bq24120 bq24123 bq24125 Actual Size 3,5 mm x 4,5 mm www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 SINGLE-CHIP SWITCHMODE, LI-ION AND LI-POLYMER CHARGE-MANAGEMENT IC WITH ENHANCED EMI PERFORMANCE(bqSWITCHER™) FEATURES 1 • • • • • Handheld Products Portable Media Players Industrial and Medical Equipment Portable Equipment Portable DVD Players The bqSWITCHER™ series are highly integrated Li-ion and Li-polymer switch-mode charge management devices targeted at a wide range of portable applications. The bqSWITCHER™ series offers integrated synchronous PWM controller and power FETs, high-accuracy current and voltage regulation, charge preconditioning, charge status, and charge termination, in a small, thermally enhanced QFN package. The bqSWITCHER charges the battery in three phases: conditioning, constant current, and constant voltage. Charge is terminated based on userselectable minimum current level. A programmable charge timer provides a safety backup for charge termination. The bqSWITCHER automatically restarts the charge cycle if the battery voltage falls below an internal threshold. The bqSWITCHER automatically enters sleep mode when VCC supply is removed. STAT1 IN IN PG VCC TTC ISET1 ISET2 2 1 OUT OUT RHL PACKAGE (TOP VIEW BQ24123) 20 19 3 18 4 17 5 16 6 15 7 14 8 13 9 10 11 12 STAT2 PGND PGND CE SNS BAT CELLS TS VTSB APPLICATIONS DESCRIPTION VSS • Enhanced EMI Performance • Integrated Power FETs For Up To 2-A Charge Rate • Suitable For 1-, 2-, or 3-Cell Li-Ion and Li-Polymer Battery Packs • Synchronous Fixed-Frequency PWM Controller Operating at 1.1 MHz With 0% to 100% Duty Cycle • High-Accuracy Voltage and Current Regulation • Status Outputs For LED or Host Processor Interface Indicates Charge-In-Progress, Charge Completion, Fault, and AC-Adapter Present Conditions • 20-V Absolute Maximum Voltage Rating on IN and OUT Pins • Accurate High-Side Battery Current Sensing • Battery Temperature Monitoring • Automatic Sleep Mode for Low Power Consumption • Reverse Leakage Protection Prevents Battery Drainage • Thermal Shutdown and Protection • Built-In Battery Detection • Available in 20 pin 3,5 mm x 4,5 mm QFN Package 2 1 2 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. bqSWITCHER, PowerPAD are trademarks of Texas Instruments. UNLESS OTHERWISE NOTED this document contains PRODUCTION DATA information current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2006–2007, Texas Instruments Incorporated bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED 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. ORDERING INFORMATION (1) TJ CHARGE REGULATION VOLTAGE (V) INTENDED APPLICATION 4.2 V –40°C to 125°C Stand-alone 4.2 V/8.4 V 2.1 V to 15.5 V (1) (2) (3) Externally Programmable PART NUMBER (2) (3) MARKINGS BQ24120RHLR / BQ24120RHLT BQU BQ24123RHLR / BQ24123RHLT BQV BQ24125RHLR / BQ24125RHLT CDZ 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. The RHL package is available in the following options: R - taped and reeled in quantities of 3,000 devices per reel T - taped and reeled in quantities of 250 devices per reel This product is RoHS compatible, including a lead concentration that does not exceed 0.1% of total product weight, and is suitable for use in specified lead-free soldering processes. PACKAGE DISSIPATION RATINGS (1) PACKAGE ΘJA ΘJC TA < 40°C POWER RATING DERATING FACTOR ABOVE TA = 40°C RHL (1) 46.87°C/W 2.15°C/W 1.81 W 0.021 W/°C This data is based on using the JEDEC High-K board, and the exposed die pad is connected to a copper pad on the board. This is connected to the ground plane by a 2x3 via matrix. ABSOLUTE MAXIMUM RATINGS (1) over operating free-air temperature range (unless otherwise noted) UNIT Supply voltage range (with respect to VSS) Input voltage range (with respect to VSS and PGND) IN, VCC 20 V STAT1, STAT2, PG, CE, CELLS, SNS, BAT –0.3 V to 20 V OUT –0.7 V to 20 V TS, TTC 7V VTSB 3.6 V ISET1, ISET2 3.3 V Voltage difference between SNS and BAT inputs (VSNS - VBAT) Output sink STAT1, STAT2, PG Output current (average) OUT ±1 V 10 mA 2.2 A TA Operating free-air temperature range –40°C to 85°C TJ Junction temperature range –40°C to 125°C Tstg Storage temperature –65°C to 150°C Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds (1) 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. RECOMMENDED OPERATING CONDITIONS MIN NOM MAX UNIT Supply voltage, VCC and IN (Tie together) 4.35 (1) 16.0 (2) V Operating junction temperature range, TJ –40 125 °C (1) (2) 2 The IC continues to operate below Vmin, to 3.5 V, but these conditions are not tested, and are not specified. The inherent switching noise voltage spikes should not exceed the absolute maximum rating on either the IN or OUT pins. A tight layout minimizes switching noise. Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 ELECTRICAL CHARACTERISTICS TJ = 0°C to 125°C and recommended supply voltage range (unless otherwise stated) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT INPUT CURRENTS VCC > VCC(min), PWM switching IVCC(VCC) VCC supply current Battery discharge sleep current, (SNS, BAT, OUT pins) I(SLP) 10 VCC > VCC(min), PWM NOT switching mA 5 VCC > VCC(min), CE = HIGH 315 0°C ≤ TJ ≤ 65°C, VI(BAT) = 4.2 V, VCC < V(SLP) or VCC > V(SLP) but not in charge 3.5 0°C ≤ TJ ≤ 65°C, VI(BAT) = 8.4 V, VCC < V(SLP) or VCC > V(SLP) but not in charge 5.5 0°C ≤ TJ ≤ 65°C, VI(BAT) = 12.6 V, VCC < V(SLP) or VCC > V(SLP) but not in charge 7.7 µA µA VOLTAGE REGULATION VOREG Output voltage, bq24123 Output voltage, bq24120 VIBAT CELLS = Low, in voltage regulation 4.2 CELLS = High, in voltage regulation 8.4 Operating in voltage regulation 4.2 Feedback regulation REF for bq24125 only IIBAT = 25 nA typical into pin (W/FB) 2.1 TA = 25°C Voltage regulation accuracy V –0.5% 0.5% –1% 1% 150 2000 –10% 10% CURRENT REGULATION - FAST CHARGE IOCHARGE VLOWV ≤ VI(BAT) < VOREG, V(VCC) - VI(BAT) > V(DO-MAX) Output current range of converter 100 mV ≤ VIREG≤ 200 mV, V IREG + mA (1) 1V RSET1 1000, VIREG Voltage regulated across R(SNS) Accuracy V(ISET1) Output current set voltage V(LOWV) ≤ VI(BAT) ≤ VO(REG), V(VCC) ≥ VI(BAT) + V (DO-MAX) 1 K(ISET1) Output current set factor VLOWV ≤ VI(BAT) < VO(REG) , V(VCC) ≥ VI(BAT) + V(DO-MAX) 1000 Programmed Where 5 kΩ ≤ RSET1 ≤ 10 kΩ, Select RSET1 to program VIREG, VIREG(measured) = IOCHARGE ×RSNS (–10% to 10% excludes errors due to RSET1 and R(SNS) tolerances) V V/A PRECHARGE AND SHORT-CIRCUIT CURRENT REGULATION VLOWV Precharge to fast-charge transition voltage threshold, BAT t Deglitch time for precharge to fast charge transition IOPRECHG V(ISET2) K(ISET2) Precharge current set factor 68 71.4 75 %VO(REG) Rising voltage; tRISE, tFALL = 100 ns, 2-mV overdrive 20 30 40 ms Precharge range VI(BAT) < VLOWV, t < tPRECHG 15 200 mA Precharge set voltage, ISET2 VI(BAT) < VLOWV, t < tPRECHG 10 mV ≤ VIREG-PRE ≤ 100 mV, V VIREG-PRE Voltage regulated across RSNS-Accuracy IREG*PRE 100 mV 1000 V/A (1) + 0.1V RSET2 1000, Where 1.0 kΩ ≤ RSET2 ≤ 10 kΩ, Select RSET2 to program VIREG-PRE, VIREG-PRE (Measured) = IOPRE-CHG × RSNS (–20% to 20% excludes errors due to RSET2 and RSNS tolerances) –20% 20% 15 200 CHARGE TERMINATION (CURRENT TAPER) DETECTION ITERM (1) Charge current termination detection range VI(BAT) > VOREG- VRCH mA Inductor peak current should be less than 2.6 A. Use equations 12, 13, 15, 18, and 19 to make sure the peak inductor current is less than 2.6 A. Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 3 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 ELECTRICAL CHARACTERISTICS (continued) TJ = 0°C to 125°C and recommended supply voltage range (unless otherwise stated) PARAMETER TEST CONDITIONS VTERM Charge termination detection set voltage, ISET2 K(ISET2) Termination current set factor tdg-TERM MIN VI(BAT) > VOREG- VRCH TYP MAX 100 mV 1000 Charger termination accuracy VI(BAT) > VOREG- VRCH Deglitch time for charge termination Both rising and falling, 2-mV overdrive tRISE, tFALL = 100 ns –20% UNIT V/A 20% 20 30 40 ms TEMPERATURE COMPARATOR AND VTSB BIAS REGULATOR VLTF Cold temperature threshold, TS 72.8 73.5 74.2 VHTF Hot temperature threshold, TS Initiate Charge 33.7 34.4 35.1 VTCO Cutoff temperature threshold, TS During Charge 28.7 29.3 29.9 0.5 1.0 1.5 20 30 40 LTF hysteresis tdg-TS Deglitch time for temperature fault, TS Both rising and falling, 2-mV overdrive tRISE, tFALL = 100 ns VO(VTSB) TS bias output voltage VCC > VIN(min), I(VTSB) = 10 mA 0.1 µF ≤ CO(VTSB) ≤ 1 µF VO(VTSB) TS bias voltage regulation accuracy VCC > IN(min), I(VTSB) = 10 mA 0.1 µF ≤ CO(VTSB) ≤ 1 µF 3.15 –10% %VO(VTSB) ms V 10% BATTERY RECHARGE THRESHOLD VRCH tdg-RCH Recharge threshold voltage Below VOREG 75 100 125 mV/cell Deglitch time VI(BAT) < decreasing below threshold, tFALL = 100 ns 10-mV overdrive 20 30 40 ms STAT1, STAT2, AND PG OUTPUTS VOL(STATx) Low-level output saturation voltage, STATx IO = 5 mA 0.5 VOL(PG) Low-level output saturation voltage, PG IO = 10 mA 0.1 V CE , CELLS INPUTS VIL Low-level input voltage IIL = 5 µA VIH High-level input voltage IIH = 20 µA 0 0.4 1.3 VCC V TTC INPUT tPRECHG Precharge timer tCHARGE Programmable charge timer range t(CHG) = C(TTC) × K(TTC) Charge timer accuracy 0.01 µF ≤ C(TTC) ≤ 0.18 µF KTTC Timer multiplier CTTC Charge time capacitor range VTTC_EN TTC enable threshold voltage 1440 1800 2160 s 25 572 minutes -10% 10% 2.6 0.01 V(TTC) rising min/nF 0.22 200 µF mV SLEEP COMPARATOR VSLP-ENT Sleep-mode entry threshold VSLP-EXIT Sleep-mode exit hysteresis, tdg-SLP Deglitch time for sleep mode 2.3 V ≤ VI(OUT) ≤ VOREG, for 1 or 2 cells VCC ≤ VIBAT +5 mV VCC ≤ VIBAT +75 mV VI(OUT) = 12.6 V, RIN = 1kΩ, bq24125 (2) VCC ≤ VIBAT –4 mV VCC ≤ VIBAT +73 mV 40 160 2.3 V ≤ VI(OUT)≤ VOREG VCC decreasing below threshold, tFALL = 100 ns, 10-mV overdrive, PMOS turns off mV µs 5 VCC decreasing below threshold, tFALL = 100 ns, 10-mV overdrive, STATx pins turn off V 20 30 40 3.50 ms UVLO VUVLO-ON (2) 4 IC active threshold voltage VCC rising 3.15 3.30 IC active hysteresis VCC falling 120 150 V mV For bq24125 only. RIN is connected between IN and PGND pins and needed to ensure sleep entry. Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 ELECTRICAL CHARACTERISTICS (continued) TJ = 0°C to 125°C and recommended supply voltage range (unless otherwise stated) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT PWM Internal P-channel MOSFET on-resistance Internal N-channel MOSFET on-resistance fOSC 7 V ≤ VCC ≤ VCC(max) 400 4.5 V ≤ VCC ≤ 7 V 500 7 V ≤ VCC ≤ VCC(max) 130 4.5 V ≤ VCC ≤ 7 V mΩ 150 Oscillator frequency 1.1 Frequency accuracy –9% MHz 9% DMAX Maximum duty cycle DMIN Minimum duty cycle 100% tTOD Switching delay time (dead time) 20 ns tsyncmin Minimum synchronous FET on time 60 ns 0% Synchronous FET minimum current-off threshold (3) 50 400 mA BATTERY DETECTION IDETECT Battery detection current during time-out fault VI(BAT) < VOREG – VRCH IDISCHRG1 Discharge current tDISCHRG1 Discharge time IWAKE tWAKE 2 mA VSHORT < VI(BAT) < VOREG – VRCH 400 µA VSHORT < VI(BAT) < VOREG – VRCH 1 s Wake current VSHORT < VI(BAT) < VOREG – VRCH 2 mA Wake time VSHORT < VI(BAT) < VOREG – VRCH 0.5 s IDISCHRG2 Termination discharge current Begins after termination detected, VI(BAT) ≤ VOREG 400 µA tDISCHRG2 Termination time 262 ms OUTPUT CAPACITOR COUT Required output ceramic capacitor range from SNS to PGND, between inductor and RSNS CSNS Required SNS capacitor (ceramic) at SNS pin 4.7 10 µF 47 µF 0.1 PROTECTION Threshold over VOREG to turn off P-channel MOSFET, STAT1, and STAT2 during charge or termination states 110 117 2.6 3.6 4.5 A Short-circuit voltage threshold, BAT VI(BAT) falling 1.95 2 2.05 V/cell ISHORT Short-circuit current VI(BAT) ≤ VSHORT TSHTDWN Thermal trip VOVP OVP threshold voltage ILIMIT Cycle-by-cycle current limit VSHORT %VO(REG) 65 165 Thermal hysteresis (3) 35 121 10 mA °C N-channel always turns on for ~60 ns and then turns off if current is too low. Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 5 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 TERMINAL FUNCTIONS TERMINAL NAME I/O DESCRIPTION bq24120 bq24123 bq24125 BAT 14 14 14 I Battery voltage sense input. Bypass it with a capacitor to VSS if there are long inductive leads to battery. CE 16 16 16 I Charger enable input. This active low input, if set high, suspends charge and places the device in the low-power sleep mode. Do not pull up this input to VTSB. I Available on parts with selectable output voltage. Ground or float for single-cell operation (4.2 V). For two-cell operation (8.4 V) pull up this pin with a resistor to VIN. 13 I Output voltage analog feedback adjustment. Connect the output of a resistive voltage divider powered from the battery terminals to this node to adjust the output battery voltage regulation. Charger input voltage. Bypass it with a 10µF capacitor from IN to PGND. CELLS 13 FB IN 3, 4 3, 4 3, 4 I ISET1 8 8 8 I/O Charger current set point 1 (fast charge). Use a resistor to ground to set this value. ISET2 9 9 9 I/O Charge current set point 2 (precharge and termination), set by a resistor connected to ground. N/C 13 – No connection. This pin must be left floating in the application. 