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1 introduction 1.1 features 1.2 applications 1.3 description bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 battery fuel gauge for 1-series li-ion smartphones applications pdas resides on system main board digital still and video cameras ? works with embedded or removable handheld terminals battery packs mp3 or multimedia players uses pack+, pack?, and t battery terminals microcontroller peripheral provides: ? accurate battery fuel gauging ? internal temperature sensor for battery the texas instruments bq27505 system-side li-ion temperature 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 ? configurable level of state of charge microcontroller firmware development. the bq27505 (soc) interrupts resides on the system?s main board and manages an ? state of health indicator embedded battery (non-removable) or a removable ? 96 bytes of non-volatile scratch-pad battery pack. flash the bq27505 uses the patented impedance track? battery fuel gauge based on patented algorithm for fuel gauging, and provides information impedance track? technology such as remaining battery capacity (mah), ? models the battery discharge curve for state-of-charge (%), run-time to empty (min), battery accurate time-to-empty predictions voltage (mv), temperature ( c) and state of health ? automatically adjusts for battery aging, (%). battery self-discharge, and temperature/rate inefficiencies battery fuel gauging with the bq27505 requires only ? low-value sense resistor (10 m w or less) pack+ (p+), pack? (p?), and thermistor (t) 400khz i 2 c? interface for connection to connections to a removable battery pack or system microcontroller port embedded battery circuit. the csp option is a 12-ball in a 12-pin nanofree? (csp) packaging package in the dimensions of 2,43 mm 1,96 mm with 0,5 mm lead pitch. it is ideal for space constrained applications. typical application please be aware that an important notice concerning availability, standard warranty, and use in critical applications of texas instruments semiconductor products and disclaimers thereto appears at the end of this document. impedance track, nanofree are trademarks of texas instruments. 400khz i 2 c is a trademark of philips electronics. production data information is current as of publication date. copyright ? 2009, texas instruments incorporated products conform to specifications per the terms of the texas instruments standard warranty. production processing does not necessarily include testing of all parameters. host system single cell li-lon battery pack pack- protection ic chg dsg temp sense soc_int current sense t pack+ voltage sense bat_gd low fets bq27505 power management controller vcc data ldo i2c battery
contents bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com 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. 1 introduction .......................................... 1 4.3 manufacturer information blocks ...... 20 1.1 features ........................................... 1 4.4 access modes ................................... 21 1.2 applications ...................................... 1 4.5 sealing/unsealing data flash .............. 21 1.3 description ....................................... 1 4.6 data flash summary ........................... 21 2 device information ................................. 3 5 functional description ........................ 23 2.1 available options ............................... 3 5.1 fuel gauging .................................... 23 2.2 dissipation ratings ............................. 3 5.2 impedance track? variables ............... 24 2.1 pin assignment ................................... 4 5.3 detailed pin description ..................... 26 3 electrical specifications ...................... 5 5.4 temperature measurement ................. 30 3.1 absolute maximum ratings ................... 5 5.5 overtemperature indication ............... 30 5.6 charging and charge-termination 3.2 recommended operating conditions ...... 5 indication ......................................... 30 3.3 power-on reset .................................. 6 5.7 power modes .................................... 31 3.4 internal temperature sensor characteristics ................................. 6 5.8 power control ................................. 32 3.5 high-frequency oscillator .................. 6 5.9 autocalibration ................................ 33 3.6 low-frequency oscillator .................. 6 6 application-specific information .......... 33 3.7 integrating adc (coulomb counter) 6.1 battery profile storage and selection 33 characteristics ................................. 6 6.2 application-specific flow and control . 34 3.8 adc (temperature and cell 7 communications measurement) characteristics ............. 7 ............................................................. 35 3.9 data flash memory characteristics ...... 7 7.1 i 2 c interface ..................................... 35 3.10 i 2 c-compatible interface communication 7.2 i 2 c time out ........................................ 36 timing characteristics ........................ 8 7.3 i 2 c command waiting time ......................... 36 4 general description .............................. 9 7.4 package information ......................... 36 4.1 data commands ................................. 10 8 reference schematics .......................... 37 4.2 data flash interface ......................... 19 8.1 schematic ........................................ 37 2 contents submit documentation feedback
2 device information 2.1 available options 2.2 dissipation ratings bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 firmware communication tape and reel part number package (1) t a version format quantity bq27505yzgr-j1 3000 2.07 csp-12 ?40 c to 85 c i 2 c BQ27505YZGT-J1 250 (1) for the most current package and ordering information, see the package option addendum at the end of this document, or see the ti website at www.ti.com . power rating derating factor package thermal resistance (1) (2) t a = 25 c above (1) (2) t a = 25 c yzg q ja = 89 c/w q jb = 35 c/w 1.1 w 12 mw/ c (1) measured with high-k board. (2) maximum power dissipation is a function of t j(max) , q ja and t a . the maximum allowable power dissipation at any allowable ambient temperature is pd = (t j(max) ? t a )/ q ja . submit documentation feedback device information 3
2.1 pin assignment bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com table 2-1. pin functions terminal type (1) description name no. analog input pin connected to the internal coulomb counter where srp is nearest the pack? srp a1 ia connection. connect to 5-m w to 20-m w sense resistor. analog input pin connected to the internal coulomb counter where srn is nearest the vss srn b1 ia connection. connect to 5-m w to 20-m w sense resistor. battery low output indicator. active high by default, though polarity can be configured through bat_low c1 o the [batl_pol] bit of operation configuration. push-pull output. vss d1 p device ground battery-good indicator. active- low by default, though polarity can be configured through the bat_gd a2 o [batg_pol] bit of operation configuration. push-pull output. soc state interrupts output. generate a pulse under the conditions specified by table 5-5 . open soc_int b2 i/o drain output. cell-voltage measurement input. adc input. recommend 4.8v maximum for conversion bat c2 i accuracy. vcc d2 p processor power input. decouple with minimum 0.1 m f ceramic capacitor. slave i 2 c serial communications data line for communication with system (master). open-drain sda a3 i/o i/o. use with 10k w pull-up resistor (typical). slave i 2 c serial communications clock input line for communication with system (master). use scl b3 i with 10k w pull-up resistor (typical). battery-insertion detection input. power pin for pack thermistor network. thermistor-multiplexer bi/tout c3 i/o control pin. use with pull-up resistor >1m w (1.8 m w typical). ts d3 ia pack thermistor voltage sense (use 103at-type thermistor). adc input (1) i/o = digital input/output, ia = analog input, p = power connection 4 device information submit documentation feedback csp-12 (top view) a1 a2 a3 b1 b2 c1 c2 c3 d1 d2 d3 b3 a1 a2 a3 b1 b2 b3 c1 c2 c3 d1 d2 d3 csp-12 (bottom view)
3 electrical specifications 3.1 absolute maximum ratings 3.2 recommended operating conditions bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 over operating free-air temperature range (unless otherwise noted) (1) parameter value unit v cc supply voltage range ?0.3 to 2.75 v v iod open-drain i/o pins (sda, scl, soc_int) ?0.3 to 6 v v bat bat input pin ?0.3 to 6 v i input voltage range to all other pins (bi/tout, ts, srp, srn, bat_gd) ?0.3 to v cc + 0.3 v human-body model (hbm), bat pin 1.5 esd kv human-body model (hbm), all other pins 2 t a operating free-air temperature range ?40 to 85 c t f functional temperature range ?40 to 100 c t 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 ratings only, and functional operation of the device at these or any other conditions beyond those indicated under "recommended operating conditions" is not implied. exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 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 cc supply voltage 2.4 2.5 2.6 v fuel gauge in normal mode. i cc normal operating-mode current (1) 114 m a i load > sleep current fuel gauge in sleep+ mode. i slp+ sleep+ operating mode current (1) 58 m a i load < sleep current fuel gauge in sleep mode. i slp low-power storage-mode current (1) 19 m a i load < sleep current fuel gauge in hibernate mode. i hib hibernate operating-mode current (1) 4 m a i load < hibernate current v ol output voltage, low (scl, sda, soc_int, i ol = 3 ma 0.4 v bat_low) v oh(pp) output voltage, high (bat_low, bat_gd) i oh = ?1 ma v cc ? 0.5 v external pullup resistor connected to v oh(od) output voltage, high (sda, scl, soc_int) v cc ? 0.5 v v cc input voltage, low (sda, scl) ?0.3 0.6 v il input voltage, low (bi/tout) bat insert check mode active ?0.3 0.6 v input voltage, high (sda, scl) 1.2 6 v ih(od) v cc + input voltage, high (bi/tout) bat insert check mode active 1.2 0.3 v a1 input voltage range (ts) v ss ? 0.125 2 v v a2 input voltage range (bat) v ss ? 0.125 5 v v a3 input voltage range (srp, srn) v ss ? 0.125 0.125 v i lkg input leakage current (i/o pins) 0.3 m a t pucd power-up communication delay 250 ms (1) specified by design. not production tested. submit documentation feedback electrical specifications 5
