LTC4012CUF-3-PBF

FeaTures n LTC4012-3 High Efficiency, Multi-Chemistry Battery Charger with PowerPath Control DescripTion The LTC®4012-3 is a constant-current/constant-voltage battery charger controller. It uses a synchronous quasiconstant frequency PWM control architecture that will not generate audible noise with ceramic bulk capacitors. Charge current is set by external resistors and can be monitored as an output voltage across the programming resistor. With no built-in termination, the LTC4012-3 charges a wide range of batteries under external control. The LTC4012-3 features fully adjustable output voltage. For charge management and safety, the IC includes an input P-channel MOSFET ideal diode controller, battery (output) overvoltage protection, reverse charge current protection, PWM soft-start and robust non-overlap control for an all N-channel MOSFET PWM power stage. The device includes AC adapter input current limiting, which maximizes the charge rate for a fixed input power level. An external sense resistor programs the input current limit, and the ICL status pin indicates reduced charge current as a result of AC adapter current limiting. Ideal diode control at the adaptor input improves charger efficiency. The CHRG status pin is active during all charging modes, including special indication for low charge current. General Purpose Battery Charger Controller n Efficient 550kHz Synchronous Buck PWM Topology n ±0.5% Output Float Voltage Accuracy n Programmable Charge Current: 4% Accuracy n Programmable AC Adapter Current Limit: 3% Accuracy n No Audible Noise with Ceramic Capacitors n INFET Low Loss Ideal Diode PowerPath™ Control n Wide Input Voltage Range: 6V to 28V n Wide Output Voltage Range: 2V to 28V n Indicator Outputs for Charging, C/10 Current Detection and Input Current Limiting n Analog Charge Current Monitor n Micropower Shutdown n 20-Pin 4mm × 4mm × 0.75mm QFN Package applicaTions n n n Notebook Computers Portable Instruments Battery Backup Systems L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5723970. Typical applicaTion FROM ADAPTER 13V TO 20V INFET DCIN 0.1µF CLP CLN BOOST TGATE SW INTVDD BGATE GND CSP 25m 0.1µF 5.1k 20µF POWER TO SYSTEM 100 95 0.1µF EFFICIENCY (%) 90 85 80 75 33m 70 VOUT = 12.3V RSENSE = 33m RIN = 3.01k RPROG = 26.7k 0 0.5 1 1.5 2 CHARGE CURRENT (A) PIN 5 NAME ACP X 4012-3 TA02 Efficiency at DCIN = 20V 10000 EFFICIENCY POWER LOSS (mW) CHRG TO/FROM MCU ICL SHDN ITH 6.04k 0.1µF PROG 26.7k 4.7nF POWER LOSS 1000 2µF 6.8µH 3.01k LTC4012-3 CSN BAT FBDIV VFB 3.01k 2.5 3 100 301k 32.8k 20µF + 12.3V Li-Ion BATTERY 4012-3 TA01 PART GND LTC4012 LTC4012-3 X 40123fb  LTC4012-3 absoluTe MaxiMuM raTings (Note 1) pin conFiguraTion TOP VIEW INTVDD BOOST BGATE 15 CSP 14 CSN 21 13 PROG 12 ITH 11 BAT 6 SHDN 7 CHRG 8 ICL 9 10 FBDIV VFB TGATE SW DCIN ............................................................–14V to 30V DCIN to CLP ................................................ –32V to 20V CLP, CLN or SW to GND............................. –0.3V to 30V CLP to CLN ............................................................±0.3V CSP, CSN or BAT to GND ........................... –0.3V to 28V CSP to CSN ............................................................±0.3V BOOST to GND ........................................... –0.3V to 36V BOOST to SW............................................... –0.3V to 7V SHDN or VFB to GND .................................... –0.3V to 7V CHRG or ICL to GND .................................. –0.3V to 30V Operating Temperature Range (Note 2) ............................................. –40°C to 125°C Junction Temperature (Note 3) ............................. 