BQ20851DBT-V1P2

   www.ti.com SLUS575 − AUGUST 2003          
 FEATURES D Provides Accurate Measurement of Available D D D D D D D Charge in Li-Ion and Li-Polymer Batteries Supports the Smart Battery Specification (SBS) V1.1 Integrated Time Base Removes Need for External Crystal Works With the TI bq29311 Analog Front End (AFE) Protection IC to Provide Complete Pack Electronics for 10.8-V or 14.4-V Battery Packs With Few External Components Based on a Powerful Low-Power RISC CPU Core With High-Performance Peripherals Integrated Flash Memory Eliminates the Need for External Configuration EEPROM Measures Charge Flow Using a High Resolution 16-Bit Integrating Converter − Better Than 3-nVh of Resolution − Self-Calibrating − Offset Error Less Than 1-µV Uses 16-Bit Delta Sigma Converter for Accurate Voltage and Temperature Measurements D Programmable Cell Modeling for Maximum D D Battery Fuel Gauge Accuracy Drives 3-, 4-, or 5-Segment LED Display for Remaining Capacity Indication 38-Pin TSSOP (DBT) APPLICATIONS D Notebook PCs DESCRIPTION The bq20851−V1P2 SBS-compliant gas gauge IC for battery pack installation maintains an accurate record of available charge in Li-ion or Li-polymer batteries. The bq20851−V1P2 monitors capacity and other critical parameters of the battery pack and reports the information to the system host controller over a serial communication bus. It is designed to work with the bq29311 analog front-end (AFE) protection IC to maximize functionality and safety and minimize component count and cost in smart battery circuits. Using information from the bq20851−V1P2, the host controller can manage remaining battery power to extend the system run time as much as possible. BLOCK DIAGRAM Pack+ Charge/Discharge Power FETs LDO Supply Voltage bq29311 SMBus bq20851−V1P2 Temp Sensor 512 Bytes Config. Flash EPROM ADC Voltage Integrating ADC Coulomb Counting Glueless Interface Cell Inputs Safety Control Level Translator + − + Li-Ion − Cells + − Sense Resistor (10 mΩ - 20 mΩ) Pack− Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.   !"#$%&'(!$" !) *+%%,"( ') $# -+
.!*'(!$" /'(,0 %$/+*() *$"#$%& ($ )-,*!#!*'(!$") -,% (1, (,%&) $# ,2') ")(%+&,"() )('"/'%/ 3'%%'"(40 %$/+*(!$" -%$*,))!"5 /$,) "$( ",*,))'%!.4 !"*.+/, (,)(!"5 $# '.. -'%'&,(,%)0 Copyright  2003, Texas Instruments Incorporated 
   www.ti.com SLUS575 − AUGUST 2003 DESCRIPTION (CONTINUED) The bq20851−V1P2 uses an integrating converter with continuous sampling for the measurement of battery charge and discharge currents. Optimized for coulomb counting in portable applications, the self-calibrating integrating converter has a resolution better than 3-nVh and an offset measurement error of less than 1-µV (typical). For voltage and temperature reporting, the bq20851−V1P2 uses a 16-bit A-to-D converter. In conjunction with the bq29311, the onboard ADC also monitors individual cell voltages in a battery pack and allows the bq20851−V1P2 to generate the control signals necessary to implement the cell balancing and the required safety protection for Li-ion and Li-polymer battery chemistries. The bq20851−V1P2 supports the Smart Battery Data (SBData) commands and charge-control functions. It communicates data using the System Management Bus (SMBus) 2-wire protocol. The data available include the battery’s remaining capacity, temperature, voltage, current, and remaining run-time predictions. The bq20851−V1P2 provides LED drivers and a push-button input to depict remaining battery capacity from full to empty in 20%, 25%, or 33% increments with a 3-, 4-, or 5-segment display. The bq20851−V1P2 contains 512 bytes of internal data flash memory, which store configuration information. The information includes nominal capacity and voltage, self-discharge rate, rate compensation factors, and other programmable cell-modeling factors used to accurately adjust remaining capacity for use-conditions based on time, rate, and temperature. The bq20851−V1P2 also automatically calibrates or learns the true battery capacity in the course of a discharge cycle from programmable near full to near empty levels. 2 The bq29311 AFE protection IC provides power to the bq20851−V1P2 from a 3 or 4 series Li-ion cell stack, eliminating the need for an external regulator circuit. TSSOP PACKAGE (TOP VIEW) VIN TS LED5 LED4 LED3 SCLK N/C VDDD RBI SDATA VSSD SAFE N/C N/C SMBC SMBD DISP EVENT VSSD 1 38 2 37 3 36 4 35 5 34 6 33 7 32 8 31 9 30 10 29 11 28 12 27 13 26 14 25 15 24 16 23 17 22 18 21 19 20 VSSD LED1 LED2 CLKOUT VSSA ROSC FILT VDDA VSSA VSSP SR1 SR2 MRST N/C N/C N/C N/C N/C N/C NC − No internal connection AVAILABLE OPTIONS TA PACKAGE 38-PIN TSSOP (DBT) −20°C to 85°C bq20851DBT−V1P2(1) (1) The bq20851−V1P2 is available taped and reeled. Add an R suffix to the device type (e.g., bq20851DBTR−V1P2) to order tape and reel version. 
   www.ti.com SLUS575 − AUGUST 2003 Terminal Functions TERMINAL I/O DESCRIPTION NAME No. CLKOUT 35 I 32.768-kHz output to the bq29311 DISP 17 I Display control for the LED drivers LED1 through LED5 FILT 32 I Analog input connected to the external PLL filter EVENT 18 I Input from bq29311 XALERT output LED1 37 O LED2 36 O LED3 5 O LED4 4 O LED5 3 O MRST LED display segments that each may drive an external LED 26 I Master reset input that forces the device into reset when held high N/C 20−24, 7, 13, 14, 25, − No connection RBI 9 I Register backup that provides backup potential to the bq20851−V1P2 data registers during periods of low operating voltage. RBI accepts a storage capacitor or a battery input. ROSC 33 I Internal time base bias input SAFE 12 O Output for additional level of safety protection; e.g., fuse blow. SCLK 6 O Communication clock to the bq29311 SDATA 10 I/O Data transfer to and from bq29311 SMBC 15 I/O SMBus clock open-drain bidirectional pin used to clock the data transfer to and from the bq20851−V1P2 SMBD 16 I/O SMBus data open-drain bidirectional pin used to transfer address and data to and from the bq20851−V1P2 SR1 28 I SR2 27 I TS 2 I Thermistor voltage input connection to monitor temperature VDDA 31 I Positive supply for analog circuitry VDDD 8 I Positive supply for digital circuitry and I/O pins VIN 1 I Single cell voltage input from the bq29311 VSSA 30, 34 I Negative supply for analog circuitry VSSD 11, 19, 38 I Negative supply for digital circuitry VSSP 29 I Negative supply for output circuitry Connections for a small-value sense resistor to monitor the battery charge- and discharge-current flow 3 
   www.ti.com SLUS575 − AUGUST 2003 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. ABSOLUTE MAXIMUM RATINGS over operating free-air temperature (unless otherwise noted)(1) UNITS Supply voltage range, VDD relative to VSS(2) Open-drain I/O pins, V(IOD) relative to VSS (2) −0.3 V to 6 V −0.3 V to 6 V Input voltage range to all other pins, VI relative to VSS (2) −0.3 V to VDD + 0.3 V Operating free-air temperature range, TA −20°C to 85°C Storage temperature range, Tstg −65°C to 150°C ESD rating HBM 1.5 kV CDM 1.5 kV MM 50 V (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. (2) VSS refers to the common node of V(SSA), V(SSD), and V(SSP). ELECTRICAL CHARACTERISTICS VDD = 3.0 V to 3.6 V, TA = −20°C to 85°C (unless otherwise noted) PARAMETER TEST CONDITIONS VDD IDD Supply voltage Operating current VDDA and VDDD No flash programming I(SLP) V(OLS) Low-power storage mode current Hibernate mode Output voltage low: (LED1−LED5) I(OLS) = 10 mA VIL VIH Input voltage low DISP Input voltage high DISP MIN TYP MAX 3.0 3.3 3.6 UNIT V µA 350 µA 1 0.4 V −0.3 0.8 V 2 VCC + 0.3 V 0.4 V VOL Output voltage low SMBC, SMBD, SDATA, SCLK, EVENT, SAFE V(ILS) Input voltage low SMBC, SMBD, SDATA, SCLK, EVENT, SAFE −0.3 0.8 V V(IHS) Input voltage high SMBC, SMBD, SDATA, SCLK, EVENT, SAFE 1.7 6 V 1.0 IOL = 0.5 mA V(AI) Z(AI1) Input voltage range VIN, TS, OC Input impedance SR1, SR2 0 V–1.0 V VSS − 0.3 10 Z(AI2) Input impedance VIN, TS, OC 0 V–1.0 V 8 V MΩ MΩ Power-On Reset (see Figure 1) PARAMETER VIT− Vhys 4 TEST CONDITIONS MIN TYP MAX UNIT Negative-going voltage input 2.1 2.3 2.5 V Power-on reset hysteresis 50 125 210 mV 
   www.ti.com SLUS575 − AUGUST 2003 2.50 150 2.45 145 140 2.40 VIT− Vhys 2.35 135 2.30 130 2.25 125 2.20 120 2.15 115 2.10 −20 V hys − Hysteresis Voltage − mV V IT− − Negative-Going Input Threshold Voltage − V POR BEHAVIOR vs FREE-AIR TEMPERATURE 110 −5 10 25 40 55 70 85 TA − Free-Air Temperature − °C Figure 1 INTEGRATING ADC CHARACTERISTICS VDD = 3.0 V to 3.6 V, TA = −20°C to 85°C (unless otherwise noted) PARAMETER V(SR) V(SROS) Input voltage range, V(SR2) and V(SR1) INL Integral nonlinearity error TEST CONDITIONS VSR = V(SR2) – V(SR1) MIN TYP MAX –0.3 1.0 Input offset UNIT V µV 1 0.003% 0.009% PLL SWITCHING CHARACTERISTICS VDD = 3.0 V to 3.6 V, TA = −20°C to 85°C (unless otherwise noted) PARAMETER t(sp) Start-up time(1) (1) The frequency error is measured from 32.768 Hz. TEST CONDITIONS MIN ±0.5% frequency error TYP MAX 2 5 UNIT ms Internal Oscillator VDD = 3.0 V to 3.6 V, TA = −20°C to 85°C (unless otherwise noted) PARAMETER f(exo) Frequency error(1) TEST CONDITIONS VDD = 3.3 V f(sxo) Start-up time(2) (1) The frequency error is measured from 32.768 Hz. (2) The start-up time is defined as the time it takes for the oscillator output frequency to be ±1%. MIN TYP MAX −2% 2% −1% 1% 275 UNIT µs 5 