3.3 power-on reset 3.4 internal temperature sensor characteristics 3.5 high-frequency oscillator 3.6 low-frequency oscillator 3.7 integrating adc (coulomb counter) characteristics bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com 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 2.20 2.31 v v hys power-on reset hysteresis 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 mhz t 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 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 m s (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 (srn) and v (srp) v sr = v (srn) ? v (srp) ?0.125 0.125 v t sr_conv conversion time single conversion 1 s resolution 14 15 bits v os(sr) input offset 10 m v inl integral nonlinearity error 0.007 0.034 % fsr z in(sr) effective input resistance (1) 2.5 m w i lkg(sr) input leakage current (1) 0.3 m a (1) specified by design. not tested in production. electrical specifications 6 submit documentation feedback
3.8 adc (temperature and cell measurement) characteristics 3.9 data flash memory characteristics bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 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 in(adc) input voltage range ?0.2 1 v t adc_conv conversion time 125 ms resolution 14 15 bits v os(adc) input offset 1 mv z adc1 effective input resistance (ts) (1) 8 m w bq27505 not measuring cell voltage 8 m w z adc2 effective input resistance (bat) (1) bq27505 measuring cell voltage 100 k w i lkg(adc) input leakage current (1) 0.3 m a (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 dr data retention (1) 10 years flash-programming write cycles (1) 20,000 cycles t wordprog word programming time (1) 2 ms i ccprog flash-write supply current (1) 5 10 ma t dferase data flash master erase time (1) 200 ms t iferase instruction flash master erase time (1) 200 ms t pgerase flash page erase time (1) 20 ms (1) specified by design. not production tested submit documentation feedback electrical specifications 7
3.10 i 2 c-compatible interface communication timing characteristics bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com 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 ns t f scl/sda fall time 300 ns t w(h) scl pulse duration (high) 600 ns t w(l) scl pulse duration (low) 1.3 m s t su(sta) setup for repeated start 600 ns t d(sta) start to first falling edge of scl 600 ns t su(dat) data setup time 100 ns t h(dat) data hold time 0 ns t su(stop) setup time for stop 600 ns t (buf) bus free time between stop and start 66 m s f scl clock frequency 400 khz figure 3-1. i 2 c-compatible interface timing diagrams 8 electrical specifications submit documentation feedback
4 general description bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 the bq27505 accurately predicts the battery capacity and other operational characteristics of a single li-based rechargeable cell. it can be interrogated by a system processor to provide cell information, such as time-to-empty (tte), time-to-full (ttf) and state-of-charge (soc) as well as soc interrupt signal to the host. information is accessed through a series of commands, called standard commands. further capabilities are provided by the additional extended commands set. both sets of commands, indicated by the general format command( ), are used to read and write information contained within the bq27505 control and status registers, as well as its data flash locations. commands are sent from system to gauge using the bq27505?s i 2 c serial communications engine, and can be executed during application development, pack manufacture, or end-equipment operation. cell information is stored in the bq27505 in non-volatile flash memory. many of these data flash locations are accessible during application development. they cannot, generally, be accessed directly during end-equipment operation. access to these locations is achieved by either use of the bq27505?s companion evaluation software, through individual commands, or through a sequence of data-flash-access commands. to access a desired data flash location, the correct data flash subclass and offset must be known. the bq27505 provides two 32-byte user-programmable data flash memory blocks: manufacturer info block a and manufacturer info block b. this data space is accessed through a data flash interface. for specifics on accessing the data flash, manufacturer information blocks . the key to the bq27505?s high-accuracy gas gauging prediction is texas instrument?s proprietary impedance track? algorithm. this algorithm uses cell measurements, characteristics, and properties to create state-of-charge predictions that can achieve less than 1% error across a wide variety of operating conditions and over the lifetime of the battery. the bq27505 measures charge/discharge activity by monitoring the voltage across a small-value series sense resistor (5 m w to 20 m w typ.) located between the system?s vss and the battery?s pack- terminal. when a cell is attached to the bq27505, cell impedance is computed, based on cell current, cell open-circuit voltage (ocv), and cell voltage under loading conditions. the bq27505 external temperature sensing is optimized with the use of a high accuracy negative temperature coefficient (ntc) thermistor with r 25 = 10.0k w 1%. b25/85 = 3435k 1% (such as semitec ntc 103at). the bq27505 can also be configured to use its internal temperature sensor. when an external themistor is used, a 18.2k pull up resistor between bt/tout and ts pins is also required. the bq27505 uses temperature to monitor the battery-pack environment, which is used for fuel gauging and cell protection functionality. to minimize power consumption, the bq27505 has different power modes: normal, sleep, sleep+, hibernate, and bat insert check. the bq27505 passes automatically between these modes, depending upon the occurrence of specific events, though a system processor can initiate some of these modes directly. more details can be found in 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. submit documentation feedback general description 9
4.1 data commands 4.1.1 standard data commands bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com the bq27505 uses a series of 2-byte standard commands to enable system reading and writing of battery information. each standard command has an associated command-code pair, as indicated in table 4-1 . because each command consists of two bytes of data, two consecutive i 2 c transmissions must be executed both to initiate the command function, and to read or write the corresponding two bytes of data. additional options for transferring data, such as spooling, are described in section of communication. standard commands are accessible in normal operation. read/write permissions depend on the active access mode, sealed or unsealed (for details on the sealed and unsealed states, refer to section 4.4, access modes.) table 4-1. standard commands sealed unsealed name command code units 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/w temperature( ) temp 0x06 / 0x07 0.1 k r r/w voltage( ) volt 0x08 / 0x09 mv r r/w flags( ) flags 0x0a / 0x0b n/a r r/w nominalavailablecapacity( ) nac 0x0c / 0x0d mah r r/w fullavailablecapacity( ) fac 0x0e / 0x0f mah r r/w remainingcapacity( ) rm 0x10 / 0x11 mah r r/w fullchargecapacity( ) fcc 0x12 / 0x13 mah r r/w averagecurrent( ) ai 0x14 / 0x15 ma r r/w timetoempty( ) tte 0x16 / 0x17 minutes r r/w timetofull( ) ttf 0x18 / 0x19 minutes r r/w standbycurrent( ) si 0x1a / 0x1b ma r r/w standbytimetoempty( ) stte 0x1c / 0x1d minutes r r/w maxloadcurrent( ) mli 0x1e / 0x1f ma r r/w maxloadtimetoempty( ) mltte 0x20 / 0x21 minutes r r/w availableenergy( ) ae 0x22 / 0x23 mwh r r/w averagepower( ) ap 0x24 / 0x25 mw r r/w tteatconstantpower( ) ttecp 0x26 / 0x27 minutes r r/w stateofhealth() soh 0x28 / 0x29 % / num r r/w stateofcharge( ) soc 0x2c / 0x2d % r r/w normalizedimpedancecal( ) nic 0x2e / 0x2f mohm r r/w instaneouscurrent reading( ) icr 0x30 / 0x31 ma r r/w general description 10 submit documentation feedback
4.1.1.1 control( ): 0x00/0x01 bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 issuing a control( ) command requires a subsequent 2-byte subcommand. these additional bytes specify the particular control function desired. the control( ) command allows the system to control specific features of the bq27505 during normal operation and additional features when the bq27505 is in different access modes, as described in table 4-2 . table 4-2. control( ) subcommands cntl sealed cntl function description data access control_status 0x0000 yes reports the status of df checksum, hibernate, it, etc. device_type 0x0001 yes reports the device type (eg: bq27505) fw_version 0x0002 yes reports the firmware version on the device type hw_version 0x0003 yes reports the hardware version of the device type df_checksum 0x0004 no enables a data flash checksum to be generated and reports on a read write_temperature 0x0006 yes write temperature to the gauge when the [wrtemp] is 1 prev_macwrite 0x0007 yes returns previous mac command code chem_id 0x0008 yes reports the chemical identifier of the impedance track? configuration board_offset 0x0009 no forces the device to measure and store the board offset cc_int_offset 0x000a no forces the device to measure the internal cc offset write_cc_offset 0x000b no forces the device to store the internal cc offset ocv_cmd 0x000c yes request the gauge to take a ocv measurement bat_insert 0x000d yes forces the bat_det bit set when the [bie] bit is 0 bat_remov 0x000e yes forces the bat_det bit clear when the [bie] bit is 0 set_hibernate 0x0011 yes forces control_status [hibernate] to 1 clear_hibernate 0x0012 yes forces control_status [hibernate] to 0 set_sleep+ 0x0013 yes forces control_status [snooze] to 1 clear_sleep+ 0x0014 yes forces control_status [snooze] to 0 sealed 0x0020 no places the bq27505 in sealed access mode it_enable 0x0021 no enables the impedance track? algorithm it_disable 0x0023 no disables the impedance track? algorithm cal_mode 0x0040 no places the bq27505 in calibration mode reset 0x0041 no forces a full reset of the bq27505 submit documentation feedback general description 11
bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com 4.1.1.1.1 control_status: 0x0000 instructs the fuel gauge to return status information to control addresses 0x00/0x01. the status word includes the following information. table 4-3. control_status bit definitions bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 high byte ? fas ss csv cca bca ocvcmdcomp ocvfail low byte initcomp hibernate snooze sleep ldmd rup_dis vok qen fas = status bit indicating the bq27505 is in full access sealed state. active when set. ss = status bit indicating the bq27505 is in sealed state. active when set. csv = status bit indicating a valid data flash checksum has been generated. active when set. cca = status bit indicating the bq27505 coulomb counter calibration routine is active. the cca routine will take place approximately 1 minute after the initialization. active when set. bca = status bit indicating the bq27505 board calibration routine is active. active when set. ocvcmdcomp = status bit indicating the bq27505 has executed the ocv command. this bit can only be set with battery?s presence. true when set. ocvfail = status bit indicating bq27505 ocv reading is failed due to the current. this bit can only be set with battery?s presence. true when set. initcomp = initialization completion bit indicating the initialization completed. this bit can only be set with battery?s presence. true when set. hibernate = status bit indicating a request for entry into hibernate from sleep mode. true when set. default is 0. snooze = status bit indicating the bq27505 sleep+ mode is enabled. true when set. sleep = status bit indicating the bq27505 is in sleep mode. true when set. ldmd = status bit indicating the bq27505 impedance track? algorithm is using constant-power mode. true when set. default is 0 (constant-current mode). rup_dis = status bit indicating the bq27505 ra table updates are disabled. updates disabled when set. vok = status bit indicating the bq27505 voltages are okay for qmax. true when set. qen = status bit indicating the bq27505 qmax updates enabled. true when set. 4.1.1.1.2 device_type: 0x0001 instructs the fuel gauge to return the device type to addresses 0x00/0x01. 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. the checksum value is written and returned to addresses 0x00/0x01 (unsealed mode only). the checksum will not be calculated in sealed mode; however, the checksum value can still be read. 4.1.1.1.6 write_temperature: 0x0006 instructs the gauge to write the temperature. the temperature should be in the hexadecimal format with the unit of 0.1k. 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 to addresses 0x00/0x01. general description 12 submit documentation feedback
bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 4.1.1.1.9 board_offset: 0x0009 instructs the fuel gauge to compute the coulomb counter offset with internal short and then without internal short applied across the sensing resistor (sr) inputs. the difference between the two measurements is the board offset. after a delay of approximately 32 seconds, this offset value is returned to addresses 0x00/0x01 and written to data flash. the conrol status [bca] is also set. the user must prevent any charge or discharge current from flowing during the process. this function is only available when the fuel gauge is unsealed. when sealed, this command only reads back the board-offset value stored in data 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 short applied across the sr inputs. the offset value is returned to addresses 0x00/0x01, after a delay of approximately 16 seconds. this function is only available when the fuel gauge is unsealed. when sealed, 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 ocv cmd: 0x000c this command is to request the gauge to take a ocv reading. this command can only be issued after the [inicomp] has been set, indicating the initialization has been completed. the ocv measurement take place at the beginning of the next repeated 1s firmware synchronization clock. the measurement takes about 183ms. during the same time period, the soc_int will be negated. the host should use this signal to reduce the load current below the c/20 in 8ms for a valid ocv reading. the ocv command [ocvfail] bit will be set if the ocv_cmd is issued when [chg_inh] is set. 4.1.1.1.13 bat_insert: 0x000d this command is to force the bat_det bit to be set when the battery insertion detection is disabled. when the bie is set to 0, the battery insertion detection is disabled. the gauge relies on the host to inform the battery insertion with this command to set the bat_det bit. 4.1.1.1.14 bat_remove: 0x000e this command is to force the bat_det bit to be clear when the battery insertion detection is disabled. when the bie is set to 0, the battery insertion detection is disabled. the gauge relies on the host to inform the battery insertion with this command to set the bat_det bit. 4.1.1.1.15 set_hibernate: 0x0011 instructs the fuel gauge to force the control_status [hibernate] bit to 1. this will allow the gauge to enter the hibernate power mode after the transition to sleep power state is detected. the [hibernate] bit is automatically cleared upon exiting from hibernate mode. 4.1.1.1.16 clear_hibernate: 0x0012 instructs the fuel gauge to force the control_status [hibernate] bit to 0. this prevents the gauge from entering the hibernate power mode after the transition to the sleep power state is detected. it can also be used to force the gauge out of hibernate mode. 4.1.1.1.17 enable sleep+ mode: 0x0013 instructs the fuel gauge to set the control_status [snooze] bit to 1. this will enable the sleep+ mode. the gauge will enter sleep+ power mode after the transition conditions are meet. 4.1.1.1.18 disable sleep+ mode: 0x0014 instructs the fuel gauge to set the control_status [snooze] bit to 0. this will disable the sleep+ mode. the gauge will exit from the sleep+ power mode after the snooz bit is cleared. submit documentation feedback general description 13
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 bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com 4.1.1.1.19 sealed: 0x0020 instructs the fuel gauge to transition from the unsealed state to the sealed state. the fuel gauge must always be set to the sealed state for use in end equipment. 4.1.1.1.20 it_enable: 0x0021 this command forces the fuel gauge to begin the impedance track? algorithm, sets the it enable to 0x01 and causes the [vok] and [qen] flags to be set in the control_status register. [vok] is cleared if the voltages are not suitable for a qmax update. this command is only available when the fuel gauge is unsealed. 4.1.1.1.21 it_disable: 0x0023 this command disables the fuel gauge the impedance track? algorithm, clears the it enable to 0x00 and causes the [qen] flags to be cleared in the control_status register. this command is only available when the fuel gauge is unsealed. 4.1.1.1.22 cal_mode: 0x0040 this command instructs the fuel gauge to enter calibration mode. this command is only available when the fuel gauge is unsealed. 4.1.1.1.23 reset: 0x0041 this command instructs the fuel gauge to perform a full reset. this command is only available when the fuel gauge is unsealed. the atrate( ) read-/write-word function is the first half of a two-function command set used to set the atrate value used in calculations made by the atratetimetoempty( ) function. the atrate( ) units are in ma. the atrate( ) value is a signed integer, with negative values interpreted as a discharge current value. the atratetimetoempty( ) function returns the predicted operating time at the atrate value of discharge. the default value for atrate( ) is zero and forces atratetimetoempty( ) to return 65,535. both the atrate( ) and atratetimetoempty( ) commands must only be used in normal mode. this read-word function returns an unsigned integer value of the predicted remaining operating time if the battery is discharged at the atrate( ) value in minutes with a range of 0 to 65,534. a value of 65,535 indicates atrate( ) = 0. the fuel gauge updates atratetimetoempty( ) within 1 s after the system sets the atrate( ) value. the fuel gauge automatically updates atratetimetoempty( ) based on the atrate( ) value every 1 s. both the atrate( ) and atratetimetoempty( ) commands must only be used in normal mode. this read-word function returns an unsigned integer value of the temperature in units of 0.1 k measured by the fuel gauge. this read-word function returns an unsigned integer value of the measured cell-pack voltage in mv with a range of 0 to 6000 mv. general description 14 submit documentation feedback
4.1.1.6 flags( ): 0x0a/0x0b 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 bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 this read-word function returns the contents of the fuel-gauge status register, depicting the current operating status. table 4-4. flags bit definitions bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 high byte otc otd ? ? chg_inh xchg fc chg low byte ? ? ocv_gd wait_id bat_det soc1 sysdown 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 temp high]). true when set. xchg = charge suspend alert (temperature outside the range [suspend temperature low, suspend temperature high]). true when set. fc = full-charged condition reached. set when charge termination condition is met. (rmfcc=1; set fc_set % = -1% when rmfcc = 0). 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) reached. true when set. sysdown = systemdown bit indicating the system shut down. true when set dsg = discharging detected. true when set. this read-only command pair returns the uncompensated (less than c/20 load) battery capacity remaining. units are mah. this read-only command pair returns the uncompensated (less than c/20 load) capacity of the battery when fully charged. units are mah. fullavailablecapacity( ) is updated at regular intervals, as specified by the it algorithm. 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. units are 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 the sense 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 the present 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 battery reaches full charge, in minutes, based upon averagecurrent( ). the computation accounts for the taper current time extension from the linear ttf computation based on a fixed averagecurrent( ) rate of charge accumulation. a value of 65,535 indicates the battery is not being charged. submit documentation feedback general description 15
