bq24745 www.ti.com SLUS761 – DECEMBER 2007 SMBus-Controlled Level 2 Multi-Chemistry Battery Charger With Input Current Detect Comparator UGAT PHAS DCIN 27 26 25 24 23 22 ICREF 1 21 VDDP ACIN 2 20 LGATE VREF 3 19 PGND EAO 4 18 CSOP EAI 5 17 CSON FBO 6 16 NC CE 7 15 VFB 8 9 10 11 12 13 14 NC bq24745 28 LD QFN TOP VIEW ACOK • • • 28 GND • The bq24745 is a high-efficiency, synchronous battery charger with an integrated input-current comparator, offering low component count for space-constrained, multi-chemistry battery-charging applications. SMBus input-current, charge-current, and charge-voltage DACs allow very high regulation accuracies that can be easily programmed by the system power-management microcontroller using the SMBus. The bq24745 charges two, three, or four series Li+ cells, and is available in a 28-pin, 5x5 mm2 thin QFN package. BOOT • DESCRIPTION VDDSMB • • • Notebook and Ultra-Mobile Computers Portable Data-Capture Terminals Portable Printers Medical Diagnostics Equipment Battery Bay Chargers Battery Back-up Systems ICOUT • • • • • • • SCL • APPLICATIONS CSSN • • SDA • NMOS-NMOS Synchronous Buck Converter with 300 kHz Frequency and >95% Efficiency 30-ns Minimum Driver Dead-time and 99.5% Maximum Effective Duty Cycle High-Accuracy Voltage and Current Regulation – ±0.5% Charge Voltage Accuracy – ±3% Charge Current Accuracy – ±3% Adapter Current Accuracy – ±2% Input Current Sense Amp Accuracy Integration – Input Current Comparator, With Adjustable Threshold and Hysteresis – Internal Soft-Start Safety – Input Overvoltage Protection (OVP) – Dynamic Power Management (DPM) Up to 19.2 V Battery Voltage 6 V–24 V AC/DC-Adapter Operating Range Simplified SMBus Control – Charge Voltage DAC (1.024 V–19.2 V) – Charge Current DAC (128 mA–8.064 A) – Adapter Current Limit DPM DAC (256 mA–11.004 A) Status and Monitoring Outputs – AC/DC Adapter Present with Adjustable Voltage Threshold – Input Current Comparator, With Adjustable Threshold and Hysteresis – Current Sense Amplifier for Current Drawn From Input Source Charge Any Battery Chemistry: Li+, NiCd, NiMH, Lead Acid, etc. Cells Pin Supports Two to Four Li-Ion Cells Charge Enable Pin < 10-µBattery Current with Adapter Removed < 1 mA Input DCIN Current with Adapter Present and Charge Disabled 28-pin, 5x5-mm2 QFN Package CSSP • • VICM FEATURES 1 1 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 © 2007, Texas Instruments Incorporated bq24745 www.ti.com SLUS761 – DECEMBER 2007 These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. DESCRIPTION (CONTINUED) The bq24745 features Dynamic Power Management (DPM) and input power limiting. These features reduce battery-charge current when the input power limit is reached to avoid overloading the AC adaptor when supplying the load and the battery charger simultaneously. A highly accurate current-sense amplifier enables precise measurement of input current from the AC adapter, allowing monitoring the overall system power. If the adapter current is above the programmed low-power threshold, a signal is sent to host so that the system optimizes its performance to the power available from the adapter. An integrated comparator monitors the input current through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold limit. TYPICAL APPLICATIONS VIN = 20 V, VBAT = 4-cell Li-Ion, ICHARGE = 4.5 A, VICMer_limit = 6 A ADAPTER + CHRG_IN R10 4 C1 1uF Controlled by HOST C5 0.1uF Q5 (BATFET) SI4835BDY 17 CSSN 18 CSSP P 309k 1% P 22 DCIN 2 R2 49.9k 1% ACIN bq24745 +3.3V_ALWAYS OR +5V_ALWAYS 11 VDDSMB C6 1uF PHASE 23 BOOT 25 R3 10k 3 R4 10k R5 10k C7 VREF 1uF BAT54 C11 1uF L1 RSR 0.010 PACK+ 5.6uH PACK- LGATE 20 PGND 19 CSOP 28 CSON 27 C14 3x10uF C12 0.1uF Q4 FDS6680A C13 0.1uF 26 ICOUT R6 10k VFB 15 Dig I/O HOST (EC) D1 C10 0.1uF VDDP 21 13 ACOK DISCRETE LOGIC Q3 FDS6680A UGATE 24 12 GND N R1 P Q2 (DFET) Q1 (ACFET) SI4835BDY SI4835BDY Controlled by HOST C4 0.1uF C3 0.1uF C9 2x10uF N ADAPTER - RAC 0.010 7 CE 9 SDA C15 0.1u ICREF 1 SMBus 10 SCL 8 DISCRETE LOGIC C8 100pF 14 NC 16 NC R8 4.7k R7 7.5k VICM EAO 4 EAI 5 FBO 6 C16 51pF C18 130pF C17 2000pF R9 200k Pull-up rail could be either VREF or other system rail. Figure 1. Typical System Schematic: Using External Input Current Comparator (discrete logic) Instead of Internal Comparator VIN = 20 V, VBAT = 4-cell Li-Ion, ICHARGE = 4.5 A, VICMer_limit = 6 A 2 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 VIN = 20 V, VBAT = 4-cell Li-Ion, ICHARGE = 4.5 A, VICMer_limit = 6 A ADAPTER + CHRG_IN R10 4 P P Q1 (ACFET) Q2 (DFET) SI4835BDY SI4835BDY Controlled by HOST C4 0.1uF C3 0.1uF C1 1uF R1 Controlled by HOST C5 0.1uF Q5 (BATFET) SI4835BDY 17 CSSN 18 CSSP P 309k 1% C9 2x10uF 22 DCIN 2 ACIN bq24745 +3.3V_ALWAYS OR +5V_ALWAYS PHASE 23 BOOT 11 VDDSMB C6 1uF 25 13 ACOK 3 R14 10k R4 10k R5 10k C7 VREF 1uF BAT54 C11 1uF R6 10k 7 LGATE 20 PGND 19 CSOP 28 CSON 27 VREF 1 SDA 8 100pF C14 3x10uF C13 R12 17.4k 1% R7 7.5k 10 SCL C8 PACK- C15 0.1u R11 51.1k 1% CE ICREF 9 SMBus DISCRETE LOGIC PACK+ 5.6uH C12 0.1uF Q4 FDS6680A VFB 15 Dig I/O RSR 0.010 0.1uF 26 ICOUT HOST (EC) D1 L1 C10 0.1uF VDDP 21 R3 10k DISCRETE LOGIC Q3 FDS6680A UGATE 24 12 GND N R2 49.9k 1% N ADAPTER - RAC 0.010 VICM 14 NC EAO 4 EAI 5 FBO 6 R8 4.7k C16 51pF 16 NC C18 130pF C17 2000pF R13 R9 200k 1400K Pull-up rail could be either VREF or other system rail. Figure 2. Typical System Schematic, Using Internal Input Current Comparator ORDERING INFORMATION PART NUMBER PACKAGE bq24745 28-PIN 5 x 5 mm2 QFN ORDERING NUMBER (Tape and Reel) QUANTITY bq24745RHDR 3000 bq24745RHDT 250 PACKAGE THERMAL DATA (1) PACKAGE θJA TA = 70°C POWER RATING DERATING FACTOR ABOVE TA = 25°C QFN – RHD (1) 39°C/W 2.36 W 0.028 W/°C For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI Web site at www.ti.com. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 3 bq24745 www.ti.com SLUS761 – DECEMBER 2007 Table 1. TERMINAL FUNCTIONS – 28-PIN QFN TERMINAL FUNCTION NO. 4 1 ICREF Low-power voltage set input. Connect a resistor-divider from VREF to ICREF, and GND to program the reference for the LOPWR comparator. The ICREF pin voltage is compared to the VICM pin voltage and the logic output is given on the ICOUT open-drain pin. Connecting a positive feedback resistor from the ICREF pin to the ICOUT pin programs the hysteresis. 2 ACIN Adapter detected voltage set input. Program the adapter detect threshold by connecting a resistor divider from adapter input to ACIN pin to GND pin. Adapter voltage is detected if ACIN pin voltage is greater than 2.4 V. VICM current sense amplifier is active when ACIN pin voltage is greater than 0.6 V. 3 VREF 3.3 V regulated voltage output. Place a 1 µF ceramic capacitor from VREF to GND pin close to the IC. This voltage could be used for ratiometric programming of voltage and current regulation and for programming the ICREF threshold. 4 EAO Error Amplifier Output for compensation. Connect the feedback-compensation components from EAO to EAI. Typically, a capacitor in parallel with a series resistor and capacitor. This node is internally compared to the PWM saw-tooth oscillator signal. 5 EAI Error Amplifier Input for compensation. Connect the feedback compensation components from EAI to EAO. Connect the input compensation from FBO to EAI. 6 FBO Feedback Output for compensation. Connect the input compensation from FBO to EAI. Typically, a resistor in parallel with a series resistor and capacitor. 7 CE Charge enable active-high logic input. HI enables charge. LO disables charge. 8 VICM Adapter current sense amplifier output. VICM voltage is 20 times the differential voltage across CSSP-CSSN. Place a 100pF (max) or less ceramic decoupling capacitor from VICM to GND. 9 SDA SMBus Data input. Connect to SMBus data line from the host controller. A 10-kΩ pull-up resistor to the host controller power rail is needed. 10 SCL SMBus Clock input. Connect to SMBus clock line from the host controller. A 10-kΩ pull-up resistor to the host controller power rail is needed. 11 VDDSMB Input voltage for SMBus logic. Connect a 3.3 V always supply rail, or 5 V always rail to VDDSMB pin. Connect a 0.1µF ceramic capacitor from VDDSMB to GND for decoupling. 