PW RTH bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 TWO-CELL, THREE-CELL, AND FOUR-CELL LITHIUM-ION OR LITHIUM-POLYMER BATTERY PROTECTION AFE FEATURES APPLICATIONS • • • • • • • • • • • • • • • 2-, 3-, or 4-Cell Series Protection Control Can Directly Interface With the bq2084 Gas Gauges Provides Individual Cell Voltages and Battery Voltage to Battery Management Host Integrated Cell Balancing Drive I2C Compatible User Interface Allows Access to Battery Information Programmable Threshold and Delay for Overload and Short Circuit During Charge and Discharge System Alert Interrupt Output Host Control Can Initiate Sleep Power Mode and Ship Mode Integrated 3.3-V, 25-mA LDO Supply Voltage Range From 4.5 V to 25 V Low Supply Current of 60-µA Typical bq29312A is 100% specification compatible with the bq29312 Notebook PCs Medical and Test Equipment Portable Instrumentation DESCRIPTION The bq29312A is a 2-, 3-, or 4-cell lithium-ion battery pack protection analog front end (AFE) IC that incorporates a 3.3-V, 25-mA low-dropout regulator (LDO). The bq29312A also integrates an I2C compatible interface to extract battery parameters such as cell voltages and control output status. Other parameters such as current protection thresholds and delays can be programmed into the bq29312A to increase the flexibility of the battery management system. The bq29312A provides safety protection for overcharge, overload, short-circuit, overvoltage, and undervoltage conditions with the battery management host. In overload and short-circuit conditions, the bq29312A turns the FET drive off autonomously dependant on the internal configuration setting. SYSTEM PARTITIONING DIAGRAM Discharge / Charge / Precharge FETs Fuse Pack + Power Management LDO, TOUT, and Power Mode control Temperature Measurement <1% Error 768 Bytes of User Flash SMBus bq29312A PF Input PCH FET Drive Fail-Safe Protection TINT 32-kHz Clock Generator Supply V oltage T1 Precharge FET Drive Cell Balancing Drive LDO, Therm Output Drive & UVLO System Watchdog Delay Counters System Interface RAM Registers 32 kHz Cell Balancing Algorithm and Control SBS v1.1 Data System Interface bq29312 RAM/Comms Validation 1st Level OC Protection 1st Level OV and UV Protection Pack Undervoltage Power Mode Control Cell and Pack Voltage Measurement I2 C XAlert Sleep 2 nd Level Overvoltage Protection bq2084 Precharge Control Power Mode Control 2-Tier Overcurrent Protection Capacity Prediction <1% Error Voltage Level Translator Pack Sense Resistor (10 - 30 m W) 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. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2005, Texas Instruments Incorporated bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. DESCRIPTION (Continued) The communications interface allows the host to observe and control the current status of the bq29312A. It enables cell balancing, enters different power modes, sets overload levels, sets the overload blanking delay time, sets short-circuit threshold levels for charge and discharge, and sets the short-circuit blanking delay time. Cell balancing of each cell is performed via a cell bypass path, which is enabled via the internal control register accessible via the I2C compatible interface. The maximum bypass current is set via an external series resistor and internal FET on resistance (typical 400 Ω). ORDERING INFORMATION (1) PACKAGED TA TSSOP (PW) (2) –40°C to 85°C (1) (2) (3) QFN (RTH) bq29312APWR-SA (3) bq29312ARTH For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. The bq29312A can be ordered in tape and reel by adding the suffix R to the orderable part number, ie: bq29312APWR bq29312ARTHR. The QFN package is also made available in mini reel, add suffix T to the orderable part number, ie: bq29312ARTHT. PACKAGE DISSIPATION RATINGS POWER RATING PACKAGE POWER RATING TA ≤ 25°C DERATING FACTOR ABOVE TA ≤ 25°C TA ≤ 70°C TA = 85°C PW 874 mW 6.99 W/°C 559 mW 454 mW ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range unless otherwise noted (1) (2) bq29312A VCC VI Supply voltage range Input voltage range PACK, BAT –0.3 V to 34 V SR1, SR2 –1.0 V to 1.0 V VC5 –1.0 V to 4.0 V VC1 to VC2, VC2 to VC3, VC3 to VC4, VC4 to VC5 –0.3 to 8.5 V WDI, SLEEP, SCLK, SDATA –0.3 to 8.5 V ZVCHG VO Output voltage range –0.3 V to BAT OD –0.3 V to 34 V PMS Current for cell balancing Continuous total power dissipation Storage temperature range Lead temperature (soldering, 10 s) (1) (2) 2 –0.3 V to 34 V DSG, CHG TOUT, SCLK, SDATA, CELL, XALERT Tstg –0.3 V to 34 V VC1, VC2, VC3, VC4 –0.3 V to PACK–0.2 V –0.3 to 7 V 10 mA See Dissipation Rating Table –65°C to 150°C 300°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. All voltages are with respect to ground of this device except VCn–VC(n+1), where n = 1-, 2-, 3-, 4-cell voltage. bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 RECOMMENDED OPERATING CONDITIONS MIN Supply Voltage (BAT or PACK) VI(STARTUP) Start-up voltage (PACK) VIH Input voltage range MAX 25 5.0 VC1, VC2, VC3, VC4 VI NOM 4.5 (1) UNIT V V 0 BAT SR1, SR2 –0.5 0.5 VC5 –0.5 3.0 VCn – VC(n+1), (n = 1, 2, 3, 4 ) 0 5.0 PMS 0 PACK SLEEP 0 REG 0.8 × REG REG 0 0.2 × REG V(PACK) – 0.2 V(PACK) 0 0.2 100 1000 V V Logic level input voltage SCLK, SDATA, WDI PMS logic level PMS PMS pullup/pulldown resistance RPMS VO Output voltage OD 25 V IO Output current XALERT, SDATA 200 µA CELL ±10 µA II Input current, External 3.3-V REG capacitor 1.0 µA VIL VIH VIL Extend CELL output filter IOL Input frequency WDI high time TA (1) Operating temperature SLEEP -0.5 C(REG) 4.7 V kΩ µF R(CELL) 100 Ω C(CELL) 100 nF OD 1 WDI 32.768 mA kHz 2 28 µs –40 85 °C V(PACK) supply voltage must rise above start-up voltage on power up to enable the internal regulator which drives REG and TOUT as required. Once V(PACK) is above the start-up voltage, it can fall down to the minimum supply voltage and still meet the specifications of the bq29312A. 3 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 ELECTRICAL CHARACTERISTICS TA = 25°C, C(REG) = 4.7 µF, BAT = 14 V (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT SUPPLY CURRENT ICC1 Supply current 1 No load at REG, TOUT, XALERT, SCLK, and SDATA. ZVCHG = off ,VMEN = on, WDI no clock, Select VC5 = VC4 = 0 V TA = –25°C to 85°C 60 90 ICC2 Supply current 2(Depends of VM topology selected) No load at REG, TOUT, XALERT, SCLK, and SDATA. ZVCHG = off, VMEN = off, WDI no clock TA = –25°C to 85°C 25 50 µA I(SLEEP) Sleep current No load at REG, TOUT, XALERT, SCLK, and SDATA.CHG, DSG and ZVCHG = off, REG = on, VMEN = off, WDI no clock, SLEEP = REG or OPEN TA = –25°C to 85°C 20 40 µA I(SHIP) Ship current REG, CHG, DSG and ZVCHG = off, REG = off, VMEN = off, WDI no clock, VPACK= 0 V TA = –25°C to 85°C 0.1 1.0 µA 100 µA 3.3 V LDO Regulator output voltage V(REG) 8.0 V < BAT or PACK ≤ 25 V, IOUT ≤ 25 mA –4% 3.3 2% 6.5 V < BAT or PACK ≤ 8 V, IOUT ≤ 25 mA –9% 3.3 2% –9% 3.3 2% V –2% 3.3 2% V mV 5.4 V ≤ BATor PACK ≤ 6.5 V, IO ≤ 16 mA TA = –25°C to 85°C 4.5 V ≤ BAT or PACK ≤ 25 V, IO ≤ 2 mA ∆V(EGTEMP) Regulator output change with temperature 5.4 V ≤ BAT ≤ 25 V, IO = 2 mA, ∆V(REGLINE) Line regulation 5.4 V ≤ BAT or PACK ≤ 25 V, IO = 2 mA ∆V(REGLOAD) Load regulation IMAX Current limit TA = –25°C to 85°C V ±0.2% 10 20 BAT = 14 V, 0.2 mA ≤ IO ≤ 2 mA 7 15 BAT = 14 V, 0.2 mA ≤ IO ≤ 25 mA 40 100 