BQ2085DBT

bq2085 SLUS541 – OCTOBER 2002 SBS-COMPLIANT GAS GAUGE IC FOR USE WITH THE bq29311 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 D Medical and Test Equipment D Portable Instrumentation DESCRIPTION The bq2085 SBS-compliant gas gauge IC for battery pack or in-system installation maintains an accurate record of available charge in Li-ion or Li-polymer batteries. The bq2085 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 bq2085, 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 bq2085 Temp Sensor 512 Bytes Config. FLASH EPROM ADC Voltage Glueless Interface Cell Inputs Safety Control Integrating ADC Coulomb Counting 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. Copyright  2002, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. www.ti.com 1 bq2085 SLUS541 – OCTOBER 2002 DESCRIPTION (CONTINUED) The bq2085 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 bq2085 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 bq2085 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 bq29311 AFE protection IC provides power to the bq2085 from a 3 or 4 series Li-ion cell stack, eliminating the need for an external regulator circuit. TSSOP PACKAGE (TOP VIEW) VIN TS OC N/C N/C SCLK N/C VDDD RBI SDATA VSSD SAFE N/C N/C SMBC SMBD DISP EVENT VSSD The bq2085 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 bq2085 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 bq2085 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 bq2085 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 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 N/C N/C CLKOUT VSSA ROSC FILT VDDA VSSA VSSP SR1 SR2 MRST N/C LED1 LED2 LED3 LED4 LED5 NC – No internal connection AVAILABLE OPTIONS TA PACKAGE 38-PIN TSSOP (DBT) bq2085DBT{ –20°C to 85°C † The bq2085 is available taped and reeled. Add an R suffix to the device type (e.g., bq2085DBTR) to order tape and reel version. www.ti.com bq2085 SLUS541 – OCTOBER 2002 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 24 O LED2 23 O LED3 22 O LED4 21 O LED5 20 O MRST LED dis display lay segments that each may drive an external LED 26 I Master reset input that forces the device into reset when held high N/C 4, 5, 7, 13, 14, 25, 36, 37 – No connection OC 3 I Analog input for auto ADC offset compensation; should be connected to VSSA RBI 9 I Register backup that provides backup potential to the bq2085 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 bq2085 SMBD 16 I/O SMBus data open-drain bidirectional pin used to transfer address and data to and from the bq2085 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 Connections for a small small-value value sense resistor to monitor the battery charge charge- and discharge discharge-current current flow 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 www.ti.com 3 bq2085 SLUS541 – OCTOBER 2002 ABSOLUTE MAXIMUM RATINGS over operating free-air temperature (unless otherwise noted)† Supply voltage range, VDD relative to VSS (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6 V Open-drain I/O pins, V(IOD) relative to VSS (see Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to 6 V Input voltage range to all other pins, VI relative to VSS (see Note 1) . . . . . . . . . . . . . . . . . . . . . –0.3 V to VDD + 0.3V Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 20°C to 85°C Storage temperature range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . – 65°C to 150°C † 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. NOTE 1: 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 450 µA 1 µA 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 bq2085 SLUS541 – OCTOBER 2002 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 (see Note 2) NOTE 2: 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 TEST CONDITIONS MIN –2% f(exo) ( ) Frequency error (see Note 3) VDD = 3.3 V f(sxo) Start-up time (see Note 4) NOTES: 3. The frequency error is measured from 32.768 Hz. 4. The start-up time is defined as the time it takes for the oscillator output frequency to be ±1%. www.ti.com –1% TYP MAX UNIT 2% 1% 275 µs 5 bq2085 SLUS541 – OCTOBER 2002 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:DAT TTIMEOUT Data setup time TLOW THIGH Clock low period Clock high period See Note 6 50 µs TLOW:SEXT TLOW:MEXT Cumulative clock low slave extend time See Note 7 25 ms Cumulative clock low master extend time See Note 8 10 ms TF TR Clock/data fall time See Note 9 300 ns Clock/data rise time See Note 10 1000 ns NOTES: 5. 6. 7. 8. 9. 10. Error signal/detect 10 MAX FSMB FMAS 51.2 Receive mode 0 Transmit mode 300 kHz µss µs 250 See Note 5 25 35 ms µs 4.7 4.0 The bq2085 times out when any clock low exceeds TTIMEOUT THIGH Max. is minimum bus idle time. SMBC = 1 for t > 50 µs causes reset of any transaction involving bq2085 that is in progress. 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. 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. Rise time TR = (VILMAX – 0.15 V) to (VIHMIN + 0.15 V). 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 11 Flash programming write-cycles See Note 11 Word programming time See Note 11 I(DDPROG) Flash-write supply current NOTE 11: Specified by design. Not production tested. MIN TYP MAX 10 105 See Note 11 UNIT Years Cycles 2 ms 14 16 mA TYP MAX UNIT 10 100 nA Register Backup PARAMETER I(RBI) TEST CONDITIONS RBI data-retention input current (see Note 12) V(RBI) RBI data-retention voltage NOTE 12: Specified by design. Not production tested. 6 MIN VRB > 3.0 V, VDD < VIT 1.3 www.ti.com V bq2085 SLUS541 – OCTOBER 2002 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 SCLKACK† SCLKACK† TLOW:MEXT TLOW:MEXT TLOW:MEXT SCLK SDATA † SCLKACK is the acknowledge-related clock pulse generated by the master. Figure 2. SMBus Timing Diagram FUNCTIONAL DESCRIPTION Internal Oscillator Function 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 bq2085 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 bq2085 determines battery capacity by monitoring the amount of charge input or removed from a rechargeable battery. In addition to measuring charge and discharge, the bq2085 measures battery voltage, temperature, and current, estimates battery self-discharge, and monitors the battery for low-voltage thresholds. The bq2085 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 bq2085 interfaces with the bq29311 to perform battery protection, cell balancing, and voltage translation functions. The bq2085 can accept any NTC thermistor (default is Semitec 103AT) for temperature measurement or can be configured to use its internal temperature sensor. The bq2085 uses temperature to monitor the battery pack and to compensate the self-discharge estimate. www.ti.com 7 bq2085 SLUS541 – OCTOBER 2002 Measurements The bq2085 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 bq2085 detects charge activity when VSR = V(SR1)–V(SR2) is positive and discharge activity when VSR = V(SR1)–V(SR2) is negative. The bq2085 continuously integrates the signal over time, using an internal counter. The fundamental rate of the counter is 2.6 nVh. The bq2085 updates Remaining Capacity() with the charge or discharge accumulated in this internal counter once every second. Offset Calibration The bq2085 provides an autocalibration feature to cancel the voltage offset error across SR1 and SR2 for maximum charge measurement accuracy. The bq2085 performs autocalibration when the SMBus lines stay low for a minimum of 20 s. The bq2085 is capable of automatic offset calibration down to 1µV. Digital Filter The bq2085 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 bq2085 monitors the individual series cell voltages through the bq29311. The bq2085 configures the bq29311 to present the selected cell to the VCELL pin of the bq29311 which should be connected to VIN of the bq2085. The internal ADC of the bq2085 then measures the voltage and scales it appropriately. The bq2085 then reports the Voltage( ) and the individual cell voltages in VCELL1, VCELL2, VCELL3, and VCELL4 located in 0x3c–0x3f. Current The bq2085 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 bq2085 in conjunction with an NTC thermistor measures the battery temperature as shown in the schematic. The bq2085 reports temperature in Temperature( ). The bq2085 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. Gas