1 1 1 O 20 20 20 O Charge current output inductor connection. Connect a zener TVS diode between OUT pin and PGND to clamp the voltage spike to protect the power MOSFETs during abnormal conditions. 5 5 5 O 17,18 17,18 17,18 SNS 15 15 15 I Charge current-sense input. Battery current is sensed via the voltage drop developed on this pin by an external sense resistor in series with the battery pack. A 0.1µF capacitor to VSS is required. STAT1 2 2 2 O Charge status 1 (open-drain output). When the transistor turns on indicates charge in process. When it is off and with the condition of STAT2 indicates various charger conditions (See Table 1) STAT2 19 19 19 O Charge status 2 (open-drain output). When the transistor turns on indicates charge is done. When it is off and with the condition of STAT1 indicates various charger conditions (See Table 1) TS 12 12 12 I Temperature sense input. This input monitors its voltage against an internal threshold to determine if charging is allowed. Use an NTC thermistor and a voltage divider powered from VTSB to develop this voltage. (See Figure 13) TTC 7 7 7 I Timer and termination control. Connect a capacitor from this node to VSS to set the bqSWITCHER timer. When this input is low, the timer and termination detection are disabled. I Analog device input. A 0.1µF capacitor to VSS is required. OUT PG PGND VCC 6 6 6 VSS 10 10 10 VTSB 11 11 11 Exposed Thermal Pad 6 Pad Pad Submit Documentation Feedback Pad Power-good status output (open drain). The transistor turns on when a valid VCC is detected. It is turned off in the sleep mode. PG can be used to drive a LED or communicate with a host processor. Power ground input Analog ground input O TS internal bias regulator voltage. Connect capacitor (with a value between a 0.1µF and 1µF) between this output and VSS. There is an internal electrical connection between the exposed thermal pad and VSS. The exposed thermal pad must be connected to the same potential as the VSS pin on the printed circuit board. The power pad can be used as a star ground connection between VSS and PGND. A common ground plane may be used. VSS pin must be connected to ground at all times. Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 TYPICAL APPLICATION CIRCUITS ICHARGE = 1.3A, IPRECHARGE = 133mA, Charge Safety Timer = 5.0 hours, Battery Charging Qualification Temperature Range = 0°C to 45°C LO BQ24120 VIN CIN 1.5 KW 10 mF 1.5 KW Adapter Present 1.5 KW Done Charge 3 IN OUT 1 4 IN OUT 20 6 VCC PGND 17 RSNS 10mH COUT 10mF Battery Pack Pack+ 0.1W Pack- MMBZ18VALT1 103AT 2 STAT1 PGND 18 19 STAT2 CTTC 5 PG 7 TTC 16 CE 0.1 mF SNS 15 BAT 14 ISET1 8 ISET2 9 13 NC 7.5 KW R ISET2 VTSB 9.31 KW R T1 442 KW RT2 TS 12 10 VSS 0.1 mF 7.5 KW R ISET1 VTSB 11 0.1 mF 0.1 mF Figure 1. Stand-Alone 1-Cell Application LO BQ24123 VIN 1.5 KW CIN 10 mF 1.5 KW Adapter Present 1.5 KW Done 3 IN OUT 1 4 IN OUT 20 6 VCC RSNS 10 mH Charge PGND 17 COUT 10mF 0.1W Battery Pack Pack+ Pack- MMBZ18VALT1 103AT 2 STAT1 PGND 18 19 STAT2 C TTC 5 PG 7 TTC BAT 14 ISET2 9 10 VSS 0.1 mF ISET1 8 7.5 KW R ISET1 7.5 KW 16 CE 0.1 mF SNS 15 TS 12 RT1 9.31 KW RISET2 13 CELLS VTSB 11 VIN VTSB 442 KW RT2 0.1 mF 0.1 mF 10 KW Figure 2. Stand-Alone 2-Cells Application Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 7 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 TYPICAL APPLICATION CIRCUITS (continued) ICHARGE = 1.3A, IPRECHARGE = 133mA, Charge Safety Timer = 5.0 hours, Battery Charging Qualification Temperature Range = 0°C to 45°C LOUT BQ24125 VIN CIN 1.5 KW 10 mF 1.5 KW Adapter Present 1.5 KW Done 3 Charge IN OUT 1 4 IN 6 VCC 2 STAT1 PGND 18 RSNS 10 mH OUT 20 COUT D1 0.1W 10 mF 5 PG 7 TTC Pack+ Pack- MMBZ18VALT1 PGND 17 103AT (See Note) 19 STAT2 Battery Pack SNS 15 BAT 14 ISET1 8 7.5 KW RISET1 VTSB 7.5 KW CTTC 16 CE ISET2 9 0.1 mF 10 VSS 0.1 mF 13 FB 9.31 KW RT1 442 KW RT2 RISET2 TS 12 VTSB 11 0.1 mF 0.1 mF 301 KW 100 KW A. Zener diode not needed for bq24125. Figure 3. Externally Programmable Application 8 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 TYPICAL OPERATING PERFORMANCE See Figure 1 for a 1-cell application test circuit schematic and Figure 2 for the stand-alone cells application test circuits schematic. Level [dBµV] BQ2412X Typical Radiated EMI Performance on EVM 60 VIN = 16 V 50 ICHARGE = 1 A 40 30 20 10 0 -10 30M 50M 70M 100M Frequency [Hz] 200M 300M 500M 700M 1G MES bq2412x_16v_1.0A Figure 4. Typical Radiated EMI Performance Measured on EVM 100 100 VI = 5 V 90 Efficiency - % Efficiency - % 90 VI = 9 V Vbat = 8.4 V Vbat = 4.2 V 80 VI = 16 V 70 60 VI = 16 V 80 70 60 50 50 0 1 Charge Current Ibat - A Figure 5. Efficiency 1-Cell 2 0 1 Charge Current Ibat - A 2 Figure 6. Efficiency 2-Cells Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 9 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 CH3 1.38 A CH3 200 mA/div CH3 = Inductor Current CH1 = BAT CH1 2 V/div CH1 3.8 V CH2 = OUT CH2 5 V/div CH2 9V t = Time = 400 ns/div Figure 7. Switching Waveforms in Fast Charge Mode CH3 = Inductor Current CH3 500 mA CH3 500 mA/div CH1 = BAT CH1 8.4 V CH1 5 V/div CH2 = OUT CH2 16 V CH2 10 V/div t - Time = 400 ns/div Figure 8. Switching Waveforms in Voltage Regulation Mode 10 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 CH1 = BAT CH1 2 V/div CH1 4.2 V CH3 = Inductor Current CH3 200 mA/div CH3 480 mA CH2 = OUT CH2 5V CH2 2 V/div 20 ns 35 ns t = Time = 50 ns/div Figure 9. Dead Time CH1 = BAT CH1 3.8 V CH1 2 V/div CH3 = Inductor Current CH3 1.3 A CH2 = OUT CH2 5V CH3 500 mA/div CH2 5 V/div t = Time = 1 ms/div Figure 10. Soft Start Waveforms Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 11 12 Submit Documentation Feedback Product Folder Link(s): bq24120 bq24123 bq24125 VCC Term & Timer Disable VCC VTSB VCC VSS TTC STAT2 STAT1 CE PG VTSB VCC IN IN 0.5V 1V 0.25V TERM OVP Charge *Patent Pending #36889 TIMER FF CHAIN PRE-CHG TIMEOUT TIMER CLK DSABL_TERM PRE-CHARGE W AKE DISCHARGE (STATE MACHINE) CONTROL LOGIC TG MOD SYNCH SLEEP SYNCH PkILim VSHORT BA T_PRS_ disch LowV T erm_Det Vrch UVLO/ POR SUSPEND TIMEOUT OVP FAST CHG TIMEOUT RESET PkILim MOD 6V VCC-6V VCC V(150 mA) Isynch Vovp VSHORT Q S Q R I 2.1V BAT VCC + - SNS+ 1V TS SPIN SUSPEND FASTCHG Disable BA T 20uA VCC + - TCO HTF LTF 30ms dgltch PRE-CHG Disable 0.1V TEMP SUSPEND 0.1V SNS + 1k - + - 2.1V FASTCHG Disable 1V Vbat Reg + - Ibat Reg + - TERM SLEEP SUSPEND 20uA VCC VCC RAMP (Vpp=VCC/10) VCC RAMP OSC VCC/10 COMPENSA TION Discharge 30ms Dgltch BA T_PRS_dischg LowV + BG * Synch Gate