4.1.1.14 standbycurrent( ): 0x1a/0x1b 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 bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com this read-only function returns a signed integer value of the measured standby current through the sense resistor. the standbycurrent( ) is an adaptive measurement. initially it reports the standby current programmed in initial standby, and after spending several seconds in standby, reports the measured standby current. the register value is updated every 1 second when the measured current is above the deadband and is less than or equal to 2 initial standby. the first and last values that meet this criteria are not averaged in, since they may not be stable values. to approximate a 1 minute time constant, each new standbycurrent( ) value is computed by taking approximate 93% weight of the last standby current and approximate 7% of the current measured average current. this read-only function returns an unsigned integer value of the predicted remaining battery life at the standby rate of discharge, in minutes. the computation uses nominal available capacity (nac), the uncompensated remaining capacity, for this computation. a value of 65,535 indicates battery is not being discharged. this read-only function returns a signed integer value, in units of ma, of the maximum load conditions. the maxloadcurrent( ) is an adaptive measurement which is initially reported as the maximum load current programmed in initial max load current. if the measured current is ever greater than initial max load current, then maxloadcurrent( ) updates to the new current. maxloadcurrent( ) is reduced to the average of the previous value and initial max load current whenever the battery is charged to full after a previous discharge to an soc less than 50%. this prevents the reported value from maintaining an unusually high value. this read-only function returns an unsigned integer value of the predicted remaining battery life at the maximum load current discharge rate, in minutes. a value of 65,535 indicates that the battery is not being discharged. this read-only function returns an unsigned integer value of the predicted charge or energy remaining in the battery. the value is reported in units of mwh. this read-only function returns an signed integer value of the average power during battery charging and discharging. it is negative during discharge and positive during charge. a value of 0 indicates that the battery is not being discharged. the value is reported in units of mw. this read-only function returns an unsigned integer value of the predicted remaining operating time if the battery is discharged at the averagepower( ) value in minutes. a value of 65,535 indicates averagepower( ) = 0. the fuel gauge automatically updates timetoemptyatcontantpower( ) based on the averagepower( ) value every 1 s. general description 16 submit documentation feedback
4.1.1.21 stateofhealth( ): 0x28/0x29 4.1.1.22 stateofcharge( ): 0x2c/0x2d 4.1.1.23 normalizedimpedancecal( ): 0x2e/0x2f 4.1.1.24 instaneouscurrent reading( ) 0x30/0x31 4.1.2 extended data commands bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 0x28 soh percentage: this read-only function returns an unsigned integer value, expressed as a percentage of the ration of predicted fcc(25 c, soh loadi) over the designcapacity(). the fcc(25 c, soh loadi) is the calculated full charge capacity at 25 c and the soh loadi which is specified in the data flash. the range of the returned soh percentage is 0x00 to 0x64, indicating 0 to 100% correspondingly. 0x29 soh status: this read-only function returns an unsigned integer value, indicating the status of the soh percentage. the meanings of the returned value are: 0x00: soh not valid (initialization) 0x01: instant soh value ready 0x02: initial soh value ready ? calculation based on uncompensated qmax ? updated at first grid point update after cell insertion 0x03: soh value ready ? utilize the updated qmax update ? calculation based on compensated qmax ? updated after complete charge and relax is complete 0x04-0xff: reserved this read-only function returns an unsigned integer value of the predicted remaining battery capacity expressed as a percentage of fullchargecapacity( ), with a range of 0 to 100%. this read-only function returns an unsigned integer value of the calculated normalized impedance to 0 c at the current depth of discharge, with the unit of m w . this read-only function returns a signed integer value that is the instantaneous current flow through the sense resistor. the conversion time is 125ms. it is updated every 1 second. units are ma. extended commands offer additional functionality beyond the standard set of commands. they are used in the same manner; however, unlike standard commands, extended commands are not limited to 2-byte words. the number of commands bytes for a given extended command ranges in size from single to multiple bytes, as specified in table 4-5 . table 4-5. extended data commands command sealed unsealed name units code access (1) (2) access (1) (2) reserved rsvd 0x34...0x3b n/a r r designcapacity( ) dcap 0x3c / 0x3d mah r r dataflashclass( ) (2) dfcls 0x3e n/a n/a r/w dataflashblock( ) (2) dfblk 0x3f n/a r/w r/w authenticate( )/blockdata( ) a/df 0x40 ? 0x53 n/a r/w r/w authenticatechecksum( )/blockdata( ) acks/dfd 0x54 n/a r/w r/w blockdata( ) dfd 0x40 ? 0x5f n/a r r/w blockdatachecksum( ) dfdcks 0x60 n/a r/w r/w blockdatacontrol( ) dfdcntl 0x61 n/a n/a r/w (1) sealed and unsealed states are entered via commands to control() 0x00/0x01. (2) in sealed mode, data flash cannot be accessed through commands 0x3e and 0x3f. submit documentation feedback general description 17
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 4.1.2.6 blockdatacontrol( ): 0x61 4.1.2.7 devicenamelength( ): 0x62 bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com table 4-5. extended data commands (continued) command sealed unsealed name units code access (1) (2) access (1) (2) devicenamelength( ) dnamelen 0x62 n/a r r devicename( ) dname 0x63...0x69 n/a r r applicationstatus( ) appstat 0x6a n/a r r reserved rsvd 0x6b...0x7f n/a r r sealed and unsealed access: this command returns the value is stored in design capacity and is expressed in mah. this is intended to be the theoretical or nominal capacity of a new pack, but has no bearing on the operation of the fuel gauge functionality. unsealed access: this command sets the data flash class to be accessed. the class to be accessed must 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 to blockdatacontrol( ), dataflashblock( ) holds the block number of the data flash to be read or written. example: writing a 0x00 to dataflashblock( ) specifies access to the first 32-byte block, a 0x01 specifies access 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 or 0x02 instructs the blockdata( ) command to transfer manufacturer info block a or b, respectively. unsealed access: this data block is the remainder of the 32 byte data block when accessing data flash. sealed access: this data block is the remainder of the 32 byte data block when accessing manufacturer block info a or b. unsealed access: this byte contains the checksum on the 32 bytes of block data read or written to data flash. the least-significant byte of the sum of the data bytes written must be complemented ([255 ? x], for x the least-significant byte) before being written to 0x60. sealed access: this byte contains the checksum for the 32 bytes of block data written to manufacturer info block a or b. the least-significant byte of the sum of the data bytes written must be complemented ([255 ? x], for x the least-significant byte) before being written to 0x60. unsealed access: this command is used to control data flash access mode. writing 0x00 to this command enables blockdata( ) to access general data flash. writing a 0x01 to this command enables sealed mode operation of dataflashblock( ). sealed access: this command is not available in sealed mode. unsealed and sealed access: this byte contains the length of the device name. general description 18 submit documentation feedback
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 bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 unsealed and sealed access: this block contains the device name that is programmed in device name. this byte function allows the system to read the bq27505 application status data flash location. see table 6-1 for specific bit definitions. the bq27505 data flash is a non-volatile memory that contains bq27505 initialization, default, cell status, calibration, configuration, and user information. the data flash can be accessed in several different ways, depending on what mode the bq27505 is operating in and what data is being accessed. commonly accessed data flash memory locations, frequently read by a system, are conveniently accessed through specific instructions, already described in section 4.1 , data commands. these commands are available when the bq27505 is either in unsealed or sealed modes. most data flash locations, however, are only accessible in unsealed mode by use of the bq27505 evaluation software or by data flash block transfers. these locations should be optimized and/or fixed during the development and manufacture processes. they become part of a golden image file and can then be written to multiple battery packs. once established, the values generally remain unchanged during end-equipment operation. to access data flash locations individually, the block containing the desired data flash location(s) must be transferred to the command register locations, where they can be read to the system or changed directly. this is accomplished by sending the set-up command blockdatacontrol( ) (0x61) with data 0x00. up to 32 bytes of data can be read directly from the blockdata( ) (0x40 ? 0x5f), externally altered, then rewritten to the blockdata( ) command space. alternatively, specific locations can be read, altered, and rewritten if their corresponding offsets are used to index into the blockdata( ) command space. finally, the data residing in the command space is transferred to data flash, once the correct checksum for the whole block is written to blockdatachecksum( ) (0x60). occasionally, a data flash class will be larger than the 32-byte block size. in this case, the dataflashblock( ) command is used to designate which 32-byte block the desired locations reside in. the correct command address is then given by 0x40 + offset modulo 32. for example, to access terminate voltage in the gas gauging class, dataflashclass( ) is issued 80 (0x50) to set the class. because the offset is 48, it must reside in the second 32-byte block. hence, dataflashblock( ) is issued 0x01 to set the block offset, and the offset used to index into the blockdata( ) memory area is 0x40 + 48 modulo 32 = 0x40 + 16 = 0x40 + 0x10 = 0x50. reading and writing subclass data are block operations up to 32 bytes in length. if during a write the data length exceeds the maximum block size, then the data is ignored. none of the data written to memory are bounded by the bq27505 ? the values are not rejected by the fuel gauge. writing an incorrect value may result in hardware failure due to firmware program interpretation of the invalid data. the written data is persistent, so a power-on reset does resolve the fault. submit documentation feedback general description 19