Gauge Operation Table 1. Data Flash Settings for Internal or External Temperature Sensor LOCATION Dec (Hex) INTERNAL TEMP SENSOR SETTING Dec (Hex) Misc. Configuration 42 (0x2a) Bit 7 = 1 Bit 7 = 0 TS Const1 164/5 (0xa4/5) 0 (a3) 37251 (0x9183) TS Const2 166/7 (0xa6/7) 0 (a2) 20848 (0x5170) TS Const3 168/9 (0xa8/9) –11136 (a1) 57999 (0xe28f) TS Const4 170/1 (0xaa/b) 5754 (a0) 4012 (0x0fac) TS Const5 172/3 (0xac/d) 13348 (3424) 5190 (0x1446) LABEL 8 www.ti.com EXTERNAL TEMP SENSOR SETTING Dec (Hex) bq2085 SLUS541 – OCTOBER 2002 General The operational overview in Figure 3 illustrates the gas gauge operation of the bq2085. Table 3 describes the bq2085 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) + + Discharge Count Register Qualified (DCR) Transfer Temperature, Other Data Outputs Chip-Controlled Available Charge LED Display Two-Wire Serial Port Figure 3. bq2085 Operational Overview The bq2085 accumulates a measure of charge and discharge currents and estimates self-discharge of the battery. The bq2085 compensates the charge current measurement for temperature and state-of-charge of the battery. The bq2085 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 bq2085 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 bq2085 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 bq2085 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 bq2085 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. www.ti.com 9 bq2085 SLUS541 – OCTOBER 2002 RemainingCapacity( ) (RM) RM represents the remaining capacity in the battery. The bq2085 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 bq2085 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 bq2085 sets FCC to the value stored in Last Measured Discharge DF 0x35-0x36. During subsequent discharges, the bq2085 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 bq2085 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 bq2085 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 = 0 (bit 5 in Gauge Configuration) and is not reduced if SC = 1. DCR stops counting when the battery voltage reaches the EDV2 threshold on discharge. Capacity learning (FCC Update) and Qualified Discharge The bq2085 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) ÷ 2.56 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 No more than 256 mAh of self-discharge or battery load estimation occurs during the discharge period. D The temperature does not drop below the low temperature thresholds programmed in Learning Low Temp DF 0x9b 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 bq2085 detected EDV2. D No midrange voltage correction occurs during the discharge period. D Current remains ≥ 3C/32 when EDV2 or Battery Low % level is reached. D No overload condition exists when EDV2 threshold is reached or if RM( ) has dropped to Battery Low% *FCC. 10 www.ti.com bq2085 SLUS541 – OCTOBER 2002 The bq2085 sets VDQ=1 in pack status when qualified discharge begins. The bq2085 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 bq2085 saves the new FCC value to the data flash within 4 seconds of being updated. End-of-Discharge Thresholds and Capacity Correction The bq2085 monitors the battery for three low-voltage thresholds, EDV0, EDV1, and EDV2. The EDV thresholds can be programmed for determination based on the overall pack voltage or an individual cell level. The EDVV bit in Pack Configuration DF 0x28 configures the bq2085 for overall voltage or single-cell EDV thresholds. If programmed for single cell EDV determination, the bq2085 determines EDV on the basis of the lowest single-cell voltage. Fixed EDV thresholds may be programmed in EMF/EDV0 DF 0x84-0x85, EDV C0 Factor/EDV1 DF 0x86-0x87, and EDV R Factor/EDV2 DF 0x88-0x89. If the CEDV bit in Gauge Configuration DF 0x29 is set, automatic EDV compensation is enabled and the bq2085 computes the EDV0, EDV1, and EDV2 thresholds based on the values in DF 0x84-0x8d and the battery’s current discharge rate and temperature. The bq2085 disables EDV detection if Current( ) exceeds the Overload Current threshold programmed in DF 0x58 – DF 0x59. The bq2085 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 10mAh of charge. Table 2. State of Charge Based on Low Battery Voltage THRESHOLD RELATIVE STATE OF CHARGE EDV0 0% EDV1 3% EDV2 Battery Low % The bq2085 uses the EDV thresholds to apply voltage-based corrections to the RM register according to Table 1. The bq2085 performs EDV-based RM adjustments with Current( ) ≥ C/32. No EDVs are set if current < C/32. The bq2085 adjusts RM as it detects each threshold. If the voltage threshold is reached before the corresponding capacity on discharge, the bq2085 reduces RM to the appropriate amount as shown in Table 2. This reduction occurs only if current ≥ C/32 when the EDV threshold is detected. If RM reaches the capacity level before the voltage threshold is reached on discharge, the bq2085 prevents RM from decreasing further until the battery voltage reaches the corresponding threshold only on a full learning cycle discharge. RM is not held at the associated EDV percentage on a nonlearning discharge cycle (VDQ=0) or if current < C/32. If Battery Low % is set to zero, EDV1 and EDV0 corrections are disabled. Table 3. bq2085 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 www.ti.com 11 bq2085 SLUS541 – OCTOBER 2002 Table 3. bq2085 Register Functions (Continued) FUNCTION COMMAND CODE ACCESS UNITS 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 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 0 0 Reserved 0x1d-0x1f ManufacturerName 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 bq2085 estimates the self-discharge of the battery to maintain an accurate measure of the battery capacity during periods of inactivity. The bq2085 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). 12 www.ti.com bq2085 SLUS541 – OCTOBER 2002 Table 4. Self-Discharge for Rate Programmed TEMPERATURE (°C) SELF-DISCHARGE RATE Temp < 10 1/4 Y% per day 10 ≤ Temp Safety Temperature (DF 0x6a and 0x6b) D When Misc Configuration (DF 0x2a) bit 5 AC is set and the AFE has failed at least AFE Fail Times (DF 0xd3, d4) The bq2085 checks the programming of the AFE registers at a period determined by AFE Check Time DF 0xe4. The units of the check period are seconds unless the bq2085 is in sleep mode, in which case the period is AFE Check Time x Sleep Current Time (DF 0xe7). If the data is not correct, the bq2085 increments an internal counter. An example circuit using the SAFE output to blow a fuse is shown in Figure 5. FUSE BAT+ VCC 1 MΩ Cell 4 0.1 µF BSS84 100 kΩ 2N7002 SAFE 1 MΩ Figure 5. Example SAFE Circuit Implementation www.ti.com 19 bq2085 SLUS541 – OCTOBER 2002 Low-Power Modes The bq2085 enters sleep mode when the charge and discharge current is less than the threshold programmed in Sleep Current Threshold DF 0xe5, the SMBus lines are low for at least 2 s, and bit 4 of Misc. Configuration DF 0x2a is set to zero. The bq2085 wakes up periodically to monitor voltage and temperature and to apply self-discharge adjustment. The sleep period is set in Sleep Timer DF 0xe7. The bq2085 wakes up at a period set by Sleep Current Time DF 0xe6 to measure current. The bq2085 comes out of sleep when the SMBus lines go high or if the current is greater than Sleep Current Threshold. A rising edge on SMBC or SMBD restores the bq2085 to the full operating mode. Reset Conditions On power-up the entire IC is reset and data is loaded from Data Flash to configure the SBS Data and the system. On a partial reset (loss of VCC but RBI holds RAM valid) then a limited number of locations are taken. These actions are the following: D D D D D The AFE registers are rewritten. PackStatus() VDQ flag is cleared (the proposed change is not to clear VDQ). PackStatus() EDV2 flag is cleared. BatteryStatus() DISCHARGING flag is cleared. The charger and alarm broadcast period is set to 10 seconds between broadcasts. COMMUNICATION The bq2085 includes an SMBus communication port. The SMBus interface is a 2-wire bidirectional protocol using the SMBC (clock) and SMBD (data) pins. The communication lines are isolated from VCC and may be pulled-up higher than VCC. Also, the bq2085 does not pull these lines low if VCC to the part is zero. The communication ports allow a