125°C Storage Temperature Range .................. –65°C to 150°C 20 19 18 17 16 CLN 1 CLP 2 INFET 3 DCIN 4 GND 5 UF PACKAGE 20-LEAD (4mm 4mm) PLASTIC QFN TJMAX = 125°C, JA = 37°C/W EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB orDer inForMaTion LEAD FREE FINISH LTC4012CUF-3#PBF LTC4012IUF-3#PBF TAPE AND REEL LTC4012CUF-3#TRPBF LTC4012IUF-3#TRPBF PART MARKING* 40123 40123 PACKAGE DESCRIPTION 20-Lead (4mm × 4mm) Plastic QFN 20-Lead (4mm × 4mm) Plastic QFN TEMPERATURE RANGE 0°C to 85°C –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 40123fb  LTC4012-3 elecTrical characTerisTics SYMBOL VTOL IVFB RON ILEAK-FBDIV VBOV ITOL PARAMETER VBAT Accuracy (See Test Circuits) VFB Input Bias Current FBDIV On Resistance FBDIV Output Leakage Current VFB Overvoltage Threshold Charge Current Accuracy with RIN = 3.01k, 6V < BAT < 18V RPROG = 26.7k C-Grade I-Grade VSENSE = 0mV, PROG = 1.2V AI VCS-MAX VC10 VREV VCL ICLN VICL CLP Supply OVR VUVLO VUV(HYST) ICLPO Shutdown VIL VIH RIN ICLPS ILEAK-BAT ILEAK-CSN ILEAK-CSP ILEAK-SW SHDN Input Voltage Low SHDN Input Voltage High SHDN Pull-Down Resistance CLP Shutdown Current BAT Leakage Current CSN Leakage Current CSP Leakage Current SW Leakage Current CLP = 12V, DCIN = 0V SHDN = 0V SHDN = 0V or DCIN = 0V, 0V ≤ CSP = CSN = BAT ≤ 18V SHDN = 0V or DCIN = 0V, 0V ≤ CSP = CSN = BAT ≤ 20V SHDN = 0V or DCIN = 0V, 0V ≤ CSP = CSN = BAT ≤ 20V SHDN = 0V or DCIN = 0V, 0V ≤ SW ≤ 20V l l l l l l l The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. DCIN = 20V, BAT = 12V, GND = 0V unless otherwise noted. (Note 2) CONDITIONS l l MIN –0.5 –0.8 –1.0 TYP MAX 0.5 0.8 1.0 UNITS % % % nA Ω µA V % % % µA µA mV mV mV mV mV mV mV mV nA mV V V mV mA mV V kΩ Charge Voltage Regulation C-Grade I-Grade VFB = 1.2V ILOAD = 100µA SHDN = 0V, FBDIV = 0V l l l ±20 85 –1 1.235 –4 –5 –9.5 –12.75 –1.78 l l l 190 1 1.32 4 5 9.5 0 1.281 Charge Current Regulation l l –11.67 –1.66 195 325 400 253 100 100 ±100 –10.95 –1.54 250 265 430 460 295 103 104 108 –2 28 Current Sense Amplifier Gain (PROG ∆I) with RIN = 3.01k, 6V < BAT < 18V Maximum Peak Current Sense Threshold Voltage per Cycle (RIN = 3.01k) C/10 Indicator Threshold Voltage Reverse Current Threshold Voltage Current Limit Threshold VSENSE Step from 0mV to 5mV, PROG = 1.2V ITH = 2V, C-Grade ITH = 2V, I-Grade ITH = 5V PROG Falling PROG Falling CLP – CLN C-Grade I-Grade CLN = CLP (CLP – CLN) – VCL l l 140 125 340 180 97 96 92 –8 6 Input Current Regulation CLN Input Bias Current ICL Indicator Threshold Operating Voltage Range CLP Undervoltage Lockout Threshold UVLO Threshold Hysteresis CLP Operating Current –5 CLP Increasing CLP = 20V, No Gate Loads l 4.65 4.85 200 2 5.25 3 300 1.4 40 15 350 –1.5 –1.5 –1.5 –1 0 0 0 0 26 500 1.5 1.5 1.5 2 µA µA µA µA µA µA 40123fb  LTC4012-3 elecTrical characTerisTics SYMBOL INTVDD ∆VDD IDD VACP IITH fTYP fMIN DCMAX tR-TG tF-TG tR-BG tF-BG tNO IDCIN VFTO VFR VRTO VOL(INFET) VOH(INFET) tIF(ON) tIF(OFF) VOL ILEAK IC10 PARAMETER Output Voltage Load Regulation Short-Circuit Current (Note 5) AC Present Charge Enable Threshold Voltage INTVDD Regulator No Load IDD = 20mA INTVDD = 0V DCIN – BAT, DCIN Rising C-Grade I-Grade ITH = 1.4V 467 CLOAD = 3.3nF CLOAD = 3.3nF CLOAD = 3.3nF, 10% – 90% CLOAD = 3.3nF, 90% – 10% CLOAD = 3.3nF, 10% – 90% CLOAD = 3.3nF, 90% – 10% CLOAD = 3.3nF, 10% – 10% 0V ≤ DCIN ≤ CLP DCIN-CLP, DCIN Rising DCIN-CLP DCIN-CLP DCIN Falling , DCIN-CLP = 0.1V, IINFET =1µA DCIN-CLP = –0.1V, IINFET = –5µA To CLP-INFET > 3V, CINFET = 1nF To CLP-INFET < 1.5V, CINFET = 1nF ILOAD = 100µA, PROG = 1.2V SHDN = 0V, DCIN = 0V, VOUT = 20V CHRG = 2.5V l l l l l l l l l The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. DCIN = 20V, BAT = 12V, GND = 0V unless otherwise noted. (Note 2) CONDITIONS MIN 4.85 50 TYP 5 –0.4 85 MAX 5.15 –1 130 UNITS V % mA Switching Regulator 350 300 500 –40/+90 550 25 99 60 50 60 60 110 –10 15 15 –45 –6.5 –250 85 2.5 25 –25 60 60 35 –15 –5 250 180 6 500 –10 15 25 10 38 110 110 110 110 633 20 98 650 700 mV mV µA kHz kHz % ns ns ns ns ns µA mV mV mV V mV µs µs mV µA µA ITH Current Typical Switching Frequency Minimum Switching Frequency Maximum Duty Cycle TGATE Rise Time TGATE Fall Time BGATE Rise Time BGATE Fall Time TGATE, BGATE Non-Overlap Time DCIN Input Current Forward Turn-On Voltage (DCIN Detection Threshold) Forward Regulation Voltage Reverse Turn-Off Voltage INFET Output Low Voltage, Relative to CLP INFET Output High Voltage, Relative to CLP INFET Turn-On Time INFET Turn-Off Time Output Voltage Low Output Leakage CHRG C/10 Current Sink PowerPath Control Indicator Outputs Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC4012C-3 is guaranteed to meet performance specifications over the 0°C to 85°C operating temperature range. The LTC4012I-3 is guaranteed to meet performance specifications over the –40°C to 125°C operating temperature range. Note 3: Operating junction temperature TJ (in °C) is calculated from the ambient temperature TA and the total continuous package power dissipation PD (in watts) by the formula TJ = TA + (θJA • PD). Refer to the Applications Information section for details. Note 4: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to GND, unless otherwise specified. Note 5: Output current may be limited by internal power dissipation. Refer to the Applications Information section for details. 40123fb  LTC4012-3 (TA = 25°C unless otherwise noted. L = IHLP-2525 6.8µH) Efficiency at DCIN = 20V, BAT = 8V 100 RSENSE = 33m RIN = 3.01k 10000 100 RSENSE = 33m RIN = 3.01k 95 POWER LOSS(mW) EFFICIENCY 90 POWER LOSS 1000 EFFICIENCY (%) EFFICIENCY POWER LOSS(mW) Typical perForMance characTerisTics Efficiency at DCIN = 20V, BAT = 12V 10000 95 EFFICIENCY (%) 90 POWER LOSS 1000 85 85 80 0 0.5 1 1.5 2 CHARGE CURRENT (A) 2.5 3 100 80 0 0.5 4012-3 G01 1 1.5 2 CHARGE CURRENT (A) 2.5 3 100 4012-3 G02 Efficiency at DCIN = 20V, BAT = 16V 100 EFFICIENCY 95 POWER LOSS(mW) EFFICIENCY (%) VFB ERROR (%) 10000 0.10 0.08 0.06 0.04 0.02 0 –0.02 –0.04 –0.06 –0.08 3 100 –0.10 VFB Line Regulation LTC4012-3 TEST CIRCUIT 90 POWER LOSS 1000 85 RSENSE = 33m RIN = 3.01k 80 0 0.5 1 1.5 2 CHARGE CURRENT (A) 2.5 5 10 4012-3 G03 20 15 CLP (V) 25 30 4012-3 G04 FBDIV Pin RON vs Battery Voltage 300 275 250 225 RON ( ) 200 175 150 125 100 75 0 5 15 10 BAT (V) 20 25 4012-3 G05 Battery Load Dump BATTERY VOLTAGE (500mV/DIV) 2A 12.1V 1A 3A RECONNECT DISCONNECT TIME (1ms/DIV) CLP = 20V VOUT = 12.3V 4012-3 G06 CLP = BAT + 3V (CLP ≥ 6V) 1A LOAD STATE 40123fb  LTC4012-3 (TA = 25°C unless otherwise noted. L = IHLP-2525 6.8µH) Charge Current Accuracy 2 1 CHARGE CURRENT ERROR (%) CHARGE CURRENT ERROR (%) 0 –1 –2 –3 –4 –5 –6 0 2 4 6 RSENSE = 33m RIN = 3.01k 8 10 12 14 16 18 20 22 24 BAT (V) 4012-3 G07 Typical perForMance characTerisTics Charge Current Line Regulation 0.5 0.4 0.3 0.2 0.1 0 –0.1 –0.2 –0.3 –0.4 –0.5 5 10 15 DCIN (V) 20 25 4012-3 G08 BAT = 6V RSENSE = 33m RIN = 3.01k ICHG = 1A DCIN = 24V RPROG = 35.7k DCIN = 12V RPROG = 26.7k ICHG = 2A ICHG = 3A Charge Current Load