4.3 manufacturer information blocks bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com the bq27505 contains 96 bytes of user programmable data flash storage: manufacturer info block a, and manufacturer info block b. the method for accessing these memory locations is slightly different, depending on whether the device is in unsealed or sealed modes. when in unsealed mode and when and 0x00 has been written to blockdatacontrol( ), accessing the manufacturer information blocks is identical to accessing general data flash locations. first, a dataflashclass( ) command is used to set the subclass, then a dataflashblock( ) command sets the offset for the first data flash address within the subclass. the blockdata( ) command codes contain the referenced data flash data. when writing the data flash, a checksum is expected to be received by blockdatachecksum( ). only when the checksum is received and verified is the data actually written to data flash. as an example, the data flash location for manufacturer info block b is defined as having a subclass = 58 and an offset = 32 through 63 (32 byte block). the specification of class = system data is not needed to address manufacturer info block b, but is used instead for grouping purposes when viewing data flash info in the bq27505 evaluation software. when in sealed mode or when 0x01 blockdatacontrol( ) does not contain 0x00, data flash is no longer available in the manner used in unsealed mode. rather than issuing subclass information, a designated manufacturer information block is selected with the dataflashblock( ) command. issuing a 0x01 or 0x02 with this command causes the corresponding information block (a or b, 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. general description 20 submit documentation feedback
4.4 access modes 4.5 sealing/unsealing data flash 4.6 data flash summary bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 the bq27505 provides three security modes (full access, unsealed, and sealed) that control data 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-byte blocks. table 4-6. data flash access security mode data flash manufacture information full access r/w r/w unsealed r/w r/w sealed none r(a); r/w(b) although full access and unsealed modes appear identical, only full access allows the bq27505 to write access-mode transition keys. the bq27505 implements a key-access scheme to transition between sealed, unsealed, and full-access modes. each transition requires that a unique set of two keys be sent to the bq27505 via the control( ) control command. the keys must be sent consecutively, with no other data being written to the control( ) register in between. note that to avoid conflict, the keys must be different from the codes presented in the cntl data column of table 4-2 subcommands. when in sealed mode, the control_status [ss] bit is set, but when the unseal keys are correctly received by the bq27505, the [ss] bit is cleared. when the full-access keys are correctly received, then the control_status [fas] bit is cleared. both the sets of keys for each level are 2 bytes each in length and are stored in data flash. the unseal key (stored at unseal key 0 and unseal key 1) and the full-access key (stored at full-access key 0 and full-access key 1) can only be updated when in full-access mode. the order of the keys is key 1 followed by key 0. the order of the bytes entered through the control( ) command is the reverse of what is read from the part. for example, if the key 1 and key 0 of the unseal keys returns 0x1234 and 0x5678, 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, and maximum values. table 4-7. data flash summary subclass data min max default class subclass offset name units id 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 inhibit configuration 32 0 charge inhibit temp low i2 ?400 1200 0 0.1 c temp low charge inhibit configuration 32 2 charge inhibit temp high i2 ?400 1200 450 0.1 c temp high temp configuration 32 4 temp hys i2 0 100 50 0.1 c hysteresis configuration 34 charge 2 charging voltage i2 0 4600 4200 mv configuration 34 charge 4 delta temp i2 0 500 50 0.1 c submit documentation feedback general description 21
bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com table 4-7. data flash summary (continued) subclass data min max default class subclass offset name units id type value value value configuration 34 charge 6 suspend low temp i2 ?400 1200 -50 0.1 c configuration 34 charge 8 suspend high temp i2 ?400 1200 550 0.1 c charge configuration 36 2 taper current i2 0 1000 100 ma termination charge configuration 36 4 minimum taper charge i2 0 1000 25 0.01mah termination charge configuration 36 6 taper voltage i2 0 1000 100 mv termination charge configuration 36 8 current taper window u1 0 60 40 s termination charge configuration 36 11 fc set % i1 ?1 100 100 % termination charge configuration 36 12 fc clear % i1 ?1 100 98 % termination 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 soh load i2 ?32,767 0 ?400 ma configuration 48 data 14 default temp i2 0 1000 25 (1) 0.1 c configuration 48 data 16 device name s8 x x bq27505 ? 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 5 sysdown set volt threshold i2 0 4200 3150 mv configuration 49 discharge 7 sysdown set volt time u1 0 60 2 s configuration 49 discharge 8 sysdown clear volt threshold i2 0 4200 3400 mv manufacturer system data 57 0 block a 0 h1 0x00 0xff 0x00 ? info manufacturer system data 57 1?31 block a [10?31] h1 0x00 0xff 0x00 ? info manufacturer system data 57 32?63 block b [0?31] h1 0x00 0xff 0x00 ? info configuration 64 registers 0 operation configuration h2 0x0000 0xffff 0x0973 ? configuration 64 registers 7 soc delta u1 0 25 1 % configuration 64 registers 9 opconfigb h1 0x00 0xff 0x50 ? 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 gas gauging 80 it cfg 0 load select u1 0 255 1 ? gas gauging 80 it cfg 1 load mode u1 0 255 0 ? gas gauging 80 it cfg 48 terminate voltage i2 ?32,768 32,767 3000 mv gas gauging 80 it cfg 53 user rate-ma i2 ?2000 ?100 0 ma gas gauging 80 it cfg 55 user rate-mw i2 ?7200 ?350 0 mw gas gauging 80 it cfg 57 reserve cap-mah i2 0 9000 0 mah gas gauging 80 it cfg 59 reserve cap-mwh i2 0 14,000 0 mwh current gas gauging 81 0 dsg current threshold i2 0 2000 60 ma thresholds current gas gauging 81 2 chg current threshold i2 0 2000 75 ma thresholds (1) display as the value evsw displayed. data flash value is different. general description 22 submit documentation feedback
5 functional description 5.1 fuel gauging bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 table 4-7. data flash summary (continued) subclass data min max default class subclass offset name units id type value value value current gas gauging 81 4 quit current i2 0 1000 40 ma thresholds current gas gauging 81 6 dsg relax time u2 0 8191 60 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 state 0 it enable h1 0x00 0x03 0x00 ? gas gauging 82 state 1 application status h1 0x00 0xff 0x00 ? gas gauging 82 state 2 qmax 0 i2 0 32,767 1000 mah gas gauging 82 state 4 cycle count 0 u2 0 65,535 0 ? gas gauging 82 state 6 update status 0 h1 0x00 0x03 0x00 ? gas gauging 82 state 7 qmax 1 i2 0 32767 1000 mah gas gauging 82 state 9 cycle count 1 u2 0 65,535 0 count gas gauging 82 state 11 update status 1 h1 0x00 0x03 0x00 ? gas gauging 82 state 12 cell0 chg dod i2 0 16384 0 ? gas gauging 82 state 14 cell1 chg dod at eoc i2 0 16384 0 ? gas gauging 82 state 16 avg i last run i2 ?32,768 32,767 ?299 ma gas gauging 82 state 18 avg p last run i2 ?32,768 32,767 ?1131 mah calibration 104 data 0 cc gain f4 (2) 0.1 47 10 (1) mohm calibration 104 data 4 cc delta f4 (2) 4.7 188 10 (1) mohm calibration 104 data 8 cc offset i2 ?2.4 2.4 ?0.088 (1) mv calibration 104 data 10 adc offset i2 ?500 500 0 mv calibration 104 data 12 board offset i1 ?128 127 0 mv calibration 104 data 13 int temp offset i1 ?128 127 0 0.1 c calibration 104 data 14 ext temp offset i1 ?128 127 0 0.1 c calibration 104 data 15 pack v offset i1 ?128 127 0 mv 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 ? (2) not ieee floating point. the bq27505 measures the cell voltage, temperature, and current to determine battery soc. the bq27505 monitors charge and discharge activity by sensing the voltage across a small-value resistor (5 m w to 20 m w typ.) between the srp and srn pins and in series with the cell. by integrating charge passing through the battery, the battery?s soc is adjusted during battery charge or discharge. the total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. when an application load is applied, the impedance of the cell is measured by comparing the ocv obtained from a predefined function for present soc with the measured voltage under load. measurements of ocv and charge integration determine chemical state of charge and chemical capacity (qmax). the initial qmax values are taken from a cell manufacturers' data sheet multiplied by the number of parallel cells. it is also used for the value in design capacity. the bq27505 acquires and updates the battery-impedance profile during normal battery usage. it uses this profile, along submit documentation feedback functional description 23
5.2 impedance track? variables 5.2.1 load mode 5.2.2 load select bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com with soc and the qmax value, to determine fullchargecapacity( ) and stateofcharge( ), specifically for the present load and temperature. fullchargecapacity( ) is reported as capacity available from a fully charged battery under the present load and temperature until voltage( ) reaches the term voltage. nominalavailablecapacity( ) and fullavailablecapacity( ) are the uncompensated (no or light load) versions of remainingcapacity( ) and fullchargecapacity( ) respectively. the bq27505 has two flags accessed by the flags( ) function that warns when the battery?s soc has fallen to critical levels. when remainingcapacity( ) falls below the first capacity threshold, specified in so c1 set threshold, the [soc1] (state of charge initial) flag is set. the flag is cleared once remainingcapacity( ) rises above soc1 set threshold. the bq27505?s bat_low pin automatically reflects the status of the [soc1] flag. all units are in mah. when voltage( ) falls below the system shut down threshold voltage, sysdown set volt threshold, the [sysdown] flag is set, serving as a final warning to shut down the system. the soc_int also signals. when voltage( ) rises above sysdown clear voltage and the [sysdowm] flag has already been set, the [sysdown] flag is cleared. the soc_int also signals such change. all units are in mv. the bq27505 has several data flash variables that permit the user to customize the impedance track? algorithm for optimized performance. these variables are dependent upon the power characteristics of the application as well as the cell itself. load mode is used to select either the constant-current or constant-power model for the impedance track? algorithm as used in load select (see load select). when load mode is 0, the constant current model is used (default). when 1, the constant power model is used. the [ldmd] bit of control_status reflects the status of load mode. load select defines the type of power or current model to be used to compute load-compensated capacity in the impedance track? algorithm. if load mode = 0 ( constant-current) then the options presented in table 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 discharge 0 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 cycle 1(default) until present time. 2 average current: based on averagecurrent( ) 3 current: based off of a low-pass-filtered version of averagecurrent( ) ( t =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. functional description 24 submit documentation feedback