host controller, an SMBus compatible device, or other processor to access the memory registers of the bq2085. In this way a system can efficiently monitor and manage the battery. SMBus The SMBus interface is a command-based protocol. A processor acting as the bus master initiates communication to the bq2085 by generating a start condition. A start condition consists of a high-to-low transition of the SMBD line while the SMBC is high. The processor then sends the bq2085 device address of 0001011 (bits 7-1) plus a R/W bit (bit 0) followed by an SMBus command code. The R/W bit (LSB) and the command code instruct the bq2085 to either store the forthcoming data to a register specified by the SMBus command code or output the data from the specified register. The processor completes the access with a stop condition. A stop condition consists of a low-to-high transition of the SMBD line while the SMBC is high. With SMBus, the most-significant bit (MSB) of a data byte is transmitted first. In some instances, the bq2085 acts as the bus master. This occurs when the bq2085 broadcasts charging requirements and alarm conditions to device addresses 0x12 (SBS Smart Charger) and 0x10 (SBS Host Controller.) SMBus Protocol The bq2085 supports the following SMBus protocols: D Read word D Write word D Block read A processor acting as the bus master uses the three protocols to communicate with the bq2085. The bq2085 acting as the bus master uses the write word protocol. 20 www.ti.com bq2085 SLUS541 – OCTOBER 2002 The SMBD and SMBC pins are open drain and require external pullup resistors. A 1-MΩ pulldown resistor in the battery pack on SMBC and SMBD is required to assure the detection of the SMBus offstate, the performance of automatic offset calibration, and the initiation of the low-power sleep mode when the battery pack is removed. SMBus Packet Error Checking The bq2085 supports packet error checking as a mechanism to confirm proper communication between it and another SMBus device. Packet error checking requires that both the transmitter and receiver calculate a packet error code (PEC) for each communication message. The device that supplies the last byte in the communication message appends the PEC to the message. The receiver compares the transmitted PEC to its PEC result to determine if there is a communication error. PEC Protocol The bq2085 can receive or transmit data with or without PEC. Figure 6 shows the communication protocol for the read word, write word, and read block messages without PEC. Figure 7 includes PEC. In the read word protocol, the bq2085 receives the PEC after the last byte of data from the host. If the host does not support PEC, the last byte of data is followed by a stop condition. After receipt of the PEC, the bq2085 compares the value to its calculation. If the PEC is correct, the bq2085 responds with an ACKNOWLEDGE. If it is not correct, the bq2085 responds with a NOT ACKNOWLEDGE and sets an error code. In the write word and block read, the host generates an ACKNOWLEDGE after the last byte of data sent by the bq2085. The bq2085 then sends the PEC and the host acting as a master-receiver generates a NOT ACKNOWLEDGE and a stop condition. 1 S 1 S 7 Battery Address 0001011 7 Battery Address 0001011 1 0 1 0 ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ 1 8 A Command Code 8 1 8 A Command Code Data Byte Low A 1 S 8 Data Byte High 7 Battery Address 0001011 1 0 ÎÎ ÎÎ 1 8 A Data Byte Low Write Word 1 ÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ ÎÎ 1 8 A Data Byte High ÎÎ ÎÎ 1 1 7 1 1 A S Battery Address 1 A 1 1 A P 1 A P Read Word 1 8 A Command Code ÎÎ ÎÎ ÎÎ ÎÎ 1 1 7 1 1 A S Battery Address 1 A ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎ 8 1 8 1 8 1 8 1 1 Byte Count = N A Data Byte 1 A Data Byte 2 A Data Byte N A P Block Read Host Processor A – ACKNOWLEDGE bq2083 A – NOT ACKNOWLEDGE S – START P – STOP ÎÎ ÎÎ Figure 6. SMBus Communication Protocol Without PEC www.ti.com 21 bq2085 SLUS541 – OCTOBER 2002 PEC Protocol (Continued) 1 S 1 S ÎÎ ÎÎ 7 1 Battery Address 0 0001011 1 8 A Command Code ÎÎ ÎÎ 7 1 Battery Address 0 0001011 Write Word 1 8 A Command Code ÎÎ ÎÎ ÎÎ ÎÎ 1 8 A Data Byte Low ÎÎ ÎÎ 1 1 A S 8 Data Byte High 1 8 A PEC ÎÎ ÎÎ 1 A 1 P ÎÎÎ ÎÎÎ 7 1 1 Battery Address 1 A ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ ÎÎ ÎÎ 1 A 8 1 8 1 8 1 1 Data Byte Low A Data Byte High A PEC A P Read Word 1 S ÎÎ ÎÎ 7 1 Battery Address 0 0001011 1 8 A Command Code ÎÎ ÎÎ 1 1 A S ÎÎÎ ÎÎÎ 1 1 Battery Address 1 7 A ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ ÎÎÎÎÎÎÎÎÎÎ 8 Byte Count = N 1 8 1 8 1 8 1 8 1 1 A Data Byte 1 A Data Byte 2 A Data Byte N A PEC A P Block Read ÎÎ ÎÎ ÎÎ A– A– S– P– Host Processor bq2083 ACKNOWLEDGE NOT ACKNOWLEDGE START STOP Figure 7. SMBus Communication Protocol With PEC PEC Calculation The basis of the PEC calculation is an 8-bit cyclic redundancy check (CRC-8) based on the polynomial C(X) = X8 + X2 + X1 + 1. The PEC calculation includes all bytes in the transmission, including address, command, and data. The PEC calculation does not include ACKNOWLEDGE, NOT ACKNOWLEDGE, start, stop, and repeated start bits. For example, the host requests RemainingCapacity( ) from the bq2085. This includes the host following the read word protocol. The bq2085 calculates the PEC based on the following 5 bytes of data, assuming the remaining capacity of the battery is 1001 mAh. D D D D Battery Address with R/W = 0: 0x16 Command Code for RemainingCapacity( ): 0x0f Battery Address with R/W = 1: 0x17 RemainingCapacity( ): 0x03e9 For 0x160f17e903, the bq2085 transmits a PEC of 0xe8 to the host. PEC Enable in Master Mode PEC for master mode broadcasts to the charger, host, or both can be enabled/disabled with the combination of the bits hpe and cpe in Pack Configuration DF 0x28. 22 www.ti.com bq2085 SLUS541 – OCTOBER 2002 SMBus On and Off State The bq2085 detects whether the SMBus enters the Off State by monitoring the SMBC and SMBD lines. When both signals are continually low for at least 2.0 s, the bq2085 detects the Off State. When the SMBC and SMBD lines go high, the bq2085 detects the On State and can begin communication within 1 ms. One-MΩ pulldown resistors on SMBC and SMBD are recommended for reliable Off State detection. Command Codes The SMBus command codes are in ( ). Temperature( ), Voltage( ), Current( ), and AverageCurrent( ), performance specifications are at bq29311 regulated VCC (V(REG)) and a temperature of 0-70_C. ManufacturerAccess( ) (0x00) Description: This function provides writable command codes to control the bq2085 during normal operation and pack manufacture. The following commands are available: 0x0001 Device Type instructs the bq2085 to return the IC part number; i.e., 2083 (0823h) to Manufacture Access( ) so it can be read. 0x0002 Firmware Revision instructs the bq2085 to return the firmware revision. 0x0003 EDV Level instructs the bq2085 to return the pending end-of-discharge voltage level so it can be read. 0x062b SEAL instructs the bq2085 to restrict access to those functions listed in Table 3. The bq2085 completes the seal function and clears ManufacturerAccess( ). Purpose: The ManufacturerAccess( ) function provides the system host access to bq2085 functions that are not defined by the SBD. SMBus protocol: Read or write word Input/Output: Word RemainingCapacityAlarm( ) (0x01) Description: Sets or gets the low-capacity threshold value. Whenever the RemainingCapacity( ) falls below the low capacity value, the bq2085 sends AlarmWarning( ) messages to the SMBus host with the REMAINING_CAPACITY_ALARM bit set. A low-capacity value of 0 disables this alarm. The bq2085 initially sets the low-capacity value to Remaining Capacity Alarm value programmed in DF 0x02–0x03. The low-capacity value remains unchanged until altered by the RemainingCapacityAlarm( ) function. The low-capacity value may be expressed in either current (mA) or power (10 mWh) depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. Purpose: The RemainingCapacityAlarm( ) function can be used by systems that know how much power they require to save their operating state. It enables those systems to more finely control the point at which they transition into suspend or hibernate state. The low-capacity value can be read to verify the value