT) BAT INSERT CHECK MODE active 1.2
0.3C
IN
Input capacitance (SDA, SCL, BI/TOUT) 35 pFV
A1
Input voltage range (TS) V
SS
– 0.125 2 VV
A2
Input voltage range (BAT) V
SS
– 0.125 5 VV
A3
Input voltage range (SRP, SRN) V
SS
– 0.125 0.125 VI
lkg
Input leakage current (I/O pins) 0.3 µAt
PUCD
Power-up communication delay 250 ms
T
A
= –40 °C to 85 °C, typical values at T
A
= 25 °C and V
BAT
= 3.6 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
IT+
Positive-going battery voltage input at V
CC
2.09 2.2 2.31 VV
HYS
Hysteresis voltage 45 115 185 mV
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
G
TEMP
Temperature sensor voltage gain –2 mV/ °C
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
f
OSC
Operating frequency 2.097 MHzT
A
= 0 °C to 60 °C –2% 0.38% 2%f
EIO
Frequency error
(1) (2)
T
A
= –20 °C to 70 °C –3% 0.38% 3%T
A
= –40 °C to 85 °C –4.5% 0.38% 4.5%t
SXO
Start-up time
(3)
2.5 5 ms
(1) The frequency error is measured from 2.097 MHz.(2) The frequency drift is included and measured from the trimmed frequency at V
CC
= 2.5 V, T
A
= 25 °C.(3) The start-up time is defined as the time it takes for the oscillator output frequency to be within ±3% of typical oscillator frequency.
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
f
LOSC
Operating frequency 32.768 kHz
Submit Documentation Feedback ELECTRICAL SPECIFICATIONS 5
3.7 INTEGRATING ADC (COULOMB COUNTER) CHARACTERISTICS
3.8 ADC (TEMPERATURE AND CELL MEASUREMENT) CHARACTERISTICS
3.9 DATA FLASH MEMORY CHARACTERISTICS
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
www.ti.com
LOW-FREQUENCY OSCILLATOR (continued)
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
T
A
= 0 °C to 60 °C –1.5% 0.25% 1.5%f
LEIO
Frequency error
(1) (2)
T
A
= –20 °C to 70 °C –2.5% 0.25% 2.5%T
A
= –40 °C to 85 °C –4% 0.25% 4%t
LSXO
Start-up time
(3)
500 µs
(1) The frequency drift is included and measured from the trimmed frequency at V
CC
= 2.5 V, T
A
= 25 °C.(2) The frequency error is measured from 32.768 kHz.(3) The start-up time is defined as the time it takes for the oscillator output frequency to be within ±3% of typical oscillator frequency.
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
SR
Input voltage range (V
SR
= V
(SRN)
– V
(SRP)
) –0.125 0.125 Vt
SR_CONV
Conversion time Single conversion 1 sResolution 14 15 bitsV
SR_OS
Input offset 10 µVINL Integral nonlinearity error ±0.007 ±0.034 % FSRZ
SR_IN
Effective input resistance
(1)
2.5 M ΩI
SR_LKG
Input leakage current
(1)
0.3 µA
(1) Specified by design. Not tested in production.
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
ADC_IN
Input voltage range –0.2 1 Vt
ADC_CONV
Conversion time 125 msResolution 14 15 bitsV
ADC_OS
Input offset 1 mVZ
ADC1
Effective input resistance (TS, NC)
(1)
8 M Ωbq27500 not measuring cell voltage 8 M ΩZ
ADC2
Effective input resistance (BAT)
(1)
bq27500 measuging cell voltage 100 k ΩI
ADC_LKG
Input leakage current
(1)
0.3 µA
(1) Specified by design. Not tested in production.
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
t
ON
Data retention
(1)
10 YearsFlash-programming write cycles
(1)
20,000 Cyclest
WORDPROG
Word programming time
(1)
2 msI
CCPROG
Flash-write supply current
(1)
5 10 mA
(1) Specified by design. Not production tested
ELECTRICAL SPECIFICATIONS6Submit Documentation Feedback
3.10 I
2
C-COMPATIBLE INTERFACE COMMUNICATION TIMING CHARACTERISTICS
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
www.ti.com
SLUS880 – OCTOBER 2008
T
A
= –40 °C to 85 °C, 2.4 V < V
CC
< 2.6 V; typical values at T
A
= 25 °C and V
CC
= 2.5 V (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
t
r
SCL/SDA rise time 300 nst
f
SCL/SDA fall time 300 nst
w(H)
SCL pulse duration (high) 600 nst
w(L)
SCL pulse duration (low) 1.3 µst
su(STA)
Setup for repeated start 600 nst
d(STA)
Start to first falling edge of SCL 600 nst
su(DAT)
Data setup time 100 nst
h(DAT)
Data hold time 0 nst
su(STOP)
Setup time for stop 600 nst
(BUF)
Bus free time between stop and start 1.3 µsf
SCL
Clock frequency 400 kHz
Figure 3-1. I
2
C-Compatible Interface Timing Diagrams
Submit Documentation Feedback ELECTRICAL SPECIFICATIONS 7
4 GENERAL DESCRIPTION
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
www.ti.com
The bq27500 accurately predicts the battery capacity and other operational characteristics of a singleLi-based rechargeable cell. It can be interrogated by a system processor to provide cell information, suchas 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 capabilitiesare provided by the additional Extended Commands set. Both sets of commands, indicated by the generalformat Command( ), are used to read and write information contained within the bq27500 control andstatus registers, as well as its data flash locations. Commands are sent from system to gauge using thebq27500 I
2
C serial communications engine, and can be executed during application development, packmanufacture, or end-equipment operation.
Cell information is stored in the bq27500 in non-volatile flash memory. Many of these data flash locationsare accessible during application development. They cannot be accessed directly during end-equipmentoperation. Access to these locations is achieved by either use of the bq27500 companion evaluationsoftware, through individual commands, or through a sequence of data-flash-access commands. Toaccess a desired data flash location, the correct data flash subclass and offset must be known.
The bq27500 provides 96 bytes of user-programmable data flash memory, partitioned into three 32-byteblocks: Manufacturer Info Block A,Manufacturer Info Block B, and Manufacturer Info Block C. Thisdata space is accessed through a data flash interface. For specifics on accessing the data flash, seeSection 4.3 , Manufacturer Information Blocks.
The key to the high-accuracy fuel gauging prediction of the bq27500 is Texas Instruments' proprietaryImpedance Track™ algorithm. This algorithm uses cell measurements, characteristics, and properties tocreate state-of-charge predictions that can achieve less than 1% error across a wide variety of operatingconditions and over the lifetime of the battery.
The bq27500 measures charge/discharge activity by monitoring the voltage across a small-value seriessense resistor (5 m Ωto 20 m Ω, typ.) located between the system Vss and the battery PACK– terminal.When a cell is attached to the bq27500, cell impedance is computed, based on cell current, cellopen-circuit voltage (OCV), and cell voltage under loading conditions.
The bq27500 external temperature sensing is optimized with the use of a high accuracy negativetemperature coefficient (NTC) thermistor with R
25
= 10.0K ±1% and B25/85 = 3435K ±1% (such asSemitec NTC 103AT). The bq27500 can also be configured to use its internal temperature sensor. Whenan external themistor is used, a 18.2k pull up resistor between BT/TOUT and TS pins is also required. Thebq27500 uses temperature to monitor the battery-pack environment, which is used for fuel gauging andcell protection functionality.
To minimize power consumption, the bq27500 has different power modes: NORMAL, SLEEP+, SLEEP,HIBERNATE, and BAT INSERT CHECK. The bq27500 passes automatically between these modes,depending upon the occurrence of specific events, though a system processor can initiate some of thesemodes directly. More details can be found in Section 5.7 ,Power Modes.
NOTE
FORMATTING CONVENTIONS IN THIS DOCUMENT:
Commands: italics with parentheses and no breaking spaces, e.g., RemainingCapacity( ).
Data flash: italics,bold, and breaking spaces, e.g., Design Capacity
Register bits and flags: brackets and italics, e.g., [TDA]
Data flash bits: brackets, italics and bold, e.g., [LED1]
Modes and states: ALL CAPITALS, e.g., UNSEALED mode.
GENERAL DESCRIPTION8Submit Documentation Feedback
4.1 DATA COMMANDS
4.1.1 STANDARD DATA COMMANDS
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
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SLUS880 – OCTOBER 2008
The bq27500 uses a series of 2-byte standard commands to enable system reading and writing of batteryinformation. Each standard command has an associated command-code pair, as indicated in Table 4-1 .Because each command consists of two bytes of data, two consecutive I
2
C transmissions must beexecuted both to initiate the command function, and to read or write the corresponding two bytes of data.Additional options for transferring data, such as spooling, are described in Section 7 ,I
2
C Interface.Standard commands are accessible in NORMAL operation.