Drive TG Charge Wake Vrch 30ms Dgltch Vreg BA T CLAMP PkILim or OVP TIMEOUT F AUL T SUSPEND TERM UVLO/POR OVP BG Sense FET 1C 2C FB SPIN BAT 1k T erm_Det VTSB + - 10 Co 10 F H Lo TS ISET2 ISET1 VTSB RSET2 RSET1 CELLS (bq24123) FB (bq24125) N/C (bq24120) BAT SNS PGND PGND OUT OUT FB VTSB Rsns to FB FB SPIN ONL Y Temp Pack- + Pack+ SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 bq2410x CE CHARGE 50 mV BA T Icntrl V(3.6A) Sense FET VCC-6V VCC PG VCC Poff 2.1V 0.75V SLEEP VCC-6V bqSWITCHER VCC VTSB Voltage Reference Vuvlo UVLO/POR POR CHARGE SLEEP + - VIN Protection PMOS FET is OFF when not charging or in SLEEP to prevent discharge of battery when IN < BAT bq24120 bq24123 bq24125 www.ti.com FUNCTIONAL BLOCK DIAGRAM Copyright © 2006–2007, Texas Instruments Incorporated bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 OPERATIONAL FLOW CHART POR Check for battery Presence Battery Detected? No Indicate BATTERY ABSENT Yes Suspend charge TS pin in LTF to HTF range? No Indicate CHARGE SUSPEND Yes VBAT <VLOWV Yes Regulate IPRECHG Reset and Start T30min timer Indicate ChargeIn-Progress No Suspend charge Reset and Start FSTCHG timer TS pin in LTF to TCO range? Regulate Current or Voltage Yes No Indicate CHARGE SUSPEND No TS pin in LTF to HTF range? Indicate ChargeIn-Progress No V BAT <V LOWV Suspend charge TS pin in LTF to TCO range? No Yes Yes Indicate CHARGE SUSPEND Yes No T30min Expired? TS pin in LTF to HTF range? FSTCHG timer Expired? No Yes No - Fault Condition - Enable I DETECT No Indicate Fault Yes Yes No V BAT <VLOWV Yes V BAT > VOREG - VRCH ? No No VBAT > VOREG V RCH ? ITERM detection? Yes - Disable I DETECT Indicate Fault Yes Yes - Fault Condition - Turn off charge - Enable I DISCHG2 for tDISCHG2 Indicate Fault No Indicate ChargeIn-Progress Battery Replaced? VBAT< VOREG V RCH ? Charge Complete VBAT < V OREG VRCH? No Indicate DONE Yes Battery Removed Yes Indicate BATTERY ABSENT Figure 11. Operational Flow Chart Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 13 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 DETAIL DESCRIPTION The bqSWITCHER™ supports a precision Li-ion or Li-polymer charging system for single cell or two cell applications. See Figure 11 and Figure 12 for a typical charge profile. The bq2412X has enhanced EMI performance that helps minimize the number of components needed to meet the FCC-B Standard. The rise time of the OUT pin was slowed down to minimize the radiated EMI. Precharge Phase Voltage Regulation and Charge Termination Phase Current Regulation Phase Regulation V oltage Regulation Current Charge Voltage VLOW VSHORT Charge Current Precharge and Termination ISHORT UDG-04037 Precharge Timer Programmable Safety Timer Figure 12. Typical Charging Profile PWM Controller The bq2412X provides an integrated fixed 1MHz frequency voltage-mode controller with Feed-Forward function to regulate charge current or voltage. This type of controller is used to help improve line transient response, thereby simplifying the compensation network used for both continuous and discontinuous current conduction operation. The voltage and current loops are internally compensated using a Type-III compensation scheme that provides enough phase boost for stable operation, allowing the use of small ceramic capacitors with very low ESR. There is a 0.5V offset on the bottom of the PWM ramp to allow the device to operate between 0% to 100% duty cycle. The internal PWM gate drive can directly control the internal PMOS and NMOS power MOSFETs. The high-side gate voltage swings from VCC (when off), to VCC-6 (when on and VCC is greater than 6V) to help reduce the conduction losses of the converter by enhancing the gate an extra volt beyond the standard 5V. The low-side gate voltage swings from 6V, to turn on the NMOS, down to PGND to turn it off. The bq2412X has two back to back common-drain P-MOSFETs on the high side. An input P-MOSFET prevents battery discharge when IN is lower than BAT. The second P-MOSFET behaves as the switching control FET, eliminating the need of a bootstrap capacitor. 14 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Cycle-by-cycle current limit is sensed through the internal high-side sense FET. The threshold is set to a nominal 3.6A peak current. The low-side FET also has a current limit that decides if the PWM Controller will operate in synchronous or non-synchronous mode. This threshold is set to 100mA and it turns off the low-side NMOS before the current reverses, preventing the battery from discharging. Synchronous operation is used when the current of the low-side FET is greater than 100mA to minimize power losses. Temperature Qualification The bqSWITCHER continuously monitors battery temperature by measuring the voltage between the TS pin and VSS pin. A negative temperature coefficient thermistor (NTC) and an external voltage divider typically develop this voltage. The bqSWITCHER compares this voltage against its internal thresholds to determine if charging is allowed. To initiate a charge cycle, the battery temperature must be within the V(LTF)-to-V(HTF) thresholds. If battery temperature is outside of this range, the bqSWITCHER suspends charge and waits until the battery temperature is within the V(LTF)-to-V(HTF) range. During the charge cycle (both precharge and fast charge), the battery temperature must be within the V(LTF)-to-V(TCO) thresholds. If battery temperature is outside of this range, the bqSWITCHER suspends charge and waits until the battery temperature is within the V(LTF)-to-V(HTF) range. The bqSWITCHER suspends charge by turning off the PWM and holding the timer value (i.e., timers are not reset during a suspend condition). Note that the bias for the external resistor divider is provided from the VTSB output. Applying a constant voltage between the V(LTF)-to-V(HTF) thresholds to the TS pin disables the temperature-sensing feature. V O(VTSB) RT2 + ǒ V RTH HOT V O(VTSB) V RT1 + LTF RTH COLD O(VTSB) V HTF RTH HOT Ǔ *1 ƪ 1 V LTF ǒ V * RTH COLD * 1 V HTF ƫ O(VTSB) V LTF Ǔ *1 *1 1 ) 1 RT2 RTH COLD (1) VCC Charge Suspend Charge Suspend V(LTF) V(HTF) V(TCO) Temperature Range to Initiate Charge Charge Suspend Temperature Range During Charge Cycle Charge Suspend VSS Figure 13. TS Pin Thresholds Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 15 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Battery Preconditioning (Precharge) On power up, if the battery voltage is below the VLOWV threshold, the bqSWITCHER applies a precharge current, IPRECHG, to the