12 GND Analog Ground. On PCB layout, connect to the analog ground plane, and only connect to PGND through the power-pad underneath the IC. 13 ACOK Valid adapter active-high detect logic open-drain output. Pulled HI when Input voltage is above ACIN programmed threshold. Connect a 10-kΩ pull-up resistor from ACOK pin to pull-up supply rail. 14 NC No Connect. Pin floating internally. 15 VFB Battery-voltage remote sense. Directly connect a Kelvin sense trace from the battery-pack positive terminal to the VFB pin to accurately sense the battery pack voltage. Place a 0.1-µF capacitor from VFB to GND close to the IC to filter high-frequency noise. 16 NC No Connect. Pin floating internally. 17 CSON Charge-current sense resistor, negative input. An optional 0.1-µF ceramic capacitor is placed from CSON pin to GND for common-mode filtering. An optional 0.1-µF ceramic capacitor is placed from CSON to CSOP to provide differential-mode filtering. 18 CSOP Charge-current sense resistor, positive input. An optional 0.1-µF ceramic capacitor is placed from CSOP pin to GND for common mode filtering. An optional 0.1-µF ceramic capacitor is placed from CSON to CSOP to provide differential-mode filtering. 19 PGND Power ground. On PCB layout, connect directly to source of low-side power MOSFET, to ground connection of input and output capacitors of the charger. Only connect to GND through the power-pad underneath the IC. 20 LGATE PWM low-side driver output. Connect to the gate of the low-side power MOSFET with a short trace. 21 VDDP PWM low-side driver positive 6-V supply output. Connect a 1-µF ceramic capacitor from VDDP to PGND pin, close to the IC. Use for high-side driver bootstrap voltage by connecting a small signal Schottky diode from VDDP to BOOT. 22 DCIN IC-power positive supply. Connect to the common-source (diode-OR) point: source of high-side P-channel MOSFET and source of reverse blocking power P-channel MOSFET. Place a 1µF ceramic capacitor from DCIN to PGND pin close to the IC. 23 PHASE PWM high-side driver negative supply. Connect to the phase switching node (junction of the low-side power MOSFET drain, high-side power MOSFET source, and output inductor). Connect the 0.1µF bootstrap capacitor from PHASE to BOOT. 24 UGATE PWM high-side driver output. Connect to the gate of the high-side power MOSFET with a short trace. 25 BOOT PWM high-side driver positive supply. Connect a 0.1µF bootstrap ceramic capacitor from BOOT to PHASE. Connect a small bootstrap Schottky diode from VDDP to BOOT. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 Table 1. TERMINAL FUNCTIONS – 28-PIN QFN (continued) TERMINAL FUNCTION NO. 26 ICOUT Low power mode detect active-high open-drain logic output. Place a 10 kΩ pull-up resistor from ICOUT pin to the pull-up voltage rail. Place a positive feedback resistor from ICOUT pin to ICREF pin for programming hysteresis. The output is HI when VICM pin voltage is lower than ICREF pin voltage. The output is LO when VICM pin voltage is higher than ICREF pin voltage. 27 CSSN Adapter current-sense resistor, negative input. An optional 0.1-µF ceramic capacitor is placed from CSSN pin to GND for common-mode filtering. An optional 0.1-µF ceramic capacitor is placed from CSSN to CSSP to provide differential-mode filtering. 28 CSSP Adapter current-sense resistor, positive input. An optional 0.1-µF ceramic capacitor is placed from CSSP pin to GND for common-mode filtering. An optional 0.1-µF ceramic capacitor is placed from CSSN to CSSP to provide differential-mode filtering. ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (1) (2) VALUE DCIN, CSOP, CSON, CSSP, CSSN, VFB Voltage range UNIT –0.3 to 30 PHASE –1 to 30 EAI, EAO, FBO, VDDP, LGATE, ACIN, VICM, ICOUT, ICREF, CE, ACOK –0.3 to 7 VDDSMB –0.3 to 7 VREF –0.3 to 3.6 BOOT, UGATE with respect to GND and PGND –0.3 to 36 GND, PGND –1 to 1 Maximum difference voltage: CSOP–CSON, CSSP–CSSN –0.5 to 0.5 Junction temperature range –40 to 155 Storage temperature range –55 to 155 (1) (2) V °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 GND if not specified. Currents are positive into, and negative out of the specified terminal. Consult Packaging Section of the data book for thermal limitations and considerations of packages. RECOMMENDED OPERATING CONDITIONS over operating free-air temperature range (unless otherwise noted) MIN PHASE Voltage range –1 NOM MAX 24 DCIN, CSOP, CSON, CSSP, CSSN, VFB 0 24 VDDP, LGATE 0 6.5 VREF 3.3 EAI, EAO, FBO, ACIN, VICM, ICOUT, ICREF, CE, ACOK, VDDSMB 0 5.5 BOOT, UGATE with respect to GND and PGND 0 30 –0.3 0.3 GND, PGND Maximum difference voltage: CSOP–CSON, CSSP–CSSN –0.3 0.3 Junction temperature range –40 125 Storage temperature range –55 150 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 UNIT V °C 5 bq24745 www.ti.com SLUS761 – DECEMBER 2007 ELECTRICAL CHARACTERISTICS 7.0 V ≤ V(DCIN) ≤ 24 V, 0°C < TJ < +125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT OPERATING CONDITIONS VDCIN_OP DCIN input voltage operating range 5 24 V DCIN V 16.884 V CHARGE VOLTAGE REGULATION VVFB_OP VFB input voltage range 0 16.716 ChargeVoltage() = 0x41A0 –0.5% 12.592 ChargeVoltage() = 0x3130 VVFB_REG _ACC VFB charge voltage regulation accuracy 8.350 4.154 TJ = 0 to 125°C, 1.024 V–19.2 V, Max DAC value is 19.2 V Charge voltage regulation range 12.529 12.655 V 0.5% 8.4 –0.6% ChargeVoltage() = 0x1060 RNG 0.5% –0.5% ChargeVoltage() = 0x20D0 VVFB_REG_ 16.8 8.450 V 0.6% 4.192 4.230 V –0.9% 0.9% 1.024 19.2 V 0 80.64 mV CHARGE CURRENT REGULATION VIREG_CHG_RNG Charge current regulation differential voltage range VIREG_CHG = VCSOP – VCSON, Max DAC value is 80.64 mV 3968 ChargeCurrent() = 0x0F80 –3% 2048 ChargeCurrent() = 0x0800 ICHRG_REG_ACC mA 3% –5% Charge current regulation accuracy mA 5% 512 ChargeCurrent() = 0x0200 –25% mA 25% 128 ChargeCurrent() = 0x0080 mA –33% 33% 0 110.1 INPUT CURRENT REGULATION VIREG_DPM_RNG Adapter current regulation differential voltage range VIREG_DPM = VCSSP – VCSSN, Max DAC value is 110.084 mV InputCurrent() ≥ 0x0800 InputCurrent() = 0x0400 IINPUT_REG_ACC Input current regulation accuracy InputCurrent() = 0x0100 InputCurrent() = 0x0080 4096 –3% mV mA 3% 2048 –5% mA 5% 512 –25% mA 25% 256 –33% mA 33% VREF REGULATOR VVREF_REG VREF regulator voltage VACIN > 0.6 V, 0 - 30 mA IVREF_LIM VREF current limit VVREF = 0 V, VACIN > 0.6 V 3.267 35 VACIN > 0.6 V, 0 - 50 mA 5.7 VVDDP = 0 V, VACIN > 0.6 V 90 VVDDP = 5 V, VACIN > 0.6 V 80 3.3 3.333 V 80 mA 6.3 V VDDP REGULATOR VVDDP_REG VDDP regulator voltage IVDDP_LIM VDDP current limit 6 Submit Documentation Feedback 6.0 135 mA Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 ELECTRICAL CHARACTERISTICS (continued) 7.0 V ≤ V(DCIN) ≤ 24 V, 0°C < TJ < +125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ADAPTER CURRENT SENSE AMPLIFIER VCSSP/N_OP Input common mode range VVICM VICM output voltage range IVICM VICM output current AVICM Current sense amplifier voltage gain Voltage on CSSP/CSSN 0 24 V 0 2.25 V 0 AVICM = VVICM/ VIREG_DPM Adapter current sense accuracy 1 20 VIREG_DPM = V(CSSP–CSSN) ≥ 40 mV –2% VIREG_DPM = V(CSSP–CSSN) =20 mV –3% 3% VIREG_DPM = V(CSSP–CSSN) =5 mV –25% 25% VIREG_DPM = V(CSSP–CSSN) =1.5 mV –33% 33% IVICM_LIM Output current limit VVICM = 0 V CVICM_MAX Maximum output load capacitance For stability with 0 mA to 1 mA load mA V/V 2% 1 mA 100 pF 24 V ACIN COMPARATOR INPUT UNDERVOLTAGE) VDCIN_VFB_OP Differential voltage from DCIN to VFB VACIN_CHG ACIN rising threshold Min voltage to enable charging, VACIN rising VACIN_CHG_HYS ACIN falling hysteresis VACIN falling ACIN rising deglitch (1) VACIN rising ACIN falling deglitch VACIN falling VACIN_BIAS Adapter present rising threshold Min voltage to enable all bias, VACIN rising VACIN_BIAS_HYS Adapter present falling hysteresis VACIN falling 20 VACIN rising 200 VACIN falling 1 ACIN rising deglitch –20 (1) ACIN falling deglitch 2.376 2.40 2.424 40 50 100 150 0.62 µs µs 1 0.56 V mV 0.68 V mV µs DCIN / VFB COMPARATOR (REVERSE DISCHARGING PROTECTION) VDCIN-VFB_FALL DCIN to VFB falling threshold VDCIN-VFB__HYS DCIN to VFB hysteresis VDCIN – VVFB to turn off ACFET 140 185 240 mV 50 mV DCIN to VFB rising deglitch VDCIN – VVFB > VDCIN-VFB_RISE 1 ms DCIN to VFB falling deglitch VDCIN – VVFB < VDCIN-VFB_FALL 3.3 µs VFB SHORT (UNDERVOLTAGE and TRICKLE CHARGE) COMPARATOR VVFB_SHORT_RISE VFB short rising threshold VVFB_SHORT_HYS 2.6 VFB short rising hysteresis VFB short rising deglitch VVFB > VVFB_SHORT+VVFB_SHORT_HYS Detection delay VFB short falling deglitch VVFB < VVFB_SHORT ITRKL_REG_ACC Trickle Charge current regulation accuracy in BATSHORT VVFB < VVFB_SHORT ILOW_MAX_REG Maximum Charge current regulation at Low Voltage (<4V) VVFB_SHORT < VVFB < 4 2.7 2.9 mV 1.5 µs µs 3.3 60 V 215 200 300 3 mA A CHARGE OVERCURRENT COMPARATOR VOC Charge overcurrent falling threshold As percentage of IREG_CHG 145% Minimum Current Limit (CSOP–CSON) Internal Filter Pole Frequency 50 mV 160 kHz INPUT OVERVOLTAGE COMPARATOR (ACOV) VACOV AC overvoltage rising threshold on ACIN VACOV_HYS AC overvoltage rising deglitch Measure on ACIN pin 3.007 3.1 1.3 3.193 ms V AC overvoltage falling deglitch 1.3 ms INPUT UNDERVOLTAGE LOCK-OUT COMPARATOR (UVLO) UVLO AC undervoltage rising threshold VUVLO_HYS AC undervoltage hysteresis, falling Measure on DCIN pin 3.5 4 4.5 260 V mV INPUT CURRENT COMPARATOR VICCOMP_OFFSET (1) AC Low power mode comparator offset voltage -6.8 0.12 6.8 mV Verified by design. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 7 bq24745 www.ti.com SLUS761 – DECEMBER 2007 ELECTRICAL CHARACTERISTICS (continued) 7.0 V ≤ V(DCIN) ≤ 24 V, 0°C < TJ < +125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT THERMAL SHUTDOWN COMPARATOR TSHUT Thermal shutdown rising temperature TSHUT_HYS Thermal shutdown hysteresis, falling Temperature Increasing 162 °C 20 PWM HIGH SIDE DRIVER (UGATE) RDS_HI_ON High side driver (HSD) turn-on resistance VBOOT – VPHASE = 5.5 V 6 Ω RDS_HI_OFF High side driver turn-off resistance VBOOT – VPHASE = 5.5 V 1 Ω VBOOT_REFRESH Bootstrap refresh comparator threshold voltage VBOOT – VPHASE when low side refresh pulse is requested IBOOT_LEAK BOOT leakage current when charge enabled High Side is on; Charge enabled 4 V 200 µA PWM LOW SIDE DRIVER (LGATE) RDS_LO_ON Low side driver (LSD) turn-on resistance 6 Ω RDS_LO_OFF Low side driver turn-off resistance 1 Ω PWM DRIVERS TIMING Dead time when switching between LGATE and UGATE , no load at LGATE and UGATE Driver Dead Time 30 ns PWM OSCILLATOR FSW PWM switching frequency VRAMP_HEIGHT PWM ramp height 240 As percentage of DCIN 360 6.67 kHz %DCIN QUIESCENT CURRENT IOFF_STATE Total off-state battery current from CSOP, CSON, VFB, DCIN, BOOT, PHASE, etc VVFB = 16.8 V, VACIN < 0.6 V, VDCIN > 5 V, TJ = 85°C IBAT_ON Battery on-state quiescent current IBAT_LOAD_CD 7 10 µA VVFB = 16.8 V, 0.6V < VACIN < 2.4 V, VDCIN > 5 V 0.7 1 mA Internal battery load current, charge disabled Charge is disabled: VVFB = 16.8 V, VACIN > 2.4 V, VDCIN > 5 V 0.7 1 mA IBAT_LOAD_CE Internal battery load current, charge enabled Charge is enabled: VVFB = 16.8 V, VACIN > 2.4 V, VDCIN > 5 V 10 12 mA IAC Adapter quiescent current Charge disabled, VDCIN = 20 V 0.7 1 mA Adapter switching quiescent current Charge enabled, VDCIN = 20 V, converter running 25 mA IAC_SWITCH 6 INTERNAL SOFT START (8 steps to regulation current ICHG) Soft start steps Soft start step time 8 step 1.5 ms 1.5 ms CHARGER SECTION POWER-UP SEQUENCING Charge-Enable Delay after Power-up Delay from when adapter is detected to when the charger is allowed to turn on CHARGE UNDERCURRENT COMPARATOR (CYCLE-BY-CYCLE SYNCHRONOUS TO NON-SYNCHRONOUS) VUCP Cycle-by-cycle Synchronous to Non-Synchronous Transition Threshold Cycle-by-cycle, (CSSOP-CSSON) voltage, falling, LGATE turns-off and latches off until next cycle Blankout Time after LGATE turns-on Blankout comparator after LGATE turns-on 5 10 15 100 mV ns LOGIC INPUT PIN CHARACTERISTICS (CE) (2) Pull-up CE with ≥2.2 kΩ resistor or directly to VREF. VIN_LO Input low threshold voltage VIN_HI Input high threshold voltage VBIAS Input bias current 0.8 V 1 µA 0.5 V 5.5 V 2.1 V = 0 TO VVDDP OPEN-DRAIN LOGIC OUTPUT PIN CHARACTERISTICS (ACOK, ICOUT) VOUT_LO Output low saturation voltage Sink Current = 5 mA VDDSMB INPUT SUPPLY FOR SMBus VVDDSMB_RANGE VDDSMB input voltage range VVDDSMB_UVLO_ VDDSMB undervoltage lockout threshold voltage, rising VVDDSMB Rising 2.4 2.5 2.6 V VDDSMB undervoltage lockout hysteresis voltage, falling VVDDSMB Falling 100 150 200 V Threshold_Rising VVDDSMB_UVLO_ Hyst_Rising (2) 8 2.7 Pull up CE with ≥ 2 kΩ resistor, or connect directly to VREF. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 ELECTRICAL CHARACTERISTICS (continued) 7.0 V ≤ V(DCIN) ≤ 24 V, 0°C < TJ < +125°C, typical values are at TA = 25°C, with respect to AGND (unless otherwise noted) PARAMETER IVDDSMB_Iq VDDSMB quiescent current TEST CONDITIONS MIN VVDDSMB = SCL = SDA = 5.5 V TYP MAX 20 27 UNIT µA ELECTRICAL CHARACTERISTICS 7 Vdc ≤ V(VCC) ≤ 24 Vdc, –20°C<TJ <125°C, ref = AGND (unless otherwise noted) (1) PARAMETER [SMB TIMING SPECIFICATION (VDD = 2.7 V to 5.5 V) (see Figures 4 and 5)] MIN TYP MAX UNIT SMBus TIMING CHARACTERISTICS 1 µs 300 ns 50 µs tR SCLK/SDATA rise time tF SCLK/SDATA fall time tW(H) SCLK pulse width high 4 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 µs tSU(DAT) Data setup time 250 ns tH(DAT) Data hold time 300 ns tSU(STOP) Setup time for STOP condition 4 µs t(BUF) Bus free time between START and STOP condition 4.7 FS(CL) Clock Frequency 10 µs 100 kHz 25 35 ms 170 210 s 0.4 V HOST COMMUNICATION FAILURE ttimeout SMBus bus release timeout 22 tBOOT Deglitch for watchdog reset signal 10 tWDI Watchdog timeout period 140 ms OUTPUT BUFFER CHARACTERISTICS V(SDAL) (1) Output LO voltage at SDA, I(SDA) = 3 mA Devices participating in a transfer will timeout when any clock low exceeds the 25 ms minimum timeout period. Devices that have detected a timeout condition must reset the communication no later than the 35 ms maximum timeout period. Both a master and a slave must adhere to the maximum value specified as it incorporates the cumulative stretch limit for both a master (10 ms) and a slave (25 ms). Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 9 bq24745 www.ti.com SLUS761 – DECEMBER 2007 Figure 3. SMBus Communication Timing Waveforms TYPICAL CHARACTERISTICS VREF LOAD AND LINE REGULATION vs LOAD CURRENT VDDP LOAD AND LINE REGULATION vs LOAD CURRENT 0 0.40 0.20 VDDP - Error - % VREF - Error - % 0 -0.20 DCIN = 20 V -0.40 DCIN = 10 V -1 DCIN = 10 V -2 -0.60 DCIN = 20 V -0.80 -1 0 5 10 15 20 25 30 35 40 -3 0 IL - Load Current - mA Figure 4. 10 20 40 60 IL - Load Current - mA 80 100 Figure 5. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 TYPICAL CHARACTERISTICS (continued) VFB (BATTERY) VOLTAGE REGULATION ACCURACY vs CHARGE CURRENT VFB (BATTERY) VOLTAGE REGULATION ACCURACY vs DAC VBAT SETPOINT 1 1.2 DCIN = 20 V Battery Voltage Regulation Accuracy - % Battery Voltage Accuracy - % 3 CELL @ 12.592 V, ICHG @ 8.064 A, DCIN = 20 V 0 -1 -2 -3 0 1 2 3 4 5 6 Battery Charge Current - A 7 8 0.8 0.6 0.4 0.2 0 -0.2 0 9 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 VFB programmed Setpoint - mV Figure 6. Figure 7. CHARGE CURRENT REGULATION ACCURACY vs DAC ICHRG SETPOINT CHARGE CURRENT REGULATION ACCURACY vs VFB (BATTERY) VOLTAGE 4.5 0 4 Battery Charge Current - A -2 Charge Current Accuracy - % 1 -4 -6 -8 -10 -12 DCIN = 20 V, VFB = 9 V -14 1000 2000 3000 4000 5000 6000 7000 8000 3 2.5 2 1.5 1 3 CELL @ 12.592 V, ICHG @ 4.096 A, DCIN = 20 V 0.5 -16 0 3.5 9000 0 0 ICHG DAC Programmed Setpoint - mA Figure 8. 2 4 6 8 Battery Voltage - V 10 12 14 Figure 9. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 11 bq24745 www.ti.com SLUS761 – DECEMBER 2007 TYPICAL CHARACTERISTICS (continued) INPUT CURRENT REGULATION (DPM) ACCURACY vs DAC IDPM SETPOINT VICM INPUT CURRENT SENSE AMPLIFIER ACCURACY INPUT CHARGE CURRENT 0 0 DCIN = 20 V, VFB = 9 V -0.2 Input Current Regulation Accuracy - % -0.5 -0.4 VICM Accuracy - % -0.6 -1 -1.5 -2 VFB = 9 V, DCIN = 20 V -0.8 -1 -1.2 -1.4 -1.6 -2.5 -1.8 -2 0 -3 2000 4000 6000 8000 10000 12000 2000 DPM Programmed Setpoint - mA INPUT CURRENT REGULATION (DPM) AND CHARGE CURRENT vs SYSTEM CURRENT INPUT CURRENT REGULATION (DPM) TRANSIENT SYSTEM LOAD RESPONSE CCM TO CCM Ch1 2 A/div 5 4.5 3 3.5 2 Charge Current Ch2 2 A/div 4 Ch3 2 A/div Input Current 4 I(DCIN) ILOAD Input Current - A Charge Current - A 5 I(SYS) VICM 3 1 2.5 1 1.5 2 2.5 System Current - A 3 3.5 t − Time = 1 ms/div 4 Figure 12. 