Table 4-1. Standard Commands
NAME COMMAND CODE UNITS SEALED ACCESS
Control( ) CNTL 0x00 / 0x01 N/A R/WAtRate( ) AR 0x02 / 0x03 mA R/WAtRateTimeToEmpty( ) ARTTE 0x04 / 0x05 Minutes RTemperature( ) TEMP 0x06 / 0x07 0.1 K RVoltage( ) VOLT 0x08 / 0x09 mV RFlags( ) FLAGS 0x0a / 0x0b N/A RNominalAvailableCapacity( ) NAC 0x0c / 0x0d mAh RFullAvailableCapacity( ) FAC 0x0e / 0x0f mAh RRemainingCapacity( ) RM 0x10 / 0x11 mAh RFullChargeCapacity( ) FCC 0x12 / 0x13 mAh RAverageCurrent( ) AI 0x14 / 0x15 mA RTimeToEmpty( ) TTE 0x16 / 0x17 Minutes RTimeToFull( ) TTF 0x18 / 0x19 Minutes RStandbyCurrent( ) SI 0x1a / 0x1b mA RStandbyTimeToEmpty( ) STTE 0x1c / 0x1d Minutes RMaxLoadCurrent( ) MLI 0x1e / 0x1f mA RMaxLoadTimeToEmpty( ) MLTTE 0x20 / 0x21 Minutes RAvailableEnergy( ) AE 0x22 / 0x23 mWh RAveragePower( ) AP 0x24 / 0x25 mW RTimeToEmptyAtConstantPower( ) TTECP 0x26 / 0x27 Minutes RReserved RSVD 0x28 / 0x29 N/A RCycleCount( ) CC 0x2a / 0x2b Counts RStateOfCharge( ) SOC 0x2c / 0x2d % R
Submit Documentation Feedback GENERAL DESCRIPTION 9
4.1.1.1 Control( ): 0x00/0x01
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
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Issuing a Control( ) command requires a subsequent 2-byte subcommand. These additional bytes specifythe particular control function desired. The Control( ) command allows the system to control specificfeatures of the bq27500 during normal operation and additional features when the bq27500 is in differentaccess modes, as described in Table 4-2 .
Table 4-2. Control( ) Subcommands
CNTL SEALEDCNTL FUNCTION DESCRIPTIONDATA ACCESS
CONTROL_STATUS 0x0000 Yes Reports the status of DF checksum, hibernate, IT, etc.DEVICE_TYPE 0x0001 Yes Reports the device type (eg: "bq27500")FW_VERSION 0x0002 Yes Reports the firmware version on the device typeHW_VERSION 0x0003 Yes Reports the hardware version of the device typeEnables a data flash checksum to be generated andDF_CHECKSUM 0x0004 No
reports on a readRESET_DATA 0x0005 Yes Returns reset dataReserved 0x0006 No Not to be usedPREV_MACWRITE 0x0007 Yes Returns previous MAC command codeReports the chemical identifier of the Impedance Track™CHEM_ID 0x0008 Yes
configurationBoard_OFFSET 0x0009 No Forces the device to measure and store the board offsetCC_INT_OFFSET 0x000a No Forces the device to measure the internal CC offsetWRITE_CC_OFFSET 0x000b No Forces the device to store the internal CC offsetSET_HIBERNATE 0x0011 Yes Forces CONTROL_STATUS [HIBERNATE] to 1CLEAR_HIBERNATE 0x0012 Yes Forces CONTROL_STATUS [HIBERNATE] to 0SET_SLEEP+ 0x0013 Yes Forces CONTROL_STATUS [SNOOZE] to 1CLEAR_SLEEP+ 0x0014 Yes Forces CONTROL_STATUS [SNOOZE] to 0SEALED 0x0020 No Places the bq27500 in SEALED access modeIT_ENABLE 0x0021 No Enables the Impedance Track™ algorithmCAL_MODE 0x0040 No Places the bq27500 in calibration modeRESET 0x0041 No Forces a full reset of the bq27500
4.1.1.1.1 CONTROL_STATUS: 0x0000
Instructs the fuel gauge to return status information to control addresses 0x00/0x01. The status wordincludes the following information.
Table 4-3. CONTROL_STATUS Bit DefinitionsFlags( ) bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0High byte – FAS SS CSV CCA BCA – –Low byte – HIBERNATE SNOOZE SLEEP LDMD RUP_DIS VOK QEN
FAS = Status bit indicating the bq27500 is in FULL ACCESS SEALED state. Active when setSS = Status bit indicating the bq27500 is in SEALED state. Active when setCSV = Status bit indicating a valid data flash checksum has been generated. Active when setCCA = Status bit indicating the bq27500 coulomb counter calibration routine is active. Active when set. The first CCA routine will take placeapproximately 3 minutes and 45 seconds after the initializationBCA = Status bit indicating the bq27500 board calibration routine is active. Active when setHIBERNATE = Status bit indicating a request for entry into HIBERNATE from SLEEP mode. True when set. Default is 0.SNOOZE = Status bit indicating the bq27500 SLEEP+ mode is enabled. True when setSLEEP = Status bit indicating the bq27500 is in SLEEP mode. True when setLDMD = Status bit indicating the bq27500 Impedance Track™ algorithm is using constant-power mode. True when set. Default is 0.(constant-current mode).RUP_DIS = Status bit indicating the bq27500 Ra table updates are disabled. Updates disabled when setVOK = Status bit indicating the bq27500 voltages are okay for Qmax. True when setQEN = Status bit indicating the bq27500 Qmax updates enabled. True when set
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4.1.1.1.2 DEVICE_TYPE: 0x0001
Instructs the fuel gauge to return the device type to addresses 0x00/0x01.4.1.1.1.3 FW_VERSION: 0x0002
Instructs the fuel gauge to return the firmware version to addresses 0x00/0x01.4.1.1.1.4 HW_VERSION: 0x0003
Instructs the fuel gauge to return the hardware version to addresses 0x00/0x01.4.1.1.1.5 DF_CHECKSUM: 0x0004
Instructs the fuel gauge to compute the checksum of the data flash memory. Once the checksum hasbeen calculated and stored, CONTROL_STATUS [CVS] is set. The checksum value is written andreturned to addresses 0x00/0x01 (UNSEALED mode only). The checksum is not calculated in SEALEDmode; however, the checksum value can still be read.4.1.1.1.6 RESET_DATA: 0x0005
Instructs the fuel gauge to return the reset data to addresses 0x00/0x01.4.1.1.1.7 PREV_MACWRITE: 0x0007
Instructs the fuel gauge to return the previous command written to addresses 0x00/0x01.4.1.1.1.8 CHEM_ID: 0x0008
Instructs the fuel gauge to return the chemical identifier for the Impedance Track™ configuration toaddresses 0x00/0x01.4.1.1.1.9 Board_OFFSET: 0x0009
Instructs the fuel gauge to compute the coulomb counter offset with internal short and then without internalshort applied across the sensing resistor (SR) inputs. The difference between the two measurements isthe board offset. After a delay of approximately 32 seconds, this offset value is returned to addresses0x00/0x01 and written to data flash. The CONROL STATUS [BCA] is also set. The user must prevent anycharge or discharge current from flowing during the process. This function is only available when the fuelgauge is UNSEALED. When SEALED, this command only reads back the board-offset value stored indata flash.4.1.1.1.10 CC_INT_OFFSET: 0X000A
Control data of 0x000a instructs the fuel gauge to compute the coulomb counter offset with internal shortapplied across the SR inputs. The offset value is returned to addresses 0x00/0x01, after a delay ofapproximately 16 seconds. This function is only available when the fuel gauge is UNSEALED. WhenSEALED, this command only reads back the CC_INT_OFFSET value stored in data flash.4.1.1.1.11 WRITE_OFFSET: 0X000B
Control data of 0x000b causes the fuel gauge to write the coulomb counter offset to data flash.4.1.1.1.12 SET_HIBERNATE: 0x0011
Instructs the fuel gauge to force the CONTROL_STATUS [HIBERNATE] bit to 1. This allows the gauge toenter the HIBERNATE power mode after the transition to SLEEP power state is detected. The[HIBERNATE] bit is automatically cleared upon exiting from HIBERNATE mode.4.1.1.1.13 CLEAR_HIBERNATE: 0x0012
Instructs the fuel gauge to force the CONTROL_STATUS [HIBERNATE] bit to 0. This prevents the gaugefrom entering the HIBERNATE power mode after the transition to the SLEEP power state is detected. Itcan also be used to force the gauge out of HIBERNATE mode.
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4.1.1.2 AtRate( ): 0x02/0x03
4.1.1.3 AtRateTimeToEmpty( ): 0x04/0x05
4.1.1.4 Temperature( ): 0x06/0x07
4.1.1.5 Voltage( ): 0x08/0x09
4.1.1.6 Flags( ): 0x0a/0x0b
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4.1.1.1.14 ENABLE SLEEP+ MODE: 0x0013
Instructs the fuel gauge to set the CONTROL_STATUS [SNOOZE] bit bit to 1. This will enable theSLEEP+ mode. The gauge will enter SLEEP+ power mode after the transition conditions are meet.4.1.1.1.15 DISABLE SLEEP+ MODE: 0x0014
Instructs the fuel gauge to set the CONTROL_STATUS [SNOOZE] bit bit to 0. This will disable theSLEEP+ mode. The gauge will exit from the SLEEP+ power mode after the SNOOZ bit is cleared.4.1.1.1.16 SEALED: 0x0020
Instructs the fuel gauge to transition from the UNSEALED state to the SEALED state. The fuel gauge mustalways be set to the SEALED state for use in end equipment.4.1.1.1.17 IT_ENABLE: 0x0021
This command forces the fuel gauge to begin the Impedance Track™ algorithm, sets the activeUpdateStatus nlocation to 0x01 and causes the [VOK] and [QEN] flags to be set in theCONTROL_STATUS register. [VOK] is cleared if the voltages are not suitable for a Qmax update. Onceset, [QEN] cannot be cleared. This command is only available when the fuel gauge is UNSEALED.4.1.1.1.18 CAL_MODE: 0x0040
This command instructs the fuel gauge to enter calibration mode. This command is only available whenthe fuel gauge is UNSEALED.4.1.1.1.19 RESET: 0x0041
This command instructs the fuel gauge to perform a full reset. This command is only available when thefuel gauge is UNSEALED.