battery. This feature revives deeply discharged cells. The bqSWITCHER activates a safety timer, tPRECHG, during the conditioning phase. If the VLOWV threshold is not reached within the timer period, the bqSWITCHER turns off the charger and enunciates FAULT on the STATx pins. In the case of a FAULT condition, the bqSWITCHER reduces the current to IDETECT. IDETECT is used to detect a battery replacement condition. Fault condition is cleared by POR or battery replacement. The magnitude of the precharge current, IO(PRECHG), is determined by the value of programming resistor, R(ISET2), connected to the ISET2 pin. K (ISET2) V (ISET2) I O(PRECHG) + ǒR(ISET2) R(SNS)Ǔ (2) where RSNS is the external current-sense resistor V(ISET2) is the output voltage of the ISET2 pin K(ISET2) is the V/A gain factor V(ISET2) and K(ISET2) are specified in the Electrical Characteristics table. Battery Charge Current The battery charge current, IO(CHARGE), is established by setting the external sense resistor, R(SNS), and the resistor, R(ISET1), connected to the ISET1 pin. In order to set the current, first choose R(SNS) based on the regulation threshold VIREG across this resistor. The best accuracy is achieved whe the VIREG is between 100mV and 200mV. V IREG R (SNS) + I OCHARGE (3) If the results is not a standard sense resistor value, choose the next larger value. Using the selected standard value, solve for VIREG. Once the sense resistor is selected, the ISET1 resistor can be calculated using the following equation: K V ISET1 R ISET1 + ISET1 RSNS I CHARGE (4) Battery Voltage Regulation The voltage regulation feedback occurs through the BAT pin. This input is tied directly to the positive side of the battery pack. The bqSWITCHER monitors the battery-pack voltage between the BAT and VSS pins. The bqSWITCHER is offered in a fixed single-cell voltage version (4.2 V) and as a one-cell or two-cell version selected by the CELLS input. A low or floating input on the CELLS selects single-cell mode (4.2 V) while a high-input through a resistor selects two-cell mode (8.4 V). Charge Termination and Recharge The bqSWITCHER monitors the charging current during the voltage regulation phase. Once the termination threshold, ITERM, is detected, the bqSWITCHER terminates charge. The termination current level is selected by the value of programming resistor, R(ISET2), connected to the ISET2 pin. K (ISET2) V TERM I TERM + ǒR(ISET2) R(SNS)Ǔ (5) 16 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 where R(SNS) is the external current-sense resistor VTERM is the output of the ISET2 pin K(ISET2) is the A/V gain factor VTERM and K(ISET2) are specified in the Electrical Characteristics table As a safety backup, the bqSWITCHER also provides a programmable charge timer. The charge time is programmed by the value of a capacitor connected between the TTC pin and GND by the following formula: t CHARGE + C(TTC) K(TTC) (6) where C(TTC) is the capacitor connected to the TTC pin K(TTC) is the multiplier A • • • • new charge cycle is initiated when one of the following conditions is detected: The battery voltage falls below the VRCH threshold. Power-on reset (POR), if battery voltage is below the VRCH threshold CE toggle TTC pin, described as follows. In order to disable the charge termination and safety timer, the user can pull the TTC input below the VTTC_EN threshold. Going above this threshold enables the termination and safety timer features and also resets the timer. Tying TTC high disables the safety timer only. Sleep Mode The bqSWITCHER enters the low-power sleep mode if the VCC pin is removed from the circuit. This feature prevents draining the battery during the absence of VCC. Charge Status Outputs The open-drain STAT1 and STAT2 outputs indicate various charger operations as shown in Table 1. These status pins can be used to drive LEDs or communicate to the host processor. Note that OFF indicates that the open-drain transistor is turned off. Table 1. Status Pins Summary Charge State STAT1 STAT2 Charge-in-progress ON OFF Charge complete OFF ON Charge suspend, timer fault, overvoltage, sleep mode, battery absent OFF OFF PG Output The open-drain PG (power good) indicates when the AC-to-DC adapter (i.e., VCC) is present. The output turns on when sleep-mode exit threshold, VSLP-EXIT, is detected. This output is turned off in the sleep mode. The PG pin can be used to drive an LED or communicate to the host processor. CE Input (Charge Enable) The CE digital input is used to disable or enable the charge process. A low-level signal on this pin enables the charge and a high-level VCC signal disables the charge. A high-to-low transition on this pin also resets all timers and fault conditions. Note that the CE pin should not be tied to VTSB. This may create power-up issues. Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 17 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Timer Fault Recovery As shown in Figure 11, bqSWITCHER provides a recovery method to deal with timer fault conditions. The following summarizes this method. Condition 1 VI(BAT) above recharge threshold (VOREG - VRCH) and timeout fault occurs. Recovery method: bqSWITCHER waits for the battery voltage to fall below the recharge threshold. This could happen as a result of a load on the battery, self-discharge or battery removal. Once the battery falls below the recharge threshold, the bqSWITCHER clears the fault and enters the battery absent detection routine. A POR or CE toggle also clears the fault. Condition 2 Charge voltage below recharge threshold (VOREG – VRCH) and timeout fault occurs Recovery method: Under this scenario, the bqSWITCHER applies the IDETECT current. This small current is used to detect a battery removal condition and remains on as long as the battery voltage stays below the recharge threshold. If the battery voltage goes above the recharge threshold, then the bqSWITCHER disables the IDETECT current and executes the recovery method described in Condition 1. Once the battery falls below the recharge threshold, the bqSWITCHER clears the fault and enters the battery absent detection routine. A POR or CE toggle also clears the fault. Output Overvoltage Protection (Applies To All Versions) The bqSWITCHER provides a built-in overvoltage protection to protect the device and other components against damages if the battery voltage gets too high, as when the battery is suddenly removed. When an overvoltage condition is detected, this feature turns off the PWM and STATx pins. The fault is cleared once VIBAT drops to the recharge threshold (VOREG - VRCH). Inductor, Capacitor, and Sense Resistor Selection Guidelines The bqSWITCHER provides internal loop compensation. With this scheme, best stability occurs when LC resonant frequency, fo is approximately 16 kHz (8 kHz to 32 kHz). Equation 7 can be used to calculate the value of the output inductor and capacitor. Table 2 provides a summary of typical component values for various charge rates. 