Texas Instruments System-Side Impedance Track bq27500 Instruction Manual Download Page 2

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Contents

bq27500
bq27501
System-Side Impedance Track™ Fuel Gauge

SLUS785 – SEPTEMBER 2007

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in
conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.

INTRODUCTION

..........................................

4.2

DATA FLASH INTERFACE

.........................

1.1

FEATURES

...........................................

4.3

MANUFACTURER INFORMATION BLOCKS

......

1.2

APPLICATIONS

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4.4

ACCESS MODES

...................................

1.3

DESCRIPTION

.......................................

4.5

SEALING/UNSEALING DATA FLASH

..............

DEVICE INFORMATION

.................................

4.6

DATA FLASH SUMMARY

...........................

2.1

AVAILABLE OPTIONS

...............................

FUNCTIONAL DESCRIPTION

........................

2.2

PIN DIAGRAMS

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5.1

FUEL GAUGING

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2.3

TERMINAL FUNCTIONS

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5.2

IMPEDANCE TRACK™ VARIABLES

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ELECTRICAL SPECIFICATIONS

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5.3

DETAILED DESCRIPTION OF DEDICATED PINS

3.1

ABSOLUTE MAXIMUM RATINGS

...................

5.4

TEMPERATURE MEASUREMENT

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3.2

RECOMMENDED OPERATING CONDITIONS

......

5.5

OVERTEMPERATURE INDICATION

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5.6

CHARGING AND CHARGE-TERMINATION

3.3

POWER-ON RESET

..................................

INDICATION

.........................................

3.4

INTERNAL TEMPERATURE SENSOR
CHARACTERISTICS

.................................

5.7

POWER MODES

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3.5

HIGH FREQUENCY OSCILLATOR

..................

5.8

POWER CONTROL

.................................

3.6

LOW FREQUENCY OSCILLATOR

...................

5.9

AUTOCALIBRATION

................................

3.7

INTEGRATING ADC (COULOMB COUNTER)

APPLICATION-SPECIFIC INFORMATION

..........

CHARACTERISTICS

.................................

6.1

BATTERY PROFILE STORAGE AND SELECTION

3.8

ADC (TEMPERATURE AND CELL

6.2

APPLICATION-SPECIFIC FLOW AND CONTROL

MEASUREMENT) CHARACTERISTICS

.............

COMMUNICATIONS

....................................

3.9

DATA FLASH MEMORY CHARACTERISTICS

......

7.1

C INTERFACE

.....................................

3.10

C-COMPATIBLE INTERFACE COMMUNICATION

REFERENCE SCHEMATICS

..........................

TIMING CHARACTERISTICS

........................

8.1

SCHEMATIC

........................................

GENERAL DESCRIPTION

..............................

4.1

DATA COMMANDS

..................................

Contents

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Summary of Contents for System-Side Impedance Track bq27500

Page 1: ...s the patented Impedance FLASH Track algorithm for fuel gauging and provides information such as remaining battery capacity Battery Fuel Gauge Based on Patented mAh state of charge run time to empty min Impedance Track Technology battery voltage mV and temperature C Models the Battery Discharge Curve for Accurate Time to Empty Predictions Battery fuel gauging with the bq27500 requires only Automat...

Page 2: ... DESCRIPTION OF DEDICATED PINS 23 3 1 ABSOLUTE MAXIMUM RATINGS 4 5 4 TEMPERATURE MEASUREMENT 26 3 2 RECOMMENDED OPERATING CONDITIONS 4 5 5 OVERTEMPERATURE INDICATION 26 5 6 CHARGING AND CHARGE TERMINATION 3 3 POWER ON RESET 4 INDICATION 26 3 4 INTERNAL TEMPERATURE SENSOR CHARACTERISTICS 5 5 7 POWER MODES 27 3 5 HIGH FREQUENCY OSCILLATOR 5 5 8 POWER CONTROL 29 3 6 LOW FREQUENCY OSCILLATOR 5 5 9 AUT...

Page 3: ...l pin Open drain I O use with pull up resistor 1MΩ 1 8MΩ typical 3 TS TS P Pack thermistor voltage sense use 103AT type thermistor ADC input 4 BAT BAT I Cell voltage measurement input ADC input 5 VCC VCC P Processor power input Decouple with 0 1μF capacitor minimum 6 VSS VSS P Device ground Analog input pin connected to the internal coulomb counter where SRP is nearest the 7 SRP SRP IA CELL connec...