12 12000 Figure 11. DCIN = 20 V 0.5 10000 Figure 10. 6 0 0 4000 6000 8000 DPM Program Value - mA Ch4 500 mV/div 0 Figure 13. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 TYPICAL CHARACTERISTICS (continued) INPUT CURRENT REGULATION (DPM) TRANSIENT SYSTEM LOAD RESPONSE CCM TO DCM CHARGE CURRENT REGULATION ACCURACY VFB (BATTERY) VOLTAGE Ch1 2 A/div 0.5 I(DCIN) Ch3 2 A/div ILOAD Ch4 500 mV/div I(SYS) VICM Battery Charge Current Accuracy - % Ch2 5 A/div 0 t − Time = 1 ms/div -0.5 -1 -1.5 -2 -2.5 3-Cell at 12.592 V, ICHG at 4.096A with DCIN = 20 V -3 4 5 6 7 9 8 10 11 12 13 Battery Voltage - V Figure 14. Figure 15. EFFICIENCY BATTERY CHARGE CURRENT BATTERY REMOVAL (From Constant Current Mode) Ch4 2 V/div 98 4-Cell 96 VFB 94 Ch2 10 V/div 3-Cell Efficiency - % 92 2-Cell 90 PH 1-Cell 88 Ch1 2 A/div 86 1 - 4 Cell ICHG at 8.064A with DCIN = 20 V 84 I(IND) 82 t − Time = 4 ms/div 80 0 1 2 3 4 5 6 7 8 9 Battery Charge Current - A CHARGER WHEN ADAPTER REMOVED ADAPTER REMOVED WHILE CHARGING Ch1 5 V/div Figure 17. Ch1 5 V/div Figure 16. DCIN VREF ACOK VREF ACOK Ch4 2 V/div Ch3 2 V/div ACIN Ch4 2 V/div Ch2 Ch3 2 V/div 2 V/div DCIN Ch2 10 V/div PH t − Time = 4 ms/div t − Time = 4 ms/div Figure 18. Figure 19. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 13 bq24745 www.ti.com SLUS761 – DECEMBER 2007 TYPICAL CHARACTERISTICS (continued) SOFT-START, INDUCTOR CURRENT AND CHARGE CURRENT Ch4 1 A/div Ch3 1 V/div CE I(IND) Ch1 1 A/div ILOAD Ch4 5 V/div PH VDDP t − Time = 1 ms/div Figure 20. Figure 21. CHARGE ENABLED by SMBSus CHARGE DISABLED by SMBSus Ch1 2 V/div Ch4 5 V/div PH VDDP VDDP t − Time = 10 ms/div Figure 22. Figure 23. DEAD-TIME BETWEEN UGATE OFF AND LGATE ON DEAD-TIME BETWEEN LGATE OFF AND UGATE ON Ch1 2 A/div I(IND) PH UGATE-PH Ch4 10 V/div Ch2 10 V/div UGATE Math1 5 V/div Ch3 5 V/div LGATE Ch3 Ch2 5 V/div 10 V/div Ch1 2 A/div t − Time = 10 ms/div I(IND) UGATE PH UGATE-PH LGATE t − Time = 40 ns/div t − Time = 40 ns/div Figure 24. 14 Ch3 1 V/div ACGOOD Ch2 10 V/div ACGOOD Ch2 10 V/div SDA Ch3 1 V/div SDA Ch4 5 V/div Ch1 2 V/div t − Time = 10 ms/div Ch4 10 V/div Ch2 10 V/div ACGOOD Math1 5 V/div Ch1 2 V/div CHARGE ENABLE/DISABLE Figure 25. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 TYPICAL CHARACTERISTICS (continued) BATTERY SHORTED CHARGER RESPONSE, OVERCURRENT PROTECTION (OCP) AND CHARGE CURRENT REGULATION UGATE Ch3 2 A/div PHASE Ch2 10 V/div Ch2 10 V/div Ch1 10 V/div NEAR 100% DUTY CYCLE BOOTSTRAP RECHARGE PULSE Ch3 2 A/div Ch4 5 V/div I(IND) VFB I(IND) LGATE t − Time = 400 ms/div Figure 27. CONTINUOUS CONDUCTION MODE (CCM) SWITCHING WAVEFORMS, ICHARGE = 3986 mA DISCONTINUOUS CONDUCTION MODE (DCM) SWITCHING WAVEFORMS, ICHARGE = 256 mA I(IND) UGATE Ch2 10 V/div PH PH LGATE Math1 5 V/div Ch3 5 V/div UGATE-PH LGATE Math1 5 V/div UGATE-PH t − Time = 1 ms/div t − Time = 1 ms/div Figure 28. Figure 29. OFF-STATE BATTERY CURRENT (LOW Iq) vs VFB (BATTERY) VOLTAGE OFF-STATE DCIN CURRENT (LOW Iq) vs DCIN INPUT VOLTAGE (With Adapter Connected) 7 700 6 600 Standby DCIN Current − mA I(DCIN) − Off-State Current − mA Ch2 Ch3 5 V/div 10 V/div UGATE Ch4 10 V/div I(IND) Ch1 500 mA/div Figure 26. Ch4 10 V/div Ch1 2 A/div t − Time = 400 ms/div 5 4 3 Including current from: DCIN, CSSP/N, VFB, CSOP/N, BOOT, PHASE 2 1 500 400 300 200 Adapter Connected ACIN > 2.4 V, Charge Disabled by CE pin CE = Low 100 0 0 -100 0 5 10 15 VFB - Voltage - V 20 25 0 Figure 30. 5 10 15 DCIN - Voltage - V 20 25 Figure 31. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 15 bq24745 www.ti.com SLUS761 – DECEMBER 2007 TYPICAL CHARACTERISTICS (continued) Ch2 5 V/div PROGRAMMABLE REFERENCE AND HYSTERESIS INPUT CURRENT COMPARATOR (With Pulsed Current) ICOUT Ch3 100 mV/div Ch4 1 V/div ICREF IIN VICM t − Time = 4 ms/div Figure 32. 16 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 FUNCTIONAL BLOCK DIAGRAM ENA_BIAS - 0.6V ACIN ACOK ACOK + 2.4V + ENA DCIN_UVLO 3.3V LDO DCIN DCIN VREF VREF DCIN_UVLO (DCIN-VFB)_CMP ENA CE CHRG_ENA FBO CSSP + - - IIN_REG FBO EAI V(CSSP-CSSN) EAI IIN_ER COMP ERROR AMPLIFIER + CSSN EAO EAO CHRG_ENA 1V VFB VBAT_REG 10mA BOOT + BAT_ER + 20uA CHRG_ENA LEVEL SHIFTER UGATE CSOP + 20X - EN V(CSOP-CSON) IBAT _ REG CSON V(CSOP-CSON) + ICH_ER SYNCH + 20uA DC-DC CONVERTER PWM LOGIC PHASE BAT_SHORT DCIN SYNCH VDDP 6V LDO 10mV +- V(BTST-PHASE) - REFRESH C BTST ENA_BIAS + VFB VDDSMB - LGATE + 4V _ BAT_SHORT + 2.9V +- IC Tj + 145degC - TSHUT PGND SMBus_Bias SDA SMBus Logic SCL CHRG_V (11 bit DAC) CHRG_I (6 bit DAC) INPUT_I (6 bit DAC) V(DCIN-VFB) - 185mV + VBAT_REG 145% X IBAT_REG - V(CSOP-CSON) + ACIN + EN IBAT_REG (DCIN-VFB)_CMP CSSP CSSN + VICM 20x ENA VICM ENA_BIAS CHG_OCP GND IIN_REG ACOV 3.1V VICM ICREF + - + - NC DCIN - DCIN_UVLO + 4V +- NC VDDSMB ICOUT + 2.5V +- VDDSMB_UVLO bq24745 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 17 bq24745 www.ti.com SLUS761 – DECEMBER 2007 DETAILED DESCRIPTION BATTERY VOLTAGE REGULATION The bq24745 uses a high-accuracy voltage regulator to supply charging voltage. The battery voltage regulation setting is programmed by the host microcontroller (µC), through the SMBus interface that sets an 11-bit DAC. The input voltage range of VFB is between 1.024 V and 19.2 V. The per-cell battery termination voltage is a function of the battery chemistry. (Consult the battery manufacturer to determine this voltage.) The programmed value should be the per-cell voltage times the number of series cells. The VFB pin is used to sense the battery voltage for voltage regulation and should be connected as close to the battery as possible, or directly on the output capacitor. A 0.1-µF ceramic capacitor from VFB to GND is recommended to be as close to the VFB pin as possible to decouple high frequency noise. BATTERY CURRENT REGULATION The ChargeCurrent() SMBus 6-bit DAC register sets the maximum charging current. Battery current is sensed by resistor RSR connected between the CSOP and CSON pins. The maximum full-scale differential voltage between CSOP and CSON is 80.64 mV. Thus, for a 0.010-Ω sense resistor, the maximum charging current is 8.064 A. The CSOP and CSON pins are used to measure the voltage across RSR, which has a default value of 10 mΩ. However, resistors of other values can also be used. A larger sense resistor gives a larger sense voltage and higher regulation accuracy, but at the expense of higher conduction loss. INPUT ADAPTER CURRENT REGULATION The total input current from an AC adapter or other DC source is a function of the system supply current and the battery charging current. System current normally fluctuates as portions of the systems are powered up or down. Without Dynamic Power Management (DPM), the source must be able to supply the maximum system current and the maximum charger input current simultaneously. By using DPM, the input current regulator reduces the charging current when the input current exceeds the limit set by the InputCurrent() SMBus 6 bit DAC register. With the high-accuracy limiting, the current capability of the AC adaptor can be lowered, reducing system cost. In a manner similar to battery-current regulation, adaptor current is sensed by resistor RAC connected between the CSSP and CSSN pins. The maximum full-scale differential voltage between CSSP and CSSN is 110.04 mV. Thus, for a 0.010Ω sense resistor, the maximum input current is 11.004 A. The CSSP and CSSN pins are used to sense RAC with default value of 10 mΩ. However, resistors of other values can also be used. A larger sense resistor gives a larger sense voltage and a higher regulation accuracy, but at the expense of higher conduction loss. ADAPTER DETECT AND POWER UP An external resistor voltage divider attenuates the adapter voltage before it goes to ACIN. The adapter-detect threshold should typically be programmed to a value greater than the maximum battery voltage and lower than the minimum allowed adapter voltage. If DCIN is below 4 V, the charger is disabled and ACOK goes low. If ACIN is below 0.6 V but DCIN is above 4 V, part of the bias is enabled, including a crude bandgap reference, ACFET drive and BATFET drive. VICM is disabled and pulled down to GND. The total quiescent current is less than 10µA. When ACIN rises above 0.6 V and DCIN is above 4 V, all the bias circuits are enabled, the VDDP output goes to 6 V, and VREF goes to 3.3 V. VICM becomes valid to proportionally reflect the adapter current. When ACIN keeps rising and passes 2.4 V, it indicates that a valid AC adapter is present. 