The AtRate( ) read-/write function is the first half of a two-function command set used to set the AtRatevalue 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. TheAtRateTimeToEmpty( ) function returns the predicted operating time at the AtRate value of discharge. Thedefault value for AtRate( ) is zero and forces AtRateTimeToEmpty( ) to return 65,535. Both the AtRate( )and AtRateTimeToEmpty( ) commands must only be used in NORMAL mode.
This read-only function returns an unsigned integer value of the predicted remaining operating time if thebattery is discharged at the AtRate( ) value in minutes with a range of 0 to 65,534. A value of 65,535indicates AtRate( ) = 0. The fuel gauge updates AtRateTimeToEmpty( ) within 1 s after the system sets theAtRate( ) value. The fuel gauge automatically updates AtRateTimeToEmpty( ) based on the AtRate( )value every 1 s. Both the AtRate( ) and AtRateTimeToEmpty( ) commands must only be used in NORMALmode.
This read-only function returns an unsigned integer value of the temperature in units of 0.1 K measured bythe fuel gauge.
This read-only function returns an unsigned integer value of the measured cell-pack voltage in mV with arange of 0 to 5,000 mV.
This read-only function returns the contents of the fuel-gauge status register, depicting the currentoperating status.
GENERAL DESCRIPTION12 Submit Documentation Feedback
4.1.1.7 NominalAvailableCapacity( ): 0x0c/0x0d
4.1.1.8 FullAvailableCapacity( ): 0x0e/0x0f
4.1.1.9 RemainingCapacity( ): 0x10/0x11
4.1.1.10 FullChargeCapacity( ): 0x12/13
4.1.1.11 AverageCurrent( ): 0x14/0x15
4.1.1.12 TimeToEmpty( ): 0x16/0x17
4.1.1.13 TimeToFull( ): 0x18/0x19
4.1.1.14 StandbyCurrent( ): 0x1a/0x1b
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Table 4-4. Flags Bit Definitionsbit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0High byte OTC OTD – – CHG_INH XCHG FC CHGLow byte – – OCV_GD WAIT_ID BAT_DET SOC1 SOCF DSG
OTC = Overtemperature in charge condition is detected. True when set.OTD = Overtemperature in discharge condition is detected. True when set.CHG_INH = Charge inhibit: unable to begin charging (temperature outside the range [Charge Inhibit Temp Low, Charge Inhibit TempHigh]). True when set.XCHG = Charge suspend alert (temperature outside the range [Suspend Temp Low, Suspend Temp High]). True when set.FC = Fully charged. Set when charge termination condition is met. True when set.CHG = (Fast) charging allowed. True when set.OCV_GD = Good OCV measurement taken. True when set.WAIT_ID = Waiting to identify inserted battery. True when set.BAT_DET = Battery detected. True when set.SOC1 = State-of-charge threshold 1 ( SOC1 Set Threshold) reached. True when set.SOCF = State-of-charge threshold final ( SOCF Set Threshold) reached. True when set.DSG = Discharging detected. True when set.
This read-only command pair returns the uncompensated (less than C/20 load) battery capacityremaining. Units are mAh.
This read-only command pair returns the uncompensated (less than C/20 load) capacity of the batterywhen fully charged. Units are mAh. FullAvailableCapacity( ) is updated at regular intervals, as specified bythe IT algorithm.
This read-only command pair returns the compensated battery capacity remaining. Units are mAh.
This read-only command pair returns the compensated capacity of the battery when fully charged. Unitsare mAh. FullChargeCapacity( ) is updated at regular intervals, as specified by the IT algorithm.
This read-only command pair returns a signed integer value that is the average current flow through thesense resistor. It is updated every 1 second. Units are mA.
This read-only function returns an unsigned integer value of the predicted remaining battery life at thepresent rate of discharge, in minutes. A value of 65,535 indicates battery is not being discharged.
This read-only function returns an unsigned integer value of predicted remaining time until the batteryreaches full charge, in minutes, based upon AverageCurrent( ). The computation accounts for the tapercurrent time extension from the linear TTF computation based on a fixed AverageCurrent( ) rate of chargeaccumulation. A value of 65,535 indicates the battery is not being charged.
This read-only function returns a signed integer value of the measured standby current through the senseresistor. The StandbyCurrent( ) is an adaptive measurement. Initially it reports the standby currentprogrammed in Initial Standby, and after spending several seconds in standby, reports the measuredstandby current.
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4.1.1.15 StandbyTimeToEmpty( ): 0x1c/0x1d
4.1.1.16 MaxLoadCurrent( ): 0x1e/0x1f
4.1.1.17 MaxLoadTimeToEmpty( ): 0x20/0x21
4.1.1.18 AvailableEnergy( ): 0x22/0x23
4.1.1.19 AveragePower( ): 0x24/0x25
4.1.1.20 TimeToEmptyAtConstantPower( ): 0x26/0x27
4.1.1.21 CycleCount( ): 0x2a/0x2b
4.1.1.22 StateOfCharge( ): 0x2c/0x2d
4.1.2 EXTENDED DATA COMMANDS
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The register value is updated every 1 second when the measured current is above the Deadband inTable 4-7 and is less than or equal to 2 ×Initial Standby. The first and last values that meet this criteriaare not averaged in, because 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 standbycurrent and approximate 7% of the current measured average current.
This read-only function returns an unsigned integer value of the predicted remaining battery life at thestandby rate of discharge, in minutes. The computation uses Nominal Available Capacity (NAC), theuncompensated remaining capacity, for this computation. A value of 65,535 indicates battery is not beingdischarged.
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 loadcurrent programmed in Initial Max Load Current. If the measured current is ever greater than Initial MaxLoad Current, then MaxLoadCurrent( ) updates to the new current. MaxLoadCurrent( ) is reduced to theaverage of the previous value and Initial Max Load Current whenever the battery is charged to full aftera previous discharge to an SOC less than 50%. This prevents the reported value from maintaining anunusually high value.
This read-only function returns an unsigned integer value of the predicted remaining battery life at themaximum load current discharge rate, in minutes. A value of 65,535 indicates that the battery is not beingdischarged.
This read-only function returns an unsigned integer value of the predicted charge or energy remaining inthe battery. The value is reported in units of mWh.
This read-only function returns an signed integer value of the average power during battery charging anddischarging. A value of 0 indicates that the battery is not being discharged. The value is reported in unitsof mW.
This read-only function returns an unsigned integer value of the predicted remaining operating time if thebattery is discharged at the AveragePower( ) value in minutes. A value of 65,535 indicatesAveragePower( ) = 0. The fuel gauge automatically updates TimeToEmptyatContantPower( ) based on theAveragePower( ) value every 1 s.
This read-only function returns an unsigned integer value of the number of cycles the battery hasexperienced with a range of 0 to 65,535. One cycle occurs when accumulated discharge ≥CC Threshold.
This read-only function returns an unsigned integer value of the predicted remaining battery capacityexpressed as a percentage of FullChargeCapacity( ), with a range of 0 to 100%.
Extended commands offer additional functionality beyond the standard set of commands. They are used inthe same manner; however, unlike standard commands, extended commands are not limited to 2-bytewords. The number of commands bytes for a given extended command ranges in size from single tomultiple bytes, as specified in Table 4-5 .
GENERAL DESCRIPTION14 Submit Documentation Feedback
4.1.2.1 DesignCapacity( ): 0x3c/0x3d
4.1.2.2 DataFlashClass( ): 0x3e
4.1.2.3 DataFlashBlock( ): 0x3f
4.1.2.4 BlockData( ): 0x40 …0x5f
4.1.2.5 BlockDataChecksum( ): 0x60
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Table 4-5. Extended Data Commands
COMMAND SEALED UNSEALEDNAME UNITSCODE ACCESS
(1) (2)
ACCESS
(1) (2)
Reserved RSVD 0x34...0x3b N/A R RDesignCapacity( ) DCAP 0x3c / 0x3d mAh R RDataFlashClass( )
(2)
DFCLS 0x3e N/A N/A R/WDataFlashBlock( )
(2)
DFBLK 0x3f N/A R/W R/WBlockData( ) DFD 0x40 …0x5f N/A R R/WBlockDataCheckSum( ) DFDCKS 0x60 N/A R/W R/WBlockDataControl( ) DFDCNTL 0x61 N/A N/A R/WDeviceNameLength( ) DNAMELEN 0x62 N/A R RDeviceName( ) DNAME 0x63...0x69 N/A R RApplicationStatus( ) APPSTAT 0x6a N/A R RReserved RSVD 0x6b...0x7f N/A R R
(1) SEALED and UNSEALED states are entered via commands to CNTL 0x00/0x01.(2) In sealed mode, data flash CANNOT be accessed through commands 0x3e and 0x3f.
SEALED and UNSEALED Access: This command returns the theoretical or nominal capacity of a newpack. The value is stored in Design Capacity and is expressed in mAh. This is intended to be thetheoretical or nominal capacity of a new pack, but has no bearing on the operation of the fuel gaugefunctionality.