   www.ti.com SLUS575 − AUGUST 2003 SMBUS TIMING SPECIFICATIONS VDD = 3.0 V to 3.6 V, TA = −20°C to 85°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP UNIT 100 kHz SMBus operating frequency Slave mode, SMBC 50% duty cycle SMBus master clock frequency Master mode, no clock low slave extend tBUF thd(STA) Bus free time between start and stop 4.7 µs Hold time after (repeated) start 4.0 µs tsu(STA) tsu(STO) Repeated start setup time 4.7 µs Stop setup time 4.0 µs thd(DAT) Data hold time tsu(DA) tTIMEOUT Data setup time tlow thigh Clock low period Clock high period See Note 2 tlow(SEXT) tlow(MEXT) Cumulative clock low slave extend time Cumulative clock low master extend time Error signal/detect 10 MAX fSMB fMAS 51.2 Receive mode 0 Transmit mode 300 kHz ns 250 See Note 1 ns 25 35 ms 125 ms See Note 3 25 ms See Note 4 10 ms µs 4.7 0.05 tf Clock/data fall time See Note 5 300 ns tr Clock/data rise time See Note 6 1000 ns (1) The bq20851−V1P2 times out when any clock low exceeds tTIMEOUT (2) thigh Max. is minimum bus idle time. SMBC = 1 for t > 125 ms causes reset of any transaction involving bq20851−V1P2 that is in progress. (3) tlow(SEXT) is the cumulative time a slave device is allowed to extend the clock cycles in one message from initial start to the stop. (4) tlow(MEXT) is the cumulative time a master device is allowed to extend the clock cycles in one message from initial start to the stop. (5) Rise time, tr = (VILMAX − 0.15 V) to (VIHMIN + 0.15 V) (6) Fall time, tf = 0.9 VDD to (VILMAX − 0.15 V) DATA FLASH MEMORY SWITCHING CHARACTERISTICS VDD = 3.0 V to 3.6 V, TA = −20°C to 85°C (unless otherwise noted) PARAMETER t(RETENSION) t(WORDPROG) TEST CONDITIONS Data retention See Note 1 Flash programming write-cycles See Note 1 Word programming time See Note 1 I(DDPROG) Flash-write supply current (1) Specified by design. Not production tested. MIN TYP MAX 10 Years 105 See Note 1 UNIT Cycles 2 ms 14 16 mA TYP MAX UNIT 10 100 nA Register Backup PARAMETER I(RBI) RBI data-retention input current (1) V(RBI) RBI data-retention voltage (1) Specified by design. Not production tested. 6 TEST CONDITIONS MIN VRB > 3.0 V, VDD < VIT 1.3 V 
   www.ti.com SLUS575 − AUGUST 2003 SMBUS TIMING DIAGRAMS tlow SCLK tr thd(STA) thigh thd(DAT) thd(STA) tf tsu(STA) tsu(STO) tsu(DAT) SDATA tBUF P S S Start P Stop tlow(SEXT) SCLK(ACK)(1) SCLK(ACK)(1) tlow(MEXT) tlow(MEXT) tlow(MEXT) SCLK SDATA (1) SCLKACK is the acknowledge-related clock pulse generated by the master. Figure 2. SMBus Timing Diagram FUNCTIONAL DESCRIPTION Internal Oscillator The internal oscillator performance is additionally dependent on the tolerance of the 113k resistor connected between RSOC (pin 33) and VSSA (pin 34). It is recommended that this resistor be as close to the bq20851−V1P2 as possible and that it have a specification of ±0.1% tolerance and ±50 ppm temperature drift or better. The layout of the PCBA is also an additional contributing factor to performance degradation. The average temperature drift error of the oscillator function over a learning charge or discharge cycle introduces an equal capacity prediction error in a learned full charge capacity (FCC). General Operation The bq20851−V1P2 determines battery capacity by monitoring the amount of charge input or removed from a rechargeable battery. In addition to measuring charge and discharge, the bq20851−V1P2 measures battery voltage, temperature, and current, estimates battery self-discharge, and monitors the battery for low-voltage thresholds. The bq20851−V1P2 measures charge and discharge activity by monitoring the voltage across a small-value series sense resistor between the battery’s negative terminal and the negative terminal of the battery pack. The available battery charge is determined by monitoring this voltage and correcting the measurement for environmental and operating conditions. The bq20851−V1P2 interfaces with the bq29311 to perform battery protection, cell balancing, and voltage translation functions. The bq20851−V1P2 can accept any NTC thermistor (default is Semitec 103AT) for temperature measurement or can be configured to use its internal temperature sensor. The bq20851−V1P2 uses temperature to monitor the battery pack and to compensate the self-discharge estimate. Measurements The bq20851−V1P2 uses an integrating sigma-delta analog-to-digital converter (ADC) for current measurement and a second sigma delta ADC for battery voltage and temperature measurement. Voltage, current, and temperature measurements are made every second. Charge and Discharge Counting The integrating ADC measures the charge and discharge flow of the battery by monitoring a small-value sense resistor between the SR1 and SR2 pins as shown in the schematic. The integrating ADC measures bipolar signals from −0.3 to 1.0 V. The bq20851−V1P2 detects charge activity when VSR = V(SR1)–V(SR2) is positive and discharge activity when 7 
   www.ti.com SLUS575 − AUGUST 2003 VSR = V(SR1)–V(SR2) is negative. The bq20851−V1P2 continuously integrates the signal over time, using an internal counter. The fundamental rate of the counter is 2.6 nVh. The bq20851−V1P2 updates Remaining Capacity() with the charge or discharge accumulated in this internal counter once every second. Offset Calibration The bq20851−V1P2 provides an autocalibration feature to cancel the voltage offset error across SR1 and SR2 for maximum charge measurement accuracy. The bq20851−V1P2 performs autocalibration when the SMBus lines stay low for a minimum of 20 s. The bq20851−V1P2 is capable of automatic offset calibration down to 1µV. Digital Filter The bq20851−V1P2 does not measure charge or discharge counts below the digital filter threshold. The digital filter threshold is programmed in the Digital Filter DF 0x2b and should be set sufficiently high to prevent false signal detection with no charge or discharge flowing through the sense resistor. Voltage While monitoring SR1 and SR2 for charge and discharge currents, the bq20851−V1P2 monitors the individual series cell voltages through the bq29311. The bq20851−V1P2 configures the bq29311 to present the selected cell to the VCELL pin of the bq29311 which should be connected to VIN of the bq20851−V1P2. The internal ADC of the bq20851−V1P2 then measures the voltage and scales it appropriately. The bq20851−V1P2 then reports the Voltage( ) and the individual cell voltages in VCELL1, VCELL2, VCELL3, and VCELL4 located in 0x3c−0x3f. Current The bq20851−V1P2 uses the SR1 and SR2 inputs to measure and calculate the battery charge and discharge current as represented in the data register Current(). Temperature The TS input of the bq20851−V1P2 in conjunction with an NTC thermistor measures the battery temperature as shown in the schematic. The bq20851−V1P2 reports temperature in Temperature( ). The bq20851−V1P2 can also be configured to use its internal temperature sensor by setting the IT bit in Misc Configuration DF 0x2a. Data flash locations DF 0xa4 through DF 0xad also have to be changed to prescribed values if the internal temperature sensor option is selected. Table 1. Data Flash Settings for Internal or External Temperature Sensor LABEL LOCATION Dec (Hex) INTERNAL TEMP SENSOR SETTING Dec (Hex) EXTERNAL TEMP SENSOR SETTING (Semitec 103AT) Dec (Hex) Misc. Configuration 42 (0x2a) Bit 7 = 1 Bit 7 = 0 TS Const1 A3 164/5 (0xa4/5) 0 (0x0000) −28285 (0x9183) TS Const2 A2 166/7 (0xa6/7) 0 (0x0000) 20848 (0x5170) TS Const3 A1 168/9 (0xa8/9) −11136 (0xd480) −7537 (0xe28f) TS Const4 A0 170/1 (0xaa/b) 5734 (0x1666) 4012 (0x0fac) Min temp AD 172/3 (0xac/d) 0 (0x0000) 0 (0x000) Max temp 174/5 (0xae/f) 5734 (0x1666) 4012 (0x0fac) If AD < Min Temp AD then Temp = Max Temp else Temp = [(A3 × AD × 2^ − 16 + A2) × AD × 2 ^ −16 + A1] × AD × 2 ^ −16 + A0 8 