BAT = 14 V, REG = 3 V 25 100 BAT = 14 V, REG = 0 V 12 50 mV mA CELL VOLTAGE MONITOR V(CELL OUT) CELL output V(Cn) – V(Cn + 1) = 0 V, 8 V ≤ BAT or PACK ≤ 25 V V(Cn) – V(Cn + 1) = 4.5 V, 8 V ≤ BAT or PACK ≤ 25 V CELL output Mode (1), 8 V ≤ BAT or PACK ≤ 25 V PACK CELL output Mode (2) K CELL scale factor REF 0.975 1% V –5% PACK/ 25 5% V K = (CELL output (VC5 = 0 V, VC4 = 4.5 V) –CELL output (VC5 = VC4 = 0 V)/ 4.5 0.147 0.150 0.153 K = (CELL output (VC2 = 13.5 V, VC1 = 18 V) –CELL output (VC2 = VC1 = 13.5 V)/ 4.5 0.147 0.150 0.153 CELL output offset error CELL output (VC2 = 17 V, VC1 = 17 V) CELL output (VC2 = VC1 = 0 V) R(BAL) Cell balance internal resistance rds(ON) for internal FET switch at VDS = 2 V 4 V 0.3 –1% VICR (1) (2) 0.975 Register Address =0x04, b2(CAL0) = b3(CAL1) = 1, Register Address = 0x03, b0(VMEN) = 1 Register Address = 0x03, b1(PACKOUT) = 1, b0( VMEN) = 1 –1 200 400 mV 800 Ω bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 ELECTRICAL CHARACTERISTICS (Continued) TA = 25°C, C(REG) = 4.7 µF, BAT = 14 V (unless otherwise noted) PARAMETER TEST CONDITION MIN NOM MAX UNIT –205 mV OVERLOAD (OL) AND SHORT-CIRCUIT (SC) DETECTION VOL OL detection threshold range, typical (1) ∆VOL OL detection threshold program step VHYS(OL) OL detection threshold hysteresis V(SC) SC detection threshold range, typical (2) ∆V(SC) SC detection threshold program step VHYS(SC) SC detection threshold hysteresis –50 5 7 Charge Discharge OL detection threshold accuracy (1) –475 25 Charge and Discharge VOL = 100 mV VSC = 100 mV (min) SC detection threshold accuracy (2) –100 Charge and Discharge mV mV mV –25 VOL = 205 mV (max) V(SC_acr) 475 Discharge Discharge mV 13 100 Charge VOL = 50 mV (min) V(OL_acr) 10 40 50 60 40 50 60 90 100 110 184 205 226 80 100 120 VSC = 200 mV 180 200 220 VSC = 475 mV (max) 426 475 523 mV mV mV FET DRIVE CIRCUIT V(FETOND)= V(BAT)– V(DSG)VGS connect 1 MΩ 12 15 18 V(FETONC)=V(PACK)– V(CHG)VGS connect 1 MΩ PACK = 20 V BAT= 20 V 12 15 18 PACK= 4.5 V 3.3 3.5 3.7 V(FETON) Output voltage, charge, and discharge FETs on V(ZCHG) ZVCHG clamp voltage V(FETOFF) Output voltage, charge and discharge FETs off V(FETOFF)= V(PACK)– V(DSG) PACK= 16 V 0.2 V(FETOFF)=V(BAT)– V(CHG) BAT = 16 V 0.2 tr Rise time CL = 4700 pF tf Fall time CL = 4700 pF VDSG :10%–90% 40 200 VCHG :10%–90% 40 200 VDSG :90%–10% 40 200 VCHG :90%–10% 40 200 50 100 V V V µs µs THERMISTOR DRIVE rDS(on) TOUT pass-element series resistance IO = –1 mA at TOUT pin, rds(ON) = (VREG– VO (TOUT))/1 mA, TA = –25°C to 85°C Ω LOGIC R(PUP) Internal pullup resistance VOL Logic level output voltage (1) (2) XALERT TA = –25°C to 85°C 60 100 200 SDATA, SCLK, TA = –25°C to 85°C 6 10 20 XALERT, IO = 200 µA, TA = –25°C to 85°C 0.2 SDATA, IO = 50 µA, TA = –25°C to 85°C 0.4 OD IO=1 mA, TA = –25°C to 85°C 0.6 kΩ V See OL register for setting detection threshold See SC register for setting detection threshold 5 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 AC ELECTRICAL CHARACTERISTICS TA = 25°C, C(REG) = 4.7 µF, BAT = 14 V (unless otherwise noted) PARAMETER TEST CONDITION t(WDTINT) WDT start-up detect time t(WDWT) WDT detect time MIN NOM MAX 250 700 2000 UNIT ms 100 µs AC TIMING SPECIFICATIONS (I2C COMPATIBLE SERIAL INTERFACE) PARAMETER MIN MAX UNIT 1000 ns 300 ns tr SCLK SDATA rise time tf SCLK SDAT fall time tw(H) SCLK pulse width high 4.0 µs tw(L) SCLK pulse width low 4.7 µs tsu(STA) Setup time for START condition 4.7 µs th(STA) START condition hold time after which first clock pulse is generated 4.0 µs tsu(DAT) Data setup time 250 ns th(DAT) Data hold time 0 µs tsu(STOP) Setup time for STOP condition 4.0 µs tsu(BUF) Time the bus must be free before new transmission can start 4.7 tV Clock low to data out valid th(CH) Data out hold time after clock low 0 fSCL Clock frequency 0 tsu(STA) tw(H) tf tw(L) µs 900 ns 100 kHz ns tr SCLK tr SDATA Start Condition SDA Input th(STA) 1 SCLK tf Stop Condition SDA Change th(DAT) tsu(DAT) 3 7 2 th(ch) 8 9 MSB SDATA ACK Start Condition tv tsu(STOP) SCLK SDATA 1 MSB 2 3 7 8 9 ACK Stop Condition 6 tsu(BUF) bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 PIN ASSIGNMENTS PW PACKAGE (TOP VIEW) VC1 DSG BAT OD PMS PACK 24 23 22 21 20 19 18 17 16 15 14 13 OD PMS PACK ZVCHG CHG SLEEP REG TOUT XALERT GND SDATA SCLK ZVCHG CHG SLEEP REG TOUT XALERT VC2 VC3 VC4 VC5 SR1 SR2 WDI CELL GND SCLK SDATA GND 1 2 3 4 5 6 7 8 9 10 11 12 BAT DSG VC1 VC2 VC3 VC4 VC5 SR1 SR2 WDI CELL GND RTH PACKAGE (TOP VIEW) Terminal Functions TERMINAL NAME PIN NO. DESCRIPTION RTH PW BAT 22 1 Diode protected BAT+ terminal and primary power source. DSG 23 2 Push-pull output discharge FET gate drive VC1 24 3 Sense voltage input terminal for most-positive cell and balance current input for most-positive cell. VC2 1 4 Sense voltage input terminal for second most-positive cell, balance current input for second most-positive cell and return balance current for most-positive cell. VC3 2 5 Sense voltage input terminal for third most-positive cell, balance current input for third most-positive cell and return balance current for second most-positive cell. VC4 3 6 Sense voltage input terminal for least-positive cell, balance current input for least-positive cell and return balance current for third most-positive cell. VC5 4 7 Sense voltage input terminal for most-negative cell, return balance current for least-positive cell. SR1 5 8 Current sense positive terminal when charging relative to SR2 SR2 6 9 Current sense negative terminal when discharging relative to SR2 current sense terminal WDI 7 10 Digital input that provides the timing clock for the OC and SC delays and also acts as the watchdog clock. CELL 8 11 Output of scaled value of the measured cell voltage. GND 9 12 Analog ground pin and negative pack terminal SCLK 10 13 Open-drain bidirectional serial interface clock with internal 10-kΩ pullup to V(REG). SDATA 11 14 Open-drain bidirectional serial interface data with internal 10-kΩ pullup to V(REG). GND 12 15 Connect to GND XALERT 13 16 Open-drain output used to indicate status register changes. With internal 100-kΩ pullup to V(REG) TOUT 14 17 Provides thermistor bias current REG 15 18 Integrated 3.3-V regulator output SLEEP 16 19 This pin is pulled up to V(REG) internally, open or H level makes Sleep mode CHG 17 20 Push-pull output charge FET gate drive ZVCHG 18 21 The ZVCHG FET drive is connected here PACK 19 22 PACK positive terminal and alternative power source PMS 20 23 0-V charge configuration select pin, CHG terminal ON/OFF is determined by this pin. OD 21 24 NCH FET open-drain output 7 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL BLOCK DIAGRAM PACK- GG VDD PACK+ R(ZVCHG) C (REG) PMS ZVCHG REG 0.2-A Current Source CHG DSG BAT ZVCHG_ON Gate Driver CHG_ON DSG_ON + _ - PACK FET Logic REG 3.3V LDO POR SLEEP CONTROL 32-kHz INPUT FROM GG SLEEP Watchdog Timer WDI GG INTERFACE SDATA GG INTERFACE SCLK SDATA SCLK REG SERIAL INTERFACE Registers Status Function Ctl CELL 2 VC4 CELL 1 VC5 Drive Control TOUT C THERM THERMISTOR R CELL VCELL OCDV OCDT Overload Comparator SCC OpenDrain Output C CELL GG ANALOG INPUT OVERCURRENT SR1 DELAY SHORT-CIRCUIT Short-Circuit Comparator R SNS SR2 GND 8 GG TS INPUT R THERM Cell Voltage Translation CELL_SEL SCD OD CELL 3 VC3 State Ctl 200 k OPEN-DRAIN OUTPUT Power Mode Circuit CELL 4 VC2 Output Ctl