UNSEALED Access: This command sets the data flash class to be accessed. The class to be accessedmust be entered in hexadecimal.
SEALED Access: This command is not available in SEALED mode.
UNSEALED Access: This command sets the data flash block to be accessed. When 0x00 is written toBlockDataControl( ),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, a 0x01 specifiesaccess to the second 32-byte block, and so on.
SEALED Access: This command directs which data flash block is accessed by the BlockData( ) command.Writing a 0x00 to DataFlashBlock( ) specifies that the BlockData( ) command transfers authentication data.Issuing a 0x01, 0x02, or 0x03 instructs the BlockData( ) command to transfer Manufacturer Info Block A,B, or C, respectively.
This command range is the 32-byte data block used to access Manufacturer Info Block A, B, or C.
UNSEALED access is read/write. SEALED access is read only.
UNSEALED Access: This byte contains the checksum on the 32 bytes of block data read or written todata flash. The least-significant byte of the sum of the data bytes written must be complemented([255 – x], for xthe least-significant byte) before being written to 0x60.
SEALED Access: This byte contains the checksum for the 32 bytes of block data written to ManufacturerInfo Block A, B, or C. The least-significant byte of the sum of the data bytes written must becomplemented ([255 – x], for xthe least-significant byte) before being written to 0x60.
Submit Documentation Feedback GENERAL DESCRIPTION 15
4.1.2.6 BlockDataControl( ): 0x61
4.1.2.7 DeviceNameLength( ): 0x62
4.1.2.8 DeviceName( ): 0x63 …0x69
4.1.2.9 ApplicationStatus( ): 0x6a
4.1.2.10 Reserved — 0x6b–0x7f
4.2 DATA FLASH INTERFACE
4.2.1 ACCESSING THE DATA FLASH
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UNSEALED Access: This command is used to control data flash access mode. Writing 0x00 to thiscommand enables BlockData( ) to access general data flash. Writing a 0x01 to this command enablesSEALED mode operation of DataFlashBlock( ).
SEALED Access: This command is not available in SEALED mode.
UNSEALED and SEALED Access: This byte contains the length of the Device Name.
UNSEALED and SEALED Access: This block contains the device name that is programmed in DeviceName.
This byte function allows the system to read the bq27500 Application Status data flash location. SeeTable 6-1 for specific bit definitions.
The bq27500 data flash is a non-volatile memory that contains bq27500 initialization, default, cell status,calibration, configuration, and user information. The data flash can be accessed in several different ways,depending on what mode the bq27500 is operating in and what data is being accessed.
Commonly accessed data flash memory locations, frequently read by a system, are convenientlyaccessed through specific instructions, already described in Section 4.1 ,DATA COMMANDS. Thesecommands are available when the bq27500 is either in UNSEALED or SEALED modes.
Most data flash locations, however, are only accessible in UNSEALED mode by use of the bq27500evaluation software or by data flash block transfers. These locations must be optimized and/or fixed duringthe development and manufacture processes. They become part of a golden image file and can then bewritten to multiple battery packs. Once established, the values generally remain unchanged duringend-equipment operation.
To access data flash locations individually, the block containing the desired data flash location(s) must betransferred to the command register locations, where the information can be read to the system orchanged directly. This is accomplished by sending the setup command BlockDataControl( ) (0x61) withdata 0x00. Up to 32 bytes of data can be read directly from the BlockData( ) (0x40 …0x5f), externallyaltered, 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( ) commandspace. Finally, the data residing in the command space is transferred to data flash, once the correctchecksum for the whole block is written to BlockDataChecksum( ) (0x60).
Occasionally, a data flash CLASS is larger than the 32-byte block size. In this case, the DataFlashBlock( )command is used to designate in which 32-byte block the desired information resides. The correctcommand address is then given by 0x40 + offset modulo 32. For example, to access Terminate Voltagein the Fuel 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 datalength exceeds the maximum block size, then the data is ignored.
GENERAL DESCRIPTION16 Submit Documentation Feedback
4.3 MANUFACTURER INFORMATION BLOCKS
4.4 ACCESS MODES
4.5 SEALING/UNSEALING DATA FLASH
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None of the data written to memory are bounded by the bq27500– the values are not rejected by the fuelgauge. Writing an incorrect value may result in hardware failure due to firmware program interpretation ofthe invalid data. The written data is persistent, so a power-on reset does resolve the fault.
The bq27500 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 memorylocations 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 themanufacturer information blocks is identical to accessing general data flash locations. First, aDataFlashClass( ) command is used to set the subclass, then a DataFlashBlock( ) command sets theoffset for the first data flash address within the subclass. The BlockData( ) command codes contain thereferenced data flash data. When writing the data flash, a checksum is expected to be received byBlockDataChecksum( ). Only when the checksum is received and verified is the data actually written todata 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 neededto address Manufacturer Info Block B, but is used instead for grouping purposes when viewing dataflash info in the bq27500 evaluation software.
When in SEALED mode or when 0x01 BlockDataControl( ) does not contain 0x00, data flash is no longeravailable in the manner used in UNSEALED mode. Rather than issuing subclass information, adesignated manufacturer information block is selected with the DataFlashBlock( ) command. Issuing a0x01, 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 returnedto data flash. Note: Manufacturer Info Block A is read-only when in SEALED mode.
The bq27500 provides three security modes (FULL ACCESS, UNSEALED, and SEALED) that controldata flash access permissions, according to Table 4-6 .Data Flash refers to those data flash locations,specified in Table 4-7 , that are accessible to the user. Manufacture Information refers to the three 32-byteblocks.
Table 4-6. Data Flash Access
Security Mode Data Flash Manufacture Information
FULL ACCESS R/W RUNSEALED R/W RSEALED None R
Although FULL ACCESS and UNSEALED modes appear identical, only FULL ACCESS allows thebq27500 to write access-mode transition keys.
The bq27500 implements a key-access scheme to transition between SEALED, UNSEALED, andFULL-ACCESS modes. Each transition requires that a unique set of two keys be sent to the bq27500 viathe Control( ) control command. The keys must be sent consecutively, with no other data being written tothe Control( ) register between them. Note that to avoid conflict, the keys must be different from the codespresented in the CNTL DATA column of Table 4-2 Control( ) subcommands.
When in SEALED mode, the CONTROL_STATUS [SS] bit is set, but when the unseal keys are correctlyreceived by the bq27500, the [SS] bit is cleared. When the full-access keys are correctly received, thenthe CONTROL_STATUS [FAS] bit is cleared.
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4.6 DATA FLASH SUMMARY
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Both the sets of keys for each level are 2 bytes each in length and are stored in data flash. The unsealkey (stored at Unseal Key 0 and Unseal Key 1) and the full-access key (stored at Full-Access Key 0and Full-Access Key 1) can only be updated when in FULL-ACCESS mode. The order of the keys is Key1followed by Key 0. The order of the bytes entered through the Control( ) command is the reverse ofwhat is read from the part. For example, if the Key 1 and Key 0 of the Unseal Key returns 0x1234 and0x5678, then the Control( ) should supply 0x3412 and 0x7856 to unseal the part.
Table 4-7 summarizes the data flash locations available to the user, including their default, minimum, andmaximum values.