   www.ti.com SLUS575 − AUGUST 2003 Gas Gauge Operation General The operational overview in Figure 3 illustrates the gas gauge operation of the bq20851−V1P2. Table 3 describes the bq20851−V1P2 registers. Inputs Charge Current Battery Electronics Load Estimate Discharge Current Charge Efficiency Compensation Temperature Compensation − Main Counters and Capacity Reference (FCC) Self-Discharge Timer + − − Remaining Capacity (RM) + ≤ Full Charge Capacity (FCC) Qualified Transfer + + Discharge Count Register (DCR) Temperature, Other Data Outputs Chip-Controlled Available Charge LED Display Two-Wire Serial Port Figure 3. bq20851−V1P2 Operational Overview The bq20851−V1P2 accumulates a measure of charge and discharge currents and estimates self-discharge of the battery. The bq20851−V1P2 compensates the charge current measurement for temperature and state-of-charge of the battery. The bq20851−V1P2 also adjusts the self-discharge estimation based on temperature. The main charge counter RemainingCapacity( ) (RM) represents the available capacity or energy in the battery at any given time. The bq20851−V1P2 adjusts RM for charge, self-discharge, and other compensation factors. The information in the RM register is accessible through the SMBus interface and is also represented through the LED display. The FullChargeCapacity( ) (FCC) register represents the last measured full discharge of the battery. It is used as the battery full-charge reference for relative capacity indication. The bq20851−V1P2 updates FCC after the battery undergoes a qualified discharge from nearly full to a low battery level. FCC is accessible through the SMBus interface. The Discharge Count Register (DCR) is a non-accessible register that tracks discharge of the battery. The bq20851−V1P2 uses the DCR register to update the FCC register if the battery undergoes a qualified discharge from nearly full to a low battery level. In this way, the bq20851−V1P2 learns the true discharge capacity of the battery under system use conditions. Main Gas-Gauge Registers The gas-gauge register functions are described in Table 3. 9 
   www.ti.com SLUS575 − AUGUST 2003 RemainingCapacity( ) (RM) RM represents the remaining capacity in the battery. The bq20851−V1P2 computes RM in units of either mAh or 10 mWh depending on the selected mode. See Battery Mode( ) (0x03) for units configuration. RM counts up during charge to a maximum value of FCC and down during discharge and self-discharge to a minimum of 0. In addition to charge and self-discharge compensation, the bq20851−V1P2 calibrates RM at three low-battery-voltage thresholds, EDV2, EDV1, and EDV0 and three programmable midrange thresholds VOC25, VOC50, and VOC75. This provides a voltage-based calibration to the RM counter. DesignCapacity( ) (DC) DC is the user-specified battery full capacity. It is calculated from Pack Capacity DF 0x31-0x32 and is represented in units of mAh or 10 mWh. It also represents the full-battery reference for the absolute display mode. FullChargeCapacity( ) (FCC) FCC is the last measured discharge capacity of the battery. It is represented in units of either mAh or 10 mWh, depending on the selected mode. On initialization, the bq20851−V1P2 sets FCC to the value stored in Last Measured Discharge DF 0x35-0x36. During subsequent discharges, the bq20851−V1P2 updates FCC with the last measured discharge capacity of the battery. The last measured discharge of the battery is based on the value in the DCR register after a qualified discharge occurs. Once updated, the bq20851−V1P2 writes the new FCC value to data flash in mAh to Last Measured Discharge. FCC represents the full battery reference for the relative display mode and relative state of charge calculations. Discharge Count Register (DCR) The DCR register counts up during discharge, independent of RM. DCR counts discharge activity, battery load estimation, and self-discharge increment. The bq20851−V1P2 initializes DCR, at the beginning of a discharge, to FCC − RM when RM is within the programmed value in Near Full DF 0x2f. The DCR initial value of FCC − RM is reduced by FCC/128 if SC = 1 (bit 5 in Gauge Configuration) and is not reduced if SC = 0. DCR stops counting when the battery voltage reaches the EDV2 threshold on discharge. Capacity Learning (FCC Update) and Qualified Discharge The bq20851−V1P2 updates FCC with an amount based on the value in DCR if a qualified discharge occurs. The new value for FCC equals the DCR value plus the programmable nearly full and low battery levels, according to the following equation: FCC (new) + DCR (final) + DCR (initial) ) Measured Discharge to EDV2 ) (FCC Battery Low%) (1) Battery Low % = ((value stored in DF 0x2e [MSByte] and 0xE3[LSByte]) x 2.56)/655.36 A qualified discharge occurs if the battery discharges from RM ≥ FCC – Near Full to the EDV2 voltage threshold with the following conditions: D No valid charge activity occurs during the discharge period. A valid charge is defined as a charge of 10 mAh into the battery. D D No more than 256 mAh of self-discharge or battery load estimation occurs during the discharge period. D The battery voltage reaches the EDV2 threshold during the discharge period and the voltage is greater than or equal to the EDV2 threshold minus 256 mV when the bq20851−V1P2 detected EDV2. D D D No midrange voltage correction occurs during the discharge period. The temperature does not drop below the low temperature thresholds programmed in Learning Low Temp DF 0x9b during the discharge period. Current remains ≥ 3C/32 when EDV2 or Battery Low % level is reached. No overload condition exists when EDV2 threshold is reached or if RM( ) has dropped to Battery Low% *FCC. The bq20851−V1P2 sets VDQ=1 in pack status when qualified discharge begins. The bq20851−V1P2 sets VDQ=0 if any disqualifying condition occurs. FCC cannot be reduced by more than 256 mAh or increased by more than 512 mAh during any single update cycle. The bq20851−V1P2 saves the new FCC value to the data flash immediately. 10 
   www.ti.com SLUS575 − AUGUST 2003 End-of-Discharge Thresholds and Capacity Correction The bq20851−V1P2 monitors each cell for four low-voltage thresholds. From highest to lowest, these are EDV2, EDV1, EDV0 and Cell Under Voltage. EDV2 and EDV1 are calculated as a function of the various CEDV coefficients along with the present discharge rate, temperature and relative state of charge (RSOC). EDV2 is the variable voltage threshold that corresponds to the RSOC value stored in Battery Low %. This is typically 3−4%. EDV1 is the variable voltage threshold that corresponds to RSOC = 0%. EDV0 and Cell Under Voltage are typically fixed at 3.0 V and 2.75 V respectively. EDV0 sets the Terminate Discharge Alarm (TDA) bit. Cell Under Voltage causes shutdown of both the bq20851−V1P2 and the bq29311. The various low-voltage thresholds are determined on the basis of the lowest single-cell voltage. The bq20851−V1P2 disables EDV detection if Current( ) exceeds the Overload Current threshold programmed in DF 0x58 − DF 0x59. The bq20851−V1P2 resumes EDV threshold detection after Current( ) drops below the Overload Current threshold. Any EDV threshold detected is reset after charge is applied and VDQ is cleared after 10 mAh of charge. Table 2. State of Charge Based on Low Battery Voltage THRESHOLD RELATIVE STATE OF CHARGE EDV0 0% (Terminate Discharge Alarm) EDV1 0% (Fully Discharged Flag) EDV2 Battery Low % The bq20851−V1P2 uses the EDV thresholds to apply voltage-based corrections to the RM register according to Table 2. The bq20851−V1P2 adjusts RM as it detects each threshold. If the voltage threshold is reached before the corresponding capacity on discharge, the bq20851−V1P2 reduces RM to the appropriate amount as shown in Table 2. If RM reaches the capacity level before the voltage threshold is reached on discharge, the bq20851−V1P2 prevents RM from decreasing further until the battery voltage reaches the corresponding threshold. If 0% RSOC occurs before the EDV1 threshold voltage is reached, then the Fully Discharged (FD) bit will be set. This is to accommodate the case of a partial charge/discharge cycle. When a partial charge is performed, the portion of the cell lattice structure that receives the charge has a lower series resistance than the sections that are charged later in the charge cycle. The subsequent discharge therefore provides a higher voltage as a function of remaining capacity than would be the case after a full charge. The coulometric value is more accurate than the voltage in this case. Table 3. bq20851−V1P2 Register Functions FUNCTION COMMAND CODE ACCESS UNITS ManufacturerAccess 0x00 read/write NA RemainingCapacityAlarm 0x01 read/write mAh, 10 mWh RemainingTimeAlarm 0x02 read/write minutes BatteryMode 0x03 read/write NA AtRate 0x04 read/write mA, 10mW AtRateTimeToFull 0x05 read minutes AtRateTimeToEmpty 0x06 read minutes AtRateOK 0x07 read Boolean Temperature 0x08 read 0.1°K Voltage 0x09 read mV Current 0x0a read mA AverageCurrent 0x0b read mA MaxError 0x0c read percent RelativeStateOfCharge 0x0d read percent AbsoluteStateOfCharge 0x0e read percent RemainingCapacity 0x0f read mAh, 10 mWh FullChargeCapacity 0x10 read mAh, 10 mWh RunTimeToEmpty 0x11 read minutes AverageTimeToEmpty 0x12 read minutes AverageTimeToFull 0x13 read minutes 11 