Page 4: ...ty TA 25 C VCC 2 5 V unless otherwise noted PARAMETER TEST CONDITIONS MIN TYP MAX UNIT VCC Supply Voltage 2 4 2 5 2 6 V ICC Normal operating mode current 1 95 μA ISLP Low power storage mode current 2 15 μA ICC Hibernate operating mode current 3 2 μA VOL Output voltage low SDA BAT_LOW BI TOUT IOL 0 5 mA 0 4 V VOH PP Output high voltage BAT_LOW IOH 1 mA VCC 0 5 V External pull up resistor VOH OD Out...

Page 5: ...pical Values at TA 25 C and VCC 2 5 V unless otherwise noted PARAMETER TEST CONDITIONS MIN TYP MAX UNIT fLOSC Operating frequency 32 768 kHz TA 0 C to 60 C 1 5 0 25 1 5 fLEIO Frequency error 1 2 TA 20 C to 70 C 2 5 0 25 2 5 TA 40 C to 85 C 4 0 0 25 4 0 tLSXO Start up time 3 500 μs 1 The frequency drift is included and measured from the trimmed frequency at VCC 2 5V TA 25 C 2 The frequency error is...

Page 6: ...2 6 V Typical Values at TA 25 C and VCC 2 5 V unless otherwise noted PARAMETER TEST CONDITIONS MIN TYP MAX UNIT tON Data retention See 1 10 1 Years Flash programming write cycles See 1 20 000 Cycles tWORDPROG Word programming time See 1 2 ms ICCPROG Flash write supply current 5 10 mA 1 Specified by design Not production tested TA 40 C to 85 C 2 4 V VCC 2 6 V Typical Values at TA 25 C and VCC 2 5 V...

Page 7: ...www ti com bq27500 bq27501 System Side Impedance Track Fuel Gauge SLUS785 SEPTEMBER 2007 Figure 3 1 I2 C Compatible Interface Timing Diagrams Submit Documentation Feedback ELECTRICAL SPECIFICATIONS 7 ...

Page 8: ...ugh a data flash interface For specifics on accessing the data flash see Section 4 3 Manufacturer Information Blocks The key to the bq27500 1 s high accuracy gas gauging prediction is Texas Instrument s proprietary Impedance Track algorithm This algorithm uses cell measurements characteristics and properties to create state of charge predictions that can achieve less than 1 error across a wide var...

Page 9: ...ccess Modes Table 4 1 Standard Commands COMMAND SEALED UNSEALED NAME UNITS CODE ACCESS ACCESS Control CNTL 0x00 0x01 N A R W R W AtRate AR 0x02 0x03 mA R W R W AtRateTimeToEmpty ARTTE 0x04 0x05 Minutes R R Temperature TEMP 0x06 0x07 0 1 K R R Voltage VOLT 0x08 0x09 mV R R Flags FLAGS 0x0a 0x0b N A R R NominalAvailableCapacity NAC 0x0c 0x0d mAh R R FullAvailableCapacity FAC 0x0e 0x0f mAh R R Remain...

Page 10: ...21 No Enables the Impedance Track algorithm IFCHECKSUM 0x0022 No Reports the instruction flash checksum CALMODE 0x0040 No Places the bq27500 1 in calibration mode RESET 0x0041 No Forces a full reset of the bq27500 1 4 1 1 1 1 CONTROL STATUS 0X0000 Instructs the gas gauge to return status information to Control addresses 0x00 0x01 The status word includes the following information Table 4 3 CONTROL...

Page 11: ...lash and is also returned to addresses 0x00 0x01 This function is only available when the fuel gauge is UNSEALED When SEALED this command will only read back the CC_INT_OFFSET value stored in data flash 4 1 1 1 10 SET_HIBERNATE 0x0011 Instructs the fuel gauge to force the CONTROL STATUS HIBERNATE bit to 1 This will allow the gauge to enter the HIBERNATE power mode after the transition to SLEEP pow...