1 f0 + Ǹ 2p L OUT C OUT (7) Table 2. Output Components Summary CHARGE CURRENT 0.5 A 1A Output inductor, LOUT 22 µH 10 µH 4.7 µH Output capacitor, COUT 4.7 µF 10 µF 22 µF (or 2 × 10 µH) ceramic Sense resistor, R(SNS) 0.2 Ω 0.1 Ω 0.05 Ω 18 Submit Documentation Feedback 2A Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Battery Detection For applications with removable battery packs, bqSWITCHER provides a battery absent detection scheme to reliably detect insertion and/or removal of battery packs. POR or VRCH Detection routine runs on power up and if VBAT drops below refresh threshold due to removing battery or discharging battery. Yes Enable I(DETECT) for t(DETECT) VI(BAT)<V(SHORT) No BATTERY PRESENT, Begin Charge No BATTERY PRESENT, Begin Charge Yes Apply I(WAKE) for t(WAKE) VI(BAT) > VO(REG) −VRCH Yes BATTERY ABSENT Figure 14. Battery Detection for bq2412x ICs The voltage at the BAT pin is held above the battery recharge threshold, VOREG – VRCH, by the charged battery following fast charging. When the voltage at the BAT pin falls to the recharge threshold, either by a load on the battery or due to battery removal, the bqSWITCHER begins a battery absent detection test. This test involves enabling a detection current, IDISCHARGE1, for a period of tDISCHARGE1 and checking to see if the battery voltage is below the short circuit threshold, VSHORT. Following this, the wake current, IWAKE is applied for a period of tWAKE and the battery voltage is checked again to ensure that it is above the recharge threshold. The purpose of this current is to attempt to close an open battery pack protector, if one is connected to the bqSWITCHER. Passing both of the discharge and charge tests indicates a battery absent fault at the STAT pins. Failure of either test starts a new charge cycle. For the absent battery condition, typically the voltage on the BAT pin rises and falls between 0V and VOVPthresholds indefinitely. Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 19 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 VBAT Battery Connected VOREG No Battery Detected 2V/cell No Battery Detected Yes Battery Detected IWAKE IBAT - IDISCHRG1 t DISCHRG1 tWAKE t DISCHRG1 Figure 15. Battery Detect Timing Diagram Battery Detection Example In order to detect a no battery condition during the discharge and wake tests, the maximum output capacitance should not exceed the following: a. Discharge (IDISCHRG1 = 400 µA, tDISCHRG1 = 1s, VSHORT = 2V) I t DISCHRG1 C MAX_DIS + DISCHRG1 V OREG * V SHORT C MAX_DIS + 400 mA 1s 4.2 V * 2 V C MAX_DIS + 182 mF (8) b. Wake (IWAKE = 2 mA, tWAKE = 0.5 s, VOREG – VRCH = 4.1V) I WAKE t WAKE C MAX_WAKE + VOREG * VRCH * 0 V ǒ C MAX_WAKE + Ǔ 2 mA 0.5s (4.2 V * 0.1 V) * 0V C MAX_WAKE + 244 mF (9) Based on these calculations the recommended maximum output capacitance to ensure proper operation of the battery detection scheme is 100 µF which will allow for process and temperature variations. Figure 16 shows the battery detection scheme when a battery is inserted. Channel 3 is the output signal and Channel 4 is the output current. The output signal switches between VOREG and GND until a battery is inserted. Once the battery is detected, the output current increases from 0A to 1.3A, which is the programmed charge current for this application. 20 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Figure 16. Battery Detection Waveform When a Battery is Inserted Figure 17 shows the Battery Detection scheme when a battery is removed. Channel 3 is the output signal and Channel 4 is the output current. When the battery is removed, the output signal goes up due to the stored energy in the inductor and it crosses the VOREG – VRCH threshold. At this point the output current goes to 0A and the IC terminates the charge process and turns on the IDISCHG2 for tDISCHG2. This causes the output voltage to fall down below the VOREG – VRCHG threshold triggering a Battery Absent condition and starting the Battery Detection scheme. Figure 17. Battery Detection Waveform When a Battery is Removed Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 21 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Current Sense Amplifier BQ2412X family offers a current sense amplifier feature that translates the charge current into a DC voltage. Figure 18 is a block diagram of this feature. OUT ICHARGE SNS RSNS + KISET2 BAT + - + FASTCHG Disable ISET2 RISET2 Figure 18. Current Sense Amplifer The voltage on the ISET2 pin can be used to calculate the charge current. Equation 10 shows the relationship between the ISET2 voltage and the charge current: VISET2 K(ISET2) I CHARGE + R SNS R ISET2 (10) This feature can be used to monitor the charge current during the current regulation phase (Fastcharge only) and the voltage regulation phase. The schematics for the application circuit for this waveform is shown in Figure 2 CH3 = Inductor Current CH3 500 mA/div CH1 = ISET2 CH3 0A CH1 200 mV/div CH1 0V CH2 16 V CH2 = OUT CH2 10 V/div t = Time = 200 ms/div Figure 19. Current Sense Amplifier 22 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 SYSTEM DESIGN EXAMPLE AND APPLICATIONS INFORMATION The following section provides a detailed system design example for the bq24120. System Design Specifications: • • • • • • • 1. VIN = 16V VBAT = 4.2V (1-Cell) ICHARGE = 1.33 A IPRECHARGE = ITERM = 133 mA Safety Timer = 5.0 hours Inductor Ripple Current = 30% of Fast Charge Current Initiate Charge Temperature = 0°C to 45°C Determine the inductor value (LOUT) for the specified charge current ripple: DI L + I CHARGE I CHARGERipple L OUT + L OUT + ǒVINMAX * VBATǓ VBAT ƒ V INMAX DI L 4.2 (16 * 4.2) (1.1 106) (1.33 16 0.3) L OUT + 7.06 mH (11) Set the output inductor to standard 10 µH. Calculate the total ripple current with using the 10 µH inductor: DI L + DI L + ǒVINMAX * VBATǓ VBAT ƒ V INMAX 16 LOUT 4.2 (16 * 4.2) (1.1 106) (10 10 *6) DI L + 0.282 A (12) Calculate the maximum output current (peak current): DI I LPK + I OUT ) L 2 I LPK + 1.33 ) 0.282 2 I LPK + 1.471 A (13) Use standard 10 µH inductor with a saturation