in use by the bq2085 low-capacity alarm. SMBus protocol: Read or write word Input/Output: Unsigned integer-value below which Low Capacity messages are sent. BATTERY MODES CAPACITY_MODE BIT = 0 CAPACITY_MODE BIT = 1 Units mAh at C/5 10 mWh at P/5 Range 0–65,535 mAh 0–65,535 10 mWh Granularity Not applicable Accuracy See RemainingCapacity( ) www.ti.com 23 bq2085 SLUS541 – OCTOBER 2002 RemainingTimeAlarm( ) (0x02) Description: Sets or gets the Remaining Time Alarm value. Whenever the AverageTimeToEmpty( ) falls below the remaining time value, the bq2085 sends AlarmWarning( ) messages to the SMBus host with the REMAINING_TIME_ALARM bit set. A remaining time value of 0 effectively disables this alarm. The bq2085 initially sets the remaining time value to the Remaining Time Alarm value programmed in DF 0x00–0x01. The remaining time value remains unchanged until altered by the RemainingTimeAlarm( ) function. Purpose: The RemainingTimeAlarm( ) function can be used by systems that want to adjust when the remaining time alarm warning is sent. The remaining time value can be read to verify the value in use by the bq2085 RemainingTimeAlarm( ). SMBus protocol: Read or write word Input/Output: Unsigned integer—the point below which remaining time messages are sent. Units: Minutes Range: 0 to 65,535 minutes Granularity: Not applicable Accuracy: See AverageTimeToEmpty( ). BatteryMode( ) (0x03) Description: Selects the various battery operational modes and reports the battery’s mode and requests. Defined modes include D Whether the battery capacity information is specified in units of mAh or 10 mWh (CAPACITY_MODE bit) D Whether the ChargingCurrent( ) and ChargingVoltage( ) values are broadcast to the smart battery charger when the CHARGER_MODE bit is set. D Whether all broadcasts to the smart battery charger and host are disabled The defined request condition is the battery requesting a conditioning cycle (RELEARN_FLAG). Purpose: The CAPACITY_MODE bit allows power management systems to best match their electrical characteristics with those reported by the battery. For example, a switching power supply represents a constant power load, whereas a linear supply is better represented by a constant current model. The CHARGER_MODE bit allows a SMBus host or smart battery charger to override the smart battery desired charging parameters by disabling the bq2085 broadcasts. The RELEARN_FLAG bit allows the bq2085 to request a conditioning cycle. SMBus protocol: Read or write word Input/Output: Unsigned integer—bit mapped— see below. Units: Not applicable Range: 0-1 Granularity: Not applicable Accuracy: Not applicable The BatteryMode( ) word is divided into two halves, the MSB (bits 8-15) which is read/write and the LSB (bits 0-7) which is read only. The bq2085 forces bits 0-6 to zero and prohibits writes to bit 7. Table 12 summarizes the meanings of the individual bits in the BatteryMode( ) word and specifies the default values, where applicable, are noted. INTERNAL_CHARGE_CONTROLLER bit is not used by the bq2085. 24 www.ti.com bq2085 SLUS541 – OCTOBER 2002 PRIMARY_BATTERY_SUPPORT bit is not used by the bq2085. RELEARN_FLAG bit set indicates that the bq2085 is requesting a capacity relearn cycle for the battery. The bq2085 sets the RELEARN_FLAG on a full reset and if it detects 20 cycle counts without an FCC update. The bq2085 clears this flag after a learning cycle has been completed. CHARGE_CONTROLLER_ENABLED bit is not used by the bq2085. The bq2085 forces this bit to zero. PRIMARY_BATTERY bit is not used by the bq2085. The bq2085 forces this bit to zero. Table 12. Battery Mode Bits and Values Battery Mode( ) BITS BITS USED FORMAT INTERNAL_CHARGE_CONTROLLER 0 Read only bit flag 1 Read only bit flag PRIMARY_BATTERY_SUPPORT Reserved 2–6 RELEARN_FLAG 7 Read only bit flag CHARGE_CONTROLLER_ENABLED 8 R/W bit flag 9 R/W bit flag PRIMARY_BATTERY Reserved ALLOWABLE VALUES 0—Battery OK 1—Relearn cycle requested 10–12 ALARM_MODE 13 R/W bit flag 0—Enable alarm broadcast (default) 1—Disable alarm broadcast CHARGER_MODE 14 R/W bit flag 0—Enable charging broadcast (default) 1—Disable charging broadcast CAPACITY_MODE 15 R/W bit flag 0—Report in mA or mAh (default) 1—Report in 10mW or 10 mWh ALARM_MODE bit is set to disable the bq2085’s ability to master the SMBus and send AlarmWarning( ) messages to the SMBus host and the smart battery charger. When set, the bq2085 does not master the SMBus, and AlarmWarning( ) messages are not sent to the SMBus host and the smart battery charger for a period of no more than 60 seconds and no less than 59 seconds. When cleared (default), the smart battery sends the AlarmWarning( ) messages to the SMBus host and the smart battery charger any time an alarm condition is detected. D The ALARM broadcast does not occur more often than once every 10 s. Whenever the BATTERY_MODE command is received, the bq2085 resets the bit and starts or restarts a 60-seconds (nominal) timer. After the timer expires, the bq2085 automatically enables alarm broadcasts to ensure that the accidental deactivation of broadcasts does not persist. An SMBus host that does not want the bq2085 to be a master on the SMBus must therefore continually set this bit at least once per 59 seconds to keep the bq2085 from broadcasting alarms. D The ALARM_MODE bit defaults to a cleared state when the bq2085 enters SLEEP mode. D The condition of the ALARM-MODE bit does not affect the operation or state of the CHARGER_MODE bit, which is used to prevent broadcasts of ChargingCurrent( ) and ChargingVoltage( ) to the smart battery charger. CHARGER_MODE bit enables or disables the bq2085’s transmission of ChargingCurrent( ) and ChargingVoltage( ) messages to the smart battery charger. When set, the bq2085 does not transmit ChargingCurrent( ) and ChargingVoltage( ) values to the smart battery charger. When cleared, the bq2085 transmits the ChargingCurrent( ) and ChargingVoltage( ) values to the smart battery charger. The CHARGER_MODE bit defaults to a cleared state when the bq2085 enters SLEEP mode. www.ti.com 25 bq2085 SLUS541 – OCTOBER 2002 CAPACITY_MODE bit indicates if capacity information is reported in mA/mAh or 10mW/10 mWh. When set, the bq2085 reports capacity information in 10 mW/10 mWh as appropriate. When cleared, the bq2085 reports capacity information in mA/mAh as appropriate. The CAPACITY_MODE bit defaults to a cleared state when the bq2085 enters SLEEP mode. The following functions are changed to accept or return values in mA/mAh or 10 mW/10 mWh depending on the CAPACITY_MODE bit: D D D D D RemainingCapacityAlarm( ) AtRate( ) RemainingCapacity( ) FullChargeCapacity( ) DesignCapacity( ) The following functions are calculated on the basis of capacity and may be calculated differently depending on the CAPACITY_MODE bit: D D D D D D D D AtRateOK( ) AtRateTimeToEmpty( ) AtRateTimeToFull( ) RunTimeToEmpty( ) AverageTimeToEmpty( ) AverageTimeToFull( ) Remaining Time Alarm( ) BatteryStatus( ) The bq2085 updates the non-AtRate related register values within 1 s of changing the state of the CAPACITY_MODE bit. The AtRate( ) values are updated after the next AtRate value is written to the bq2085 (or after the next 1 s scheduled refresh calculation). AtRate( ) (0x04) Description: The AtRate( ) function is the first half of a two-function call-set used to set the AtRate value used in calculations made by the AtRateTimeToFull( ), AtRateTimeToEmpty( ), and AtRateOK( ) functions. The AtRate value may be expressed in either current (mA) or power (10 mW) depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. Purpose: Since the AtRate( ) function is the first half of a two-function call-set, it is followed by the second function of the call-set that calculates and returns a value based on the AtRate value and the battery’s present state. D When the AtRate( ) value is positive, the AtRateTimeToFull( ) function returns the predicted time to full-charge at the AtRate value of charge. D When the AtRate( ) value is negative, the AtRateTimeToEmpty( ) function returns the predicted operating time at the AtRate value of discharge. D When the AtRate( ) value is negative, the AtRateOK( ) function returns a Boolean value that predicts the battery’s ability to supply the AtRate value of additional discharge energy (current