200µs later, and the following occurs: • ACOKis pulled high through an external pull-up resistor to the host digital voltage rail; • The charger turns on if all the conditions are satisfied after an additional 2-ms deglitch time. (refer to Enable and Disable Charging) 18 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 ENABLE AND DISABLE CHARGING The following conditions must be valid before charging is enabled: • CE is HIGH; • Adapter is detected (ACIN > 2.4 V); • Adapter is higher than the DCIN-VFB threshold; • 200µs delay is complete after adapter detected; • VDDP and VREF are valid; • Thermal Shutdown (TSHUT) is not active; Any of the following conditions stop the charge cycle: • CE is LOW; • Adapter is removed; • Adapter voltage is less than 250 mV above the battery; • Adapter is over voltage; • Charge output current is over programmed current; • TSHUT IC temperature threshold is reached (145°C on rising-edge with 15°C hysteresis). AUTOMATIC INTERNAL SOFT-START CHARGER CURRENT The charger automatically soft-starts the charger regulation current every time the charger is enabled to ensure that there is no overshoot or stress on the output capacitors or the power converter. The soft-start function steps up the charge current into 8 evenly-divided steps, gradually building up to the full programmed charge current. Each step lasts approximately 1 ms, for a typical rise time of 8 ms. No external components are needed for this function. CONVERTER OPERATION The synchronous-buck PWM converter operates at a fixed frequency (300 kHz) in voltage mode with a feed-forward control scheme. A type-III compensation network allows the use of ceramic capacitors at the output of the converter. The input compensation stage is connected between the feedback output (FBO) and the error amplifier input (EAI). The feedback compensation stage is connected between the error amplifier input (EAI) and error amplifier output (EAO). The LC output filter has a characteristic resonant frequency that ensures sufficient phase margin for the target bandwidth. fo + The resonant frequency, fo, is given by: 1 2p ǸLoC o An internal saw-tooth ramp is compared to the internal EAO error control signal to vary the converter duty cycle. The ramp height is 1/15 of the input adapter voltage, always keeping it directly proportional to the input adapter voltage. This cancels out any loop-gain variation due to an input voltage change, simplifying loop-compensation design. The ramp is offset by 250 mV in order to allow a 0% duty cycle when the EAO signal is below the ramp. The EAO signal is also allowed to exceed the saw-tooth ramp signal in order to respond to a 100% duty-cycle PWM request. The internal gate-drive logic allows a 99.98% duty cycle while ensuring that the N-channel upper device always has enough voltage to stay fully on. If the BOOT-pin-to-PHASE-pin voltage falls below 4.5 V for more than 3 cycles, the high-side n-channel power MOSFET is turned off and the low-side n-channel power MOSFET is turned on to pull the PHASE node down and recharge the BOOT capacitor. Then the high-side driver returns to 100% duty-cycle operation until the (BOOT-PHASE) voltage is again detected falling low due to leakage current discharging the BOOT capacitor below 4 V, and the reset pulse is reissued. The 300-kHz fixed-frequency oscillator keeps tight control of the switching frequency under all conditions of input voltage, battery voltage, charge current, and temperature, simplifying output-filter design and keeping it out of the audible-noise region. The charge-current sense resistor (RSR) should be positioned with half or more of the total output capacitance placed before RSR, contacting both RSR and the output inductor; and the remaining capacitance placed after RSR. The output capacitance should be divided and placed on either side of RSR. A ratio of 50:50% gives the best performance, but the node in which the output inductor and RSR connect should have a minimum of 50% of the total capacitance. This capacitance provides sufficient filtering to remove the switching noise and give better accuracy. The type-III compensation provides phase boost near the crossover frequency to provide sufficient phase margin. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 19 bq24745 www.ti.com SLUS761 – DECEMBER 2007 SYNCHRONOUS AND NON-SYNCHRONOUS OPERATION The charger operates in non-synchronous mode when the sensed charge current is below the internal ISYNSET value of 13 mV (1.3 A) falling, and 0.8 mV (800 mA) rising (with built-in hysteresis). Otherwise, the charger operates in synchronous mode. In synchronous mode, the low-side n-channel power MOSFET is on, and the high-side n-channel power MOSFET is off. The internal gate-drive logic enforces break-before-make switching to prevent shoot-through currents. During the 30-ns dead time when both FETs are off, the back diode of the low-side power MOSFET conducts the inductor current. Having the low-side FET turned on keeps the power dissipation low, and safely allows high-current charging. In synchronous mode, the inductor current is always flowing and operates in Continuous Conduction Mode (CCM), creating a fixed two-pole system. In non-synchronous operation, after the high-side n-channel power MOSFET turns off, and after the break-before-make dead-time, the low-side n-channel power MOSFET turns on for approximately 80 ns, then the low-side power MOSFET turns off and stays off until the beginning of the next cycle, when the high-side power MOSFET is turned on again. The 80-ns low-side MOSFET on-time is required to ensure that the bootstrap capacitor is always charged and able to keep the high-side power MOSFET turned on during the next cycle. This is important for battery chargers, where unlike regular dc-dc converters, there is a battery load that maintains a voltage, and can both source and sink current. The 80-ns low-side pulse pulls the PHASE node (connection between high and low-side MOSFET) down, allowing the bootstrap capacitor to recharge up to the VDDP LDO value. After the 80 ns, the low-side MOSFET is kept off to prevent negative inductor current from flowing. The inductor current is blocked by the off-state low-side MOSFET, and the inductor current becomes discontinuous. This mode is called Discontinuous Conduction Mode (DCM). In DCM operation, the loop response automatically changes, and acts as a single-pole system at which the pole is proportional to the load current, because the converter does not sink current, and only the load provides a current sink. At very low currents, the loop response is slower, because there is less sinking current available to discharge the output voltage. At very low currents during non-synchronous operation, there may be a small amount of negative inductor current during the 80-ns recharge pulse. This should be low enough to be absorbed by the input capacitance. When the converter goes into 0% duty cycle, neither MOSFET turns on (no 80-ns recharge pulse), and there is no discharge from the battery. ISYNSET CONTROL (CHARGE UNDERCURRENT) In bq24745, ISYN is the internally-set ISYNSET value as the charge-current threshold at which the charger switches from non-synchronous operation to synchronous operation. The low-side driver turns on for only 80 ns to charge the boost capacitor. This is important to prevent negative inductor current, which may cause a boost effect in which the input voltage increases as power is transferred from the battery to the input capacitors. This can lead to an overvoltage condition on the DCIN node, and potentially can damage the system. This programmable value allows setting the current threshold for any inductor ripple current to avoid negative inductor current. The minimum synchronous threshold should be set from 50%-100% of the inductor ripple current, where the inductor ripple current is calculated using Equation 1. I RIPPLE_MAX v I SYN v I RIPPLE_MAX 2 ǒVIN_MAX * VBAT_MINǓ and I RIPPLE_MAX + ǒ Ǔ ǒǓ VBAT_MIN VIN_MAX 1 fs LMIN (1) where VIN_MAX: maximum adapter voltage VBAT_MIN: minimum BAT voltage fS: switching frequency LMIN: minimum output inductor The ISYNSET comparator, or charge undercurrent comparator, compares the voltage between CSOP-CSON and the 13-mV internal threshold. The threshold is set internally to 13 mV on the falling edge and 8 mV on the rising edge (with built-in hysteresis) with 10% variation. 