current higher than 1.471A. (i.e., Sumida CDRH74-100) 2. Determine the output capacitor value (COUT) using 16 kHz as the resonant frequency: 1 ƒo + 2p ǸLOUT COUT 1 C OUT + 4p 2 ƒo C OUT + 4p 2 (16 2 L OUT 1 10 3)2 (10 10 *6) C OUT + 9.89 mF (14) Use standard value 10 µF, 25V, X5R, ±20% ceramic capacitor (i.e., Panasonic 1206 ECJ-3YB1E106M Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 23 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 3. Determine the sense resistor using the following equation: V R SNS + RSNS I CHARGE (15) In order to get better current regulation accuracy (±10%), let VRSNS be between 100 mV and 200 mV. Use VRSNS = 100 mV and calculate the value for the sense resistor. R SNS + 100 mV 1.33 A R SNS + 0.075 W (16) This value is not standard in resistors. If this happens, then choose the next larger value which in this case is 0.1Ω. Using the same equation (15) the actual VRSNS will be 133mV. Calculate the power dissipation on the sense resistor: P RSNS + I CHARGE P RSNS + 1.332 2 R SNS 0.1 P RSNS + 176.9 mW (17) Select standard value 100 mΩ, 0.25W 0805, 1206 or 2010 size, high precision sensing resistor. (i.e., Vishay CRCW1210-0R10F) 4. Determine ISET 1 resistor using the following equation: K V ISET1 R ISET1 + ISET1 RSNS I CHARGE R ISET1 + 1000 1.0 0.1 1.33 R ISET1 + 7.5 kW (18) Select standard value 7.5 kΩ, 1/16W ±1% resistor (i.e., Vishay CRCWD0603-7501-F) 5. Determine ISET 2 resistor using the following equation: KISET2 VISET2 R ISET2 + RSNS I PRECHARGE R ISET2 + 1000 0.1 0.1 0.133 R ISET2 + 7.5 kW (19) Select standard value 7.5 kΩ, 1/16W ±1% resistor (i.e., Vishay CRCWD0603-7501-F) 6. Determine TTC capacitor (CTTC) for the 5.0 hours safety timer using the following equation: t C TTC + CHARGE K TTC C TTC + 300 m 2.6 mńnF C TTC + 115.4 nF (20) Select standard value 100 nF, 16V, X7R, ±10% ceramic capacitor (i.e., Panasonic ECJ-1VB1C104K). Using this capacitor the actual safety timer will be 4.3 hours. 7. Determine TS resistor network for an operating temperature range from 0°C to 45°C. 24 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 VTSB RT1 TS RTH RT2 103AT Figure 20. TS Resistor Network Assuming a 103AT NTC Thermistor on the battery pack, determine the values for RT1 and RT2 using the following equations: V O(VTSB) RT2 + ǒ V RTH HOT V O(VTSB) V RT1 + LTF RTH COLD O(VTSB) V HTF RTH HOT Ǔ *1 ƪ 1 V LTF ǒ V * RTH COLD * 1 V HTF O(VTSB) V LTF ƫ Ǔ *1 *1 1 ) 1 RT2 RTH COLD (21) RTH COLD + 27.28 kW RTH HOT + 4.912 kW RT1 + 9.31 kW RT2 + 442 kW (22) Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 25 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 APPLICATION INFORMATION Charging Battery and Powering System Without Affecting Battery Charge and Termination RSYS LO BQ24120 VIN CIN 1.5 KW 10 mF 1.5 KW Adapter Present 1.5 KW Done Charge 3 IN OUT 1 4 IN OUT 20 6 VCC 2 STAT1 PGND 18 PGND 17 RSNS 10 mH COUT 0.1W 10 mF Battery Pack Pack+ Pack- MMBZ18VALT1 103AT 19 STAT2 5 PG 7 TTC SNS 15 BAT 14 7.5 KW VTSB ISET1 8 7.5 KW 16 CE 9.31 KW ISET2 9 0.1 mF 10 VSS 0.1 mF 13 NC TS 12 VTSB 11 442 KW 0.1 mF 0.1 mF Figure 21. Application circuit for charging a battery and powering a system without affecting termination The bqSWITCHER was designed as a stand-alone battery charger but can be easily adapted to power a system load, while considering a few minor issues. Advantages: 1. The charger controller is based only on what current goes through the current-sense resistor (so precharge, constant current, and termination all work well), and is not affected by the system load. 2. The input voltage has been converted to a usable system voltage with good efficiency from the input. 3. Extra external FETs are not needed to switch power source to the battery. 4. The TTC pin can be grounded to disable termination and keep the converter running and the battery fully charged, or let the switcher terminate when the battery is full and then run off of the battery via the sense resistor. Other Issues: 1. If the system load current is large (≥ 1 A), the IR drop across the battery impedance causes the battery voltage to drop below the refresh threshold and start a new charge. The charger would then terminate due to low charge current. Therefore, the charger would cycle between charging and termination. If the load is smaller, the battery would have to discharge down to the refresh threshold resulting in a much slower cycling. Note that grounding the TTC pin keeps the converter on continuously. 2. If TTC is grounded, the battery is kept at 4.2 V (not much different than leaving a fully charged battery set unloaded). 3. Efficiency declines 2-3% hit when discharging through the sense resistor to the system. 26 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 Using bq24125 to charge the LiFePO4 battery The LiFePO4 battery has many unique features such as a very high thermal runaway temperature, high discharge current capability, and high charge current. These special features make it attractive in many applications such as power tools. The recommended charge voltage is 3.6 V and termination current is 50 mA. Figure 22 shows an application circuit for charging one cell LiFePO4 using bq24105. The charge voltage is 3.6 V and recharge voltage is 3.516 V. The fast charging current is set to 1.33 A while the termination current is 50 mA. This circuit can be easily changed to support two or three cell applications. However, only 84 mV difference between regulation set point and rechargeable threshold makes it frequently enter into recharge mode when small load current is applied. This can be solved by lower down the recharge voltage threshold to 200 mV to discharge more energy from the battery before it enters recharge mode again. See the application report, Using the bq24105/25 to Charge LiFePO4 Battery (SLUA443), for additional details. The recharge threshold should be selected according to real application conditions. LOUT BQ24125 VIN CIN 1.5 KW 10 mF 1.5 KW Adapter Present 1.5 KW Done 3 Charge IN OUT 1 4 IN 6 VCC 2 STAT1 PGND 18 RSNS 10 mH OUT 20 COUT D1 0.1W 10 mF 5 PG 7 TTC Pack+ Pack- MMBZ18VALT1 PGND 17 103AT (See Note) 19 STAT2 Battery Pack SNS 15 BAT 14 ISET1 8 7.5 KW RISET1 VTSB 20 KW CTTC 16 CE ISET2 9 0.1 mF 10 VSS 0.1 mF 13 FB 9.31 KW RT1 442 KW RT2 RISET2 TS 12 VTSB 11 0.1 mF 0.1 mF 143 KW 200 KW A. Zener diode not needed for bq24125. Figure 22. 