Regulation 3.5 3.0 CHARGE CURRENT (A) 2.5 CURRENT (A) 2.0 1.5 1.0 0.5 0 DCIN = 20V RSENSE = 33m RIN = 3.01k 11.4 11.8 12.2 BAT (V) 12.6 13.0 4012-3 G09 Input Current Limit 3.0 2.5 2.0 IIN ICHG ICHG = 3A ICHG = 2A 1.5 1.0 0.5 0 –0.5 –1.0 0 0.5 ICHG = 1A 2.5A BULK CHARGE 2.1A INPUT CURRENT LIMIT ICL STATE 1.0 1.5 SYSTEM LOAD (A) 2.0 2.5 4012-3 G10 –0.5 11.0 PWM Soft-Start EXTERNAL FET DRIVE (1V/DIV) ICHG 2A/DIV ITH 1V/DIV PROG 1V/DIV SHDN 5V/DIV TIME (500µs/DIV) 4012-3 G11 Gate Drive Non-Overlap BGATE TGATE 4012-3 G12 TIME (80ns/DIV) 40123fb  LTC4012-3 Typical perForMance characTerisTics (TA = 25°C unless otherwise noted. L = IHLP-2525 6.8µH) PWM Frequency vs Duty Cycle 600 500 PWM FREQUENCY (kHz) PWM FREQUENCY (kHz) 400 300 200 100 0 CLP = 6V CLP = 12V CLP = 20V CLP = 25V 0 20 40 60 DUTY CYCLE (%) 80 100 4012-3 G13 PWM Frequency vs Charge Current 600 500 400 300 200 100 0 BAT = 14.5V CLP = 15V RSENSE = 33m RIN = 3.01k BAT = 5V BAT = 12V ICHG = 750mA 0 0.5 1.0 1.5 2.0 CHARGE CURRENT (A) 2.5 3.0 4012-3 G14 Battery Shutdown Current 25 DC1256-CLASS APPLICATION DCIN = 0V LTC4012-3, ALL PINS DCIN = 0V LTC4012-3, BAT PINS DCIN = 20V 0 5 20 10 15 BATTERY VOLTAGE (V) 25 4012-3 G15 INFET Response Time to DCIN Short to Ground VGS = 0V PFET VGS (1V/DIV) IDCIN, REVERSE (5A/DIV) 0A TIME (1µs/DIV) 4012-3 G16 BATTERY CURRENT (µA) 20 15 10 5 0 DCIN = 15V INFET = Si7423DN IOUT = < 50mA VOUT = 12.3V COUT = 0.27F 40123fb  LTC4012-3 pin FuncTions CLN (Pin 1): Adapter Input Current Limit Negative Input. The LTC4012-3 senses voltage on this pin to determine if less charge current should be sourced to limit total input current. The threshold is set 100mV below the CLP pin. An external filter should be used to remove switching noise. This input should be tied to CLP if not used. Operating voltage range is (CLP – 110mV) to CLP. CLP (Pin 2): Adapter Input Current Limit Positive Input. The LTC4012-3 also draws power from this pin, including a small amount for some shutdown functions. Operating voltage range is GND to 28V. INFET (Pin 3): PowerPath Control Output. This output drives the gate of a PMOS pass transistor connected between the DC input (DCIN) and the raw system supply rail (CLP) to maintain a forward voltage of 25mV when a DC input source is present. INFET is internally clamped about 6V below CLP. Maximum operating voltage is CLP, which is used to turn off the input PMOS transistor when the DC input is removed. DCIN (Pin 4): DC Sense Input. One of two voltage sense inputs to the internal PowerPath controller (the other input to the controller is CLP). This input is usually supplied from an input DC power source. Operating voltage ranges from GND to 28.2V. GND (Pin 5): Ground. Internally connected to the Exposed Pad (package paddle). SHDN (Pin 6): Active-Low Shutdown Input. Driving SHDN below 300mV unconditionally forces the LTC4012-3 into the shutdown state. This input has a 40kΩ internal pull-down to GND. Operating voltage range is GND to INTVDD. CHRG (Pin 7): Active-Low Charge Indicator Output. This open-drain output provides three levels of information about charge status using a strong pull-down, 25µA weak pull-down or high impedance. Refer to the Operation and Applications Information sections for further details. This output should be left floating if not used. ICL (Pin 8): Active-Low Input Current Limit Indicator Output. This open-drain output pulls to GND when the charge current is reduced because of AC adapter input current limiting. This output should be left floating if not used. VFB (Pin 9): Battery