or power) for 10 seconds. The default value for AtRate( ) is zero. SMBus protocol: Read or write word 26 www.ti.com bq2085 SLUS541 – OCTOBER 2002 Input/Output: Signed integer-charge or discharge; the AtRate( ) value is positive for charge, negative for discharge, and zero for neither (default). BATTERY MODES CAPACITY_MODE BIT = 0 CAPACITY_MODE BIT = 1 Units mA 10 mW Charge range 1 to 32,767 mA 1 to 32,767 10 mW Discharge range –1 to –32,768 mA –1 to –32,768 10 mW Granularity 1 Unit Accuracy NA AtRateTimeToFull( ) (0x05) Description: Returns the predicted remaining time to fully charge the battery at the AtRate( ) value (mA). Purpose: The AtRateTimeToFull( ) function is part of a two-function call-set used to determine the predicted remaining charge time at the AtRate value in mA. The bq2085 updates AtRateTimeToFull( ) within 5 ms after the SMBus host sets the AtRate value. The bq2085 automatically updates AtRateTimeToFull( ) based on the AtRate( ) value every 1 s. SMBus protocol: Read word Output: Unsigned integer—predicted time in minutes to fully charge the battery. Units: Minutes Range: 0 to 65,534 min Granularity: 2 min or better Accuracy: ± MaxError( ) * FullChargeCapacity( )/|AtRate( )| Invalid Data Indication: 65,535 indicates the AtRate ≤ 0. AtRateTimeToEmpty( ) (0x06) Description: Returns the predicted remaining operating time if the battery is discharged at the AtRate( ) value. Purpose: The AtRateTimeToEmpty( ) function is part of a two-function call-set used to determine the remaining operating time at the AtRate( ) value. The bq2085 updates AtRateTimeToEmpty( ) within 5 ms after the SMBus host sets the AtRate( ) value. The bq2085 automatically updates AtRateTimeToEmpty( ) based on the AtRate( ) value every 1 s. SMBus protocol: Read word Output: Unsigned integer—estimated operating time left. Units: Minutes Range: 0 to 65,534 min Granularity: 2 min or better Accuracy: -0,+MaxError( ) × FullChargeCapacity/|AtRate( )| Invalid Data Indication: 65,535 indicates AtRate ≥ 0. AtRateOK( ) (0x07) Description: Returns a Boolean value that indicates whether or not the battery can deliver the AtRate( )value of additional energy for 10 seconds. If the AtRate value is zero or positive, the AtRateOK( ) function ALWAYS returns OK (logic 1). www.ti.com 27 bq2085 SLUS541 – OCTOBER 2002 Purpose: The AtRateOK( ) function is part of a two-function call-set used by power management systems to determine if the battery can safely supply enough energy for an additional load. The bq2085 updates AtRateOK( ) within 5 ms after the SMBus host sets the AtRate( ) value. The bq2085 automatically updates AtRateOK( ) based on the At Rate( ) value every 1 second. SMBus protocol: Read word Output: Boolean—indicates if the battery can supply the additional energy requested. Units: Boolean Range: 1, 0 Granularity: Not applicable Accuracy: Not applicable Temperature( ) (0x08) Description: Returns the temperature (K) measured by the bq2085. Purpose: The Temperature( ) function provides accurate cell temperatures for use by battery chargers and thermal management systems. A battery charger can use the temperature as a safety check. Thermal management systems may use the temperature because the battery is one of the largest thermal sources in a system. SMBus protocol: Read word Output: Unsigned integer—cell temperature in tenth-degree Kelvin increments. Units: 0.1°K Range: 0 to +6553.5°K {real range} Granularity: 0.1°K Accuracy: ±1.5°K (from ideal Semitec 103AT thermistor performance, after calibration) Voltage( ) (0x09) Description: Returns the cell-pack voltage (mV). Purpose: The Voltage( ) function provides power management systems with an accurate battery terminal voltage. Power management systems can use this voltage, along with battery current information, to characterize devices they control. This ability helps enable intelligent, adaptive power-management systems. SMBus protocol: Read word Output: Unsigned integer—battery terminal voltage in mV. Units: mV Range: 0 to 20,000 mV Granularity: 1 mV Accuracy: ±0.25% (after calibration) Current( ) (0x0a) Description: Returns the current being supplied (or accepted) by the battery (mA). Purpose: The Current( ) function provides a snapshot for the power management system of the current flowing into or out of the battery. This information is of particular use in power-management systems because they can characterize individual devices and tune their operation to actual system power behavior. SMBus protocol: Read word Output: Signed integer—charge/discharge rate in mA increments-positive for charge, negative for discharge. 28 www.ti.com bq2085 SLUS541 – OCTOBER 2002 Units: mA Range: –32,768 to 32,767 mA Granularity: 1 mA Accuracy: 0.25% or 5 mA, whichever is greater AverageCurrent( ) (0x0b) Description: Returns a value that approximates a one-minute rolling average of the current being supplied (or accepted) through the battery terminals (mA). The AverageCurrent( ) function returns values equivalent to Current( ) during the battery’s first minute of operation. Purpose: The AverageCurrent( ) function provides the average current flowing into or out of the battery for the power management system. SMBus protocol: Read word Output: Signed integer—charge/discharge rate in mA increments-positive for charge, negative for discharge. Units: mA Range: –32,768 to 32,767 mA Granularity: 1 mA Accuracy: 0.25% or 5 mA, whichever is greater MaxError( ) (0x0c) Description: Returns the expected margin of error (%) in the state of charge calculation. For example, when MaxError( ) returns 10% and RelativeStateOfCharge( ) returns 50%, the Relative StateOfCharge( ) is more likely between 50% and 60%. The bq2085 sets MaxError( ) to 100% on a full reset. The bq2085 sets MaxError( ) to 2% on completion of a learning cycle, unless the bq2085 limits the learning cycle to the +512/-256 mAh maximum adjustment values. If the learning cycle is limited, the bq2085 sets MaxError( ) to 8% unless MaxError( ) was already below 8%. In this case MaxError( ) does not change. The bq2085 increments MaxError( ) by 1% after four increments of CycleCount( ) without a learning cycle. If voltage-based corrections are applied to the coulomb counter, MaxError( ) is set to 25%. Purpose: The MaxError( ) function has real value in two ways: first, to give the user a confidence level about the state of charge and second, to give the power management system information about how aggressive it should be, particularly as the battery nears the end of its life. SMBus protocol: Read word Output: Unsigned integer—percent uncertainty for selected information. Units: % Range: 2–100% Granularity: 1% Accuracy: Not applicable RelativeStateOfCharge( ) (0x0d) Description: Returns the predicted remaining battery capacity expressed as a percentage of FullChargeCapacity( ) (%). Purpose: The RelativeStateOfCharge( ) function is used to estimate the amount of charge remaining in the battery relative to the last learned capacity. SMBus protocol: Read word www.ti.com 29 bq2085 SLUS541 – OCTOBER 2002 Output: Unsigned integer-percent of remaining capacity. Units: % Range: 0–100% Granularity: 1% Accuracy: -0, +MaxError( ) AbsoluteStateOfCharge( )(0x0e) Description: Returns the predicted remaining battery capacity expressed as a percentage of DesignCapacity( ) (%). Note that AbsoluteStateOfCharge( ) can return values greater than 100%. Purpose: The AbsoluteStateOfCharge( ) function is used to estimate the amount of charge remaining in the battery relative to the nominal or DesignCapacity( ). SMBus protocol: Read word Output: Unsigned integer—percent of remaining capacity. Units: % Range: 0–100+% Granularity: 1% Accuracy: -0, +MaxError( ) RemainingCapacity( ) (0x0f) Description: Returns the predicted charge or energy remaining in the battery. The RemainingCapacity( ) value is expressed in either charge or energy, depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. Purpose: The RemainingCapacity( ) function returns the battery’s remaining capacity. This information is a numeric indication of remaining charge or energy given by the Absolute or Relative StateOfCharge( ) functions and may be in a better form for use by power management systems. SMBus protocol: Read word Output: Unsigned integer—remaining charge in