ALERT TO GG XALERT SHIP_ON SLEEP_ON CELL1..4 200 k Cell Selection Switches VC1 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 STATE DIAGRAM No Power SHIP MODE EXIT BY POWER SUPPLY TO PACK POWER SUPPLY TO PACK INITIALIZE FETS: OFF(*2) REG: start Working I2C: OFF CURRENT FAULT : OFF CELL MONITOR : OFF WATCHDOG : OFF THERMISTOR PWER CTRL : OFF REG >2.4 V IFAULT RESET CURRENT LATCH HOST FAULT MODE FETS: OFF REG: ON I2C: ON CURRENT FAULT : OFF CELL MONITOR : OFF WATCHDOG : ON THERMISTOR PWER CTRL : OFF REG < 2.3 V NORMAL MODE FETS: ON *2 REG: ON I2C: ON CURRENT FAULT : ON CELL MONITOR : ON WATCHDOG : ON THERMISTOR PWER CTRL : ON HOST CLOCK STOP RESET WDTF LATCH STATE CTL REGISTER b1 = 1 AND NO SUPPLY POWER TO PACK SLEEP MODE EXIT BY STATE CTL REGISTER b0 = 0 AND SLEEP PIN = GND *1 STATE CTL REGISTER b0 = 1 or SLEEP PIN = REG or OPEN *1 CURRENT DETECT MODE SLEEP MODE SHIP MODE FETS: OFF REG: ON I2C: ON CURRENT FAULT : ON CELL MONITOR : ON WATCHDOG : ON THERMISTOR PWER CTRL : ON FETS: OFF REG: ON I2C: ON CURRENT FAULT : OFF CELL MONITOR : OFF WATCHDOG : OFF THERMISTOR PWER CTRL : OFF FETS: OFF REG: OFF I2C: OFF CURRENT FAULT : OFF CELL MONITOR : OFF WATCHDOG : OFF THERMISTOR PWER CTRL : OFF SHIP MODE SET BY STATE CTL REGISTER b1 = 1 AND NO SUPPLY POWER TO PACK SHIP MODE SET BY STATE CTL REGISTER b1 = 1 AND NO SUPPLY POWER TO PACK Interrupt Request When Enrering These States *1: Interrupt Request is Granted When Only External Sleep Pin Changes *2: When PMS connect to Pack, Default State of CHG FET is ON. 9 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL DESCRIPTION Low-Dropout Regulator (REG) The inputs for this regulator can be derived from the battery cell stack (BAT) or the pack positive terminal (PACK). The output is typically 3.3 V with the minimum output capacitance for stable operation is 4.7 µF and is also internally current limited. During normal operation, the regulator limits output current to typically 50 mA. Initialization The bq29312A internal control circuit is powered by the REG voltage, which it also monitors. When the voltage at REG falls below 2.3 V, the internal circuit turns off the FETs and disables all controllable functions, including the REG and TOUT outputs. REG does not start up unless a voltage above V(STARTUP) is supplied to the PACK terminal. After the regulator has started, based on PACK voltage, it keeps operating through the BAT input, even if the PACK voltage is removed. If the BAT input is below the minimum operating range, then the bq29312A does not operate if the supply to the PACK input is removed. After start up, when the REG voltage is above 2.4 V, the bq29312A is in Normal mode. The initial state of the CHG output depends on the PMS input. If PMS = PACK, then CHG = ON, however, if PMS = GND, then CHG = OFF. Overload Detection The overload detection is used to detect abnormal currents in the discharge direction. This feature is used to protect the pass FETs, cells and any other inline components from excessive current conditions. The detection circuit also incorporates a blanking delay before driving the control for the pass FETs to the OFF state. The overload sense voltage is set in the OLV register, and delay time is set in the OLT register. The overload threshold can be programmed from 50 mV to 205 mV in 5-mV steps with the default being 50 mV and hysteresis of 10 mV. Short-Circuit Detection The short current circuit detection is used to detect abnormal current in either the charge or discharge direction. This safety feature is used to protect the pass FETs, cells, and any other inline components from excessive current conditions. The detection circuit also incorporates a blanking delay before driving the control for the pass FETs to the OFF state. The short-circuit thresholds and delay time are set in the SCC and SCD registers, respectively, where SCC is for charging and SCD is for discharge. The short-circuit threshold can be programmed from 100 mV to 475 mV in 25-mV steps with the default being 100 mV and hysteresis of 50 mV. Overload and Short-Circuit Delay The overload delay (default =1 ms) allows the system to momentarily accept a high current condition without disconnecting the supply to the load. The delay time can be increased via the OLT register, which can be programmed for a range of 1 ms to 31 ms with steps of 2 ms. The short-circuit delay (default = 0 µs) is programmable in the SCC and SCD registers. This register can be programmed from 0 µs to 915 µs with steps of 61 µs. Overload and Short-Circuit Response When an overload or short-circuit fault is detected, the FETs are turned off. The STATUS (b0…b2) register reports the details of short-circuit (charge), short-circuit (discharge), and overload. The respective STATUS (b0…b2) bits are set to 1 and the XALERT output is triggered. This condition is latched until the CONTROL (b0) is set and then reset. If a FET is turned on via resetting CONTROL (b0) and the error condition is still present on the system, then the device reenters the protection response state. 10 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL DESCRIPTION (continued) Cell Voltage The cell voltage is translated to allow a system host to measure individual series elements of the battery. The series element voltage is translated to a GND-based voltage equal to 0.15 ±0.002 of the series element voltage. This provides a range from 0 V to 4.5 V. The translation output is inversely proportional to the input using the following equation. Where, V(CELL OUT) = –K × V(CELL IN) + 0.975 (V) Programming CELL_SEL (b1, b0) selects the individual series element. The CELL_SEL (b3, b2) selects the voltage monitor mode, cell monitor, offset, etc. Calibration of Cell Voltage Monitor Amplifier Gain The cell voltage monitor amplifier has an offset, and to increase accuracy, this can be calibrated. There are a couple of methods by calibration circumstance. The following procedure shows how to measure and calculate the offset and gain as an example. • Step 1 – Set CAL1=1, CAL0=1, CELL1=0, CELL0=0, VMEN=1 – VREF is trimmed to 0.975 V within ±1%, measuring VREF eliminates its error. – Measure internal reference voltage VREF from VCELL directly. – VREF=measured reference voltage • Step 2 – Set CAL1=0, CAL0=0, CELL1=0, CELL0=1, VMEN=1 – The output voltage includes the offset and represented by: VO(4-5) = VREF + (1 + K) × VOS (V) Where K = CELL Scaling Factor – VOS = Offset voltage at input of the internal operational amplifier • Step 3 – Set CAL1=1, CAL0=0, CELL1=0, CELL0=0, VMEN=1 – Measuring scaled REF voltage through VCELL amplifier. – The output voltage includes the scale factor error and offset and is represented by: V(OUTR) = VREF + (1 + K) × VOS– K × VREF (V) • Step 4 – Calculate (VO(4-5)– V(OUTR)/VREF – The result is the actual scaling factor, K(ACT), and is represented by: K(ACT) = (VO(4-5)– V(OUTR))/VREF = (VREF + (1 + K) × VOS) - (VREF + (1 + K) × VOS– K × VREF)/ VREF = K × VREF/VREF = K • Step 5 – Calculate the actual offset value where: VOS(ACT) = (VO(4-5)– VREF)/(1 + K(ACT)) • Step 6 – Calibrated cell voltage is calculated by: VCn – VC(n+1) = {VREF + (1 + K(ACT) ) × VOS(ACT) – V(CELLOUT)}/K(ACT) – {VO(4-5) – V(CELLOUT)}/K(ACT) For • • • improved measurement accuracy, VOS(ACT) for each cell voltage should be