5.2.3 reserve cap-mah 5.2.4 reserve cap-mwh 5.2.5 dsg current threshold 5.2.6 chg current threshold 5.2.7 quit current, dsg relax time, chg relax time, and quit relax time bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 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 power 0 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 cycle 1(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( ) ( t =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 0 remainingcapacity( ), before terminate voltage is reached. a no-load rate of compensation is applied to this reserve. reserve cap-mwh determines how much actual remaining capacity exists after reaching 0 availableenergy( ), before terminate voltage is reached. a no-load rate of compensation is applied to this reserve capacity. this register is used as a threshold by many functions in the bq27505 to determine if actual discharge current is flowing into or out of the cell. the default for this register is in table 4-7 , which should be sufficient for most applications. this threshold should be set low enough to be below any normal application load current but high enough to prevent noise or drift from affecting the measurement. this register is used as a threshold by many functions in the bq27505 to determine if actual charge current is flowing into or out of the cell. the default for this register is in table 4-7 , which should be sufficient for most applications. this threshold should be set low enough to be below any normal charge current but high enough to prevent noise or drift from affecting the measurement. the quit current is used as part of the impedance track? algorithm to determine when the bq27505 enters relaxation mode from a current-flowing mode in either the charge direction or the discharge direction. the value of quit current is set to a default value in table 4-7 and should be above the standby current 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 bq27505 attempts to take accurate ocv readings. an additional requirement of dv/dt < 4 m v/s is required for the bq27505 to perform qmax updates. these updates are used in the impedance track? algorithms. it is critical that the battery voltage be relaxed during ocv readings to and that the current is not be higher than c/20 when attempting to go into relaxation mode. quit relax time specifies the minimum time required for averagecurrent( ) to remain above the quitcurrent threshold before exiting relaxation mode. submit documentation feedback functional description 25
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 5.2.13 default ra and ra tables 5.3 detailed pin description 5.3.1 the operation configuration register bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com generically called qmax, these dynamic variables contain the respective maximum chemical capacity of the active cell profiles, and are determined by comparing states of charge before and after applying the load 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 bq27505 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 cell profile. the impedance track? algorithm updates these values and maintains them the associated actual cell profiles. bit 0 (0x01) of the update status n registers indicates that the bq27505 has learned new qmax parameters and is accurate. the remaining bits are reserved. bits 0 is user-configurable; however, it is also a status flag that can be set by the bq27505. bit 0 should never be modified except when creating a golden image file as explained in the application note preparing optimized default flash constants for specific battery types (slua334 ). bit 0 is updated as needed by the bq27505. the bq27505 logs the current averaged from the beginning to the end of each discharge cycle. it stores this average current from the previous discharge cycle in this register. this register should not be modified. it is only updated by the bq27505 when required. the bq27505 logs the power averaged from the beginning to the end of each discharge cycle. it stores this average power from the previous discharge cycle in this register. to get a correct average power reading the bq27505 continuously multiplies instantaneous current times voltage( ) to get power. it then logs this data to derive the average power. this register should not be modified. it is only updated by the bq27505 when required. the bq27505 stores the maximum difference of voltage( ) during short load spikes and normal load, so the impedance track? algorithm can calculate remaining capacity for pulsed loads. it is not recommended to change this value. these tables contain encoded data and, with the exception of the default ra tables, are automatically updated during device operation. no user changes should be made except for reading/writing the values from a pre-learned pack (part of the process for creating golden image files). some bq27505 pins are configured via the operation configuration data flash register, as indicated in table 5-3 . this register is programmed/read via the methods described in section 4.2.1 , accessing the data flash. the register is located at subclass = 64, offset = 0. functional description 26 submit documentation feedback
5.3.2 pin function code descriptions 5.3.3 bat_low pin bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 table 5-3. operation configuration bit definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 high byte rescap batg_ovr int_brem pfc_cfg1 pfc_cfg0 iwake rsns1 rsns0 low byte int_focv idselen sleep rmfcc soci_pol batg_pol batl_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. int_berm = battery removal interrupt bit. the soc_int negates 1ms when the battery removal interrupt is enabled. true when set. the default is 0. pfc_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 5-6 ). default is 0/0/1. int_focv = indication of the measurement of the ocv during the initialization. the soc_int will negate during the first measurement if this bit is set. true when set. default is 0. 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. soci_pol = soc interrupt polarity is active-low. true when cleared. default is 0. batg_pol = bat_gd pin is active-low. true when cleared. default is 0. batl_pol = bat_low pin is active-high. true when set. default is 1. temps = selects external thermistor for temperature( ) measurements. true when set. default is 1. some bq27505 pins are configured via the operation configuration b data flash register, as indicated in table 5-4 . this register is programmed/read via the methods described in section 4.2.1: accessing the data flash. the register is located at subclass = 64, offset = 9. table 5-4. operation configuration b bit definition bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 wrtemp bie bl_int gndsel battgdinit ? ? ? wrtemp = enables the temperature write. the temperature could be written by the host. true when set. default is 0. bie = battery insertion detection enable. when the battery insertion detection is disabled, the gauge relies on the host command to set the bat_det bit. true when set. default is 1. bl_int = battery low interrupt enable. true when set. default is 0. gndsel = the adc ground select control. the vss (pin d1) is selected as ground reference when the bit is clear. pin a1 is selected when the bit is set. default is 1. battgdinit = bat_gd will be asserted during the initialization. it is for application that needs the system be powered up asap. true when set. default is 0. the bq27505 has three possible pin-function variations that can be selected in accordance with the circuit architecture of the end application. each variation has been assigned a pin function code, or pfc. when the pfc is set to 0, only the bq27505 measures battery temperature under discharge and relaxation conditions. the charger does not receive any information from the bq27505 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 charging. if charging temperature falls outside of the preset range defined in data flash, a charger can be disabled via the bat_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 the charger. the charger has full usage of the thermistor during battery charging, while the fuel gauge uses the thermistor 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 signaling on the bat_low pin follows the status of the [soc1] bit in the flags( ) register. note that the polarity of the bat_low pin can be inverted via the [batl_pol] bit of operation configuration. submit documentation feedback functional description 27
5.3.4 power path control with the bat_gd pin bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com the bq27505 must operate in conjunction with other electronics in a system appliance, such as chargers or other ics and application circuits that draw appreciable power. after a battery is inserted into the system, there should be no charging current or a discharging current higher than c/20, so that an accurate ocv can be read. the ocv is used for helping determine which battery profile to use, as it constitutes part of the battery impedance measurement when a battery is inserted into a system, the impedance track? algorithm requires that no charging of the battery takes place and that any discharge is limited to less than c/20?these conditions are sufficient for the fuel gauge to take an accurate ocv reading. to disable these functions, the bat_gd pin is merely 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 configuration need to be changed. figure 5-1. power mode diagram figure 5-1 details how the bat_gd pin functions in the context of battery insertion and removal, as well as normal vs. sleep modes. functional description 28 submit documentation feedback system sleep exit from sleep | averagecurrent( ) | > sleep current or current is detected above i wake exit from sleep (host has set control status [hibernate] = 1 or v cell < 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 bq27505 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 bq27505 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 v cell < hibernate voltage system shutdown exit from wait _hibernate host must set control status [hibernate ] = 0 and v cell > hibernate voltage exit from hibernate communication activity and comm address is for bq27505 bq27505 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 i wake entry to sleep+ control status [snooze] = 0 entry to sleep+ control status [snooze] = 1