units of mAh or 10 mWh. BATTERY MODES CAPACITY_MODE BIT = 0 CAPACITY_MODE BIT = 1 Units mAh 10 mWh Range 0–65,535mAh 0–65,535 10 mWh Granularity mAh 10 mWh Accuracy –0, +MaxError( ) * FullCharageCapacity( ) FullChargeCapacity( ) (0x10) Description: Returns the predicted pack capacity when it is fully charged. The FullChargeCapacity( ) 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 FullChargeCapacity( ) function provides a means of understanding the tank size of the battery. This information, along with information about the original capacity of the battery, indicates battery wear. SMBus protocol: Read word Output: Unsigned integer—estimated full-charge capacity in units of mAh or 10 mWh. 30 www.ti.com bq2085 SLUS541 – OCTOBER 2002 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 mAh 10 mWh Accuracy –0, +MaxError( ) * FullCharageCapacity( ) RunTimeToEmpty( ) (0x11) Description: Returns the predicted remaining battery life at the present rate of discharge (minutes). The RunTimeToEmpty( ) value is calculated based on either current or power depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. Purpose: The RunTimeToEmpty( ) provides the power management system with information about the relative gain or loss in remaining battery life in response to a change in power policy. This information is not the same as the AverageTimeToEmpty( ), which is not suitable to determine the effects that result from a change in power policy. SMBus protocol: Read word Output: Unsigned integer—minutes of operation left. Units: Minutes Range: 0 to 65,534 min Granularity: 2 min or better Accuracy: –0, +MaxError( ) * FullChargeCapacity( ) / Current( ) Invalid Data Indication: 65,535 indicates battery is not being discharged. AverageTimeToEmpty( ) (0x12) Description: Returns a one-minute rolling average of the predicted remaining battery life (minutes). The AverageTimeToEmpty( ) value is calculated based on either current or power depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. Purpose: The AverageTimeToEmpty( ) displays state-of-charge information in a more useful way. It averages the instantaneous estimations so the remaining time does not appear to jump around. SMBus protocol: Read word Output: Unsigned integer—minutes of operation left. Units: Minutes Range: 0 to 65,534 min Granularity: 2 min or better Accuracy: –0, +MaxError( ) * FullChargeCapacity( ) / AverageCurrent( ) Invalid Data Indication: 65,535 indicates battery is not being discharged. AverageTimeToFull( ) (0x13) Description: Returns a one-minute rolling average of the predicted remaining time until the battery reaches full charge (minutes). Purpose: The AverageTimeToFull( ) function can be used by the SMBus host’s power management system to aid in its policy. It may also be used to find out how long the system must be left on to achieve full charge. SMBus protocol: Read word Output: Unsigned integer—remaining time in minutes. Units: Minutes Range: 0 to 65,534 minutes www.ti.com 31 bq2085 SLUS541 – OCTOBER 2002 Granularity: 2 minutes or better Accuracy: –0, +MaxError( ) * FullChargeCapacity( ) / AverageCurrent( ) Invalid Data Indication: 65,535 indicates the battery is not being charged. ChargingCurrent( ) (0x14) Description: Returns the desired charging rate in mA. Purpose: The ChargingCurrent( ) function sets the maximum charge current of the battery. The ChargingCurrent( ) value should be used in combination with the ChargingVoltage( ) value to set the charger’s operating point. Together, these functions permit the bq2085 to dynamically control the charging profile (current/voltage) of the battery. The bq2085 can effectively turn off a charger by returning a value of 0 for this function. The charger may be operated as a constant-voltage source above its maximum regulated current range by returning a ChargingCurrent( ) value of 65,535. SMBus protocol: Read word Output: Unsigned integer—maximum charger output current in mA. Units: mA Range: 0 to 65,535 mA Granularity: 1 mA Accuracy: Not applicable Invalid Data Indication: 65,535 indicates that a charger should operate as a voltage source outside its maximum regulated current range. ChargingVoltage( ) (0x15) Description: Returns the desired charging voltage in mV. Purpose: The ChargingVoltage( ) function sets the maximum charge voltage of the battery. The ChargingVoltage( ) value should be used in combination with the ChargingCurrent( ) value to set the charger’s operating point. Together, these functions permit the bq2085 to dynamically control the charging profile (current/voltage) of the battery. The charger may be operated as a constant-current source above its maximum regulated voltage range by returning a ChargingVoltage( ) value of 65,535. SMBus protocol: Read word Output: Unsigned integer—charger output voltage in mV. Units: mV Range: 0 to 65,535 mV Granularity: 1mV Accuracy: Not applicable Invalid Data Indication: 65,535 indicates the charger should operate as a current source outside its maximum regulated voltage range. BatteryStatus( ) (0x16) Description: Returns the bq2085 status word (flags). Some of the BatteryStatus( ) flags (REMAINING_CAPACITY_ALARM and REMAINING_TIME_ALARM) are calculated on the basis of either current or power depending on the setting of the BatteryMode( ) CAPACITY_MODE bit. This is important because use of the wrong calculation mode may result in an inaccurate alarm. Purpose: The BatteryStatus( ) function is used by the power-management system to get alarm and status bits, as well as error codes from the bq2085. This is basically the same information broadcast to both the SMBus host and the smart battery charger by the AlarmWarning( ) function except that the AlarmWarning( ) function sets the error code bits all high before sending the data. SMBus protocol: Read word 32 www.ti.com bq2085 SLUS541 – OCTOBER 2002 Output: Unsigned Integer–status register with alarm conditions bit mapped as follows: ALARM BITS 0x8000 OVER_CHARGED_ALARM 0x4000 TERMINATE_CHARGE_ALARM 0x2000 Reserved 0x1000 OVER_TEMP_ALARM 0x0800 TERMINATE_DISCHARGE_ALARM 0x0400 Reserved 0x0200 REMAINING_CAPACITY_ALARM 0x0100 REMAINING_TIME_ALARM STATUS BITS 0x0080 Initialized 0x0040 DISCHARGING 0x0020 FULLY_CHARGED 0x0010 FULLY_DISCHARGED ERROR CODES 0x0007 Unknown Error 0x0006 BadSize 0x0005 Overflow/Underflow 0x0004 AccessDenied 0x0003 UnsupportedCommand 0x0002 ReservedCommand 0x0001 Busy 0x0000 OK Alarm Bits OVER_CHARGED_ALARM bit is set whenever the bq2085 detects that the battery is being charged beyond the maximum overcharge limit. This bit is cleared when the bq2085 detects that the battery is no longer being charged and there are 2 mAh of continuous discharge (i.e., the bq2085 detects discharge activity or no activity above the digital filter). TERMINATE_CHARGE_ALARM bit is set when the bq2085 detects that one or more of the battery charging parameters are out of range (e.g., its voltage, current, or temperature is too high) or when the bq2085 detects a primary charge termination. This bit is cleared when the parameter falls back into the allowable range, the termination condition ceases, or when the bq2085 detects that the battery is no longer being charged. OVER_TEMP_ALARM bit is set when the bq2085 detects that the internal battery temperature is greater than or equal to the Max Temperature threshold. This bit is cleared when the internal temperature falls back into the acceptable range. TERMINATE_DISCHARGE_ALARM bit is set when RM = 0, Voltage( ) ≤ Terminate Voltage, or the CVUV bit in pack status is set indicating that a Li-Ion cell voltage has dropped below the limit programmed in Cell Under. The bit is cleared when Voltage( ) > Terminate Voltage, RM( ) > 0, and the CVUV bit is cleared. REMAINING_CAPACITY_ALARM bit is set when the bq2085 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. www.ti.com 33 bq2085 SLUS541 – OCTOBER 2002 REMAINING_TIME_ALARM bit is set when the bq2085 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 bq2085 is has detected a valid load of data flash at full or partial reset. It is cleared when the bq2085 detects an improper data flash load. DISCHARGING bit is set when the bq2085 determines that the battery is not being charged. This bit is cleared when the bq2085 detects that the battery is being charged. FULLY_CHARGED bit is set when the bq2085 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 EDV2 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 bq2085 processed the function code without detecting any errors. Busy The bq2085 is unable to process the function code at this time. Reserved The bq2085 detected an attempt to read or write to a function code reserved by this version of the specification. The bq2085 detected an attempt to access an unsupported optional manufacturer function code. Unsupported The bq2085 does not support this function code which is defined in this version of the specification. AccessDenied The bq2085 detected an attempt to write to a read-only function code. Over/Underflow The bq2085 detected a data overflow or underflow. BadSize The bq2085 detected an attempt to write to a function code with an incorrect data block. UnknownError The bq2085 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 bq2085 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. 