measured. Set CAL1=0, CAL0=0, CELL1=0, CELL0=1, VMEN=1 Set CAL1=0, CAL0=0, CELL1=1, CELL0=0, VMEN=1 Set CAL1=0, CAL0=0, CELL1=1, CELL0=1, VMEN=1 11 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL DESCRIPTION (continued) Measuring VO(3-4) , VO(2-3), VO(1-2), • VC4 – VC5 = {VO(4-5)– V(CELLOUT)}/ K(ACT) • VC3 – VC4 = {VO(3-4)– V(CELLOUT)}/ K(ACT) • VC2 – VC3 = {VO(2-3)– V(CELLOUT)}/ K(ACT) • VC1 – VC2 = {VO(1-2)– V(CELLOUT)}/ K(ACT) Cell Balance Control The cell balance control allows a small bypass path to be controlled for any one series element. The purpose of this bypass path is to reduce the current into any one cell during charging to bring the series elements to the same voltage. Series resistors placed between the input pins and the positive series element nodes control the bypass current value. Individual series element selection is made using bits 4 through 7 of the CELL_SEL register. Thermistor Drive Circuit (TOUT) The TOUT pin can be enabled to drive a thermistor from REG. The typical thermistor resistance is 10 kΩ at 25°C. The default-state is OFF to conserve power. The maximum output impedance is 100 Ω. TOUT is enabled in FUNCTION CTL register (bit 5). Open-Drain Drive Circuit (OD) The open-drain output has 1-mA current source drive with a maximum output voltage of 25 V. The OD output is enabled or disabled by OUTPUT CTL register (bit 4) and has a default state of OFF. XALERT (XALERT) XALERT is driven low when an OL or SC current fault is detected, if the SLEEP pin changes state or a watchdog fault occurs. To clear XALERT, toggle (from 0, set to 1 then reset to 0) OUTPUT CTL (bit 0), then read the STATUS register. Latch Clear (LTCLR) When a current limit fault or watchdog timer fault occurs, the state is latched. To clear these faults, toggle (from 0, set 1 then reset to 0) LTCLR in the OUTPUT CTL register (bit 0). Figure 1 is the LTCLR and XALERT clear example after sensing a short-circuit. 12 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL DESCRIPTION (continued) I2C OUTPUT CTRL (b2-b1) DSG, CHG OUTPUT CTRL (b3) XZVCHG LTCLR Write = 1 LTCLR Write = 0 Read STATUS Register Status Disable Access Enable Status Disable Access Enable OUTPUT CTRL (b0) LTCLR Short Current Timeout in Discharge Direction STATUS (b0) SCDSG XALERT Pin Figure 1. LTCLR and XALERT Clear Example After Sensing Short LTCLR and XALER Clear Example 13 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL DESCRIPTION (continued) 2-, 3-, or 4-Cell Configuration In a 3-cell configuration, VC1 is shorted to VC2. In a 2-cell configuration, VC1 and VC2 are shorted to VC3. Watchdog Input (WDI) The WDI input is required as a time base for delay timing when determining overload and short-circuit delay periods and is used as part of the system watchdog. Initially, the watchdog monitors the host oscillator start up; if there is no response from the host within 700 ms of the bq29312A reaching its minimum operating voltage, then the bq29312A turns both CHG, DSG, and ZVCHG FETs OFF. Once the watchdog has been started during this wake-up period, it monitors the host for an oscillation stop condition, which is defined as a period of 100 µs (typ), where no clock input is received. If an oscillator stop condition is identified, then the watchdog turns the CHG, DSG, and ZVCHG FETs OFF. When the host clock oscillation is started, WDF is released, but the flag is latched until LTCLR is toggled. REG GG 32-kHz Output GG Clock Never Starts tWDTINT ~ 700 mS EXT FET Control CHG, DSG, and ZVCHG = OFF Figure 2. Watchdog Timing Chart—WDI Fault at Startup REG GG 32-kHz Output GG Clock Stop Watchdog Sense tWDWT About 100 mS EXT FET Control CHG, DSG, and ZVCHG = OFF Figure 3. Watchdog Timing Chart—WDI Fault After Startup DSG and CHG FET Driver Control The bq29312A drives the DSG, CHG, and ZVCHG FET off if an OL or SC safety threshold is breached depending on the current direction. The host can force any FET on or off only if the bq29312A integrated protection control allows. The DSG and CHG FET drive gate-to-drain voltage is clamped to 15 V (typ). 14 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTIONAL DESCRIPTION (continued) The default-state of the CHG and DSG FET drive is off, when PMS = GND. A host can control the FET drive by programming OUTPUT CTL (b3...b1) where b1 is used to control the discharge FET, b2 is used to control the charge FET, and b3 is used to control the ZVCHG FET. These controls are only valid when not in the initialized state. The CHG drive FET can be powered by PACK and the DSG FET can be powered by BAT. Precharge and 0-V Charging—Theory of Operation The bq29312A supports both a charger that has a precharge mode and one that does not. The bq29312A also supports charging even when the battery falls to 0 V. Detail is described in the application section. SLEEP Control Input (SLEEP) The SLEEP input is pulled-up internally to REG. When SLEEP is pulled to REG, the bq29312A enters the SLEEP mode. The SLEEP mode disables all the FET outputs and the OL, SC, and watchdog faults are also disabled. The RAM configuration is still valid on exit of the SLEEP mode. The host can force the bq29312A into SLEEP mode via register control also. Table 1. SLEEP Control Input ITEM SLEEP FUNCTION I2C Read/Write Active REG Output Active I2C READ/WRITE EXIT SLEEP External pin control: CHG, DSG, ZVCHG, TOUT, OD OC and SC protection: Write is available, but read is disabled SCD, SCC and OCD CELL Translation Last pre-sleep entry configuration is valid. (If change configuration, latest write data is valid.) Disabled PACKOUT, VMEN Cell Balancing: CB[3:0] Watchdog: WDDIS Power Modes The bq29312A has three power modes, Normal, Sleep, and Ship. The following table outlines the operational functions during these power modes. Table 2. Power Modes POWER MODE Normal TO ENTER POWER MODE TO EXIT POWER MODE MODE DESCRIPTION The battery is in normal operation with protection, power management, and battery monitoring functions available and operating. SLEEP = GND and STATE CTL( b0) = 0 and STATE CTL( b1) = 0 The supply current of this mode varies as the host can enable and disable various power management features. All functions stop except LDO and I2C interface. Sleep Ship {SLEEP = REG (floating) or STATE CTL( b0) = 1 } and STATE CTL( b1) = 0 SLEEP = GND and STATE CTL( b0) = 0 STATE CTL( b1) = 1 And supply at the PACK pin is removed Supply voltage to PACK On entry to this mode, all registers are masked off keeping their state. The host controller can change the RAM registers via the I2C interface, but reading data is disabled until exit of Sleep mode. The bq29312A is completely shut down as in the sleep mode. In addition, the REG output is disabled, I2C interface is powered down, and memory is not valid. 