Table 4-7. Data Flash SummarySubclass Data Min Max DefaultClass Subclass Offset Name UnitsID Type Value Value Value
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
Charge InhibitConfiguration 32 0 Charge Inhibit Temp Low I2 –400 1200 0 0.1 °CConfig
Charge InhibitConfiguration 32 2 Charge Inhibit Temp High I2 –400 1200 450 0.1 °CConfig
Charge InhibitConfiguration 32 4 Temp Hys I2 0 100 50 0.1 °CConfig
Configuration 34 Charge 2 Charging Voltage I2 0 20,000 4200 mV
Configuration 34 Charge 4 Delta Temperature I2 0 500 50 0.1 °C
Configuration 34 Charge 6 Suspend Temperature Low I2 –400 1200 -50 0.1 °C
Configuration 34 Charge 8 Suspend Temperature High I2 –400 1200 550 0.1 °C
ChargeConfiguration 36 2 Taper Current I2 0 1000 100 mATermination
ChargeConfiguration 36 4 Minimum Taper Charge I2 0 1000 25 0.01mAhTermination
ChargeConfiguration 36 6 Taper Voltage I2 0 1000 100 mVTermination
ChargeConfiguration 36 8 Current Taper Window U1 0 60 40 sTermination
Configuration 48 Data 4 Initial Standby Current I1 –128 0 –10 mA
Configuration 48 Data 5 Initial Max Load Current I2 –32,767 0 –500 mA
Configuration 48 Data 7 CC Threshold I2 100 32,767 900 mAh
Configuration 48 Data 10 Design Capacity I2 0 65,535 1000 mAh
Configuration 48 Data 12 Device Name S8 x x bq27500 –
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
ManufacturerSystem Data 57 0–31 Block A [0–31] H1 0x00 0xff 0x00 –Info
ManufacturerSystem Data 57 32–63 Block B [0–31] H1 0x00 0xff 0x00 –Info
ManufacturerSystem Data 57 64–95 Block C [0–31] H1 0x00 0xff 0x00 –Info
Configuration 64 Registers 0 Operation Configuration H2 0x0000 0xffff 0x0979 –
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Table 4-7. Data Flash Summary (continued)Subclass Data Min Max DefaultClass Subclass Offset Name UnitsID Type Value Value Value
Configuration 68 Power 0 Flash Update OK Voltage I2 0 4200 2800 mV
Configuration 68 Power 7 Sleep Current I2 0 100 10 mA
Configuration 68 Power 16 Hibernate Current U2 0 700 8 mA
Configuration 68 Power 18 Hibernate Voltage U2 2400 3000 2550 mV
Fuel Gauging 80 IT Cfg 0 Load Select U1 0 255 1 –
Fuel Gauging 80 IT Cfg 1 Load Mode U1 0 255 0 –
Fuel Gauging 80 IT Cfg 48 Terminate Voltage I2 –32,768 32,767 3000 mV
Fuel Gauging 80 IT Cfg 53 User Rate-mA I2 0 9000 0 mA
Fuel Gauging 80 IT Cfg 55 User Rate-mW I2 0 14,000 0 mW
Fuel Gauging 80 IT Cfg 57 Reserve Cap-mAh I2 0 9000 0 mAh
Fuel Gauging 80 IT Cfg 59 Reserve Cap-mWh I2 0 14,000 0 mWh
CurrentFuel Gauging 81 0 Dsg Current Threshold I2 0 2000 60 mAThresholds
CurrentFuel Gauging 81 2 Chg Current Threshold I2 0 2000 75 mAThresholds
CurrentFuel Gauging 81 4 Quit Current I2 0 1000 40 mAThresholds
CurrentFuel Gauging 81 6 Dsg Relax Time U2 0 8191 60 sThresholds
CurrentFuel Gauging 81 8 Chg Relax Time U1 0 255 60 sThresholds
CurrentFuel Gauging 81 9 Quit Relax Time U1 0 63 1 sThresholds
Fuel Gauging 82 State 0 IT Enable H1 0x00 0xff 0x00 –
Fuel Gauging 82 State 1 Application Status H1 0x00 0xff 0x00 –
Fuel Gauging 82 State 2 Qmax 0 I2 0 32,767 1000 mAh
Fuel Gauging 82 State 4 Cycle Count 0 U2 0 65,535 0 –
Fuel Gauging 82 State 6 Update Status 0 H1 0x00 0x03 0x00 –
Fuel Gauging 82 State 7 Qmax 1 I2 0 32767 1000 mAh
Fuel Gauging 82 State 9 Cycle Count 1 U2 0 65,535 0 –
Fuel Gauging 82 State 11 Update Status 1 H1 0x00 0x03 0x00 –
Fuel Gauging 82 State 16 Avg I Last Run I2 –32,768 32,767 –299 mA
Fuel Gauging 82 State 18 Avg P Last Run I2 –32,768 32,767 –1131 mAh
Default Ra
87 Def0 Ra 0–18Tables
See Note
(1)Default Ra
88 Def1 Ra 0–18Tables
Ra Tables 91 Pack0 Ra 0–18
Ra Tables 92 Pack1 Ra 0–18
See Note
(1)Ra Tables 93 Pack0 Rax 0–18
Ra Tables 94 Pack1 Rax 0–18
Calibration 104 Data 0 CC Gain F4
(2)
0.1 47 10
(3)
mΩ
Calibration 104 Data 4 CC Delta F4
(2)
4.7 188 10
(3)
mΩ
Calibration 104 Data 8 CC Offset I2 –2.4 2.4 -0.123
(3)
mV
Calibration 104 Data 10 Board Offset I1 –128 127 0 mV
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 0.1 °C
(1) Encoded battery profile information created by bqEASY software.(2) Not IEEE floating point(3) Display as the value EVSW displayed. Data Flash value is different.
Submit Documentation Feedback GENERAL DESCRIPTION 19
5 FUNCTIONAL DESCRIPTION
5.1 FUEL GAUGING
5.2 IMPEDANCE TRACK™ VARIABLES
5.2.1 Load Mode
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System-Side Impedance Track™ Fuel Gauge
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Table 4-7. Data Flash Summary (continued)Subclass Data Min Max DefaultClass Subclass Offset Name UnitsID Type Value Value Value
Calibration 107 Current 1 Deadband U1 0 255 5 mA
Security 112 Codes 0 Unseal Key 0 H2 0x0000 0xffff 0x3672 –
Security 112 Codes 2 Unseal Key 1 H2 0x0000 0xffff 0x0414 –
Security 112 Codes 4 Full-Access Key 0 H2 0x0000 0xffff 0xffff –
Security 112 Codes 6 Full-Access Key 1 H2 0x0000 0xffff 0xffff –
The bq27500 measures the cell voltage, temperature, and current to determine battery SOC. Thebq27500 monitors charge and discharge activity by sensing the voltage across a small-value resistor (5mΩto 20 m Ωtyp.) between the SRP and SRN pins and in series with the cell. By integrating chargepassing through a 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 withthe amount of charge passed. When an application load is applied, the impedance of the cell is measuredby comparing the OCV obtained from a predefined function for present SOC with the measured voltageunder load. Measurements of OCV and charge integration determine chemical state of charge andchemical capacity (Qmax). The initial Qmax values are taken from a cell manufacturers' data sheetmultiplied by the number of parallel cells. It is also used for the value in Design Capacity. The bq27500acquires and updates the battery-impedance profile during normal battery usage. It uses this profile, alongwith SOC and the Qmax value, to determine FullChargeCapacity( ) and StateOfCharge( ), specifically forthe present load and temperature. FullChargeCapacity( ) is reported as capacity available from a fullycharged battery under the present load and temperature until Voltage( ) reaches the Term Voltage.NominalAvailableCapacity( ) and FullAvailableCapacity( ) are the uncompensated (less than C/20)versions of RemainingCapacity( ) and FullChargeCapacity( ) respectively.
The bq27500 has two flags accessed by the Flags( ) function that warn when a battery's SOC has fallento critical levels. When RemainingCapacity( ) falls below the first capacity threshold, specified in SOC1Set Threshold, the [SOC1] (State of Charge Initial) flag is set. The flag is cleared onceRemainingCapacity( ) rises above SOC1 Clear Threshold. The bq27500's BAT_LOW pin automaticallyreflects the status of the [SOC1] flag. 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. Set SOCF Set Threshold = 0 todeactivate the feature. 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.
The bq27500 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 theapplication as well as the cell itself.
Load Mode is used to select either the constant-current or constant-power model for the ImpedanceTrack™ algorithm as used in Load Select (see Load Select). When Load Mode is 0, the ConstantCurrent model is used (default). When 1, the Constant Power model is used. The [LDMD] bit ofCONTROL_STATUS reflects the status of Load Mode.
FUNCTIONAL DESCRIPTION20 Submit Documentation Feedback
5.2.2 Load Select
5.2.3 Reserve Cap-mAh
5.2.4 Reserve Cap-mWh
5.2.5 Dsg Current Threshold
5.2.6 Chg Current Threshold
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Load Select defines the type of power or current model to be used to compute load-compensatedcapacity in the Impedance Track™ algorithm. If Load Mode = 0 ( Constant-Current) then the optionspresented in Table 5-1 are available.
Table 5-1. Constant-Current Model Used When Load Mode = 0
LoadSelect Value Current Model Used
Average discharge current from previous cycle: There is an internal register that records the average discharge0
current through each entire discharge cycle. The previous average is stored in this register.Present average discharge current: This is the average discharge current from the beginning of this discharge cycle1(default)
until present time.2 Average current: based on AverageCurrent( )
3 Current: based off of a low-pass-filtered version of AverageCurrent( ) (τ=14 s)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-mA. This mode provides a completely user-configurable method.
If Load Mode = 1 ( Constant Power) then the following options shown in Table 5-2 are available.
Table 5-2. Constant-Power Model Used When Load Mode = 1
LoadSelect Value Power Model Used
Average discharge power from previous cycle: There is an internal register that records the average discharge power0
through each entire discharge cycle. The previous average is stored in this register.Present average discharge power: This is the average discharge power from the beginning of this discharge cycle1(default)
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( ) (τ=14 s) 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-10mW. This mode provides a completely user-configurable method.
Reserve Cap-mAh determines how much actual remaining capacity exists after reaching 0RemainingCapacity( ), before Terminate Voltage is reached. A no-load rate of compensation is appliedto this reserve.
Reserve Cap-mWh determines how much actual remaining capacity exists after reaching 0AvailableEnergy( ), before Terminate Voltage is reached. A no-load rate of compensation is applied tothis reserve capacity.
This register is used as a threshold by many functions in the bq27500 to determine if actual dischargecurrent is flowing into or out of the cell. The default for this register is in Table 4-7 , which should besufficient for most applications. This threshold should be set low enough to be below any normalapplication load current but high enough to prevent noise or drift from affecting the measurement.
This register is used as a threshold by many functions in the bq27500 to determine if actual chargecurrent is flowing into or out of the cell. The default for this register is in Table 4-7 , which should besufficient for most applications. This threshold should be set low enough to be below any normal chargecurrent but high enough to prevent noise or drift from affecting the measurement.