   www.ti.com SLUS575 − AUGUST 2003 Table 3. bq20851−V1P2 Register Functions (Continued) FUNCTION COMMAND CODE ACCESS UNITS ChargingCurrent 0x14 read mA ChargingVoltage 0x15 read mV Battery Status 0x16 read NA CycleCount 0x17 read cycles DesignCapacity 0x18 read mAh, 10 mWh DesignVoltage 0x19 read mV SpecificationInfo 0x1a read NA ManufactureDate 0x1b read NA SerialNumber 0x1c read integer Reserved 0 0 ManufacturerName 0x1d-0x1f 0x20 read string DeviceName 0x21 read string DeviceChemistry 0x22 read string ManufacturerData 0x23 read string Pack status 0x2f (LSB) read NA Pack configuration 0x2f (MSB) read NA VCELL4 0x3c read mV VCELL3 0x3d read mV VCELL2 0x3e read mV VCELL1 0x3f read mV Self-Discharge The bq20851−V1P2 estimates the self-discharge of the battery to maintain an accurate measure of the battery capacity during periods of inactivity. The bq20851−V1P2 makes self-discharge adjustments to RM( ) every 1/4 seconds when awake and periodically when in sleep mode. The period is determined by Sleep Timer DF 0xe7. The self-discharge estimation rate for 25°C is doubled for each 10 degrees above 25°C or halved for each 10 degrees below 25°C. The following table shows the relation of the self-discharge estimation at a given temperature to the rate programmed for 25°C (Y% per day programmed in DF 0x2c). Table 4. Self-Discharge for Rate Programmed 12 TEMPERATURE (°C) SELF-DISCHARGE RATE Temp < 10 1/4 Y% per day 10 ≤ Temp Terminate Voltage, Charging Current > 0, and the CVUV bit is cleared. REMAINING_CAPACITY_ALARM bit is set when the bq20851−V1P2 detects that RemainingCapacity( ) is less than that set by the RemainingCapacityAlarm( ) function. This bit is cleared when either the value set by the RemainingCapacityAlarm( ) function is lower than the RemainingCapacity( ) or when the RemainingCapacity( ) is increased by charging. REMAINING_TIME_ALARM bit is set when the bq20851−V1P2 detects that the estimated remaining time at the present discharge rate is less than that set by the RemainingTimeAlarm( ) function. This bit is cleared when either the value set by the RemainingTimeAlarm( ) function is lower than the AverageTimeToEmpty( ) or when the AverageTimeToEmpty( ) is increased by charging. Status Bits The initialized bit is set when the bq20851−V1P2 is has detected a valid load of data flash at full or partial reset. It is cleared when the bq20851−V1P2 detects an improper data flash load. 32 
   www.ti.com SLUS575 − AUGUST 2003 DISCHARGING bit is set when the bq20851−V1P2 determines that the battery is not being charged. This bit is cleared when the bq20851−V1P2 detects that the battery is being charged. FULLY_CHARGED bit is set when the bq20851−V1P2 detects a primary charge termination or an Overcharge condition. It is cleared when RelativeStateOfCharge( ) is less than the programmed Fully Charged Clear % in DF 0x47. FULLY_DISCHARGED bit is set when Voltage( ) or VCELL is less than the EDV1 threshold and Current( ) < Overload Current or when RelativeStateOfCharge( ) < Battery Low %. This bit is cleared when RelativeStateOfCharge( ) is greater than or equal to 20%. Error Codes ERROR CODES DESCRIPTION OK The bq20851−V1P2 processed the function code without detecting any errors. Busy The bq20851−V1P2 is unable to process the function code at this time. Reserved The bq20851−V1P2 detected an attempt to read or write to a function code reserved by this version of the specification. The bq20851−V1P2 detected an attempt to access an unsupported optional manufacturer function code. Unsupported The bq20851−V1P2 does not support this function code which is defined in this version of the specification. AccessDenied The bq20851−V1P2 detected an attempt to write to a read-only function code. Over/Underflow The bq20851−V1P2 detected a data overflow or underflow. BadSize The bq20851−V1P2 detected an attempt to write to a function code with an incorrect data block. UnknownError The bq20851−V1P2 detected an unidentifiable error. CycleCount( )(0x17) Description: Returns the number of cycles the battery has experienced. The mAh value of each count is determined by programming the Cycle Count Threshold value in DF 0x37-0x38. The bq20851−V1P2 saves the cycle count value to Cycle Count DF 0x0c-0x0d after an update to CycleCount( ). Purpose: The CycleCount( ) function provides a means to determine the battery wear. It may be used to give advance warning that the battery is nearing its end of life. SMBus protocol: Read word Output: Unsigned integer—count of total charge removed from the battery over its life. Units: cycle Range: 0 to 65,534 cycles; 65,535 indicates battery has experienced 65,535 or more cycles. Granularity: 1 cycle Accuracy: Absolute count DesignCapacity( ) (0x18) Description: Returns the theoretical or nominal capacity of a new pack. The DesignCapacity( ) value is expressed in either current (mAh at a C/5 discharge rate) or power, (10 mWh at a P/5 discharge rate) depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. Purpose: The DesignCapacity( ) function is used by the SMBus host’s power management in conjunction with FullChargeCapacity( ) to determine battery wear. The power management system may present this information to the user and also adjust its power policy as a result. SMBus protocol: Read word Output: Unsigned integer—battery capacity in units of mAh or 10 mWh. BATTERY MODES CAPACITY_MODE BIT = 0 CAPACITY_MODE BIT = 1 Units mAh 10 mWh Range 0–65,535 mAh 0–65,535 10 mWh Granularity Not applicable Not applicable Accuracy Not applicable Not applicable 33 
   www.ti.com SLUS575 − AUGUST 2003 DesignVoltage( ) (0x19) Description: Returns the theoretical voltage of a new pack (mV). The bq20851−V1P2 sets DesignVoltage( ) to the value programmed in Design Voltage DF 0x04−0x05. Purpose: The DesignVoltage( ) function can be used to give additional information about a particular smart battery expected terminal voltage. SMBus protocol: Read word Output: Unsigned integer—the battery’s designed terminal voltage in mV Units: mV Range: 0 to 65,535 mV Granularity: Not applicable Accuracy: Not applicable SpecificationInfo( ) (0x1a) Description: Returns the version number of the smart battery specification the battery pack supports, as well as voltage and current scaling information in a packed unsigned integer. Power scaling is the product of the voltage scaling times the current scaling. The SpecificationInfo is packed in the following fashion: (SpecID_H * 0x10 + SpecID_L) + (VScale + IPScale * 0x10) * 0x100. The bq20851−V1P2 VScale (voltage scaling) and IPScale (current scaling) should always be set to zero. The bq20851−V1P2 sets SpecificationInfo( ) to the value programmed in Specification Information DF 0x06-0x07. Purpose: The SpecificationInfo( ) function is used by the SMBus host’s power management system to determine what information the smart battery can provide. SMBus protocol: Read word Output: Unsigned integer—packed specification number and scaling information: FIELD BITS USED FORMAT ALLOWABLE VALUES SpecID_L 0...3 4-bit binary value 0–15 SpecID_H 4...7 4-bit binary value 0–15 VScale 8...11 4-bit binary value 0 (multiplies voltage by 10^ VScale) IPScale 12...15 4-bit binary value 0 (multiplies current by 10 ^ IPScale) ManufactureDate( ) (0x1b) Description: This function returns the date the cell pack was manufactured in a packed integer. The date is packed in the following fashion: (year-1980) * 512 + month * 32 + day. The bq20851−V1P2 sets ManufactureDate( ) to the value programmed in Manufacture Date DF 0x08−0x09. Purpose: The ManufactureDate( ) provides the system with information that can be used to uniquely identify a particular battery pack when used in conjunction with SerialNumber( ). SMBus protocol: Read word Output: Unsigned integer-packed date of manufacture: FIELD BITS USED FORMAT ALLOWABLE VALUES Day 0...4 5-bit binary value 0–31 (corresponds to date) Month 5...8 4-bit binary value 1–12 (corresponds to month number) Year 9...15 7-bit binary value 0−127 (corresponds to year biased by 1980) SerialNumber( ) (0x1c) Description: This function is used to return a serial number. This number, when combined with the ManufacturerName( ), the DeviceName( ), and the ManufactureDate( ), uniquely identifies the battery (unsigned integer). The bq20851−V1P2 sets SerialNumber( ) to the value programmed in Serial Number DF 0x0a−0x0b. Purpose: The SerialNumber( ) function can be used to identify a particular battery. This may be important in systems that are powered by multiple batteries where the system can log information about each battery that it encounters. 34 