15 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 Communications The I2C compatible serial communications provides read and write access to the bq29312A data area. The data is clocked via separate data (SDATA) and clock (SCLK) pins. The bq29312A acts as a slave device and does not generate clock pulses. Communication to the bq29312A is provided from GPIO pins or an I2C supporting port of a host system controller. The slave address for the bq29312A is 7 bits and the value is 0100 000 (0x20). I2C ADDRESS +R/W BIT (MSB) I2C (MSB) Write (1) 0 Read (1) 1 (LSB) ADDRESS (0x20) 0 0 (LSB) 0 0 0 0 1 Bit 0: 0 = write, 1= read The bq29312A does not have the following functions compatible with the I2C specification. • The bq29312A is always regarded as a slave. • The bq29312A does not return a NACK for an invalid register address. • The bq29312A does not support the general code of the I2C specification, and therefore does not return an ACK. • The bq29312A does not support the address auto increment, which allows continuous reading and writing. • The bq29312A allows data to be written to or read from the same location without resending the location address. … SCLK SDATA A6 Start … A5 A4 … A0 R7 R/W ACK 0 0 Slave Address R6 R5 … … R0 ACK 0 D7 D6 Register Address D5 … D0 ACK 0 Data Stop Note: Slave = bq29312 Figure 4. I2C-Bus Write to bq29312A … SCLK SDATA A6 … A5 … A0 R/W ACK R7 R6 … R0 ACK 0 0 A6 … A0 R/W ACK 0 Slave Address Start … 1 Register Address D7 0 D6 … D0 NACK Slave Drives The Data Slave Address Data Note: Slave = bq29312 Stop Master Drives NACK and Stop Figure 5. I2C-Bus Read from bq29312A: Protocol A … SCLK SDATA Start A6 … A5 … A0 R/W ACK 0 Slave Address 0 R7 … R6 … R0 ACK Register Address A6 A5 … … A0 R/W ACK 0 Stop Start Slave Address D7 … D0 NACK Slave Drives The Data Stop Master Drives NACK and Stop Note: Slave = bq29312 Figure 6. I2C-Bus Read from bq29312A: Protocol B 16 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 Register Map The bq29312A has nine addressable registers. These registers provide status, control, and configuration information for the battery protection system. Table 3. Addressable Registers ADDR TYPE STATUS NAME 0x00 R DESCRIPTION OUTPUT CTL 0x01 R/W Output pin control from system host STATE CTL 0x02 R/W State control FUNCTION CTL 0x03 R/W Function control CELL _SEL 0x04 R/W Battery cell select for cell translation and balance bypass and select mode for calibration OLV 0x05 R/W Overload threshold voltage OLT 0x06 R/W Overload delay time SCC 0x07 R/W Short-circuit current threshold voltage and delay for charge SCD 0x08 R/W Short-circuit current threshold voltage and delay for discharge Status register STATUS : Status register STATUS REGISTER (0x00) 7 6 5 4 3 2 1 0 0 0 ZVCLMP SLEEPDET WDF OL SCCHG SCDSG The STATUS register provides information about the current state of the bq29312A. Reading the STATUS register clears the XALERT pin. STATUS b0 (SCDSG): This bit indicates a short-circuit in the discharge direction. 0 = Current below the short-circuit threshold in the discharge direction (default). 1 = Current greater than or equal to the short-circuit threshold in the discharge direction. STATUS b1 (SCCHG): This bit indicates a short-circuit in the charge direction. 0 = Current below the short-circuit threshold in the charge direction (default). 1 = Current greater than or equal to the short-circuit threshold in the charge direction. STATUS b2 (OL): This bit indicates an overload condition. 0 = Current less than or equal to the overload threshold (default). 1 = Current greater than overload threshold. STATUS b3 (WDF): This bit indicates a watchdog fault condition has occurred. 0 = 32-kHz oscillation is normal (default). 1 = 32-kHz oscillation stopped or not started and the watchdog has timed out. STATUS b4 (SLEEPDET): This bit indicates the bq29312A is SLEEP mode. 0 = bq29312A is not in SLEEP mode (default). 1 = bq29312A is in SLEEP mode. STATUS b5 (ZVCLMP): This bit indicates ZVCHG output is clamped. 0 = ZVCHG pin is not clamped (default). 1 = ZVCHG pin is clamped. OUTPUT CTL: Output Control Register OUTPUT CTL REGISTER (0x01) 7 6 5 4 3 2 1 0 0 0 0 OD XZVCHG CHG DSG LTCLR 17 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 The OUTPUT CTL register controls the outputs of the bq29312A and can be used to clear certain states. OUTPUT CTL b0 (LTCLR): When a current limit fault or watchdog timer fault is latched, this bit releases the fault latch when toggled from 0 to 1 and back to 0 (default =0). 0 = (default) 0->1 ->0 clears the fault latches OUTPUT CTL b1 (DSG): This bit controls the external discharge FET. 0 = discharge FET is off and is controlled by the system host (default). 1 = discharge FET is on and the bq29312A is in normal operating mode. OUTPUT CTL b2 (CHG): This bit controls the external charge FET. PMS=GND 0 = charge FET is off and is controlled by the system host (default). 1 = charge FET is on and the bq29312A is in normal operating mode. PMS=PACK 0 = charge FET is off and is controlled by the system host. 1 = charge FET is on and the bq29312A is in normal operating mode (default). OUTPUT CTL b3 (XZVCHG): This bit controls the external ZVCHG FET. 0 = ZVCHG FET is on and is controlled by the system host (default). 1 = ZVCHG FET is off and the bq29312A is in normal operating mode. OUTPUT CTL b4 (OD): This bit enables or disables the OD output. 0 = OD is high impedance (default). 1 = OD output is active (GND). STATE CTL: State Control Register STATE CTL REGISTER (0x02) 7 6 5 4 3 2 1 0 0 0 0 0 0 WDDIS SHIP SLEEP The STATE CTL register controls the state of the bq29312A. STATE CTL b0 (SLEEP): This bit is used to enter the sleep power mode. 0 = bq29312A exits sleep mode (default). 1 = bq29312A enters the sleep mode. STATE CTL b1 (SHIP): This bit is used to enter the ship power mode when pack supply voltage is not applied. 0 = bq29312A in normal mode (default). 1 = bq29312A enters ship mode when pack voltage is removed. STATE CTL b2 (WDDIS): This bit is used to enable or disable the watchdog timer function. 0 = enable clock monitoring (default). 1 = disable clock monitoring. NOTE: Use caution when setting the WDDIS. For example, when the 32-kHz input fails, the overload and short-circuit delay timers no longer function because they use the same WDI input. If the WDI input clock stops, these current protections do not function. WDF should be enabled at any time for maximum safety. If the watchdog function is disabled, the CHG and DSG FETs should be turned off. 18 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 FUNCTION CTL: Function Control Register FUNCTION CTL REGISTER (0x03) 7 6 5 4 3 2 1 0 0 0 TOUT XSCD SSCC XOL PACKOUT VMEN The FUNCTION CTL register enables and disables functions of the bq29312A. FUNCTION CTL b0 (VMEN): This bit enables or disables the cell and battery voltage monitoring function. 0 = disable voltage monitoring (default). CELL output is pulled down to GND level. 1 = enable voltage monitoring. FUNCTION CTL b1 (PACKOUT): This bit is used to translate the PACK input to the CELL pin when VMEN=1. The pack voltage is divided by 25 and is presented on CELL regardless of the CELL_SEL register settings. 0 = disable PACK OUT (default). 1 = enable PACK OUT. FUNCTION CTL b2 (XOL): This bit enables or disables the overcurrent sense function. 0 = enable overload sense (default). 1 = disable overload sense. FUNCTION CTL b3 (XSCC): This bit enables or disables the short current sense function of charging. 0 = enable short-circuit current sense in charge direction (default). 1 = disable short-circuit current sense in charge direction. FUNCTION CTL b4 (XSCD): This bit enables or disables the short current sense function of discharge. 0 = enable short-circuit current sense in discharge direction (default). 