20 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 HIGH ACCURACY VICM USING CURRENT SENSE AMPLIFIER (CSA) An industry-standard, high-accuracy current-sense amplifier (CSA) provides an analog output voltage at the VICM pin that can be used by a host system to monitor the input current. The CSA amplifies the input sensed voltage of CSSP-CSSN by 20× through the VICM pin. The VICM output is a voltage source 20× the input differential voltage. When DCIN is above 4 V and ACIN is above 0.6 V, VICM no longer stays at ground, but becomes active. A lower voltage can be used by connecting a resistor divider from VICM to GND, while still achieving good accuracy over temperature if the resistors are matched by their thermal coefficients. A 0.1µF capacitor connected on the output is recommended for decoupling high-frequency noise. An additional RC filter is optional, after the 0.1µF capacitor, if additional filtering is desired. Note that adding filtering also adds additional response delay. VDDSMB INPUT SUPPLY The VDDSMB input provides bias power to the SMBus interface logic. Connect VDDSMB to an external 3.3 V or 5 V supply rail to keep the SMBus interface active while the supply to DCIN is removed. When VDDSMB is biased, the internal registers are maintained, and SMBus communication can occur between the host and the charger. Bypass VDDSMB to GND with a 0.1-µF or greater ceramic capacitor. The VDDSMB UVLO threshold is 2.7 V rising and 250 mV falling (with hysteresis). The SMBus is always active and can be written to or read from whenever VDDSMB is above the VDDSMB UVLO threshold. INPUT UNDER VOLTAGE LOCK OUT (UVLO) The system must have a minimum 4 V DCIN voltage from the input adapter to allow proper charger operation. When the DCIN voltage is below 4 V, the bias circuits VDDP and VREF stay inactive, even with ACIN above 0.6 V. BATTERY OVERVOLTAGE PROTECTION The converter will not allow the high-side FET to turn-on when the battery voltage at VFB exceeds 104% of the regulation voltage set-point, until the VFB voltage returns below 101% of the regulation voltage. This allows quick response to an overvoltage condition – such as occurs when the load is removed or the battery is disconnected. A 10-mA current sink from VFB to PGND is on only during charge and allows discharging the stored output inductor energy that is transferred to the output capacitors. BATTERY SHORTED (Battery Undervoltage) PROTECTION AND BATTERY TRICKLE CHARGING The bq24745 has a VFB SHORT comparator monitoring the output battery VFB voltage. If the voltage falls below 2.5 V (absolute, fixed), a battery-short status is detected. The charger continues charging at the value programmed on the ChargeCurrent(0x14) register down to 2.5 V falling, and 2.7 V rising on the VFB pin. The bq24745 automatically reduces the charge current limit to a fixed 128 mA to trickle charge the battery, when the voltage on the VFB pin falls below 2.5 V. The charge current returns to the value programmed on the ChargeCurrent(0x14) register, when the VFB pin voltage rises above 2.7 V. This function provides short circuit protection from the battery node, and it also provides a safe trickle charge to close deeply discharged open packs. INPUT CURRENT COMPARATOR TRIP DETECTION To optimize system performance, the host monitors the adapter current. When the adapter current is above a threshold set via ICREF, the ICOUT pin asserts low to act as an alarm signal to the host, indicating that input power has exceeded the programmed limit, allowing the host to throttle back system power by reducing clock frequency, lowering rail voltages, or disabling parts of the system. The ICOUT pin is an open-drain output, and must have a pull-up resistor connected. The output is logic HI when the VICM output voltage [VICM = 20 × V(CSSP-CSSN)] is lower than the ICREF input voltage. The ICREF threshold is set by an external resistor divider using VREF. A hysteresis can be programmed by connecting a positive feedback resistor from the ICOUT pin to the ICREF pin. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 21 bq24745 www.ti.com SLUS761 – DECEMBER 2007 ACOK Comparator ACIN ENABLE VICM Comparator 0.6V + - + 2.4V t_dg rising 100us ACOK ACOK ACOK_DG ENA_BIAS & ENA_VICM CHARGE_DISABLE CSSP 1k VICM Current Sense Amplifier + - CSSN VICM Error Amplifier Disable 20k VICM + VICM Disable Program Hysteresis of comparator by putting a resistor in feedback from ICOUT pin to ICREF pin. Input Current Comparator ICOUT + - Figure 33. ACOK, ICREF, and ICOUT Logic CHARGE OVERCURRENT PROTECTION The charger has a secondary overcurrent monitor that prevents the charge current from exceeding 145% of the programmed charge current. The high-side gate drive turns off when the overcurrent is detected, and automatically resumes when the current falls below the overcurrent threshold. THERMAL SHUTDOWN PROTECTION The QFN package has low thermal impedance, providing good thermal conduction from the silicon to the ambient air, to keep junction temperatures low. As an added level of protection, the charger converter turns off and self-protects whenever the junction temperature exceeds the TSHUT threshold of 155°C. The charger stays off until the junction temperature falls below 135°C. OPEN-DRAIN STATUS OUTPUTS (ACOK, ICOUT) Two status outputs are available; both require external pull up resistors to pull the pins to the system digital rail for a high level. The ACOK open-drain output goes high when ACIN is above 2.4 V. It indicates that a functional adapter is providing a valid input voltage. The ICOUT open-drain output goes low when the input current is higher than the threshold programmed via the ICREF pin. Hysteresis can be programmed by adding a resistor from the ICREF pin to the ICOUT pin. SMBus INTERFACE The bq24745 operates as a slave, receiving control inputs from the host through the SMBus interface. 22 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 BATTERY-CHARGER COMMANDS The bq24745 supports four battery-charger commands that use either Write-Word or Read-Word protocols, as summarized in Table 2. ManufacturerID() and DeviceID() can be used to identify the bq24745. On the bq24745, the ManufacturerID() command always returns 0x0040 and the DeviceID() command always returns 0x0006. Table 2. Battery Charger SMBus Registers REGISTER ADDRESS REGISTER NAME READ/WRITE DESCRIPTION POR STATE 0x14 ChargeCurrent() Read or Write 6-Bit Charge Current Setting 0x0000 0x15 ChargeVoltage() Read or Write 11-Bit Charge Voltage Setting 0x0000 0x3F InputCurrent() Read or Write 6-Bit Input Current Setting 0x0080 0xFE ManufacturerID() Read Only Manufacturer ID 0x0040 0xFF DeviceID() Read Only Device ID 0x0006 SMBus Interface The bq24745 receives commands from the SMBus interface. The bq24745 uses a simplified subset of the commands documented in the System Management Bus Specification V1.1, which can be downloaded from www.smbus.org. The bq24745 uses the SMBus Read-Word and Write-Word protocols (see Figure 34) to communicate with the smart battery. The bq24745 performs only as an SMBus slave device with address 0b0001001_ (0x12), and does not initiate communication on the bus. In addition, the bq24745 has two identification (ID) registers (0xFE): a 16-bit device ID register and a 16-bit manufacturer ID register (0xFF). The data (SDA) and clock (SCL) pins have Schmitt-trigger inputs that can accommodate slow edges. Choose pullup resistors (10 kΩ) for SDA and SCL to achieve rise times according to the SMBus specifications. Communication starts when the master signals a START condition; a high-to-low transition on SDA while SCL is high. When the master has finished communicating, the master issues a STOP condition, which is a low-to-high transition on SDA, while SCL is high. The bus is then free for another transmission. Figure 35 and Figure 36 show the timing diagram for signals on the SMBus interface. The address byte, command byte, and data bytes are transmitted between the START and STOP conditions. The SDA state changes only while SCL is low, except for the START and STOP conditions. Data is transmitted in 8-bit bytes, sampled on the rising edge of SCL. Nine clock cycles are required to transfer each byte to or from the bq24745 because either the master or the slave acknowledges the receipt of the correct byte during the ninth clock cycle. The bq24745 supports the charger commands as described in Table 5. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 23 bq24745 www.ti.com SLUS761 – DECEMBER 2007 a) Write-Word Format S SLAVE ADDRESS W ACK COMMAND BYTE ACK 7 BITS 1b MSB LSB 0 1b 8 BITS 1b 8 BITS 0 MSB LSB 0 MSB LSB Preset to 0b0001001 LOW DATA BYTE ChargeCurrent() = 0x14 D7 ChargeVoltage() = 0x15 InputCurrent() = 0x3F HIGH DATA BYTE ACK 1b 8 BITS 1b 0 MSB L SB 0 ACK D0 D15 P D8 b) Read-Word Format S SLAVE ADDRESS W ACK COMMAND BYTE ACK 7 BITS 1b 1b 8 BITS 1b MSB LSB 0 0 MSB LSB 0 Preset to 0b0001001 S SLAVE ADDRESS R ACK LOW DATA BYTE ACK HIGH DATA BYTE NACK 7 BITS 1b 1b 8 BITS 1b 8 BITS 1b 1 0 MSB ChargeSpecInfo() = 0x11 ChargerStatus() = 0x13 ChargeMode() = 0x14 ChargeMode() = 0x15 ChargeMode() = 0x3F LSB Preset to 0b0001001 LEGEND: S = START CONDITION OR REPEATED START CONDITION ACK = ACKNOWLEDGE (LOGIC-LOW) W = WRITE BIT (LOGIC-LOW) MSB D7 LSB 0 D0 MSB D15 LSB P 1 D8 P = STOP CONDITION NACK = NOT ACKNOWLEDGE (LOGIC-HIGH) R = READ BIT (LOGIC-HIGH) MASTER TO SLAVE SLAVE TO MASTER Figure 34. SMBus Write-Word and Read-Word Protocols Figure 35. SMBus Write Timing 24 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 A tLOW tHIGH B C D E F G H I J K SMBCLK SMBDATA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS C LOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW I = ACKNOWLEDGE CLOCK PULSE F = ACKNOWLEDGE BIT CLOCKED INTO MASTER J = STOP CONDITION G = MSB OF DATA CLOCKED INTO MASTER K = NEW START CONDITION H = LSB OF DATA CLOCKED INTO MASTER Figure 36. SMBus Read Timing Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 25 bq24745 www.ti.com SLUS761 – DECEMBER 2007 SETTING THE CHARGE VOLTAGE To program the output charge voltage regulation setpoint, use the SMBus to write a 16-bit ChargeVoltage() command using the data format listed in Table 3. The ChargeVoltage() command uses the Write-Word protocol (see Figure 34). The command code for ChargeVoltage() is 0x15 (0b00010101). The bq24745 provides a charge-voltage range of 1.024 V to 19.200 V, with 16 mV resolution. Set ChargeVoltage() below 1.024 V to terminate charging. Upon reset, the ChargeVoltage() and ChargeCurrent() values are cleared and the charger remains off until both the ChargeVoltage() and the ChargeCurrent() command are sent. Both UGATE and LGATE pins remain low until the charger is restarted. Table 3. Charge Voltage Register (0x15) 26 BIT BIT NAME 0 – Not used. DESCRIPTION 1 – Not used. 2 – Not used. 3 – Not used. 4 Charge Voltage, DACV 0 0 = Adds 0 mV of charger voltage, 1024 mV min. 1 = Adds 16 mV of charger voltage 5 Charge Voltage, DACV 1 0 = Adds 0 mV of charger voltage, 1024 mV min. 1 = Adds 32 mV of charger voltage 6 Charge Voltage, DACV 2 0 = Adds 0 mV of charger voltage, 1024 mV min. 1 = Adds 64 mV of charger voltage. 7 Charge Voltage, DACV 3 0 = Adds 0 mV of charger voltage, 1024 mV min. 1 = Adds 128 mV of charger voltage. 8 Charge Voltage, DACV 4 0 = Adds 0 mV of charger voltage, 1024 mV min. 1 = Adds 256 mV of charger voltage. 9 Charge Voltage, DACV 5 0 = Adds 0 mV of charger voltage, 1024 mV min. 1 = Adds 512 mV of charger voltage 10 Charge Voltage, DACV 6 0 = Adds 0 mV of charger voltage. 1 = Adds 1024 mV of charger voltage. 11 Charge Voltage, DACV 7 0 = Adds 0 mV of charger voltage. 1 = Adds 2048 mV of charger voltage. 12 Charge Voltage, DACV 8 0 = Adds 0 mV of charger voltage. 1 = Adds 4096 mV of charger voltage. 13 Charge Voltage, DACV 9 0 = Adds 0 mV of charger voltage. 1 = Adds 8192 mV of charger voltage. 14 Charge Voltage, DACV 10 0 = Adds 0 mV of charger voltage. 1 = Adds 16384 mV of charger voltage. 15 – Not used. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 SETTING THE CHARGE CURRENT To set the charge current, use the SMBus to write a 16bit ChargeCurrent() command using the data format listed in Table 4. The ChargeCurrent() command uses the Write-Word protocol (see Figure 34). The command code for ChargeCurrent() is 0x14 (0b00010100). When using a 10-mΩ sense resistor, the bq24745 provides a charge-current range of 128 mA to 8.064 A, with 128 mA resolution. Set ChargeCurrent() to 0 to terminate charging. Upon reset, the ChargeVoltage() and ChargeCurrent() values are cleared and the charger remains off until both the ChargeVoltage() and the ChargeCurrent() commands are received. Both UGATE and LGATE pins remain low until the charger is restarted. The bq24745 includes a foldback current limit when the battery voltage is low. If the battery voltage is less than 2.5 V, the charge current is temporarily set to 128 mA. The ChargeCurrent() register value is preserved, and becomes active again when the battery voltage is higher than 2.7 V. This function effectively provides a fold-back current limit, protecting the charger during short circuit and overload. Table 4. Charge Current Register (0x14), Using 10mΩ Sense Resistor BIT BIT NAME DESCRIPTION 0 – Not used. 1 – Not used. 2 – Not used. 3 – Not used. 4 – Not used. 5 – Not used. 6 – Not used. 7 Charge Current, DACI 0 0 = Adds 0 mA of charger current 1 = Adds 128 mA of charger current. 8 Charge Current, DACI 1 0 = Adds 0 mA of charger current 1 = Adds 256 mA of charger current. 9 Charge Current, DACI 2 0 = Adds 0 mA of charger current 1 = Adds 512 mA of charger current 10 Charge Current, DACI 3 0 = Adds 0 mA of charger current. 1 = Adds 1024 mA of charger current. 11 Charge Current, DACI 4 0 = Adds 0 mA of charger current. 1 = Adds 2048 mA of charger current. 12 Charge Current, DACI 5 0 = Adds 0 mA of charger current. 1 = Adds 4096 mA of charger current, 8064 mA. 13 – Not used. 14 – Not used. 15 – Not used. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 27 bq24745 www.ti.com SLUS761 – DECEMBER 2007 SETTING THE CHARGE CURRENT System current normally fluctuates as portions of the system are powered up or down, or enter low-power mode. By using the input-current limit circuit, the output-current requirement of the AC wall adapter can be lowered, reducing system cost. The total input current, from a power-line wall adapter or other DC source, is the sum of the system supply current and the current required by the charger. When the input current exceeds the programmed input current limit, the bq24745 decreases the charge current to provide priority to the system load current. As the system supply current rises, the available charge current drops linearly to zero. Thereafter, the total input current can increase without limit. The internal amplifier compares the differential voltage between CSSP and CSSN to a scaled voltage set by the InputCurrent() command (see Table 5). The total input current is the sum of the device supply current, the charger input current, and the system load current. The total input current can be estimated as follows: Table 5. Input Current Register (0x3F), Using 10mΩ Sense Resistor BIT BIT NAME 0 – Not used. 1 – Not used. 2 – Not used. 3 – Not used. 4 – Not used. 5 – Not used. 6 – Not used. 7 Charge Current, DACS 0 0 = Adds 0 mA of charger current 1 = Adds 256 mA of charger current. 8 Charge Current, DACS 1 0 = Adds 0 mA of charger current 1 = Adds 512 mA of charger current 9 Charge Current, DACS 2 0 = Adds 0 mA of charger current. 1 = Adds 1024 mA of charger current. 10 Charge Current, DACS 3 0 = Adds 0 mA of charger current. 1 = Adds 2048 mA of charger current. 11 Charge Current, DACS 4 0 = Adds 0 mA of charger current. 1 = Adds 4096 mA of charger current 12 Charge Current, DACS 5 0 = Adds 0 mA of charger current. 