   www.ti.com SLUS575 − AUGUST 2003 SMBus protocol: Read word Output: Unsigned integer ManufacturerName( ) (0x20) Description: The bq20851−V1P2 has an internal prefixed manufacturer name ( ). This value cannot be changed. Purpose: The ManufacturerName( ) function returns the name of the smart battery manufacturer. The manufacturer’s name can be displayed by the SMBus host’s power management system display as both an identifier and as an advertisement for the manufacturer. The name is also useful as part of the information required to uniquely identify a battery. SMBus protocol: Read block Output: String—character string with maximum length of 11 characters (11 + length byte). DeviceName( ) (0x21) Description: This function returns a character string that contains the battery name. For example, a DeviceName( ) of bq20851−V1P2 indicates that the battery is a model bq20851−V1P2. The bq20851−V1P2 sets DeviceName( ) to the value programmed in Device Name Length DF 0x1a-0x21. Purpose: The DeviceName( ) function returns the battery name for identification purposes. SMBus protocol: Read block Output: String—character string with maximum length of 7 characters (7 + length byte). DeviceChemistry( ) (0x22) Description: This function returns a character string that contains the battery chemistry. For example, if the DeviceChemistry( ) function returns NiMH, the battery pack contains nickel metal hydride cells. The bq20851−V1P2 sets DeviceChemistry( ) to the value programmed in Device Chemistry Length DF 0x22−0x26. Purpose: The DeviceChemistry( ) function gives cell chemistry information for use by charging systems. The bq20851−V1P2 does not use DeviceChemisty( ) values for internal charge control or fuel gauging. SMBus protocol: Read block Output: String—character string with maximum length of 4 characters (4 + length byte). The following is a partial list of chemistries and their expected abbreviations. These abbreviations are not case sensitive. Lead acid PbAc Lithium ion LION Nickel cadmium NiCd Nickel metal hydride NiMH Nickel zinc NiZn Rechargeable alkaline-manganese RAM Zinc air ZnAr The ManufacturerData( ) (0x23) Description: This function allows access to the manufacturer data contained in the battery (data). The bq20851−V1P2 stores seven critical operating parameters in this data area. Purpose: The ManufacturerData( ) function may be used to access the manufacturer’s data area. The data fields of this command reflect the programming of eight critical data flash locations and can be used to facilitate evaluation of the bq20851−V1P2 under various programming sets. The ManufacturerData( ) function returns the following information in order: Pack Configuration, Gauge Configuration, Misc Configuration, Digital Filter, Self Discharge Rate, Pack Load Estimate, Battery Low%, and Near Full (2 bytes) AFE Status, and the pending EDV threshold voltage (low byte and high byte). SMBus protocol: Read block Output: Block data—data that reflects data flash programming as assigned by the manufacturer with maximum length of 13 characters (12 + length byte). 35 
   www.ti.com SLUS575 − AUGUST 2003 Pack Status and Pack Configuration (0x2f) This function returns the pack status and pack configuration registers. The pack status register contains a number of status bits relating to bq20851−V1P2 operation. The pack status register is the least significant byte of the word. The pack configuration register reflects how the bq20851−V1P2 is configured as defined by the value programmed in Pack Configuration in DF 0x28. The pack status register consists of the following bits: b7 b6 b5 b4 AFE EDV2 SS VDQ b3 b2 b1 b0 0 SOV CVOV CVUV AFE The AFE bit indicates whether the bq29311 RAM integrity check has failed. 0 1 bq29311 integrity check passed bq29311 integrity check failed EDV2 The EDV2 bit indicates that pack or cell voltage (program option) is less than the EDV2 threshold. 0 1 Voltage > EDV2 threshold (discharging) Voltage ≤ EDV2 threshold SS The SS bit indicates the seal state of the bq20851−V1P2. 0 1 The bq20851−V1P2 is in the unsealed state. The bq20851−V1P2 is in the sealed state. VDQ The VDQ bit indicates if the present discharge cycle is valid for an FCC update. 0 1 Discharge cycle not valid Discharge cycle valid SOV The SOV bit indicates that the safety output limits have been exceeded. Once set, the flag stays set until the bq20851−V1P2 is reset. 0 Safety limits not exceeded 1 Safety limits exceeded CVOV The CVOV bit indicates that a protection limit has been exceeded. It is set on a Prolonged Overcurrent, Overvoltage, or Overtemperature condition. The bit is not latched and merely reflects the present fault status. 0 No secondary protection limits exceeded 1 A secondary protection limit exceeded CVUV The CVUV bit indicates that a protection limit has been exceeded. It is set on an overload or overdischarge condition. The bit is not latched and merely reflects the present fault status. 0 No secondary protection limits exceeded 1 A secondary protection limit exceeded VCELL4-VCELL1 (0x3c-0x3f) These functions return the calculated individual cell voltages in mV. 36 
   www.ti.com SLUS575 − AUGUST 2003 DATA FLASH General The bq20851−V1P2 accesses the internal data flash during reset and when storing historical data. The data flash stores basic configuration information for use by the bq20851−V1P2. The data flash must be programmed correctly for proper bq20851−V1P2 operation. Memory Map Table 10 shows the memory map for the data flash. It shows the default programming for the bq20851−V1P2. The default programming reflects example data for a 3s2p Li-Ion battery pack with a 0.02-Ω sense resistor. The data flash must be reprogrammed to meet the requirements of individual applications. Table 10. Data Flash Memory Map DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI-ION EXAMPLE MSB LSB 0x00 0x01 Remaining Time Alarm 10 minutes 00 0a 0x02 0x03 Remaining Capacity Alarm 360 mAh 01 68 0x04 0x05 Design Voltage 10800 mV 2a 30 0x06 0x07 Specification Information v1.1/PEC 00 31 0x08 0x09 Manufacture Date 2/15/02=11343 2c 4f 0x0a 0x0b Serial Number 1 00 01 0x0c 0x0d Cycle Count 0 00 00 0x0e Manufacturer Name Length 5 5 0x0f Character 1 0x10 Character 2 0x11 Character 3 0x12 Character 4 0x13 Character 5 0x14 Character 6 0x15 Character 7 0x16 Character 8 0x17 Character 9 0x18 Character 10 0x19 Character 11 0x1a Device Name Length 6 06 0x1b Character 1 b 42 0x1c Character 2 q 51 0x1d Character 3 2 32 0x1e Character 4 0 30 0x1f Character 5 8 38 0x20 Character 6 5 0x21 Character 7 1 0x22 Device Chemistry Length 4 0x23 Character 1 L 4c 0x24 Character 2 I 49 0x25 Character 3 O 4f 0x26 Character 4 N 4e 04 0x27 Manufacturer Data Length 12 09 NOTE: Reserved locations must be set as shown. Locations marked with an * are typical calibration values that can be adjusted for maximum accuracy. For these locations the table shows the appropriate default or initial setting. 37 
   www.ti.com SLUS575 − AUGUST 2003 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI-ION EXAMPLE MSB LSB 0x28 Pack Configuration DMODE, LED1, CC1 c2 0x29 Gauge Configuration CSYNC 40 0x2a Misc Configuration VOD 01 0x2b Digital Filter 9860 nV 22 0x2c Self-Discharge Rate 0.2% 14 0x2d Electronics Load 0 mA 00 0x2e Battery Low % (MSB) 7.03% 12 0x2f 0x30 Near Full 200 mAh 00 c8 0x31 0x32 Design Capacity 3600 mAh 0e 10 0x33 0x34 Reserved 0 00 00 0x35 0x36 Last Measured Discharge 3600 mAh 0e 10 0x37 0x38 Cycle Count Threshold 2880 mAh 0b 40 0x39 0x3a Charging Voltage 12600 mV 31 38 0x3b 0x3c Precharge Voltage 8000 mV 1f 40 0x3d 0x3e Fast-Charging Current 2500 mA 09 c4 0x3f 0x40 Maintenance Charging Current 0 mA 00 00 0x41 0x42 00 64 Precharge Current 100 mA 0x43 Precharge Temp 9.6°C 0x44 Reserved 0x45 Reserved 0x46 Fast Charge Termination % 100% 0x47 60 1e 00 ff Fully Charged Clear % 95% 0x48 0x49 Current Taper Threshold 240 mA 00 5f f0 0x4a 0x4b Current Taper Qual Voltage 100 mV 00 64 0x4c Reserved 28 0x4d Reserved 40 0x4e 0x4f Maximum Overcharge 0x50 Reserved 0x51 Charge Efficiency 0x52 0x53 300 mAh 01 100% ff Reserved 0x54 0x55 2c 02 64 MaxTemperature 54.6°C Temperature Hysteresis 5°C 0x56 0x57 Reserved 0x58 0x59 Overload Current 0x5a 0x5b 0x5c 0x5d 0x5e 0x5f Reserved 0x60 0x61 Cell Over Voltage 4350 mV 0x62 0x63 Cell Under Voltage 0x64 0x65 Terminate Voltage 0x66 0x67 Reserved 0x68 0x69 Safety Over Voltage 0x6a 0x6b Safety Over Temperature 02 22 32 01 ae 5000 mA 13 88 Over Voltage Margin 208 mV 00 d0 Overcurrent Margin 500 mA 01 f4 01 00 10 fe 2300 mV 08 fc 8500 mV 21 34 00 00 20000 mV 4e 20 70°C 02 bc NOTE: Reserved locations must be set as shown. Locations marked with an * are typical calibration values that can be adjusted for maximum accuracy. For these locations the table shows the appropriate default or initial setting. 38 