Voltage Feedback Input. An external resistor divider between FBDIV and GND with the center tap connected to VFB programs the charger output voltage. In constant voltage mode, this pin is nominally at 1.2085V. Refer to the Applications Information section for complete details on programming battery voltage. Operating voltage range is GND to 1.25V. FBDIV (Pin 10): Battery Voltage Feedback Resistor Divider Source. The LTC4012-3 connects this pin to BAT when charging is in progress. FBDIV is an open-drain PFET output to BAT with an operating voltage range of GND to BAT. BAT (Pin 11): Battery Pack Connection. The LTC4012-3 uses the voltage on this pin to control PWM operation when charging. Operating voltage range is GND to CLN. ITH (Pin 12): PWM Control Voltage and Compensation Node. The LTC4012-3 develops a voltage on this pin to control cycle-by-cycle peak inductor current. An external R-C network connected to ITH provides PWM loop compensation. Refer to the Applications Information section for further details on establishing loop stability. Operating voltage range is GND to INTVDD. PROG (Pin 13): Charge Current Programming and Monitoring Pin. An external resistance connected between PROG and GND, along with the current sense and PWM input resistors, programs the maximum charge current. The voltage on this pin can also provide a linearized indicator of charge current. Refer to the Applications Information section for complete details on current programming and monitoring. Operating voltage range is GND to INTVDD. CSN (Pin 14): Charge Current Sense Negative Input. Place an external input resistor (RIN , Figure 1) between this pin and the negative side of the charge current sense resistor. Operating voltage ranges from (BAT – 50mV) to (BAT + 200mV). CSP (Pin 15): Charge Current Sense Positive Input. Place an external input resistor (RIN , Figure 1) between this pin and the positive side of the charge current sense resistor. Operating voltage ranges from (BAT – 50mV) to (BAT + 200mV). 40123fb  LTC4012-3 pin FuncTions BGATE (Pin 16): External Synchronous NFET Gate Control Output. This output provides gate drive to an external NMOS power transistor switch used for synchronous rectification to increase efficiency in the step-down DC/DC converter. Operating voltage is GND to INTVDD. BGATE should be left floating if not used. INTVDD (Pin 17): Internal 5V Regulator Output. This pin provides a means of bypassing the internal 5V regulator used to power the LTC4012-3 PWM FET drivers. This supply shuts down when the LTC4012-3 shuts down. Refer to the Application Information section for details if additional power is drawn from this pin by the application circuit. SW (Pin 18): PWM Switch Node. The LTC4012-3 uses the voltage on this pin as the source reference for its topside NFET (PWM switch) driver. Refer to the Applications Information section for additional PCB layout suggestions related to this critical circuit node. Operating voltage range is GND to CLN. TGATE (Pin 19): External NFET Switch Gate Control Output. This output provides gate drive to an external NMOS power transistor switch used in the DC/DC converter. Operating voltage range is GND to (CLN + 5V). BOOST (Pin 20): TGATE Driver Supply Input. A bootstrap capacitor is returned to this pin from a charge network connected to SW and INTVDD. Refer to the Applications Information section for complete details on circuit topology and component values. Operating voltage ranges from (INTVDD – 1V) to (CLN + 5V). GND (Exposed Pad Pin 21): Ground. The package paddle provides a single-point ground for the internal voltage reference and other critical LTC4012-3 circuits. It should be soldered to a suitable PCB copper ground pad for proper electrical operation and to obtain the specified package thermal resistance. 