Submit Documentation Feedback FUNCTIONAL DESCRIPTION 21
5.2.7 Quit Current, DSG Relax Time, CHG Relax Time, and Quit Relax Time
5.2.8 Qmax 0 and Qmax 1
5.2.9 Update Status 0 and Update Status 1
5.2.10 Avg I Last Run
5.2.11 Avg P Last Run
5.2.12 Delta Voltage
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System-Side Impedance Track™ Fuel Gauge
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The Quit Current is used as part of the Impedance Track™ algorithm to determine when the bq27500enters relaxation mode from a current-flowing mode in either the charge direction or the dischargedirection. The value of Quit Current is set to a default value in Table 4-7 and should be above the standbycurrent of the system.
Either of the following criteria must be met to enter relaxation mode:•|AverageCurrent( ) |< |Quit Current | for Dsg Relax Time•|AverageCurrent( ) |< |Quit Current | for Chg Relax Time
After about 5 minutes in relaxation mode, the bq27500 attempts to take accurate OCV readings. Anadditional requirement of dV/dt < 4 µV/s is required for the bq27500 to perform Qmax updates. Theseupdates are used in the Impedance Track™ algorithms. It is critical that the battery voltage be relaxedduring OCV readings to and that the current is not be higher than C/20 when attempting to go intorelaxation mode.
Quit Relax Time specifies the minimum time required for AverageCurrent( ) to remain above theQuitCurrent threshold before exiting relaxation mode.
Generically called Qmax, these dynamic variables contain the respective maximum chemical capacity ofthe active cell profiles, and are determined by comparing states of charge before and after applying theload with the amount of charge passed. They also correspond to capacity at a very low rate of discharge,such as the C/20 rate. For high accuracy, this value is periodically updated by the bq27500 duringoperation. Based on the battery cell capacity information, the initial value of chemical capacity should beentered in the Qmax nfield for each default cell profile. The Impedance Track™ algorithm updates thesevalues and maintains them the associated actual cell profiles.
Bit 0 (0x01) of the Update Status nregisters indicates that the bq27500 has learned new Qmaxparameters and is accurate. The remaining bits are reserved. Bits 0 is is a status flag set by the bq27500.Bit 0 should not be modified except when creating a golden image file as explained in the application notePreparing Optimized Default Flash Constants for specific Battery Types (SLUA334 ). Bit 0 is updated asneeded by the bq27500.
The bq27500 logs the current averaged from the beginning to the end of each discharge cycle. It storesthis average current from the previous discharge cycle in this register. This register should not bemodified. It is only updated by the bq27500 when required.
The bq27500 logs the power averaged from the beginning to the end of each discharge cycle. It storesthis average power from the previous discharge cycle in this register. To get a correct average powerreading the bq27500 continuously multiplies instantaneous current times Voltage( ) to get power. It thenlogs this data to derive the average power. This register should not be modified. It is only updated by thebq27500 when required.
The bq27500 stores the maximum difference of Voltage( ) during short load spikes and normal load, sothe Impedance Track™ algorithm can calculate remaining capacity for pulsed loads. It is notrecommended to change this value.
FUNCTIONAL DESCRIPTION22 Submit Documentation Feedback
5.2.13 Default Ra and Ra Tables
5.3 DETAILED DESCRIPTION OF DEDICATED PINS
5.3.1 The Operation Configuration Register
5.3.2 Pin Function Code Descriptions
5.3.3 BAT_LOW Pin
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These tables contain encoded data and, with the exception of the Default Ra Tables, are automaticallyupdated during device operation. No user changes should be made except for reading/writing the valuesfrom a pre-learned pack (part of the process for creating golden image files).
Some bq27500 pins are configured via the Operation Configuration data flash register, as indicated inTable 5-3 . This register is programmed/read via the methods described in Section 4.2.1 ,Accessing theData Flash. The register is located at subclass = 64, offset = 0.
Table 5-3. Operation Configuration Bit DefinitionOperation bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0Cfg
High byte RESCAP BATG_OVR – PFC_CFG1 PFC_CFG0 IWAKE RSNS1 RSNS0Low byte – IDSELEN SLEEP RMFCC BATL_POL BATG_POL – TEMPS
RESCAP = No-load rate of compensation is applied to the reserve capacity calculation. True when set. Default is 0.BATG_OVR = BAT_GD override bit. If the gauge enters Hibernate only due to the cell voltage, the BAT_GD will not negate. True when set.Default is 0. If both current and voltage are below the Hibernation thresholds, the voltage condition check above is precedent over thecurrent condition checkPFC_CFG1/PFC_CFG0 = Pin function code (PFC) mode selection: PFC 0, 1, or 2 selected by 0/0, 0/1, or 1/0, respectively.Default is PFC 1 (0/1).IWAKE/RSNS1/RSNS0 = These bits configure the current wake function (see Table 5-4 ). Default is 0/0/1.IDSELEN = Enables cell profile selection feature. True when set. 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.BATL_POL = BAT_LOW pin is active-high. True when set. Default is 1.BATG_POL = BAT_GD pin is active-low. True when cleared. Default is 0.TEMPS = Selects external thermistor for Temperature( ) measurements. True when set. Default is 1.
The bq27500 has three possible pin-function variations that can be selected in accordance with the circuitarchitecture of the end application. Each variation has been assigned a pin function code, or PFC.
When the PFC is set to 0, only the bq27500 measures battery temperature under discharge and relaxationconditions. The charger does not receive any information from the bq27500 about the temperaturereadings, and therefore operates open-loop with respect to battery temperature.
A PFC of 1 is like a PFC of 0, except temperature is also monitored during battery charging. If chargingtemperature falls outside of the preset range defined in data flash, a charger can be disabled via theBAT_GD pin until cell temperature recovers. See Section 5.6.2 ,Charge Inhibit, for additional details.
Finally when the PFC is set to 2, the battery thermistor can be shared between the fuel gauge and thecharger. The charger has full usage of the thermistor during battery charging. The fuel gauge uses thethermistor exclusively during discharge and battery relaxation.
The PFC is specified in Operation Configuration [PFC_CFG1, PFC_CFG0]. The default is PFC = 1.
The BAT_LOW pin provides a system processor with an electrical indicator of battery status. The signalingon the BAT_LOW pin follows the status of the [SOC1] bit in the Flags( ) register. Note that the polarity ofthe BAT_LOW pin can be inverted via the [BATL_POL] bit of Operation Configuration.
Submit Documentation Feedback FUNCTIONAL DESCRIPTION 23
5.3.4 Power Path Control with the BAT_GD Pin
5.3.5 Battery Detection Using the BI/TOUT Pin
5.4 TEMPERATURE MEASUREMENT
5.5 OVERTEMPERATURE INDICATION
5.5.1 Overtemperature: Charge
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The bq27500 must operate in conjunction with other electronics in a system appliance, such as chargersor other ICs and application circuits that draw appreciable power. After a battery is inserted into thesystem, there should be no charging or discharging current higher than C/20, so that an accurate OCVcan be read. The OCV is used for helping determine which battery profile to use, as it constitutes part ofthe battery impedance measurement.
When a battery is inserted into a system, the Impedance Track™ algorithm requires that no charging ofthe battery takes place and that any discharge is limited to less than C/20—these conditions are sufficientfor the fuel gauge to take an accurate OCV reading. To disable these functions, the BAT_GD pin is merelyset negated from the default setting. Once an OCV reading has be made, the BAT_GD pin is asserted,thereby enabling battery charging and regular discharge of the battery. The Operation Configuration[BATG_POL] bit can be used to set the polarity of the battery good signal, should the default configurationneed to be changed.
In PFC 1, the BAT_GD pin is also used to disable battery charging when the bq27500 reads batterytemperatures outside the range defined by [Charge Inhibit Temp Low, Charge Inhibit Temp High]. TheBAT_GD line is returned to low once temperature falls within the range [Charge Inhibit Temp Low +Temp Hys, Charge Inhibit Temp High – Temp Hys].
During power-up or hibernate activities, or any other activity where the bq27500 must determine whether abattery is connected or not, the fuel gauge applies a test for battery presence. First, the BI/TOUT pin is putinto high-Z status. The weak 1.8-M Ωpullup resistor keeps the pin high while no battery is present. When abattery is inserted (or is already inserted) into the system device, the BI/TOUT pin is pulled low. This stateis detected by the fuel gauge, which polls this pin every second when the gauge has power. A batterydisconnected status is assumed when the bq27500 reads a thermistor voltage that is near 2.5 V.
The bq27500 measures battery temperature via its TS input, in order to supply battery temperature statusinformation to the fuel gauging algorithm and charger-control sections of the gauge. Alternatively, it canalso measure internal temperature via its on-chip temperature sensor, but only if the [TEMPS] bit of theOperation Configuration register is cleared.
Regardless of which sensor is used for measurement, a system processor can request the current batterytemperature by calling the Temperature( ) function (see Section 4.1.1 ,Standard Data Commands, forspecific information).
The bq27500 external temperature sensing is optimized with the use of a high accuracy negativetemperature coefficient (NTC) thermistor with R
25
= 10.0K ±1% and B25/85 = 3435K ±1% (such asSemitec NTC 103AT). The bq27500 can also be configured to use its internal temperature sensor. Whenan external themistor is used, a 18.2k pull up resistor between BT/TOUT and TS pins is also required.Additional circuit information for connecting this thermistor to the bq27500 is shown in Section 8 ,Reference Schematic.
If during charging, Temperature( ) reaches the threshold of OT Chg for a period of OT Chg Time andAverageCurrent( ) >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, then the feature is completely disabled.