   www.ti.com SLUS575 − AUGUST 2003 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE LOW BYTE 0x6c LI-ION EXAMPLE MSB Reserved 0x6d 0x6e DATA NAME ef Reserved 0x6f VOC75 LSB 03 11890 mV 2e 72 0x70 Reserved bf 0x71 Reserved 56 0x72 Reserved 0x73 0x74 VOC50 40 11430 mV 2c a6 0x75 Reserved 7f 0x76 Reserved 3d 0x77 0x78 Reserved 0x79 VOC25 27 11270 mV 2c 06 0x7a Reserved 3f 0x7b Reserved 24 0x7c Reserved 0e 0x7c Reserved 14 0x7e Reserved 40 0x7f 0x80 Reserved 0b e1 0x81 0x82 Reserved 0b 68 0x83 Reserved 19 0x84 0x85 EMF/EDV0 3000 mV 0b b8 0x86 0x87 EDV C0 Factor/EDV1 3250 mV 0c b2 0x88 0x89 EDV R0 Factor/EDV2 3400 mV 0d 48 0x8a 0x8b EDV T0 Factor 0 00 00 0x8c 0x8d EDV R1 Factor 0 00 00 0x8e EDV TC Factor 0 00 0x8f EDV C1 Factor 0 00 0x90 Reserved 08 0x91 Reserved 9b 0x92 Reserved c7 0x93 Reserved 64 0x94 Reserved 14 0x95 0x96 Reserved 02 00 0x97 0x98 Reserved 01 00 0x99 Reserved 08 0x9a Reserved 02 0x9b Learning Low Temp 0x9c Reserved 11.9°C 77 0a 0x9d 0x9e Reserved 01 80 0x9f 0xa0 Reserved 01 00 0xa1 Reserved 08 0xa2 Reserved 18 0xa3 Reserved 14 NOTE: Reserved locations must be set as shown. Locations marked with an * are typical calibration values that can be adjusted for maximum accuracy. For these locations the table shows the appropriate default or initial setting. 39 
   www.ti.com SLUS575 − AUGUST 2003 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI-ION EXAMPLE MSB LSB 0xa4 0xa5 TS Const 1 91 83 0xa6 0xa7 TS Const 2 51 70 0xa8 0xa9 TS Const 3 e2 8f 0xaa 0xab TS Const 4 0f ac 0xac 0xad TS Const 5 00 00 0xae 0xaf Reserved 0f ac 0xb0 Reserved 32 0xb1 AFE Brnout Shutdn Shutdown = 6.475, Brownout = 7.975 V 00 0xb2 AFE Over Curr Dsg 140 mV 12 0xb3 AFE Over Curr Chg 70 mV 04 0xb4 AFE Over Curr Delay Charge = 31 ms, Discharge = 31 ms 0xb5 Reserved 0xb6 AFE Short Circ Thrsh 275 mV ff 00 07 AFE Short Circuit Delay 61 µs (charge and discharge) 0xb8 0xb9 AFE Vref* 9750 mV 26 16 0xba 0xbb Sense Resistor Gain* 0.02 Ω 3b d0 0xbc 0xbd CC Delta* 0.0001298 mAh 94 08 0xbe 0xbf CC Delta* b1 c0 0xb7 0xc0 0xc1 11 Reserved 0xc2 fa CC Offset* 1528 0xc3 DSC Offset* 15 0xc4 ADC Offset* 16 11 0xc5 Temperature Offset* 0 00 Board Offset* 0 0xc6 05 f8 10 00 0xc7 0xc8 Reserved 00 40 0xc9 0xca Reserved 01 00 0xcb 0xcc Reserved 0xcd 0xce Version 05 1.1 Reserved 01 01 00 32 0xcf 0xd0 Cell Over Voltage Reset 4150 mV 10 36 0xd1 0xd2 Cell Under Voltage Reset 3000 mV 0b b8 0xd3 0xd4 AFE Fail Limit 2 counts 00 02 0xd5 0xd6 Reserved 0xd7 0xd8 Cell Balance Thresh 0xd9 0xda 0xdb 0xdc ff ff 3900 mV 0f 3c Cell Balance Window 100 mV 00 64 Cell Balance Min 40 mV Cell Balance Interval 20 seconds 28 14 0xdd 0xde Reserved a5 5a 0xdf 0xd0 Reserved 7a 43 0xe1 0xe2 Reserved 20 83 0xe3 Battery Low % (LSB) 0xe4 AFE Check Time 0 seconds 00 00 0xe5 Sleep Current Thresh 2 mA 04 NOTE: Reserved locations must be set as shown. Locations marked with an * are typical calibration values that can be adjusted for maximum accuracy. For these locations the table shows the appropriate default or initial setting. 40 
   www.ti.com SLUS575 − AUGUST 2003 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI-ION EXAMPLE MSB LSB 0xe6 Sleep Current Time 20 seconds 14 0xe7 Sleep Time 5 counts 05 0xe8 LED Delay 6 ms 6 0xe9 LED Flash 6 ms 6 0xea LED Blink 96 ms 60 0xeb 0xec LED Hold Time 640 ms 280 0xed 0xee LED No Display 0 mAh 00 0xef Flash Threshold 10% 0a 0xf0 LED1 Threshold 30% 1e 0xf1 LED2 Threshold 50% 32 0xf2 LED3 Threshold 70% 46 0xf3 LED4 Threshold 88% 58 0xf4 LED5 Threshold 100% 64 0xf5 Shutdown Timer 20 s 14 EDV0 Threshold 3000 mV 0xf6 0xf7 0xf8 0xf9 Reserved 0xfa EDV1 minimum 3100 mV 0b b8 00 05 0c 1c : NOTE Reserved locations must be set as shown. Locations marked with a * are typical calibration values that can be adjusted for maximum accuracy. For these locations the table shows the appropriate default or initial setting. 41 
   www.ti.com SLUS575 − AUGUST 2003 PROGRAMMING INFORMATION DATA FLASH PROGRAMMING The following sections describe the function of each data flash location and how the data is to be stored. Fundamental Parameters Sense Resistor Value The 32-bit CC Delta DF 0xbc−0xbf corrects the coulomb counter for sense resistor variations. It represents the gain factor for the coulomb counter. The 16-bit Sense Resistor Gain in DF 0xba-0xbb scales each integrating converter conversion to mAh. The Current( ) related measurement Sense Resistor Gain is based on the resistance of the series sense resistor. The following formula computes a nominal or starting value for Sense Resistor Gain from the sense resistor value. (2) Sense Resistor Gain + 306.25 Rs Digital Filter The desired digital filter threshold, VDF (V), is set by the value stored in Digital Filter DF 0x2b. Digital Filter + VDF 290 nV (3) Cell and Pack Characteristics Battery Pack Capacity and Voltage Pack capacity in mAh units is stored in Design Capacity, DF 0x31−0x32. In mAh mode, the bq20851−V1P2 copies Design Capacity to DesignCapacity( ). In mWh mode, the bq20851−V1P2 multiplies Design Capacity by Design Voltage DF 0x04−0x05 to calculate DesignCapacity( ) scaled to 10 mWh. Design Voltage is stored in mV. The initial value for Last Measured Discharge, in mAh, is stored in DF 0x35−0x36. Last Measured Discharge is modified over the course of pack usage to reflect cell aging under the particular use conditions. The bq20851−V1P2 updates Last Measured Discharge in mAh after a capacity learning cycle. The bq20851−V1P2 uses the Last Measured Discharge value to calculate FullChargeCapacity( ) in units of mAh or 10 mWh. Remaining Time and Capacity Alarms Remaining Time Alarm in DF 0x00-0x01 and Remaining Capacity Alarm in 0x02-0x03 set the alarm thresholds used in the SMBus command codes 0x01 and 0x02, respectively. Remaining Time Alarm is stored in minutes and Remaining Capacity Alarm in units of mAh or 10 mWh, depending on the BatteryMode( ) setting. EDV Thresholds and Near Full Percentage The bq20851−V1P2 uses three pack-voltage thresholds to provide voltage-based warnings of low battery capacity. The bq20851−V1P2 uses the values stored in data flash for the EDV1 and EDV2 values or calculates the three thresholds from a base value and the temperature, capacity, and rate adjustment factors stored in data flash. EDV1 has a minimum value as defined in data flash locations 0xf9−0xfa. If EDV compensation is disabled then EDV1 and EDV2 are stored directly in mV DF 0x86−0x87 and DF 0x88−0x89, respectively. EDV0 is always set to the value programmed in DF 0xf6, 0xf7 regardless of the fixed or compensated EDV selection. For capacity correction at EDV2, Battery Low % DF 0x2e, 0xe3 can be set at a desired state-of-charge, STATEOFCHARGE%, in the range of 3-19%. Typical values for STATEOFCHARGE% are 5-7%, representing 5-7% capacity. Battery Low % = (STATEOFCHARGE% × 633.56) (4) The bq20851−V1P2 updates FCC if a qualified discharge occurs from a near-full threshold of FCC − Near Full, until EDV2 condition is reached. The desired near-full threshold window is programmed in Near Full in DF 0x2f, 0x30 in mAh. EDV Discharge Rate and Temperature Compensation If EDV compensation is enabled, the bq20851−V1P2 calculates battery voltage to determine EDV1 and EDV2 thresholds as a function of battery capacity, temperature, and discharge load. The general equation for EDV0, EDV1, and EDV2 calculation is: 42 
   www.ti.com SLUS575 − AUGUST 2003 EDV1,2 = n (EMF • FBL - | ILOAD | • R0 • FTZ) (5) EMF is a no-load cell voltage higher than the highest cell EDV threshold computed. EMF is programmed in mV in EMF/EDV1 DF 0x84−0x85. ILOAD is the current discharge load magnitude. n = the number of series cells FBL is the factor that adjusts the EDV voltage for battery capacity and temperature to match the no-load characteristics of the battery. FBL = f ( C0, C + C1, T ) (6) C (either 0%, 3%, or Battery Low % for EDV0, EDV1, and EDV2, respectively) and C0 are the capacity- related EDV adjustment factors. C0 is programmed in EDV C0 Factor/EDV1 DF 0x86−87. C1 is the desired residual battery capacity remaining at EDV0 (RM = 0). The C1 factor is stored in EDV C1 Factor DF 0x8f. T is the current temperature in °K. R0 • FTZ represents the resistance of a cell as a function of temperature and capacity. FTZ = f ( R1 , T0, T, C + C1, TC) (7) R0 is the first order rate dependency factor stored in EDV R0 Factor/EDV2 DF 0x88−0x89. T is the current temperature; C is the battery capacity relating to EDV0, EDV1, and EDV2. R1 adjusts the variation of impedance with battery capacity. R1 is programmed in EDV R1 Rate Factor DF 0x8c-0x8d. T0 adjusts the variation of impedance with battery temperature. T0 is programmed in EDV T0 Rate Factor DF 0x8a−0x8b. TC adjusts the variation of impedance for cold temperatures (T < 23°C). TC is programmed in EDV TC DF 0x8e. Typical values for the EDV compensation factors, based on overall pack voltages for a Li-lon 3s2p 18650 pack, are EMF = 11550/3 T0 = 4475 C0 = 235 C1 = 0 R0 = 5350/3 R1 = 250 TC = 3 The graphs in Figures 8 and 9 show the calculated EDV0, EDV1, and EDV2 thresholds versus capacity using the typical compensation values for different temperatures and loads for a Li-Ion 3s2p 18650 pack. The compensation values vary widely for different cell types and manufacturers and must be matched exactly to the unique characteristics for optimal performance. 43 