1-Cell LiFePO4 Application Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 27 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 THERMAL CONSIDERATIONS Thermal Considerations The SWITCHER is packaged in a thermally enhanced MLP package. The package includes a thermal pad to provide an effective thermal contact between the IC and the printed circuit board (PCB). Full PCB design guidelines for this package are provided in the application report entitled: QFN/SON PCB Attachment (SLUA271). The most common measure of package thermal performance is thermal impedance (θJA) measured (or modeled) from the chip junction to the air surrounding the package surface (ambient). The mathematical expression for θJA is: T * TA q (JA) + J P (23) Where: TJ = chip junction temperature TA = ambient temperature P = device power dissipation Factors that can greatly influence the measurement and calculation of θJA include: • Whether or not the device is board mounted • Trace size, composition, thickness, and geometry • Orientation of the device (horizontal or vertical) • Volume of the ambient air surrounding the device under test and airflow • Whether or not other surfaces are in close proximity to the device being tested The device power dissipation, P, is a function of the charge rate and the voltage drop across the internal power FET. It can be calculated from the following equation: P = [Vin × lin - Vbat × Ibat] Due to the charge profile of Li-xx batteries, the maximum power dissipation is typically seen at the beginning of the charge cycle when the battery voltage is at its lowest. (See Figure 12.) 28 Submit Documentation Feedback Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 bq24120 bq24123 bq24125 www.ti.com SLUS688E – MARCH 2006 – REVISED DECEMBER 2007 PCB LAYOUT CONSIDERATION It is important to pay special attention to the PCB layout. The following provides some guidelines: • To obtain optimal performance, the power input capacitors, connected from input to PGND, should be placed as close as possible to the bqSWITCHER. The output inductor should be placed directly above the IC and the output capacitor connected between the inductor and PGND of the IC. The intent is to minimize the current path loop area from the OUT pin through the LC filter and back to the PGND pin. The sense resistor should be adjacent to the junction of the inductor and output capacitor. Route the sense leads connected across the RSNS back to the IC, close to each other (minimize loop area) or on top of each other on adjacent layers. BAT and SNS traces should be away from high di/dt traces such as the OUT pin. Use an optional capacitor downstream from the sense resistor if long (inductive) battery leads are used. • Place all small-signal components (CTTC, RSET1/2 and TS) close to their respective IC pin (do not place components such that routing interrupts power stage currents). All small control signals should be routed away from the high current paths. • The PCB should have a ground plane (return) connected directly to the return of all components through vias (3 vias per capacitor for power-stage capacitors, 3 vias for the IC PGND, 1 via per capacitor for small-signal components). A star ground design approach is typically used to keep circuit block currents isolated (high-power/low-power small-signal) which reduces noise-coupling and ground-bounce issues. A single ground plane for this design gives good results. With this small layout and a single ground plane, there is not a ground-bounce issue, and having the components segregated minimizes coupling between signals. • The high-current charge paths into IN and from the OUT pins must be sized appropriately for the maximum charge current in order to avoid voltage drops in these traces. The PGND pins should be connected to the ground plane to return current through the internal low-side FET. The thermal vias in the IC PowerPAD™ provide the return-path connection. • The bqSWITCHER is packaged in a thermally enhanced MLP package. The package includes a thermal pad to provide an effective thermal contact between the IC and the PCB. Full PCB design guidelines for this package are provided in the application report entitled: QFN/SON PCB Attachment (SLUA271). Six 10-13 mil vias are a minimum number of recommended vias, placed in the IC's power pad, connecting it to a ground thermal plane on the opposite side of the PWB. This plane must be at the same potential as VSS and PGND of this IC. • See user guide SLUU200 for an example of good layout. Copyright © 2006–2007, Texas Instruments Incorporated Product Folder Link(s): bq24120 bq24123 bq24125 Submit Documentation Feedback 29 PACKAGE OPTION ADDENDUM www.ti.com 12-Dec-2007 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty BQ24120RHLR ACTIVE QFN RHL 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24120RHLRG4 ACTIVE QFN RHL 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24120RHLT ACTIVE QFN RHL 20 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24120RHLTG4 ACTIVE QFN RHL 20 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24123RHLR ACTIVE QFN RHL 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24123RHLRG4 ACTIVE QFN RHL 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24123RHLT ACTIVE QFN RHL 20 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24123RHLTG4 ACTIVE QFN RHL 20 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24125RHLR ACTIVE QFN RHL 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR BQ24125RHLT ACTIVE QFN RHL 20 250 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 12-Dec-2007 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 BQ24120RHLR RHL 20 SITE 41 330 12 3.8 4.8 1.6 8 12 Q1 BQ24120RHLT RHL 20 SITE 41 180 12 3.8 4.8 1.6 8 12 Q1 BQ24123RHLR RHL 20 SITE 41 330 12 3.8 4.8 1.6 8 12 Q1 BQ24123RHLT RHL 20 SITE 41 180 12 3.8 4.8 1.6 8 12 Q1 BQ24125RHLR RHL 20 SITE 48 330 12 3.8 4.8 1.3 8 12 Q1 BQ24125RHLR RHL 20 SITE 41 330 12 3.8 4.8 1.6 8 12 Q1 BQ24125RHLT RHL 20 SITE 48 180 12 3.8 4.8 1.3 8 12 Q1 BQ24125RHLT RHL 20 SITE 41 180 12 3.8 4.8 1.6 8 12 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 12-Dec-2007 Device Package Pins Site Length (mm) Width (mm) BQ24120RHLR RHL 20 SITE 41 346.0 346.0 29.0 BQ24120RHLT RHL 20 SITE 41 190.0 212.7 31.75 BQ24123RHLR RHL 20 SITE 41 346.0 346.0 29.0 BQ24123RHLT RHL 20 SITE 41 190.0 212.7 31.75 BQ24125RHLR RHL 20 SITE 48 370.0 355.0 55.0 BQ24125RHLR RHL 20 SITE 41 346.0 346.0 29.0 BQ24125RHLT RHL 20 SITE 48 195.0 200.0 45.0 BQ24125RHLT RHL 20 SITE 41 190.0 212.7 31.75 Pack Materials-Page 2 Height (mm) IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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