FUNCTIONAL DESCRIPTION24 Submit Documentation Feedback
5.5.2 Overtemperature: Discharge
5.6 CHARGING AND CHARGE-TERMINATION INDICATION
5.6.1 Detecting Charge Termination
5.6.2 Charge Inhibit
5.7 POWER MODES
5.7.1 BAT-INSERT-CHECK MODE
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If during discharging, Temperature( ) reaches the threshold of OT Dsg for a period of OT Dsg Time, andAverageCurrent( ) ≤–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, then feature is completely disabled.
For proper bq27500 operation, the cell charging voltage must be specified by the user. The default valuefor this variable is Charging Voltage = 4200 mV.
The bq27500 detects charge termination when (1) during 2 consecutive periods of Current TaperWindow,the AverageCurrent( ) is < Taper Current, (2) during the same periods, the accumulatedchange in capacity > 0.25 mAh / Current Taper Window, and (3) Voltage( ) >Charging Voltage – TaperVoltage. When this occurs, the [CHG] bit of Flags( ) is cleared. Also, if the [RMFCC] bit of OperationConfiguration is set, then RemainingCapacity( ) is set equal to FullChargeCapacity( ).
When PFC = 1, the bq27500 can indicate when battery temperature has fallen below or risen abovepredefined thresholds ( Charge Inhibit Temp Low and Charge Inhibit Temp High, respectively). In thismode, the BAT_GD line is made high to indicate this condition then returned to its low state, once batterytemperature returns to the range [Charge Inhibit Temp Low + Temp Hys, Charge Inhibit Temp High –Temp Hys].
When PFC = 0 or 2, the bq27500 must be queried by the system in order to determine the batterytemperature. At that time, the bq27500 samples the temperature. This saves battery energy whenoperating from battery, as periodic temperature updates are avoided during charging mode.
The bq27500 has different power modes: NORMAL, SLEEP, HIBERNATE, and BAT INSERT CHECK. InNORMAL mode, the bq27500 is fully powered and can execute any allowable task. In SLEEP mode, thefuel gauge exists in a reduced-power state, periodically taking measurements and performing calculations.In HIBERNATE mode, the fuel gauge is in its lowest power state, but can be woken up by communicationactivity or certain I/O activity. Finally, the BAT INSERT CHECK mode is a powered-up, but low-powerhalted state, where the bq27500 resides when no battery is inserted into the system.
The relationship between these modes is shown in Figure 5-1 .
This mode is a halted-CPU state that occurs when an adapter or other power source is present to powerthe bq27500 (and system), yet no battery has been detected. When battery insertion is detected, a seriesof initialization activities begins, which includes: OCV measurement, asserting the BAT_GD pin, andselecting the appropriate battery profiles. The initialization time is less than 2 seconds.
Some commands issued by a system processor can be processed while the bq27500 is halted in thismode. The gauge wakes up to process the command, then returns to the halted state awaiting batteryinsertion.
Submit Documentation Feedback FUNCTIONAL DESCRIPTION 25
SystemSleep
ExitFromSLEEP
| AverageCurrent() | >SleepCurrent
OR
CurrentisDetectedaboveIWAKE
ExitFrom SLEEP
(Hosthasset ControlStatus
[HIBERNATE]= 1
OR
VCELL <HibernateVoltage
Fuel gauginganddata
updatedevery 1s
NORMAL
Fuel gauginganddata
updated every 20 seconds
(LFOONandHFOOFF )
SLEEP
Disableallbq 27500
subcircuitsexceptGPIO .
Negate /BAT _GD
HIBERNATE
EntrytoSLEEP
OperationConfiguration[SLEEP]= 1
AND
| AverageCurrent() |≤SleepCurrent
AND
ControlStatus[SNOOZE]= 0
Wakeup From HIBERNATE
Communication Activity
AND
CommaddressisNOT forbq27500
ExitFrom HIBERNATE
BatteryRemoved
POR
Checkforbatteryinsertion
fromHALT state .
Nogauging
BAT INSERT CHECK
EntrytoNORMAL
Flags [BAT_DET]= 1
ExitFrom NORMAL
Flags [BAT_DET]= 0
ExitFrom SLEEP
Flags [BAT_DET]= 0
Flags [BAT_DET]= 0
WAIT_HIBERNATE
Fuel gauginganddata
updated every 20 seconds
/BAT _GDunchanged
ExitFromWAIT_HIBERNATE
Cellrelaxed
AND
| AverageCurrent() |< Hibernate
Current
OR
Cellrelaxed
AND
VCELL < HibernateVoltage
SystemShutdown
ExitFrom WAIT_HIBERNATE
HostmustsetControlStatus
[HIBERNATE ] = 0
AND
VCELL > HibernateVoltage
ExitFrom HIBERNATE
Communication Activity
ANDCommaddressisforbq27500
bq27500 clearsControlStatus
[HIBERNATE] = 0
RecommendHostalsoset Control
Status [HIBERNATE] = 0
Fuel gauginganddata
updated every 20 seconds
BothLFOandHFOareON
SLEEP+
EntrytoSLEEP+
OperationConfiguration[SLEEP]= 1
AND
ControlStatus[SNOOZE]= 1
AND
| AverageCurrent() |≤SleepCurrent
ExitFromSLEEP+
Anycommunicationtothegauge
OR
| AverageCurrent() | >SleepCurrent
OR
CurrentisDetectedaboveIWAKE
EntrytoSLEEP+
ControlStatus[SNOOZE]= 0 EntrytoSLEEP+
ControlStatus[SNOOZE]= 1
5.7.2 NORMAL MODE
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Figure 5-1. Power Mode Diagram
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 isupdated. Decisions to change states are also made. This mode is exited by activating a different powermode.
Because the gauge consumes the most power in NORMAL mode, the Impedance Track™ algorithmminimizes the time the fuel gauge remains in this mode.
FUNCTIONAL DESCRIPTION26 Submit Documentation Feedback
5.7.3 SLEEP+ MODE
5.7.4 SLEEP MODE
5.7.5 HIBERNATE MODE
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Compared to the SLEEP mode, SLEEP+ mode has the high frequency oscillator in operation. Thecommunication delay could be eliminated. The SLEEP+ is entered automatically if the feature is enabled(Operation Configuration [SNOOZE] = 1) and AverageCurrent( ) is below the programmable level SleepCurrent.
During SLEEP+ mode, the bq27500 periodically takes data measurements and updates its data set.However, a majority of its time is spent in an idle condition. The bq27500 exits SLEEP+ if any entrycondition is broken, specifically when (1) any communication activity with the gauge, or (2)AverageCurrent( ) rises above Sleep Current, or (3) a current in excess of IWAKE through RSENSE isdetected.
SLEEP mode is entered automatically if the feature is enabled ( Operation Configuration [SLEEP] = 1)and AverageCurrent( ) is below the programmable level Sleep Current. Once entry into SLEEP mode hasbeen qualified, but prior to entering it, the bq27500 performs a Coulomb Counter autocalibration tominimize offset.
During SLEEP mode, the bq27500 periodically takes data measurements and updates its data set.However, a majority of its time is spent in an idle condition.
The bq27500 exits SLEEP if any entry condition is broken, specifically when (1) AverageCurrent( ) risesabove Sleep Current, or (2) a current in excess of I
WAKE
through R
SENSE
is detected.
In the event that a battery is removed from the system while a charger is present (and powering thegauge), Impedance Track™ updates are not necessary. Hence, the fuel gauge enters a state that checksfor battery insertion and does not continue executing the Impedance Track™ algorithm.
While in SLEEP mode, the fuel gauge can suspend serial communications as much as 4ms by holding theSCL line low. This delay is necessary correctly process host communication, since the fuel gaugeprocessor is mostly halted while in SLEEP mode.
HIBERNATE mode should be used when the system equipment needs to enter a low-power state, andminimal gauge power consumption is required. This mode is ideal when a system equipment is set to itsown 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 cell voltage. When the cell voltage drops below the Hibernate Voltage and avalid 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.•HIBERNATE due to the load current. If the load current drops to certain level, the fuel gauge shouldalso enter low power mode. When the fuel gauge enters the HIBERNATE mode due to the loadcurrent, the [HIBERNATE] bit of the CONTROL_STATUS register must be set. The gauge waits toenter HIBERNATE mode until it has taken a valid OCV measurement and the magnitude of theaverage cell current has fallen below Hibernate Current. The gauge remains in HIBERNATE modeuntil the system issues a direct I
2
C command to the gauge or a POR occurs. I
2
C communication that isnot directed to the gauge does not wake the gauge.During the HIBERNATE mode the BAT_GD is negated (no battery charging/discharging). Thisprevents a charger application from inadvertently charging the battery before an OCV reading can betaken. It is the system’s responsibility to wake the bq27500 after it has gone into HIBERNATE mode.After waking, the gauge can proceed with the initialization of the battery information (OCV, profileselection, etc.)
Submit Documentation Feedback FUNCTIONAL DESCRIPTION 27
5.8 POWER CONTROL
5.8.1 RESET FUNCTIONS
5.8.2 WAKE-UP COMPARATOR
5.8.3 FLASH UPDATES
5.9 AUTOCALIBRATION
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
www.ti.com
When the bq27500 detects software reset ( [RESET] bit of Control( ) initiated), it increments thecorresponding counter. This information is accessible by issuing the command Control( ) function with theRESET_DATA subcommand.