5.3.5 battery detection using the bi/tout pin 5.3.6 soc_int pin bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 in pfc 1, the bat_gd pin is also used to disable battery charging when the bq27505 reads battery temperatures outside the range defined by [charge inhibit temp low, charge inhibit temp high]. the bat_gd line is asserted 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 bq27505 needs to determine whether a battery is connected or not, the fuel gauge applies a test for battery presence. first, the bi/tout pin is put into high-z status. the weak 1.8m w pull-up resistor will keep the pin high while no battery is present. when a battery is inserted (or is already inserted) into the system device, the bi/tout pin will be pulled low. this state is detected by the fuel gauge, which polls this pin every second when the gauge has power. a battery-disconnected status is assumed when the bq27505 reads a thermistor voltage that is near 2.5v. the soc_int pin generates a pulse with different pulse width under various conditions. some features needs to be enabled by setting the operation config. table 5-5. soc_int pulse condition and width enable condition pulse width comment during charge, when the soc reaches ( 3 ) the points, 1% + n soc_delta and 100%; soc_delta during discharge, when the soc is less than ( < ) the points 1% + n soc_delta 1 0 1 ms point soc_delta and 0%; where n is an integer starting from 0 and the number generating soc no greater than 100% soc1 set always 1 ms when rsoc reached the soc1 set or clear threshold set in the data flash and bl_int bit in operation configuration b is set. soc1 clear always 1 ms sysdown set always 1 ms when the battery voltage reached the sysdown set or clear threshold sysdown set in the data flash always 1 ms clear state soc_delta 1 0 1 ms change when there is a state change including charging, discharging and relaxation - battery int_brem bit is set in 1ms removal opconfig ocv 1ms the ocv command is failed when chg_int is set. the ocv_fail bit command when chg_inh is set is also set. fail same as the ocv soc_int pulses for the ocv command after the initialization ocv after initialization command execution command time period same as the ocv this command is to generate the soc_int pulse during the ocv int_focv bit is set in command execution initialization command opconfig time period submit documentation feedback functional description 29
5.4 temperature measurement 5.5 overtemperature indication 5.5.1 overtemperature: charge 5.5.2 overtemperature: discharge 5.6 charging and charge-termination indication 5.6.1 detecting charge termination 5.6.2 charge inhibit bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com the bq27505 measures battery temperature via its ts input, in order to supply battery temperature status information to the fuel gauging algorithm and charger-control sections of the gauge. alternatively, it can also measure internal temperature via its on-chip temperature sensor, but only if the [temps] bit of the operation configuration register is cleared. the [gndsel] bit of operation configuration b register selects the ground reference of the adc converter for temperature measurement. regardless of which sensor is used for measurement, a system processor can request the current battery temperature by calling the temperature( ) function (see section 4.1.1 , standard data commands, for specific information). the thermistor circuit requires the use of an external ntc 103at-type thermistor. additional circuit information for connecting this thermistor to the bq27505 is shown in section 8 , reference schematic. if during charging, temperature( ) reaches the threshold of ot chg for a period of ot chg time and averagecurrent( ) > chg current threshold, then the [otc] bit of flags( ) is set. when temperature( ) falls to ot chg recovery, the [otc] of flags( ) is reset. if ot chg time = 0, then the feature is completely disabled. if during discharging, temperature( ) reaches the threshold of ot dsg for a period of ot dsg time, and averagecurrent( ) ?dsg current threshold, then the [otd] bit of flags( ) is set. when temperature( ) falls to ot dsg recovery, the [otd] bit of flags( ) is reset. if ot dsg time = 0, then feature is completely disabled. for proper bq27505 operation, the cell charging voltage must be specified by the user. the default value for this variable is charging voltage table 4-7 . the bq27505 detects charge termination when (1) during 2 consecutive periods of current taper window, the averagecurrent( ) is < taper current, (2) during the same periods, the accumulated change in capacity > 0.25 mah / current taper window, and (3) voltage( ) > charging voltage ? taper voltage. when this occurs, the [chg] bit of flags( ) is cleared. also, if the [rmfcc] bit of operation configuration is set, then remainingcapacity( ) is set equal to fullchargecapacity( ). when pfc = 1, the bq27505 can indicate when battery temperature has fallen below or risen above predefined thresholds ( charge inhibit temp low and charge inhibit temp high, respectively). in this mode, the bat_gd line is made high to indicate this condition then returned to its low state, once battery temperature returns to the range [charge inhibit temp low + temp hys, charge inhibit temp high ? temp hys]. when pfc = 0 or 2, the bq27505 must be queried by the system in order to determine the battery temperature. at that time, the bq27505 samples the temperature. this saves battery energy when operating from battery, as periodic temperature updates are avoided during charging mode. functional description 30 submit documentation feedback
5.7 power modes 5.7.1 bat insert check mode 5.7.2 normal mode 5.7.3 sleep mode bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 the bq27505 has different power modes: bat insert check, normal, sleep, sleep+ and hibernate. in normal mode, the bq27505 is fully powered and can execute any allowable task. in sleep+ mode, both low frequency and high frequency oscillators are active. although the sleep+ has higher current consumption than the sleep mode, it is also a reduced power mode. in sleep mode, the fuel gauge turns off the high frequency oscillator and exists in a reduced-power state, periodically taking measurements and performing calculations. in hibernate mode, the fuel gauge is in a very low power state, but can be woken up by communication or certain i/o activity. finally, the bat insert check mode is a powered-up, but low-power halted, state, where the bq27505 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 power the bq27505 (and system), yet no battery has been detected. when battery insertion is detected, a series of initialization activities begin, which include: ocv measurement, setting the bat_gd pin, and selecting the appropriate battery profiles. some commands, issued by a system processor, can be processed while the bq27505 is halted in this mode. the gauge will wake up to process the command, then return to the halted state awaiting battery insertion. the fuel gauge is in normal mode when not in any other power mode. during this mode, averagecurrent( ), voltage( ) and temperature( ) measurements are taken, and the interface data set is updated. decisions to change states are also made. this mode is exited by activating a different power mode. because the gauge consumes the most power in normal mode, the impedance track? algorithm minimizes the time the fuel gauge remains in this mode. sleep mode 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 has been qualified, but prior to entering it, the bq27505 performs an coulomb counter autocalibration to minimize offset. during sleep mode, the bq27505 periodically takes data measurements and updates its data set. however, a majority of its time is spent in an idle condition. the bq27505 exits sleep if any entry condition is broken, specifically when (1) averagecurrent( ) rises above sleep current, or (2) a current in excess of i wake through r sense is detected. in the event that a battery is removed from the system while a charger is present (and powering the gauge), impedance track? updates are not necessary. hence, the fuel gauge enters a state that checks for battery insertion and does not continue executing the impedance track? algorithm. submit documentation feedback functional description 31
5.7.4 sleep+ mode 5.7.5 hibernate mode 5.8 power control 5.8.1 wake-up comparator bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com compared to the sleep mode, sleep+ mode has the high frequency oscillator in operation. the communication delay could be eliminated. the sleep+ is entered automatically if the feature is enabled ( control status [snooze] = 1) and averagecurrent( ) is below the programmable level sleep current. during sleep+ mode, the bq27505 periodically takes data measurements and updates its data set. however, a majority of its time is spent in an idle condition. the bq27505 exits sleep+ if any entry condition 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 i wake through r sense is detected. hibernate mode should be used when the system equipment needs to enter a low-power state, and minimal gauge power consumption is required. this mode is ideal when a system equipment is set to its own hibernate, shutdown, or off modes. before the fuel gauge can enter hibernate mode, the system must set the [hibernate] bit of the control_status register. the gauge waits to enter hibernate mode until it has taken a valid ocv measurement and the magnitude of the average cell current has fallen below hibernate current. the gauge can also enter hibernate mode if the cell voltage falls below hibernate voltage and a valid ocv measurement has been taken. the gauge will remain in hibernate mode until the system issues a direct i 2 c command to the gauge or a por occurs. i 2 c communication that is not directed to the gauge will not wake the gauge. it is important that bat_gd be set to disable status (no battery charging/discharging). this prevents a charger application from inadvertently charging the battery before an ocv reading can be taken. it is the system?s responsibility to wake the bq27505 after it has gone into hibernate mode. after waking, the gauge can proceed with the initialization of the battery information (ocv, profile selection, etc.) the wake up comparator is used to indicate a change in cell current while the bq27505 is in either sleep or hibernate mode. operation configuration uses bits [rsns1?rsns0] to set the sense resistor selection. operation configuration also uses the [iwake] bit to select one of two possible voltage threshold ranges for the given sense resistor selection. an internal interrupt is generated when the threshold is breached in either the charge or discharge direction. setting both [rsns1] and [rsns0] to 0 disables this feature. 32 functional description submit documentation feedback