34 www.ti.com bq2085 SLUS541 – OCTOBER 2002 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 DesignVoltage( ) (0x19) Description: Returns the theoretical voltage of a new pack (mV). The bq2085 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 bq2085 VScale (voltage scaling) and IPScale (current scaling) should always be set to zero. The bq2085 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 bq2085 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( ). www.ti.com 35 bq2085 SLUS541 – OCTOBER 2002 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 bq2085 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. SMBus protocol: Read word Output: Unsigned integer ManufacturerName( ) (0x20) Description: This function returns a character array containing the battery manufacturer’s name. For example, MyBattCo identifies the smart battery manufacturer as MyBattCo. The bq2085 sets ManufacturerName( ) to the value programmed in Manufacturer Name Length DF 0x0e–0x19. 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 bq2085 indicates that the battery is a model bq2085. The bq2085 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 bq2085 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 bq2085 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). 36 www.ti.com bq2085 SLUS541 – OCTOBER 2002 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 bq2085 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 bq2085 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). 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 bq2085 operation. The pack status register is the least significant byte of the word. The pack configuration register reflects how the bq2085 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 bq2085. 0 1 The bq2085 is in the unsealed state. The bq2085 is in the sealed state. www.ti.com 37 bq2085 SLUS541 – OCTOBER 2002 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 bq2085 is reset. 0 1 Safety limits not exceeded 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 1 No secondary protection limits exceeded 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 1 No secondary protection limits exceeded A secondary protection limit exceeded VCELL4-VCELL1 (0x3c-0x3f) These functions return the calculated individual cell voltages in mV. Data Flash General The bq2085 accesses the internal data flash during reset and when storing historical data. The data flash stores basic configuration information for use by the bq2085. The data flash must be programmed correctly for proper bq2085 operation. Memory Map Table 13 shows the memory map for the data flash. It shows the default programming for the bq2085. 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. 38 www.ti.com bq2085 SLUS541 – OCTOBER 2002 Table 13. Data Flash Memory Map DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI ION EXAMPLE LI-ION 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 11 0b 0x0f Character 1 T 54 0x10 Character 2 e 45 0x11 Character 3 x 58 0x12 Character 4 a 41 0x13 Character 5 s 53 0x14 Character 6 0x15 Character 7 I 49 0x16 Character 8 n 4e 0x17 Character 9 s 53 0x18 Character 10 t 54 0x19 Character 11 . 2e 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 3 33 0x21 Character 7 — 00 0x22 Device Chemistry Length 4 04 0x23 Character 1 L 4c 0x24 Character 2 I 49 0x25 Character 3 O 4f 0x26 Character 4 N 4e 0x27 Manufacturer Data Length 12 09 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 % 7.03% 12 Near Full 200 mAh 0x2f 0x30 20 00 c8 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. www.ti.com 39 bq2085 SLUS541 – OCTOBER 2002 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI ION EXAMPLE LI-ION MSB LSB 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 Precharge Current 100 mA 00 64 0x43 Precharge Temp 9.6°C 0x44 Reserved 1e 0x45 Reserved 00 0x46 Fast Charge Termination % 100% ff 0x47 Fully Charged Clear % 95% 5f 60 0x48 0x49 Current Taper Threshold 240 mA 00 f0 0x4a 0x4b Current Taper Qual Voltage 100 mV 00 64 0x4c Reserved 0x4d 0x4e Reserved 0x4f Reserved 0x51 Charge Efficiency 0x52 Reserved 0x54 0x55 40 Maximum Overcharge 0x50 0x53 28 300 mAh 100% 54.6°C 5°C Reserved 0x58 0x59 Overload Current 0x5a 0x5b Over Voltage Margin 0x5c 0x5d Overcurrent Margin 0x5e 0x5f Reserved 0x60 0x61 Cell Over Voltage 0x62 0x63 0x64 0x65 0x66 0x67 Reserved 0x68 0x69 Safety Over Voltage 0x6a 0x6b Safety Over Temperature ff 64 Temperature Hysteresis 0x57 2c 02 MaxTemperature 0x56 01 02 22 32 01 ae 5000 mA 13 88 208 mV 00 d0 500 mA 01 f4 01 00 4350 mV 10 fe Cell Under Voltage 2300 mV 08 fc Terminate Voltage 8500 mV 21 34 00 00 20000 mV 4e 20 70°C 02 bc 0x6c Reserved ef 0x6d Reserved 03 0x6e 0x6f VOC75 11890 mV 2e 72 0x70 Reserved bf 0x71 Reserved 56 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 bq2085 SLUS541 – OCTOBER 2002 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE LOW BYTE 0x72 0x73 DATA NAME LI ION EXAMPLE LI-ION MSB Reserved 0x74 LSB 40 VOC50 11430 mV 2c a6 0x75 Reserved 7f 0x76 Reserved 3d 0x77 0x78 Reserved 0x79 27 VOC25 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 0x88 0x89 EDV R0 Factor/EDV2 3250 mV 0c b2 3400 mV 0d 48 0x8a 0x8b 0x8c 0x8d EDV T0 Factor 0 00 00 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 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 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. www.ti.com 41 bq2085 SLUS541 – OCTOBER 2002 Table 13. Data Flash Memory Map (Continued) DATA FLASH ADDRESS HIGH BYTE DATA NAME LOW BYTE LI ION EXAMPLE LI-ION MSB LSB 0xac 0xad TS Const 5 00 00 0xae 0xaf Reserved 0f ac 0xb0 Reserved 0xb1 AFE Brnout Shutdn Shutdown = 6.475, Brownout = 7.975 V 32 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 ff 0xb5 Reserved 0xb6 AFE Short Circ Thrsh 275 mV 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 05 f8 0xc4 ADC Offset* 16 11 0xc5 Temperature Offset* 0 00 0xc6 Board Offset* 0 00 10 0xc7 0xc8 Reserved 00 40 0xc9 0xca Reserved 01 00 0xcb 0xcc Reserved 0xcd 0xce 05 Version 1.0 Reserved 01 00 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 ff ff 3900 mV 0f 3c 00 64 Cell Balance Window 100 mV 0xdb Cell Balance Min 40 mV 28 0xdc Cell Balance Interval 20 seconds 14 0xdd 0xde Reserved a5 5a 0xdf 0xd0 Reserved 7a 43 0xe1 0xe2 Reserved 20 83 0xe3 Reserved 0xe4 AFE Check Time 0 seconds 00 00 0xe5 Sleep Current Thresh 2 mA 04 0xe6 Sleep Current Time 20 seconds 14 0xe7 Sleep Time 100 seconds 64 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. 42 www.ti.com bq2085 SLUS541 – OCTOBER 2002 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. (3) Digital Filter + VDF 290 nV 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 bq2085 copies Design Capacity to DesignCapacity( ). In mWh mode, the bq2085 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 bq2085 updates Last Measured Discharge in mAh after a capacity learning cycle. The bq2085 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 bq2085 uses three pack-voltage thresholds to provide voltage-based warnings of low battery capacity. The bq2085 uses the values stored in data flash for the EDV0, 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. If EDV compensation is disabled then EDV0, EDV1, and EDV2 are stored directly in mV in DF 0x84–0x85, DF 0x86–0x87, and DF 0x88–0x89, respectively. For capacity correction at EDV2, Battery Low % DF 0x2e 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. (4) Battery Low % = (STATEOFCHARGE% • 2.56) The bq2085 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. www.ti.com 43 bq2085 SLUS541 – OCTOBER 2002 EDV Discharge Rate and Temperature Compensation If EDV compensation is enabled, the bq2085 calculates battery voltage to determine EDV0, EDV1, and EDV2 thresholds as a function of battery capacity, temperature, and discharge load. The general equation for EDV0, EDV1, and EDV2 calculation is EDV0,1,2 = 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 capacityrelated 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. 