   www.ti.com SLUS575 − AUGUST 2003 VOLTAGE vs CAPACITY VOLTAGE vs CAPACITY 11.5 11.5 Battery Low % = 7% Load = 500 mA 11.0 20°C EDV2 EDV2 10.5 45°C 10.5 Battery Low % = 7% TA = 35°C 11.0 500 mA EDV1 V − Voltage − V V − Voltage − V EDV1 10.0 9.5 9.0 8.5 10.0 1A 2A 9.5 9.0 8.5 8.0 8.0 7.5 EDV0 7.5 7.0 0 1 2 3 4 5 6 7 8 9 10 Capacity − % Figure 8. EDV Calculations vs Capacity for Various Temperatures 0 1 2 3 4 5 6 7 8 9 10 Capacity − % Figure 9. EDV Calculations vs Capacity for Various Loads Overload Current Threshold The overload protection disables discharge when the 16-bit limit programmed in DF 0x58−0x59 is breached. The threshold is stored in mA. Midrange Capacity Corrections Three voltage-based thresholds, VOC25 DF 0x78−0x79, VOC50 DF 0x73−0x74, and VOC75 DF 0x6e−0x6f, are used to test the accuracy of the RM based on open-circuit pack voltages. These thresholds are stored in the data flash in mV. The values represent the open-circuit battery voltage at which the battery capacity should correspond to the associated state of charge for each threshold. Self-Discharge Rate The nominal self-discharge rate, %PERDAY (% per day), is programmed in an 8-bit value Self-Discharge Rate DF 0x2c by the following relation: (8) Self-Discharge Rate + %PERDAY 0.01 Charge Efficiency The bq20851−V1P2 applies the efficiency factor, EFF%, to all charge added to the battery. EFF% is encoded in Charge Efficiency DF 0x51 according to equation 16: Charge Efficiency + (EFF% • 2.56–1) (9) Other Compensation Battery Electronics Load The amount of internal battery electronics load estimate in µA, BEL, is stored in Electronics Load DF 0x2d as follows: Electronics Load + BEL 3 Change Control Charging Voltage The 16-bit value, Charging Voltage DF 0x39−0x3a programs the ChargingVoltage( ) value broadcast to a smart charger. It also sets the base value for determining overvoltage conditions during charging and voltage compliance during a constant-voltage charging methodology. It is stored in mV. 44 
   www.ti.com SLUS575 − AUGUST 2003 Over Voltage The 16-bit value, Over Voltage Margin DF 0x5a−0x5b, sets the limit over ChargingVoltage( ) in mV that is to be considered as an overvoltage charge-suspension condition. Charging Current ChargingCurrent( ) values are either broadcast to a Level 2 smart battery charger or read from the bq20851−V1P2 by a Level 3 smart battery charger. The bq20851−V1P2 sets the value of ChargingCurrent( ), depending on the charge requirements and charge conditions of the pack. When fast charge is allowed, the bq20851−V1P2 sets ChargingCurrent( ) to the rate programmed in Fast-Charging Current DF 0x3d−0x3e. Fast-Charging Current is stored in mA. When fast charge terminates, the bq20851−V1P2 sets ChargingCurrent( ) to zero and then to the Maintenance Charging Current DF 0x3f, 0x40 when the termination condition ceases. The desired maintenance current is stored in mA. When Voltage( ) is less than EDV0, the bq20851−V1P2 sets ChargingCurrent( ) to Precharge Current DF 0x41, 0x42. Typically this rate is larger than the maintenance rate to charge a deeply depleted pack up to the point where it may be fast charged. The desired precharge rate is stored in mA. If temperature is between 0° and the precharge threshold PC (°C), the bq20851−V1P2 sets ChargingCurrent( ) to PreCharge Current. The threshold is programmed in the Precharge Temp DF 0x43. Precharge Temp + PC (°C) 0.1 (10) The bq20851−V1P2 also sets ChargingCurrent( ) to the precharge rate if Voltage( ) is less than the value programmed in Precharge Voltage DF 0x3b−0x3c. Precharge Voltage is programmed in mV. Charge Suspension During charge, the bq20851−V1P2 compares the current to the ChargingCurrent( ) plus the value in OverCurrent Margin DF 0x5c−0x5d. If the pack is charged at a current above or equal to the ChargingCurrent( ) plus the programmed value, the bq20851−V1P2 sets ChargingCurrent( ) to zero to stop charging. The desired Overcurrent Margin is programmed in mA. The desired temperature threshold for charge suspension, MAXTEMP (°C), is programmed in Max Temperature DF 0x53, 0x54 and is stored as shown: Max Temperature + MAXTEMP 0.1 (11) The bq20851−V1P2 clears the maximum temperature condition when Temperature( ) drops by the amount programmed in Temperature Hysteresis DF 0x55 from MAXTEMP or when the temperature is less than or equal to 43.0°C. Temperature Hysteresis is stored in °C. The bq20851−V1P2 suspends fast charge when fast charge continues past full by the amount programmed in Maximum Overcharge DF 0x4e-0x4f. Maximum Overcharge is programmed in mAh. FULLY_CHARGED Bit Clear Threshold The bq20851−V1P2 clears the FULLY_CHARGED bit in BatteryStatus( ) when RelativeStateOfCharge( ) reaches the value, Fully Charged Clear % DF 0x47. Fully Charged Clear % is an 8-bit value and is stored in percent. Fast Charge Termination Percentage The bq20851−V1P2 sets RM to a percentage of FCC on charge termination if the CSYNC bit is set in the gauge configuration register. The percentage of FCC, FCT%, is stored in Fast Charge Termination % in DF 0x46. The value is stored as shown: Fast Charge Termination% = (FCT% * 2.56−1) Cycle Count Initialization Cycle Count DF 0x0c-0x0d stores the initial value for the CycleCount( ) function. It should be programmed to 0x0000. 45 
   www.ti.com SLUS575 − AUGUST 2003 Cycle Count Threshold Cycle Count Threshold 0x37−0x38 sets the number of mAh that must be removed from the battery to increment CycleCount( ). Cycle Count threshold is a 16-bit value stored in mAh. Current Taper Termination Characteristics Two factors in the data flash set the current taper termination for Li-Ion battery packs. The two locations are Current Taper Qual Voltage DF 0x4a and Current Taper Threshold DF 0x48−0x49. Current taper termination occurs during charging when the pack voltage is above or equal to the charging voltage minus the qualification voltage, and the charging current is below the taper threshold for at least 40 seconds. Current Taper Qual Voltage DF 0x4a is stored in mV and Current Taper Threshold DF 0x48−0x49 in mA. Cell Balancing Four constants set the cell balancing parameters. Cell Balance Threshold DF 0xd9−0xda sets the maximum voltage in mV that each cell must achieve to initiate cell balancing. Cell Balance Window DF 0xd9−0xda sets in mV the amount that the cell balance threshold can increase. Cell Balance Min DF 0xdb sets in mV the cell differential that must exist to initiate cell balancing and Cell Balance Interval DF 0xdc sets the cell balancing time interval in seconds. Programming Cell Balance Threshold to 65,535 disables cell balancing. Pack Options Pack Configuration Pack Configuration DF 0x28 contains bit-programmable features. b7 b6 b5 b4 b3 b2 b1 b0 DMODE — — HPE CPE SM CC1 CC0 DMODE The DMODE bit determines whether the LED outputs indicate AbsoluteStateOfCharge( ) or RelativeStateOfCharge( ). 0 LEDs reflect AbsoluteStateOfCharge( ) 1 LEDs reflect RelativeStateOfCharge( ) HPE The hpe bit enables/disables PEC transmissions to the smart battery host for master mode alarm messages. 0 No PEC byte on alarm warning to host 1 PEC byte on alarm warning to host CPE The CPE bit enables/disables PEC transmissions to the smart battery charger for master mode messages. 0 No PEC byte on broadcasts to charger 1 PEC byte on broadcasts to charger SM The SM bit enables/disables master mode broadcasts by the bq20851−V1P2. 0 Broadcasts to host and charger enabled 1 Broadcasts to host and charger disabled If the SM bit is set, modifications to bits in BatteryMode( ) do not re-enable broadcasts. CC1−CC0 The CC bits configure the bq20851−V1P2 for the number of series cells in the battery pack. 1−1 Configures the bq20851−V1P2 for four series cells 1−0 Configures the bq20851−V1P2 for three series cells Gauge Configuration Gauge Configuration DF 0x29 contains bit programmable features: 46 b7 b6 b5 b4 b3 b2 b1 b0 0 CSYNC SC CEDV EDVV OVSEL VCOR OTVC 