1 = disable short-circuit current sense in discharge direction. FUNCTION CTL b5 (TOUT): This bit controls the power to the thermistor. 0 = thermistor power is off (default). 1 = thermistor power is on. CELL SEL: Cell Select Register CELL_SEL REGISTER (0x04) 7 6 5 4 3 2 1 0 CB3 CB2 CB1 CB0 CAL1 CAL0 CELL1 CELL0 This register determines cell selection for voltage measurement and translation, cell balancing, and the operational mode of the cell voltage monitoring. CELL_SEL b0–b1 (CELL0–CELL1): These two bits select the series cell for voltage measurement translation. CELL1 CELL0 SELECTED CELL 0 0 VC4–VC5, Bottom series element (default) 0 1 VC4–VC3, Second lowest series element 1 0 VC3–VC2, Second highest series element 1 1 VC1–VC2, Top series element CELL_SEL b2–b3 (CAL1, CAL0): These bits determine the mode of the voltage monitor block. CAL1 CAL0 0 0 Cell translation for selected cell (default) SELECTED MODE 0 1 Offset measurement for selected cell 1 0 Monitor the VREF value for gain calibration 1 1 Monitor the VREF directly value for gain calibration, bypassing the translation circuit 19 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 CELL_SEL b4–b7 (CB0–CB3): These 4 bits select the series cell for cell balance bypass path. CELL SEL b4 (CB0): This bit enables or disables the bottom series cell balance charge bypass path. 0 = disable bottom series cell balance charge bypass path (default). 1 = enable bottom series cell balance charge bypass path. CELL SEL b5 (CB1): This bit enables or disables the second lowest series cell balance charge bypass path. 0 = disable series cell balance charge bypass path (default). 1 = enable series cell balance charge bypass path. CELL SEL b6 (CB2): This bit enables or disables the second highest cell balance charge bypass path. 0 = disable series cell balance charge bypass path (default). 1 = enable series cell balance charge bypass path. CELL SEL b7 (CB3): This bit enables or disables the highest series cell balance charge bypass path. 0 = disable series cell balance charge bypass path (default). 1 = enable series cell balance charge bypass path. OLV: Overload Voltage Threshold Register OLV REGISTER (0x05) 7 6 5 4 3 2 1 0 0 0 0 OLV4 OLV3 OLV2 OLV1 OLV0 OLV (b4–b0): These five bits select the value of the overload threshold with a default of 00000. OLV (b4–b0) configuration bits with corresponding voltage threshold 00000 0.050 V 01000 0.090 V 10000 0.130 V 11000 0.170 V 00001 0.055 V 01001 0.095 V 10001 0.135 V 11001 0.175 V 00010 0.060 V 01010 0.100 V 10010 0.140 V 11010 0.180 V 00011 0.065 V 01011 0.105 V 10011 0.145 V 11011 0.185 V 00100 0.070 V 01100 0.110 V 10100 0.150 V 11100 0.190 V 00101 0.075 V 01101 0.115 V 10101 0.155 V 11101 0.195 V 00110 0.080 V 01110 0.120 V 10110 0.160 V 11110 0.200 V 00111 0.085 V 01111 0.125 V 10111 0.165 V 11111 0.205 V OLT: Overload Blanking Delay Time Register OLT REGISTER (0x06) 7 6 5 4 3 2 1 0 0 0 0 0 OLT3 OLT2 OLT1 OLT0 OLT(b3–b0): These four bits select the value of the delay time for overload with a default of 0000. OLT(b3–b0) configuration bits with corresponding delay time 0000 1 ms 0100 9 ms 1000 17 ms 1100 25 ms 0001 3 ms 0101 11 ms 1001 19 ms 1101 27 ms 0010 5 ms 0110 13 ms 1010 21 ms 1110 29 ms 0011 7 ms 0111 15 ms 1011 23 ms 1111 31 ms SCC: Short Circuit in Charge Configuration Register SCC REGISTER (0x07) 20 7 6 5 4 3 2 1 0 SCCT3 SCCT2 SCCT1 SCCT0 SCCV3 SCCV2 SCCV1 SCCV0 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 This register selects the short-circuit threshold voltage and delay for charge. SCC(b3–b0) : These bits select the value of the short-circuit voltage threshold with 0000 as the default. SCC(b3–b0) with corresponding SC threshold voltage 0000 0.100 V 0100 0.200 V 1000 0.300 V 1100 0.400 V 0001 0.125 V 0101 0.225 V 1001 0.325 V 1101 0.425 V 0010 0.150 V 0110 0.250 V 1010 0.350 V 1110 0.450 V 0011 0.175 V 0111 0.275 V 1011 0.375 V 1111 0.475 V SCC(b7–b4): These bits select the value of the short-circuit delay time. Exceeding the short-circuit voltage threshold for longer than this period turns off the corresponding CHG, DSG, and ZVCHG output. 0000 is the default. SCC(b7–b4) with corresponding SC delay time 0000 0 µs 0100 244 µs 1000 488 µs 1100 732 µs 0001 61 µs 0101 305 µs 1001 549 µs 1101 793 µs 0010 122 µs 0110 366 µs 1010 610 µs 1110 854 µs 0011 183 µs 0111 427 µs 1011 671 µs 1111 915 µs SCD: Short Circuit in Discharge Configuration Register SCD REGISTER (0x08) 7 6 5 4 3 2 1 0 SCDT3 SCDT2 SCDT1 SCDT0 SCDV3 SCDV2 SCDV1 SCDV0 This register selects the short-circuit threshold voltage and delay for discharge. SCD(b3–b0) with corresponding SC threshold voltage with 0000 as the default. SCD(b3–b0): These bits select the value of the short-circuit voltage threshold 0000 0.10 V 0100 0.20 V 1000 0.30 V 1100 0.40 V 0001 0.125 V 0101 0.225 V 1001 0.325 V 1101 0.425 V 0010 0.150 V 0110 0.250 V 1010 0.350 V 1110 0.450 V 0011 0.175 V 0111 0.275 V 1011 0.375 V 1111 0.475 V SCD(b7–b4): These bits select the value of the short-circuit delay time. Exceeding the short-circuit voltage threshold for longer than this period turns off the corresponding CHG, DSG, and ZVCHG output as has 0000 as the default. SCD(b7-b4) with corresponding SC delay time 0000 0 µs 0100 244 µs 1000 488 µs 1100 732 µs 0001 61 µs 0101 305 µs 1001 549 µs 1101 793 µs 0010 122 µs 0110 366 µs 1010 610 µs 1110 854 µs 0011 183 µs 0111 427 µs 1011 671 µs 1111 915 µs 21 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION Precharge and 0-V Charging—Theory of Operation In order to charge, the charge FET (CHG-FET) must be turned on to create a current path. When the V(BAT) is 0 V and CHG-FET = ON, the V(PACK) is as low as the battery voltage. In this case, the supply voltage for the device is too low to operate. There are three possible configurations for this function and the bq29312A can be easily configured according to the application needs. The three modes are 0-V Charge FET Mode, Common FET Mode, and Precharge FET Mode. 1. 0-V Charge FET Mode – Dedicates a precharge current path using an additional FET (ZVCHG-FET) to sustain the PACK+ voltage level. The host charger is expected to provide a precharge function. 2. Common FET Mode – Does not use a dedicated precharge FET. The charge FET (CHG-FET) is assured to be set to ON state as default. The charger is expected to provide a precharge function. 3. Precharge FET Mode – Dedicates a precharge current path using an additional open-drain (OD) pin drive FET (PCHG-FET) FET to sustain the PACK+ voltage level. The charger does not provide any precharge function. 0-V Charge FET Mode In this mode, a dedicated precharge current path using an additional FET (ZVCHG-FET) is required to sustain a suitable PACK+ voltage level. The charger is expected to provide the precharge function in this mode where the precharge current level is suitable to charge cells below a set level, typically below 3 V per cell. When the lowest cell voltage rises above this level, then a fast charging current is applied by the charger. The circuit diagram for this method is shown in Figure 7, showing how the additional FET is added in parallel with the charge FET (CHG-FET). R(ZVCHG) Charger ZVCHG-FET CC IZVCHG DSG-FET CHG-FET DSG BAT CHG bq29312A Pack+ IFASTCHG PACK ZVCHG Battery OD REG CV PMS 4.7 mF NC I(ZVCHG) = 0 V Precharge Current I(FASTCHG) = Fast Current Figure 7. 