44 www.ti.com bq2085 SLUS541 – OCTOBER 2002 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 – % 0 1 2 3 4 5 6 7 8 9 10 Capacity – % Figure 8. EDV Calculations vs Capacity for Various Temperatures 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 bq2085 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: www.ti.com 45 bq2085 SLUS541 – OCTOBER 2002 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. 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 bq2085 by a Level 3 smart battery charger. The bq2085 sets the value of ChargingCurrent( ), depending on the charge requirements and charge conditions of the pack. When fast charge is allowed, the bq2085 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 bq2085 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 bq2085 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 bq2085 sets ChargingCurrent( ) to PreCharge Current. The threshold is programmed in the Precharge Temp DF 0x43. Precharge Temp + (10) PC (°C) 0.1 The bq2085 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 bq2085 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 bq2085 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: (11) Max Temperature + MAXTEMP 0.1 The bq2085 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 bq2085 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. 46 www.ti.com bq2085 SLUS541 – OCTOBER 2002 FULLY_CHARGED Bit Clear Threshold The bq2085 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 bq2085 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. 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 LED1 LED0 HPE CPE SM CC1 CC0 DMODE The DMODE bit determines whether the RelativeStateOfCharge( ). 0 LEDs reflect AbsoluteStateOfCharge( ) 1 LEDs reflect RelativeStateOfCharge( ) LED outputs indicate AbsoluteStateOfCharge( ) or LED1–LED0 The LED bits set the number of LEDs for Remaining Capacity ( ) indication. 0–1 Configures the bq2085 for three LEDs 1–0 Configures the bq2085 for four LEDs 1–1 or 0–0 Configures the bq2085 for five LEDs www.ti.com 47 bq2085 SLUS541 – OCTOBER 2002 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 bq2085. 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 bq2085 for the number of series cells in the battery pack. 1–1 Configures the bq2085 for four series cells 1–0 Configures the bq2085 for three series cells Gauge Configuration Gauge Configuration DF 0x29 contains bit-programmable features: b7 b6 b5 b4 b3 b2 b1 b0 0 CSYNC SC CEDV EDVV OVSEL VCOR OTVC CSYNC In usual operation of the bq2085, 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 1 The bq2085 does not alter RM at the time of a valid charge termination. The bq2085 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 bq2085 implements automatic EDV compensation to calculate the EDV0, EDV1, and EDV2 thresholds base on rate, temperature, and capacity. If the bit is cleared, the bq2085 uses the fixed values programmed in data flash for EDV0, EDV1, and EDV2. If the bit is set, the bq2085 calculates EDV0, EDV1, and EDV2. 48 0 EDV compensation disabled 1 EDV compensation enabled www.ti.com bq2085 SLUS541 – OCTOBER 2002 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 bq2085 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 bq2085 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. 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 and AFE Short Circuit Delay DF 0xb7 sets the short circuit delay time. www.ti.com 49 bq2085 SLUS541 – OCTOBER 2002 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 0 AC DS OT ECLED PHG VOD IT The IT bit configures the bq2085 to use its internal temperature sensor. 0 bq2085 requires an external thermistor. 1 bq2085 uses its internal temperature sensor. AC The AC bit enables the SAFE output to function based on the AFE integrity check. 0 SAFE is not activated based on the AFE integrity check. 1 SAFE activated based on the AFE integrity check. DS The DS bit programs the bq2085 to enter sleep mode on SMBus inactivity. 0 bq2085 enters sleep mode when the SMBus is low for 2 s. 1 bq2085 does not enter sleep mode. OT The OT bit programs the bq2085 to turn off the discharge FET when the bq2085 detects an overtemperature condition. Charge FET is always turned off in overtemperature conditions. 0 bq2085 does not turn off the discharge FET on overtemperature. 1 bq2085 turns off the discharge FET on overtemperature. ECLED The ECLED bit programs the LED activity during charging (DSG bit = 0). 50 0 The LEDs are not enabled during charging. 1 The LEDs are enabled during charging. www.ti.com bq2085 SLUS541 – OCTOBER 2002 PHG The PHG bit configures the bq2085 to control a precharge FET. 0 The bq2085 does not control a precharge FET. 1 The bq2085 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 SepcificationInfo( ). 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. Locations DF 0x0f–0x19 store the characters for ManufacturerName( ) in ASCII code. Device Name Data Device Name Length DF 0x1a stores 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. www.ti.com 51 bq2085 SLUS541 – OCTOBER 2002 APPLICATION INFORMATION The internal oscillator performance also depends on the tolerance of the 113k resistor connected between RSOC (pin 33) and VSSA (pin 34). It is recommended that this resistor be placed as close to the bq2085 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 bq2085-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 bq2085 operation. Table 13 shows the data flash memory map and outlines the programmable functions available in the bq2085. 52 www.ti.com VM VL VG X3 X4 X5 1K CO C7 .1uF 1K R10 5 C11 .1uF 6 7 C10 .1uF 8 Current sense resistor R13 should have Temp Coefficient of 75 PPM or less. C5 .1uF .1uF VC3 VSS ICT 3 C4 .1uF 1K R9 C6 VC2 VC1 SNS VCC Resistor R29 should have Temp Coefficient of 50 PPM or less @.2% or better. R7 1K R6 1K R5 1K R4 R3 1K 1K R8 4 3 2 1 2 1K 100 .1uF C3 .1uF C2 U1 S–8244 BAV99 D1 .1uF C9 .1uF 1 R2 R1 PACK_ SMBD C12 .1uF Q2 Si4435DY 8765 300 R12 C13 .1uF 1 C14 .1uF D2 BAV99 JP1 Q3 2N7002 F1 7A C R11 1M B A 8765 SMBC Tie Digital GND, Analog GND, & Sense Connections to high current path at a single point at sense resistor R13 PACK_ VH X2 .1uF C1 VP 1 2 3 4 5 6 4 4 321 321 Q4 3 4 321 7 6 5 4 3 10 2 1 1 R13 .020 1W SR1 8 VC5 VC4 VC3 VC2 VC1 CNTL VBAT CLKIN XALERT SDATA SCLK LEDOUT TOUT VREG VPACK CHG 5K R21 100 R20 100 12 16 17 15 14 20 18 19 24 R19 VCELL SR2 GND GND 9 13 11 bq29311 U2 PCHG 21 5K 5K 22 R17 R18 1MEG R15 R14 1MEG R16 1MEG DSG 23 8765 VCC Si4435DY 100 R22 C15 .047uF C16 0.1uF R24 100K Q5 BSS84 R23 1MEG C18 0.1uF 1 R25 100K 0.1uF C17 C20 0.1uF C21 0.1uF 1 C19 0.1uF 100K R26 VCC 1 ROSC 1 3 1 C23 0.1uF 1 11 Display SW1 19 38 2 4 30 1 GREEN D3 25 24 23 22 21 20 18 36 16 15 3 2 32 34 100 R30 2 R29 33 113K .2% C25 0.47uF NC VSSA 26 MRST FILT 9 RBI OC 12 SAFE TS 10 SDATA SMBC 6 SCLK SMBD 7 NC 17 DISP NC 35 CLKOUT EVENT 28 SR1 LED5 27 SR2 LED4 4 NC LED3 13 bq2085DBT NC LED2 5 U3 NC LED1 37 NC NC 29 VSSP VSSD VSSD VSSD VSSA VDDA 31 R28 10 R27 10 VCCD VIN 1 0.47uF 8 14 2 C24 TP1 C22 .47uF 1 1 1 470 150pF C27 R32 61.9K 100 R34 100 470 R36 100 R38 D4 AZ23C5V6 1 R37 61.9K GREEN D7 R35 2200pF C26 R33 8.45K GREEN D5 R31 2 Q1 1 2 Si4435DY 470 R39 GREEN D8 1M R40 1M R41 SMBD SMBC TG1 T1 C28 RT1 0.47uF 1 C8 1 2 www.ti.com 470 R42 2 X1 J1 bq2085 SLUS541 – OCTOBER 2002 APPLICATION INFORMATION Figure 10. Typical bq2085 Implementation 53 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) BQ2085DBT ACTIVE TSSOP DBT 38 50 RoHS & Green NIPDAU Level-2-260C-1 YEAR -20 to 85 2085DBT (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of