5.8.2 flash updates 5.9 autocalibration 6 application-specific information 6.1 battery profile storage and selection 6.1.1 common profile aspects bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 table 5-6. i wake threshold settings (1) rsns1 rsns0 iwake vth(srp?srn) 0 0 0 disabled 0 0 1 disabled 0 1 0 1.25 mv or ?1.25 mv 0 1 1 2.5 mv or ?2.5 mv 1 0 0 2.5 mv or ?2.5 mv 1 0 1 5 mv or ?5 mv 1 1 0 5 mv or ?5 mv 1 1 1 10 mv or ?10 mv (1) the actual resistance value vs the setting of the sense resistor is not important, just the actual voltage threshold when calculating the configuration. the votage thresholds are typical values under room temperature. data flash can only be updated if voltage( ) 3 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 bq27505 v cc voltage does not fall below its minimum of 2.4 v during flash write operations. the bq27505 provides an autocalibration feature that measures the voltage offset error across srp and srn as operating conditions change. it subtracts the resulting offset error from normal sense resistor voltage, v sr , for maximum measurement accuracy. autocalibration of the coulomb counter begins on entry to sleep mode, except if temperature( ) is 5 c or temperature( ) 3 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 3 256 mv} or {temperature change since last offset calibration is greater than 80 c for 3 60 s}. capacity and current measurements continue at the last measured rate during the offset calibration when these measurements cannot be performed. if the battery voltage drops more than 32 mv during the offset calibration, the load current has likely increased; hence, the offset calibration is aborted. when a battery pack is removed from system equipment that implements the bq27505, the fuel gauge will maintain some of the battery information, if it is re-inserted. this way the impedance track? algorithm will often have a means of recovering battery-status information; thereby, maintaining good state-of-charge (soc) estimates. two default battery profiles are available to store battery information. they are used to provide the impedance track? algorithm with the default information on two possible battery types expected to be used with the end-equipment. these default profiles can be used to support batteries of different chemistry, same chemistry but different capacities, or same chemistry but different models. default profiles are programmed by the end-equipment manufacturer. only one of the default profiles can be selected, and this selection cannot be changed during end-equipment operation. in addition to the default profiles, the bq27505 maintains two abbreviated profiles: cell0 and cell1. these tables hold dynamic battery data, and keep track of the status for up to two of the most recent batteries used. in most cases the bq27505 can administrate information on two removable battery packs. submit documentation feedback application-specific information 33
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 bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com at power-up the bat_gd pin is inactive, so that the system might not obtain power from the battery (this depends on actual implementation). in this state, the battery should be put in a condition with load current less than c/20. next, the bq27505 measures its first open-circuit voltage (ocv) via the bat pin. the [ocvcmdcomp] bit will set once the ocv measurement is completed. depending on the load current, the [ocvfail] bit indicates whether the ocv reading is valid. 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 inserted 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 default profiles, defn, for the same soc (the letter n depicts either a 0 or 1).the [initcomp] bit will be set afterwards and the ocv command could be issued the application status data flash location contains cell profile status information, and can be read using the applicationstatus( ) extended command (0x6a). the bit configuration of this function/location is shown in table 6-1 . table 6-1. applicationstatus( ) bit definitions. application bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0 configuration byte ? ? ? ? ? ? ? lu_ prof lu_prof = last profile used by fuel gauge. cell0 last used when cleared. cell1 last used when set. default is 0. the bq27505 supports only one type of battery profile. this profile is stored in both the def0 and def1 profiles. when a battery pack is inserted for the first time, the default profile is copied into the packn profiles. then the impedance track? algorithm begins gas gauging, regularly updating packn as the battery is used. when an existing pack is removed from the bq27505 and a different (or same) pack is inserted, cell impedance is measured immediately after battery detection (see section 6.1.2.1., first ocv and impedance measurement). the bq27505 chooses the profile which is closest to the measured impedance, starting with the packn profiles. that is, if the measured impedance matches pack0, then the pack0 profile is used. if the measured impedance matches pack1, then the pack1 profile is used. if the measured impedance does not match the impedance stored in either pack0 or pack1, the battery pack is deemed new (none of the previously used packs). either def0/def1 profile is copied into either the pack0 or pack1 profile, overwriting the oldest packn profile. 34 application-specific information submit documentation feedback
7 communications 7.1 i 2 c interface bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 the 27505 supports the standard i 2 c read, incremental read, quick read, one byte write, and incremental write functions. the 7 bit device address (addr) is the most significant 7 bits of the hex address and is fixed as 1010101. the 8-bit device address 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, a register internal to the i 2 c communication engine, will increment whenever data is acknowledged by the bq27505 or the i 2 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) 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): submit documentation feedback communications 35 host generated a a s 0 addr[6:0] cmd [7:0] sr 1 addr[6:0] a data [7:0] a data [7:0] p n . . . (d) incremental read a a s 0 addr[6:0] cmd [7:0] sr 1 addr[6:0] a data [7:0] p n (c) 1- byte read a a s a 0 p addr[6:0] cmd [7:0] data [7:0] (a) 1-byte write (b) quick read s 1 addr[6:0] a data [7:0] p n bq27505 generated . . . a a s a 0 p addr[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 7.3 i 2 c command waiting time 7.4 package information 7.4.1 package dimensions bq27505 system-side impedance track? fuel gauge slus884 ? february 2009 www.ti.com the i 2 c engine will release both sda and scl if the i2c bus is held low for about 2 seconds. if the bq27505 was holding the lines, releasing them will free for the master to drive the lines. if an external condition is holding either of the lines low, the i 2 c engine will enter the low power sleep mode. to make sure the correct results of a command with the 400khz i 2 c operation, a proper waiting time should be added between issuing command and reading results. for subcommands, the following diagram shows the waiting time required between issuing the control command the reading the status with the exception of checksum and ocv commands. a 100ms waiting time is required between the checksum command and reading result, and a 1.2 second waiting time is required between the ocv command and result. for read-write standard command, a minimum of 2 seconds is required to get the result updated. for read-only standard commands, there is no waiting time required, but the host should not issue all standard commands more than two times per second. otherwise, the gauge could result in a reset issue due to the expiration of the watchdog timer. the i2c clock stretch could happen in a typical application. a maximum 80ms clock stretch could be observed during the flash updates. there is up to 270ms clock stretch after the ocv command is issued. the package dimensions for this yzg package are shown in the table below. see the package drawing at the end of this data sheet for more details. table 7-1. yzg package dimensions packaged devices d e min = 2400 m m min = 1926 m m bq27505yzg max = 2460 m m max = 1986 m m 36 communications submit documentation feedback a a s 0 addr [6:0] cmd [7:0] sr 1 addr [6:0] a data [7:0] a data [7:0] p n a a s a 0 p addr [6:0] cmd [7:0] data [7:0] data [7:0] a 66 s m a a s 0 addr [6:0] cmd [7:0] sr 1 addr [6:0] a data [7:0] a data [7:0] a data [7:0] a data [7:0] p n waiting time between control subcommand and reading results waiting time between continuous reading results 66 s m 66 s m
8 reference schematics 8.1 schematic bq27505 system-side impedance track? fuel gauge www.ti.com slus884 ? february 2009 submit documentation feedback reference schematics 37
packaging information orderable device status (1) package type package drawing pins package qty eco plan (2) lead/ball finish msl peak temp (3) bq27505yzgr-j1 nrnd dsbga yzg 12 3000 green (rohs & no sb/br) snagcu level-1-260c-unlim BQ27505YZGT-J1 nrnd dsbga yzg 12 250 tbd call ti call ti (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 29-jun-2009 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 bq27505yzgr-j1 dsbga yzg 12 3000 180.0 8.4 2.1 2.57 0.81 4.0 8.0 q1 package materials information www.ti.com 29-may-2009 pack materials-page 1
*all dimensions are nominal device package type package drawing pins spq length (mm) width (mm) height (mm) bq27505yzgr-j1 dsbga yzg 12 3000 220.0 220.0 34.0 package materials information www.ti.com 29-may-2009 pack materials-page 2

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