0-V Charge FET Mode Circuit 22 DC Input bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) In order to pass 0 V or precharge current, an appropriate gate-source voltage V(GS), for ZVCHG-FET must be applied. Here, V(PACK) can be expressed in terms of V(GS) as follows: V(PACK) = V(ZVCHG) + V(GS) (ZVCHG-FET gate - source voltage) ID Point B Point A Precharge Current VGS VDS Figure 8. Drain Current vs Drain-Source Voltage Characteristics In the bq29312A, the initial state is for CHG-FET = OFF and ZVCHG-FET = ON with the V(ZVCHG) clamped at 3.5 V initially. Then, the charger applies a constant current and raises V(PACK) high enough to pass the precharge current, point A. For example, if the V(GS) is 2 V at this point, V(PACK) is 3.5 V + 2 V = 5.5 V. Also, the ZVCHG-FET is used in its MOS saturation region at this point so that V(DS) is expressed as follows: V(PACK) = V(BAT) + VF + VDS(ZVCHG-FET) where V(F) = 0.7 V is the forward voltage of a DSG-FET back diode and is typically 0.7 V. This derives the following equation: VDS = 4.8 V - V(BAT) As the battery is charged V(BAT) increases and the V(DS) voltage decreases reaching its linear region. For example: If the linear region is 0.2 V, this state continues until V(BAT) = 4.6 V, (4.8 V - 0.2 V). As V(BAT) increases further, V(PACK) and the V(GS) voltage increase. But the VDS remains at 0.2 V because the ZVCHG-FET is driven in its MOS linear region, point B. V(PACK) = VF + 0.2 V + V(BAT) where VF = 0.7 V is the forward voltage of a DSG-FET back diode and is typically 0.7 V The R(ZVCHG) purpose is to split heat dissipation across the ZVCHG-FET and the resistor. ZVCHG pin behavior is shown in Figure 9 where V(ZVCHG) is set to 0 V at the beginning. 23 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) 20 18 16 V(PACK) 14 Voltage - V V(ZVCHG)= V(PACK) - 8 V V(BAT) 12 10 8 6 4 V(ZVCHG)= V(PACK) / 2 2 3.5 V 0 0 4 8 12 t - Time - mS 16 20 Figure 9. Voltage Transition at ZVCHG, PACK, and BAT As V(PACK) exceeds 7 V, V(ZVCHG) = V(PACK)/2. However, V(ZVCHG) is maintained to limit the voltage between PACK and ZVCHG at a maximum of 8 V(typ). This limitation is intended to avoid excessive voltage between the gate and the source of ZVCHG-FET. The signal timing is shown in Figure 10. When precharge begins, (V(BAT) = 0 V) V(PACK) is clamped to 3.5 V and holds the supply voltage for bq29312A operation. After V(BAT) reaches sufficient voltage high enough for bq29312A operation, the CHG-FET and the DSG-FET are turned ON and ZVCHG-FET is turned OFF. Although the current path is changed, the same precharging current is still applied. When V(BAT) reaches the fast charging voltage (typical 3 V per cell), the charger switches into fast charging mode. 24 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) V(PACK) 3.5 V+VGS(ZVCHGFET) 0V 3.3 V 0V REG ZVCHG FET = OFF ON V = VPACK*(1/2) ZVCHG 3.5 V (typ.) 0V OFF CHG FET = ON GHD ”L” (1 V) OFF CHG FET = ON DSG ”L” (1 V) Battery Voltage 0V Charge Current Fast Charge Current 0 V and Precharge Current 0A 0 V Charge Mode Precharge Mode Fast Charge Mode Figure 10. Signal Timing of Pins During 0-V Charging and Precharging (0-V Charge FET) Common FET This mode does not require a dedicated precharge FET (ZVCHG-FET). The charge FET (CHG-FET) is ON at initialization of the bq29312A when PMS = V(PACK), allowing for 0 V or precharge current to flow. The application circuit is shown in Figure 11. The charger is expected to provide the precharge function in this mode, where the charger provides a precharge current level suitable to charge cells below a set level, typically below 3 V per cell. When the lowest cell voltage rises above this level, then a fast charging current is applied. When the charger is connected, the voltage at PMS rises. Once it is above 0.7 V, the CHG output is driven to GND which turns ON the CHG-FET. The charging current flows through the CHG-FET and a back diode of DSG-FET. The pack voltage is represented by the following equation. V(PACK) = V(BAT) + VF + VDS(CHG-FET) Where VF = 0.7 V is the forward voltage of a DSG-FET back diode and is typically 0.7 V. While V(PACK) is maintained above 0.7 V, the precharging current is maintained. While V(PACK) and V(BAT) are under the bq29312A supply voltage, then the bq29312A regulator is inactive and the host controller is not functional. Thus, any protection features of this chipset do not function during this period. This state continues until V(PACK) goes higher than the bq29312A minimum supply voltage. When V(BAT) rises and V(PACK) reaches bq29312A minimum supply voltage, the REG output is active providing a 3.3-V (typ) supply to the host. When this level is reached, the CHG pin changes its state from GND to the level controlled with CHG bit in bq29312A registers. In this state, the CHG output level is driven by a clamp circuit so that its voltage level changes from 0 V to 1 V. Also, the host controller is active and can turn ON the DSG-FET. 25 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) The disadvantages is that during 0-V charging, bq29312A is inactive. The device does not protect the battery and does not update battery information (now is 0 V charging) to the PC. There are two advantage of this configuration: 1. The voltage between BAT and PACK is lower. Higher precharge current is allowed due to less heat loss in the FET, and no external resistor is required. 2. The charge FET is turned on during precharging. The precharge current can be fully controlled by the charger. Charger CC DC Input I(ZVCHG) DSG-FET CHG-FET DSG BAT CHG bq29312A PACK ZVCHG Battery REG OD Pack+ I(FASTCHG) CV PMS 4.7 mF NC I(ZVCHG) = 0 V Precharge Current I(FASTCHG) = Fast Current Figure 11. Common FET Mode Circuit Diagram The signal timing during the common FET mode is shown in Figure 12. The CHG-FET is turned on when the charger is connected. As V(BAT) rises and V(PACK) reaches the bq29312A minimum supply voltage, the REG output becomes active and the host controller starts to work. When V(PACK) becomes high enough, the host controller turns ON the DSG-FET. The charger enters the fast charging mode when V(BAT) reaches the fast charge level. 26 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) 0.7 V 0V V(PACK) Host = Inactive Host = Active REG 3.3 V 0V PMS CHG Set to ”L” as PMS = PACK 0V Set to ”L” by Host ”L” (1 V) 0V DSG Host Sets DSG-FET to ON ”L” (1 V) Battery Voltage 0V Charge Current Fast Charge Current 0 V and Precharge Current 0A 0 V Precharge Mode Fast Charge Mode Figure 12. Signal Timing of Pins During 0-V Charging and Precharging (Common FET) Precharge FET This mode has a dedicated precharge current path using an additional open drain driven FET (PCHG-FET) and sustains the V(PACK) level. In this mode, where the PMS input is connected to GND, the bq29312A and host combine to provide the precharge function by limiting the fast charge current which is provided by the system side charger. Figure 13 shows the bq29312A application circuit in this mode. 27 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) R(PCHG) Charger PCHG-FET CC DC Input I(FASTCHG) DSG-FET CHG-FET DSG CHG PACK OD BAT bq29312A Battery Pack+ CV ZVCHG PMS REG SCLK SDATA 4.7 mF I(FASTCHG) = Fast Current Host Figure 13. Precharge FET Mode Circuit Diagram The PCHG-FET is