The wake up comparator is used to indicate a change in cell current while the bq27500 is in either SLEEPor HIBERNATE mode. Operation Configuration uses bits [RSNS1–RSNS0] to set the sense resistorselection. Operation Configuration also uses the [IWAKE] bit to select one of two possible voltagethreshold ranges for the given sense resistor selection. An internal interrupt is generated when thethreshold is reached in either the charge or discharge direction. Setting both [RSNS1] and [RSNS0] to 0disables this feature.
Table 5-4. I
WAKE
Threshold Settings
(1)
RSNS1 RSNS0 IWAKE Vth(SRP–SRN)
0 0 0 Disabled0 0 1 Disabled0 1 0 1.0 mV or –1.0 mV0 1 1 2.2 mV or –2.2 mV1 0 0 2.2 mV or –2.2 mV1 0 1 4.6 mV or –4.6 mV1 1 0 4.6 mV or –4.6 mV1 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 voltagethreshold when calculating the configuration.
Data Flash can only be updated if Voltage( ) ≥Flash Update OK Voltage. Flash programming current cancause an increase in LDO dropout. The value of Flash Update OK Voltage should be selected such thatthe bq27500 V
CC
voltage does not fall below its minimum of 2.4 V during Flash write operations.
The bq27500 provides an autocalibration feature that measures the voltage offset error across SRP andSRN as operating conditions change. It subtracts the resulting offset error from normal sense resistorvoltage, V
SR
, for maximum measurement accuracy.
Autocalibration of the Coulomb Counter begins on entry to SLEEP mode, except if Temperature( ) is ≤5°Cor Temperature( ) ≥45 °C.
The fuel gauge also performs a single offset when (1) the condition of AverageCurrent( ) ≤100 mA and (2){voltage change since last offset calibration ≥256 mV} or {temperature change since last offset calibrationis greater than 8 °C for ≥60 s}.
Capacity and current measurements continue at the last measured rate during the offset calibration whenthese measurements cannot be performed. If the battery voltage drops more than 32 mV during the offsetcalibration, the load current has likely increased considerably; hence, the offset calibration is aborted.
28 FUNCTIONAL DESCRIPTION Submit Documentation Feedback
6 APPLICATION-SPECIFIC INFORMATION
6.1 BATTERY PROFILE STORAGE AND SELECTION
6.1.1 Common Profile Aspects
6.1.2 Activities Upon Pack Insertion
6.1.2.1 First OCV and Impedance Measurement
6.1.3 Reading Application Status
6.2 APPLICATION-SPECIFIC FLOW AND CONTROL
6.2.1 Simple Battery
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
www.ti.com
SLUS880 – OCTOBER 2008
When a battery pack is removed from host equipment that implements the bq27500, the fuel gaugemaintains some of the battery information in case the battery is re-inserted. This way, the ImpedanceTrack™ algorithm has a means of recovering battery-status information, thereby maintaining goodstate-of-charge (SOC) estimates.
Two default battery profiles are available to store battery information. They are used to provide theImpedance Track™ algorithm with the default information on two possible battery types expected to beused with the end-equipment. These default profiles can be used to support batteries of differentchemistry, same chemistry but different capacities, or same chemistry but different models. Defaultprofiles are programmed by the end-equipment manufacturer. However, only one of the default profilescan be selected, and this selection cannot be changed during end-equipment operation.
In addition to the default profiles, the bq27500 maintains two profiles PACK0 and PACK1. These tableshold dynamic battery data, and keep track of the status for up to two of the most recent batteries used. Inmost cases, the bq27500 can manage the information on two removable battery packs.
At power up, the BAT_GD pin is inactive, so that the host cannot obtain power from the battery (thisdepends on the actual implementation). In this state, the battery is put in an open-circuit condition. Next,the bq27500 measures its first open-circuit voltage (OCV) via the BAT pin. From the OCV(SOC) table, theSOC of the inserted battery is found. Then the BAT_GD pin is made active, and the impedance of theinserted battery is calculated from the measured voltage and the load current: Z(SOC) = [OCV(SOC) – V]/ I. This impedance is compared with the impedance of the dynamic profiles, Packn, and the defaultprofiles, Defn, for the same SOC (the letter ndepicts either a 0or 1).
The Application Status data flash location contains cell profile status information, and can be read usingthe ApplicationStatus( ) extended command (0x6a). The bit configuration of this function/location is shownin Table 6-1 .
Table 6-1. ApplicationStatus( ) Bit Definitions.Application bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0Configuration
Byte — — — — — — — LU_ PROF
LU_PROF = Last profile used by fuel gauge. Pack0 last used when cleared. Pack1 last used when set. Default is 0.
The bq27500 supports only one type of battery profile. This profile is stored in both the Def0 and Def1profiles. The Defn and Packn profiles are the same on the first gauge start-up. Then the ImpedanceTrack™ algorithm begins fuel gauging, regularly updating Packn as the battery is used.
When an existing pack is removed from the bq27500 and a different (or same) pack is inserted, cellimpedance is measured after battery detection (see Section 6.1.2.1 ,First OCV and ImpedanceMeasurement). The bq27500 chooses the profile which is closest to the measured impedance, starting
Submit Documentation Feedback APPLICATION-SPECIFIC INFORMATION 29
7 COMMUNICATIONS
7.1 I
2
C INTERFACE
Hostgenerated
A AS 0ADDR[6:0] CMD [7:0] Sr 1ADDR[6:0] A DATA [7:0] A DATA [7:0] PN...
(d) incrementalread
A AS 0ADDR[6:0] CMD [7:0] Sr 1ADDR[6:0] A DATA [7:0] PN
(c) 1- byteread
A AS A0 PADDR[6:0] CMD[7:0] DATA [7:0]
(a) 1-bytewrite (b) quickread
S 1ADDR[6:0] A DATA [7:0] PN
bq27500/1 generated
...A AS A0 PADDR[6:0] CMD[7:0] DATA [7:0] DATA [7:0] A A
(e) incrementalwrite
(S = Start , Sr = RepeatedStart , A = Acknowledge , N = No Acknowledge , andP = Stop).
7.2 I
2
C TIME OUT
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
SLUS880 – OCTOBER 2008
www.ti.com
with the Packn profiles. That is, if the measured impedance matches Pack0, then the Pack0 profile isused. If the measured impedance matches Pack1, then the Pack1 profile is used. If the measuredimpedance does not match the impedance stored in either Pack0 or Pack1, the battery pack is deemednew (none of the previously used packs). The Def0/Def1 profile is copied into either the Pack0 or Pack1profile, overwriting the oldest Packn profile used.
The 27500 supports the standard I
2
C read, incremental read, quick read, one byte write, and incrementalwrite functions. The 7 bit device address (ADDR) is the most significant 7 bits of the hex address and isfixed as 1010101. The 8-bit device address will therefore be 0xAA or 0xAB for write or read, respectively.
The “quick read” returns data at the address indicated by the address pointer. The address pointer, aregister internal to the I
2
C communication engine, will increment whenever data is acknowledged by thebq27500 or the I
2
C master. “Quick writes” function in the same manner and are a convenient means ofsending multiple bytes to consecutive command locations (such as two-byte commands that require twobytes of data)
The following command sequences are not supported:Attempt to write a read-only address (NACK after data sent by master):
Attempt to read an address above 0x6B (NACK command):
The I
2
C engine will release both SDA and SCL if the I
2
C bus is held low for t
(BUSERR)
. If the bq27500 washolding the lines, releasing them will free the master to drive the lines. If an external condition is holdingeither of the lines low, the I
2
C engine will enter the low power sleep mode.
The I
2
C engine will release both SDA and SCL if the I
2
C bus is held low for about 2 seconds. If thebq27500 was holding the lines, releasing them will free for the master to drive the lines. If an externalcondition is holding either of the lines low, the I
2
C engine will enter the low power sleep mode.
COMMUNICATIONS 30 Submit Documentation Feedback
8 REFERENCE SCHEMATICS
8.1 SCHEMATIC
bq27500-V120
System-Side Impedance Track™ Fuel Gauge
www.ti.com
SLUS880 – OCTOBER 2008
Submit Documentation Feedback REFERENCE SCHEMATICS 31
PACKAGING INFORMATION
Orderable Device Status (1) Package
Type Package
Drawing Pins Package
Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
BQ27500DRZR-V120 NRND SON DRZ 12 3000 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ27500DRZR-V120G4 NRND SON DRZ 12 3000 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ27500DRZT-V120 NRND SON DRZ 12 250 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
BQ27500DRZT-V120G4 NRND SON DRZ 12 250 Green (RoHS &
no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR
(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.
PACKAGE OPTION ADDENDUM
www.ti.com 3-May-2010
Addendum-Page 1
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
BQ27500DRZR-V120 SON DRZ 12 3000 330.0 12.4 2.8 4.3 1.2 4.0 12.0 Q2
BQ27500DRZT-V120 SON DRZ 12 250 330.0 12.4 2.8 4.3 1.2 4.0 12.0 Q2
PACKAGE MATERIALS INFORMATION
www.ti.com 17-May-2012
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
BQ27500DRZR-V120 SON DRZ 12 3000 338.1 338.1 20.6
BQ27500DRZT-V120 SON DRZ 12 250 338.1 338.1 20.6
PACKAGE MATERIALS INFORMATION
www.ti.com 17-May-2012
Pack Materials-Page 2
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