Page 12: ...e AtRate and AtRateTimeToEmpty commands should only be used in NORMAL mode 4 1 1 4 Temperature 0x06 0x07 This read word function returns an unsigned integer value of the temperature in units of 0 1 K measured by the gas gauge and has a range of 0 to 6553 5 K 4 1 1 5 Voltage 0x08 0x09 This read word function returns an unsigned integer value of the measured cell pack voltage in mV with a range of 0...

Page 13: ...18 0x19 This read only function returns an unsigned integer value of predicted remaining time until the battery reaches full charge in minutes based upon AverageCurrent The computation accounts for the taper current time extension from the linear TTF computation based on a fixed AverageCurrent rate of charge accumulation A value of 65535 indicates the battery is not being charged 4 1 1 14 StandbyC...

Page 14: ...is read only function returns an unsigned integer value of the predicted remaining operating time if the battery is discharged at the AveragePower value in minutes A value of 65535 indicates AveragePower 0 The fuel gauge automatically updates TimeToEmptyatContantPower based on the AveragePower value every 1s 4 1 1 21 CycleCount 0x2a 0x2b This read only function returns an unsigned integer value of...

Page 15: ...to the second 32 byte block and so on SEALED Access This command directs which data flash block will be accessed by the BlockData command Writing a 0x00 to DataFlashBlock specifies the BlockData command will transfer authentication data Issuing a 0x01 0x02 or 0x03 instructs the BlockData command to transfer Manufacturer Info Block A B or C respectively 4 1 2 4 BlockData 0x40 0x5f UNSEALED Access T...

Page 16: ...ontaining the desired data flash location s must be transferred to the command register locations where they can be read to the system or changed directly This is accomplished by sending the set up command BlockDataControl 0x61 with data 0x00 Up to 32 bytes of data can be read directly from the BlockData 0x40 0x5f externally altered then re written to the BlockData command space Alternatively spec...

Page 17: ...es the corresponding information block A B or C respectively to be transferred to the command space 0x40 0x5f for editing or reading by the system Upon successful writing of checksum information to BlockDataChecksum the modified block is returned to data flash Note Manufacturer Info Block A is read only when in SEALED mode The bq27500 1 provides three security modes in which control data flash acc...

Page 18: ...ge Inhibit Configuration 32 2 Charge Inhibit Temp High 12 400 1200 450 0 1 C Config Charge Inhibit Configuration 32 4 Temp Hys 12 0 100 50 0 1 C Config Configuration 34 Charge 2 Charging Voltage I2 0 20000 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...

Page 19: ... Dsg Current Threshold I2 0 2000 75 mA Thresholds Current Gas Gauging 81 2 Chg Current Threshold I2 0 2000 75 mA Thresholds Current Gas Gauging 81 4 Quit Current I2 0 1000 50 mA Thresholds Current Gas Gauging 81 6 Dsg Relax Time U2 0 8191 1800 s Thresholds Current Gas Gauging 81 8 Chg Relax Time U1 0 255 60 s Thresholds Current Gas Gauging 81 9 Quit Relax Time U1 0 63 1 s Thresholds Gas Gauging 82...

Page 20: ...ation load is applied the impedance of the cell is measured by comparing the OCV obtained from a predefined function for present SOC with the measured voltage under load Measurements of OCV and charge integration determine chemical state of charge and Chemical Capacity Qmax The initial Qmax values are taken from a cell manufacturers data sheet multiplied by the number of parallel cells It is also ...

Page 21: ...filtered version of AverageCurrent τ 14s 4 Design Capacity 5 C Rate based off of Design Capacity 5 or a C 5 rate in mA 5 AtRate mA Use whatever current is in AtRate 6 User_Rate mA Use the value in User_Rate This gives a completely user configurable method If ILoad 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 ...

Page 22: ...ing states of charge before and after applying the load with the amount of charge passed They also correspond to capacity at very low rate of discharge such as C 20 rate For high accuracy this value is periodically updated by the bq27500 1 during operation Based on the battery cell capacity information the initial value of chemical capacity should be entered in the Qmax n field for each default ce...

Page 23: ...n assigned a Pin Function Code or PFC When the PFC is set to 0 only the bq27500 1 measures battery temperature under discharge and relaxation conditions The charger does not receive any information from the bq27500 1 about the temperature readings 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 c...