driven by the OD output, and the resister R(PCHG) in the precharge path limits the precharge current. When OD = GND, then the PCHG-FET is ON. The precharge current is represented by the following equation: I(PCHG) = ID = ( V(PACK) - V(BAT) - VDS )/R(PCHG) • A load curve of the PCHG-FET is shown in Figure 14. When the drain-source voltage (VDS) is high enough, the PCHG-FET operates in the linear region and has low resistance. By approximating VDS as 0 V, the precharge current, I(PCHG) is expressed as below. • I(PCHG) = ( V(PACK) - V(BAT) )/R(PCHG) ID ID = (V(PACK) - V(BAT) - VDS)/R(PCHG) VSD Figure 14. PCHG-FET ID—VDS Characteristic During the precharge phase, CHG-FET is turned OFF and PCHG-FET is turned ON. When all the cell voltages measured by the host reach the fast charge threshold, the host controller turns ON CHG-FET and turns OFF PCHG-FET. The signal timing is shown in Figure 15. When the charger is connected, CHG-FET, DSG-FET and PCHG-FET are already in the OFF state. When the charger in connected, it applies V(PACK). The bq29312A REG output then becomes active and supplies power to the host controller. As the host controller starts up, it turns on the OD pin and the precharge current is enabled. 28 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) In this configuration, attention must be paid to high power consumption in the PCHG-FET and the series resistor R(PCHG). The highest power is consumed when VBAT = 0 V, where it is the highest differential between the PACK and BAT pins. For example, the power consumption in 4-series cells with 17.4 V fast charge voltage and R(PCHG) = 188 Ω is expressed below. • IPCHG = (17.4 V – 0.0 V)/188 Ω = 92.6 mA • 17.4 V × 92.6 mA = 1.61 W An optional solution is to combine a thermistor with a resistor to create R(PCHG); therefore, as temperature increases, the current reduces. Once the lowest cell voltage reaches the fast charge level (typ 3.0 V per cell), the host controller turns ON CHG-FET and DSG-FET, and turns OFF PCHG-FET. It is also appropriate to turn on DSG-FET during precharge in order to supply precharge current efficiently, as shown in Figure 15. Charge CV V(PACK) 0V Host : Active REG 3.3 V 0V OD OFF PCHG FET = ON OFF 0V CHG CHG FET = OFF ”L” (1 V) DSG FET = ON DSG OFF ”L” (1 V) Battery Voltage Charge Current 0V Fast Charge Current Charge 0 V and Precharge Current 0A Charge Mode 0 V and Precharge Mode Fast Charge Mode Figure 15. Signal Timing of Pins During 0-V Charging and Precharging (Precharge FET) 29 bq29312A www.ti.com SLUS629A – JANUARY 2005 – REVISED AUGUST 2005 APPLICATION INFORMATION (continued) Summary The three types of 0-V charge options available with the bq29312A are summarized in Table 4. Table 4. Charge Options CHARGE MODE TYPE HOST CHARGE CAPABILITIES KEY APPLICATION CIRCUIT NOTES PMS = GND 1) 0-V Charge FET Fast charge and precharge ZVCHG: Drives 0-V charge FET (ZVCHG-FET) OD: Not used PMS = PACK 2) Common FET Fast charge and precharge ZVCHG: Not used OD: Not used PMS = GND 3) Precharge FET Fast charge but no precharge function ZVCHG: Not used OD: Drives the precharge FET (PCHG-FET) There a number of tradeoffs between the various 0-V charge modes which are discussed as follows: • 0-V Charge FET (1) vs Common FET (2) When the charger has both precharge and charging functions, two types of circuit configuration are available. 1. 0-V Charge FET – The bq29312A is active even during precharge. Therefore, the host can update the battery status to the system and protect the battery pack by detecting abnormal conditions. – A high voltage is applied on the 0-V charge FET at 0-V cell voltage. In order to avoid excessive heat generation, the 0-V charge current must be limited. 2. Common FET – During 0-V charge the bq29312A and the host are not active. Therefore, they cannot protect the cells and cannot update the battery status to the system. – The bq29312A can tolerate high 0-V charge current as heat generation is not excessive. – A dedicated FET for the 0-V charge is not required. • 0-V Charge FET (1) vs Precharge FET (3) The current paths of the 0-V charge FET (1) and Precharge FET (3) modes are the same. If the 0-V charge FET (1) mode is used with chargers without precharge function, the bq29312A consumes extra current of up to 1 mA in order to turn ON the ZVCHG output. 1. If the charger has a precharge function, ZVCHG-FET is turned ON only during 0-V charging. In this case, a 1-mA increase is not a concern because the charger is connected during the 0-V charging period. 2. If the charger does not have precharge function, the ZVCHG-FET must be turned ON during 0-V charging and also precharging. When the battery reaches an overdischarged state, it must turn OFF DSG-FET and CHG-FET and turn ON ZVCHG-FET. The reason for this is the battery must keep the 0-V charge path while waiting for a charger to be connected to limit the current. – Consuming 1 mA, while waiting for a charger to be connected in overdischarge state, is significant if compared to current consumption of other modes. • Precharge FET (3) If the precharge FET (3) mode is used with a charger with precharge function, care must be taken as limiting the 0-V charge current with resistance may cause some issues. The charger may start fast charge immediately, or detect an abnormal condition. When the charger is connected, the charger may raise the output voltage to force the precharge current. In order to ensure a supply voltage for the bq29312A during 0-V charging, the resistance of a series resister (RPCHG) must be high enough. This may result in a high VPACK, and some chargers may detect it as an abnormal condition. 30 PACKAGE OPTION ADDENDUM www.ti.com 5-Sep-2005 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty Lead/Ball Finish MSL Peak Temp (3) BQ29312APW ACTIVE TSSOP PW 24 60 TBD CU NIPDAU Level-1-220C-UNLIM BQ29312APWR ACTIVE TSSOP PW 24 2000 TBD CU NIPDAU Level-1-220C-UNLIM BQ29312ARTH ACTIVE QFN RTH 24 80 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ29312ARTHR ACTIVE QFN RTH 24 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 PACKAGE OPTION ADDENDUM www.ti.com 26-Sep-2005 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty Lead/Ball Finish MSL Peak Temp (3) BQ29312APW ACTIVE TSSOP PW 24 60 TBD CU NIPDAU Level-1-220C-UNLIM BQ29312APWR ACTIVE TSSOP PW 24 2000 TBD CU NIPDAU Level-1-220C-UNLIM BQ29312ARTH ACTIVE QFN RTH 24 80 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ29312ARTHR ACTIVE QFN RTH 24 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ29312ARTHRG4 ACTIVE QFN RTH 24 3000 TBD Call TI Call TI (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS) or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 MECHANICAL DATA MTSS001C – JANUARY 1995 – REVISED FEBRUARY 1999 PW (R-PDSO-G**) PLASTIC SMALL-OUTLINE PACKAGE 14 PINS SHOWN 0,30 0,19 0,65 14 0,10 M 8 0,15 NOM 4,50 4,30 6,60 6,20 Gage Plane 0,25 1 7 0°– 8° A 0,75 0,50 Seating Plane 0,15 0,05 1,20 MAX PINS ** 0,10 8 14 16 20 24 28 A MAX 3,10 5,10 5,10 6,60 7,90 9,80 A MIN 2,90 4,90 4,90 6,40 7,70 9,60 DIM 4040064/F 01/97 NOTES: A. B. C. D. All linear dimensions are in millimeters. This drawing is subject to change without notice. Body dimensions do not include mold flash or protrusion not to exceed 0,15. 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