   www.ti.com SLUS575 − AUGUST 2003 CSYNC In usual operation of the bq20851−V1P2, the CSYNC bit is set so that the coulomb counter is adjusted when a fast charge termination is detected. In some applications, especially those where an externally controlled charger is used, it may be desirable not to adjust the coulomb counter. In these cases the CSYNC bit should be cleared. 0 The bq20851−V1P2 does not alter RM at the time of a valid charge termination. 1 The bq20851−V1P2 updates RM with a programmed percentage of FCC at a valid charger termination. SC The SC bit enables learning cycle optimization for a Smart Charger or independent charge. 1 Learning cycle optimized for independent charger 0 Learning cycle optimized for Smart Charger CEDV The CEDV bit determines whether the bq20851−V1P2 implements automatic EDV compensation to calculate the EDV1 and EDV2 thresholds base on rate, temperature, and capacity. If the bit is cleared, the bq20851−V1P2 uses the fixed values programmed in data flash for EDV1 and EDV2. If the bit is set, the bq20851−V1P2 calculates EDV1 and EDV2. 0 EDV compensation disabled 1 EDV compensation enabled EDVV The EDVV bit selects whether EDV termination is to be done with regard to voltage or the lowest single-cell voltage. 0 EDV conditions determined on the basis of the lowest single-cell voltage 1 EDV conditions determined on the basis of Voltage( ) OVSEL The OVSEL bit determines if safety over voltage is based on pack or highest cell voltages. 0 Safety over voltage based on pack voltage 1 Safety over voltage based on highest cell voltage multiplied by the number of cells and then compared to the safety voltage VCOR The VCOR bit enables the midrange voltage correction algorithm. When it is set, the bq20851−V1P2 compares the pack voltage to RM and may adjust RM according to the values programmed in VOC25, VOC50, and VOC75. 0 Continuous midrange corrections disabled 1 Continuous midrange corrections enabled OTVC The OTVC bit programs the bq20851−V1P2 to perform a midrange voltage one time after a device reset. 0 One-time midrange correction disabled 1 One-time midrange correction enabled Safety Control Secondary Protection Limits for Li-Ion The cell undervoltage (VUV) and overvoltage (VOV) limits are programmed in Cell Under and Cell Over Voltage DF 0x62−0x63, DF 0x60−0x61, respectively. Both values are stored in mV. Cell Over Voltage Reset DF 0xef and Cell Under Voltage Reset 0xd1−0xd2 set the reset points in mV for these safety parameters. SAFE Threshold The safety voltage threshold is programmed in Safety Over Voltage DF 0x68−0x69. It is stored in mV. If Misc Configuration bit 2 (OVSEL) = 0 then Safety Over Voltage is based on pack voltage, but if OVSEL = 1, then it is based on highest cell voltage. 47 
   www.ti.com SLUS575 − AUGUST 2003 The safety overtemperature (SOT) in °C is programmed in Safety Over Temperature DF 0x6a−0x6b. It is stored as (12) SafetyOvertemperature + SOT 0.1 AFE CONFIGURATION The AFE protection limits are programmed as specified in the bq29311 data sheet. AFE Brnout/Shutdn 0xb1 sets the brownout and shutdown voltage levels AFE Over Curr Dsg DF 0xb2 sets the overcurrent threshold on discharge. AFE Over Curr Chg DF 0xb3 sets the overcurrent threshold on charge. AFE Over Curr Delay DF 0xb4 sets the delay timing for over current in the charge and discharge direction. AFE Short Circ Thresh DF 0xb6 sets the short circuit threshold. AFE Short Circuit Delay DF 0xb7 sets the short circuit delay time. AFE INTEGRITY CHECK AFE Check Time DF 0xe4 sets the period in seconds for the AFE integrity check. The AFE Fail Limit (DF 0xd3,d4) is the number of AFE integrity check failures that occur before the AFE flag is set. SLEEP MODE The sleep current threshold, SLP (mA), is stored in Sleep Current Thresh DF 0xe5 as: Sleep Current Thresh + (13) SLP(mA) 0.5 The wake-up period for current measurement, WAT(s), is set in Sleep Current Time DF 0xe6 as: Sleep Current Time + (14) WAT(s) 0.5 Miscellaneous Configuration Misc Configuration DF 0x2a contains additional bit programmable features. b7 b6 b5 b4 b3 b2 b1 b0 IT NC_SMB AC DS OT ECLED PHG VOD IT The IT bit configures the bq20851−V1P2 to use its internal temperature sensor. 0 bq20851−V1P2 requires an external thermistor. 1 bq20851−V1P2 uses its internal temperature sensor. NC_SMB The NC_SMB bit enables an extended bus high time-out which is not compliant with the SMBus specifications. 0 Normal bus high timeout 1 Extended bus high timeout AC The AC bit enables the SAFE output to function based on the AFE integrity check. 48 0 SAFE is not activated based on the AFE integrity check. 1 SAFE activated based on the AFE integrity check. 
   www.ti.com SLUS575 − AUGUST 2003 DS The DS bit programs the bq20851−V1P2 to enter sleep mode on SMBus inactivity. 0 bq20851−V1P2 enters sleep mode when the SMBus is low for 2 s. 1 bq20851−V1P2 does not enter sleep mode. OT The OT bit programs the bq20851−V1P2 to turn off the discharge FET when the bq20851−V1P2 detects an overtemperature condition. Charge FET is always turned off in overtemperature conditions. 0 bq20851−V1P2 does not turn off the discharge FET on overtemperature. 1 bq20851−V1P2 turns off the discharge FET on overtemperature. ECLED The ECLED bit programs the LED activity during charging (DSG bit = 0). 0 The LEDs are not enabled during charging. 1 The LEDs are enabled during charging. PHG The PHG bit configures the bq20851−V1P2 to control a precharge FET. 0 The bq20851−V1P2 does not control a precharge FET. 1 The bq20851−V1P2 may turn on or off a precharge FET according to the programmed precharge conditions. VOD The VOD bit enables a 1-second time delay on the charge and discharge FET control. 0 No delay 1 1-second delay CONSTANTS AND STRING DATA Specification Information Specification Information DF 0x06−0x07 stores the default value for the SpecificationInfo( ) function. It is stored in data flash in the same format as the data returned by the SpecificationInfo( ). Manufacture Date Manufacture Date DF 0x08−0x09 stores the default value for the ManufactureDate( ) function. It is stored in data flash in the same format as the data returned by the ManufactureDate( ). Serial Number Serial Number DF 0x0a−0x0b stores the default value for the SerialNumber( ) function. It is stored in data flash in the same format as the data returned by the SerialNumber( ). Manufacturer Name Data Manufacturer Name Length DF 0x0e stores the length of the desired string that is returned by the ManufacturerName( ) function. However, this data is always ignored as manufacturer name is internally fixed. Device Name Data Device Name Length DF 0x1a data is always ignored as manufacturer name is always fixed. The length of the desired string that is returned by the DeviceName( ) function. Locations DF 0x1b−0x21 store the characters for DeviceName( ) in ASCII code. Device Chemistry Data Device Chemistry Length DF 0x22 stores the length of the desired string that is returned by the DeviceChemistry( ) function. Locations DF 0x23−0x26 store the characters for DeviceChemistry( ) in ASCII code. Manufacturers Data Length Manufacturers Data Length DF 0x27 stores the length of the desired number of bytes that is returned by the ManufacturersData( ) function. It should be set to 9. 49 
   www.ti.com SLUS575 − AUGUST 2003 APPLICATION INFORMATION The internal oscillator performance also depends on the tolerance of the 113-kΩ resistor connected between RSOC (pin 33) and VSSA (pin 34). It is recommended that this resistor be placed as close to the bq20851−V1P2 as possible and that it have a specification of ±0.1% tolerance and ±50 ppm temperature drift or better. The layout of the PCBA is also an additional contributing factor to performance degradation. The average temperature drift error of the oscillator function over a learning charge or discharge cycle introduces an equal capacity prediction error in a learned full charge capacity (FCC). Figure 10 shows a typical bq20851−V1P2-based battery pack application. The circuit consists of the bq29311 analog front end (AFE) IC, LED display, temperature measurement network, data flash connections, serial port, and the sense resistor. The data flash stores basic battery pack configuration information and measurement calibration values. The data flash must be programmed properly for bq20851−V1P2 operation. Table 10 shows the data flash memory map and outlines the programmable functions available in the bq20851−V1P2. 50 SDATA15 17 XALERT CLKIN16 7 VC5 VCELL12 SR1 SR2 GNDGND 8 9 13 11 6 VC4 5 VC3 23 22 21 DSG PCHG CHG 1 VCC VPACK24 2 VBAT VREG19 10CNTL 18 TOUT 3 VC1 20 LEDOUT 4 VC2 SCLK14
   www.ti.com SLUS575 − AUGUST 2003 APPLICATION INFORMATION Figure 10. Typical bq20851−V1P2 Implementation 51 MECHANICAL DATA MPDS019D – FEBRUARY 1996 – REVISED FEBRUARY 2002 DBT (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 30 PINS SHOWN 0,50 0,27 0,17 30 16 0,08 M 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 15 0°–ā8° 0,75 0,50 A Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 20 24 28 30 38 44 50 A MAX 5,10 6,60 7,90 7,90 9,80 11,10 12,60 A MIN 4.90 6,40 7,70 7,70 9,60 10,90 12,40 DIM 4073252/E 02/02 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion. Falls within JEDEC MO-153 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Amplifiers Applications amplifier.ti.com Audio www.ti.com/audio Data Converters dataconverter.ti.com Automotive www.ti.com/automotive DSP dsp.ti.com Broadband www.ti.com/broadband Interface interface.ti.com Digital Control www.ti.com/digitalcontrol Logic logic.ti.com Military www.ti.com/military Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security Telephony www.ti.com/telephony Video & Imaging www.ti.com/video Wireless www.ti.com/wireless Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright  2003, Texas Instruments Incorporated