Page 24: ...harging when the bq27500 1 reads battery temperatures outside the range defined by Charge Inhibit Temp Low Charge Inhibit Temp High The BAT_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 1 needs to determine whether a battery is conn...

Page 25: ... POR Batt detected No Yes AC or USB Present Yes No IT Operations dsg chg rlx Batt removed Yes Icc Istandby OR Tr 30min No Yes Forced SLEEP Mode No Bad batt detected No Yes Bad batt detected Yes No No Yes bq27500 bq27501 System Side Impedance Track Fuel Gauge SLUS785 SEPTEMBER 2007 Figure 5 1 BAT_GD Pin Operation Based Upon Battery Presence and bq27500 Operating Mode Submit Documentation Feedback F...

Page 26: ...ture reaches the threshold of OT Dsg for a period of OT Dsg Time and AverageCurrent Dsg Current Threshold then the OTD bit of Flags is set Note if OT Dsg Time 0 then feature is completely disabled When Temperature falls to OT Dsg Recovery the OTD bit of Flags is reset For proper bq27500 1 operation the cell charging voltage must be specified by the user The default value for this variable is Charg...

Page 27: ...re is enabled Operation Configuration SLEEP 1 and AverageCurrent is below the programmable level Sleep Current Once entry into SLEEP mode has been qualified but prior to entering it the bq27500 1 performs an ADC autocalibration to minimize offset During SLEEP mode the bq27500 1 periodically takes data measurements and updates its data set However a majority of its time is spent in an idle conditio...

Page 28: ...ide Impedance Track Fuel Gauge SLUS785 SEPTEMBER 2007 Figure 5 2 Power Mode Diagram HIBERNATE mode should be used when the system equipment needs to enter a very low power state and minimal gauge power consumption is required This mode is ideal when a system equipment is set to its own SLEEP HIBERNATE or SHUTDOWN modes To enter HIBERNATE mode either the system must set the HIBERNATE bit of the CON...

Page 29: ... reset RESET bit of Control initiated it determines the type of reset and increments the corresponding counter This information is accessible by issuing the command Control function with the RESET_DATA subcommand As shown in Figure 5 3 if a partial reset was detected a RAM checksum is generated and compared against the previously stored checksum If the checksum values do not match the RAM is reini...

Page 30: ...Data Flash can only be updated if Voltage Flash Update OK Voltage Flash programming current can cause an increase in LDO dropout The value of Flash Update OK Voltage should be selected such that the bq27500 1 VCC voltage does not fall below its minimum of 2 4V during Flash write operations The bq27500 provides an autocalibration feature that measures the voltage offset error across SRP and SRN as ...

Page 31: ...t At power up the BAT_GD pin is inactive so that the system cannot obtain power from the battery this depends on actual implementation In this state the battery is put in an open circuit condition Next the bq27500 1 measures its first open circuit voltage OCV via the BAT pin From the OCV SOC table the SOC of the inserted battery is found Then the BAT_GD pin is made active and the impedance of the ...

Page 32: ...oltage threshold levels of 110mV and 1070mV respectively These resistance values assume a 300Ω resistance already exists in front of the RID pin for ESD protection If the bq27501 measures a voltage other than Pack 0 Voltage or Pack 1 Voltage then it sets the Application Configuration UNSUPBAT to 1 alerting the system that the inserted battery is not supported The system can use this information to...

Page 33: ...he address pointer a register internal to the I2 C communication engine increments whenever data is acknowledged by the bq27500 or the I2 C master Quick writes function in the same manner and are a convenient means of sending multiple bytes to consecutive command locations such as two byte commands that require two bytes of data Attempt to write a read only address NACK after data sent by master A...

Page 34: ...www ti com 8 REFERENCE SCHEMATICS 8 1 SCHEMATIC bq27500 bq27501 System Side Impedance Track Fuel Gauge SLUS785 SEPTEMBER 2007 REFERENCE SCHEMATICS 34 Submit Documentation Feedback ...

Page 35: ...rocesses 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 base...

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Page 39: ...ice and is an unfair and deceptive business practice TI is not responsible or liable for any such statements TI products are not authorized for use in safety critical applications such as life support where a failure of the TI product would reasonably be expected to cause severe personal injury or death unless officers of the parties have executed an agreement specifically governing such use Buyer...

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