1 = Adds 8192 mA of charger current, 11004 mA max. 13 – Not used. 14 – Not used. 15 – Not used. I INPUT + I LOAD ) ƪ I LOAD DESCRIPTION ƫ VBATTERY VIN h ) I BIAS (2) where η is the efficiency of the DC-DC converter (typically 85% to 95%). To set the input current limit, write a 16-bit InputCurrent() command using the data format listed in Table 5. The InputCurrent() command uses the Write-Word protocol (see Figure 34). The command code for InputCurrent() is 0x3F (0b00111111). When using a 10-mΩ sense resistor, the bq24745 provides an input-current limit range of 256 mA to 11.004 A, with 256 mA resolution. InputCurrent() settings from 1 mA to 256 mA result in a current limit of 256 mA. Upon reset the input current limit is 256 mA. CHARGER TIMEOUT The bq24745 includes a timer to terminate charging if the charger does not receive a ChargeVoltage() or ChargeCurrent() command within 175 s. If a timeout occurs, both ChargeVoltage() and ChargeCurrent() commands must be resent to re-enable charging. 28 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 REMOTE SENSE The bq24745 has a dedicated remote sense pin, VFB, which allows the rejection of board resistance and selector resistance. To fully utilize remote sensing, connect VFB directly to the battery interface through an unshared battery-sense Kelvin trace, and place a 0.1-µF ceramic capacitor near the VFB pin to GND (see Figure 1). Remote Kelvin Sensing provides higher regulation accuracy, by eliminating parasitic voltage drops. Remote sensing cancels the effect of impedance in series with the battery. This impedance normally causes the battery charger to prematurely enter constant-voltage mode with reducing charge current. INPUT CURRENT MEASUREMENT Use VICM to monitor the system-input current sensed across CSSP and CSSN. The voltage at VICM is proportional to the input current by the equation: VICM = 20 × V(CSSP-CSSN) = 20 × (Iin × Rsense) where Iin is the input DC current supplied by the AC adapter, 20 is the gain, and Rsense is the input sense resistor. VICM has a 0 to (VREF–100 mV) output voltage range. Leave VICM open if not used. Use a 100 pF (maximum) ceramic capacitor. VDDP GATE DRIVE REGULATOR An integrated low-dropout (LDO) linear regulator provides a 6-V supply derived from DCIN, for high efficiency, and delivers over 75 mA of load current. The LDO powers the gate drivers of the n-channel MOSFETs. VDDP has a minimum current limit of 90 mA. This allows the bq24745 to work with high gate charge (both high-side and low-side) MOSFETs. Bypass VDDP to PGND with a 1-µF or greater ceramic capacitor. AC ADAPTER DETECTION The bq24745 includes a hysteretic comparator that detects the presence of an AC power adapter. When ACIN is greater than 2.4 V, the open-drain ACOK output becomes high impedance. Connect a 10-kΩ pullup resistor between the pull-up rail and ACOK. Use a resistive voltage-divider from the adapter’s output to the ACIN pin to set the appropriate detection threshold. Select the resistive voltage-divider not to exceed the 7 V absolute maximum rating of ACIN. Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 29 bq24745 www.ti.com SLUS761 – DECEMBER 2007 VDDSMB SUPPLY The VDDSMB input provides power to the SMBus interface. Connect VDDSMB to VREF, or apply an external supply to VDD to keep the SMBus interface active while the supply to DCIN is removed. When VDDSMBus is biased, the internal register contents are maintained. Bypass VDDSMB to GND with a 0.1µF or greater ceramic capacitor. OPERATING CONDITIONS The bq24745 has the following operating states: • Adapter Present: When DCIN is greater than 4 V and ACIN is greater than 2.4 V, the adapter is considered to be present. In this condition, both the VDDP and VREF function properly and battery charging is allowed: – Charging: The total bq24745 quiescent current when charging is 1 mA (max) plus the current required to drive the MOSFETs. – Not Charging: To disable charging, set either ChargeCurrent() or ChargeVoltage() to zero. When the adapter is present and charging is disabled, the total adapter quiescent current is less than 1.5 mA and the total battery quiescent current is less than 200 µA. • Adapter Absent (Power Fail): When VCSSP is less than VCSON + 150 mV, the bq24745 is in the power-fail state, since the DC-DC converter is in dropout. The charger does not attempt to charge in the power-fail state. Typically, this occurs when the adapter is absent. When the adapter is absent, the total bq24745 quiescent battery current is less than 1µA (max). • VDDSMBus Undervoltage (POR): When VDD is less than 2.5 V, the VDD supply is in an undervoltage state and the internal registers are in their power-on-reset (POR) state. The SMBus interface does not respond to commands. When VDD rises above 2.7 V, the bq24745 is in a power-on-reset state. Charging does not occur until the ChargeVoltage() and ChargeCurrent() commands are sent. When VDD is greater than 2.5 V, SMBus register contents are preserved. The bq24745 allows charging under the following conditions: 1. DCIN > 4 V, VDDP > 4 V, VREF > 3.1 V 2. VCSSP > VCSON + 250 mV (15 mV falling threshold) 3. VDDSMBus > 2.5 V Charge Termination for Li-Ion or Li-Polymer The primary termination method for Li-Ion and Li-Polymer is minimum current. Secondary temperature termination also provides additional safety. The host controls the charge initiation and the termination. A battery pack gas gauge assists the hosts on setting the voltages and determining when to terminate based on the battery pack state of charge. 30 Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 bq24745 www.ti.com SLUS761 – DECEMBER 2007 Component List for Typical System Circuit of Figure 2 PART DESIGNATOR QTY DESCRIPTION Q1, Q2, Q3 3 P-channel MOSFET, –30V, –6A, SO-8, Vishay-Siliconix, Si4435 Q4, Q2 2 N-channel MOSFET, 30V, 12.5A, SO-8, Fairchild, FDS6680A D1 1 Diode, Dual Schottky, 30V, 200mA, SOT23, Fairchild, BAT54C RAC, RSR 2 Sense Resistor, 10 m W, 2010, Vishay-Dale, WSL2010R0100F L1 1 Inductor, 10µH, 7A, 31m Vishay-Dale, IHLP5050FD-01 C1, C6, C7, C11, C12 5 Capacitor, Ceramic, 10µF, 35V, 20%, X5R, 1206, Panasonic, ECJ-3YB1E106M C4, C8, C10 3 Capacitor, Ceramic, 1µF, 25V, 10%, X7R, 2012, TDK, C2012X7R1E105K C2, C3, C9, C13–C15 6 Capacitor, Ceramic, 0.1µF, 50V, 10%, X7R, 0805, Kemet, C0805C104K5RACTU C5 1 Capacitor, Ceramic, 100pF, 25V, 10%, X7R, 0805, Kemet R3, R4, R5 3 Resistor, Chip, 10kΩ, 1/16W, 5%, 0402 R1 1 Resistor, Chip, 432kΩ, 1/16W, 1%, 0402 R2 1 Resistor, Chip, 66.5kΩ, 1/16W, 1%, 0402 R6 1 Resistor, Chip, 33kΩ, 1/16W, 5%, 0402 R7 1 Resistor, Chip, 200kΩ, 1/16W, 1%, 0402 R8 1 Resistor, Chip, 24.9kΩ, 1/16W, 1%, 0402 R9 1 Resistor, Chip, 1.8MΩ, 1/16W, 1%, 0402 GLOSSARY VICM output Voltage of Input Current Monitor ICREF Input Current Reference - sets the threshold for the ??? input current ?? limit ?? DPM Dynamic Power Management CSOP, CSON Current Sense Output of battery (??) positive and negative These pins are used with an external low-value series resistor to monitor the current to and from the battery pack. CSSP, CSSN Current Sense Supply (??) positive and negative These pins are used with an external low-value series resistor to monitor the current from the adapter supply. POR Power on reset Submit Documentation Feedback Copyright © 2007, Texas Instruments Incorporated Product Folder Link(s) :bq24745 31 PACKAGE OPTION ADDENDUM www.ti.com 31-Dec-2007 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty BQ24745RHDR ACTIVE QFN RHD 28 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24745RHDT ACTIVE QFN RHD 28 250 CU NIPDAU Level-2-260C-1 YEAR Green (RoHS & no Sb/Br) Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 3-Jan-2008 TAPE AND REEL BOX INFORMATION Device Package Pins Site Reel Diameter (mm) Reel Width (mm) A0 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant BQ24745RHDR RHD 28 SITE 41 330 12 5.3 5.3 1.5 8 12 Q2 BQ24745RHDT RHD 28 SITE 41 180 12 5.3 5.3 1.5 8 12 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 3-Jan-2008 Device Package Pins Site Length (mm) Width (mm) BQ24745RHDR RHD 28 SITE 41 346.0 346.0 29.0 BQ24745RHDT RHD 28 SITE 41 190.0 212.7 31.75 Pack Materials-Page 2 Height (mm)