40123fb  LTC4012-3 block DiagraM 4 DCIN 3 INFET – IF + 2 1 8 7 9 CLP CLN ICL CHRG VFB C/10 DETECTION INPUT CURRENT LIMIT FAULT DETECTION + CA CSP 15 + 6 SHDN SHUTDOWN CONTROL SHUTDOWN TO INTERNAL CIRCUITS CC R1 – CSN 14 – EA 5 GND TO INTERNAL CIRCUITS 11 BAT OSCILLATOR ACP CHARGE FBDIV 10 PWM LOGIC TO INTERNAL CIRCIUTS 5V REGULATOR INTVDD BGATE SW 0 + – – – 1.2085V REFERENCE PROG 13 ITH 12 BOOST TGATE 20 19 18 17 16 GND (PADDLE) 21 4012-3 BD01 40123fb LTC4012-3 TesT circuiTs LTC4012-3 FROM ICL (CLP = CLN) 1.2085V – – – + EA PROG 13 9 VFB ITH 12 1.2085V TARGET + LTC1055 – 0.6V 4012-3 TC01 40123fb  LTC4012-3 operaTion Overview The LTC4012-3 is a synchronous step-down (buck) current mode PWM battery charger controller. The maximum charge current is programmed by the combination of a charge current sense resistor (RSENSE), matched input resistors (RIN , Figure 1), and a programming resistor (RPROG) between the PROG and GND pins. Battery voltage is programmed with an external resistor divider between FBDIV and GND. In addition, the PROG pin provides a linearized voltage output of the actual charge current. The LTC4012-3 does not have built-in charge termination and is flexible enough for charging any type of battery chemistry. It is a building block IC intended for use with an external circuit, such as a microcontroller, capable of managing the entire algorithm required for the specific battery being charged. The LTC4012-3 features a shutdown input and various state indicator outputs, allowing easy and direct management by a wide range of external (digital) charge controllers. Shutdown The LTC4012-3 remains in shutdown until DCIN is greater than 5.1V and exceeds CLP by 60mV and SHDN is driven above 1.4V. In shutdown, current drain from the battery is reduced to the lowest possible level, thereby increasing standby time. When in shutdown, the ITH pin is pulled to GND and CHRG, ICL , FET gate drivers and INTVDD are all disabled. Charging can be stopped at any time by forcing SHDN below 300mV. AC Present Detection AC present is detected as soon as DCIN exceeds BAT by at least 500mV. Charging is not enabled until this condition is first met. After this event, charging is no longer gated by AC present detection. If battery voltage rises due to ESR, or DCIN droops due to current load, the PWM will remain enabled, even with very low input overhead, unless DCIN falls below the supply voltage on CLP. Input PowerPath Control The input PFET controller performs many important functions. First, it monitors DCIN and enables the charger when this input voltage is higher than the raw CLP system supply. Next, it controls the gate of an external input power PFET to maintain a low forward voltage drop when charging, creating improved efficiency. It also prevents reverse current flow through this same PFET, providing a suitable input blocking function. Finally, it helps avoid synchronous boost operation during invalid operating conditions by detecting elevated CLP voltage and forcing the charger off. If DCIN voltage is less than CLP, then DCIN must rise 60mV higher than CLP to enable the charger and activate the ideal diode control. The gate of the input PFET is driven to a voltage sufficient to regulate a forward drop between DCIN and CLP of about 25mV. If the input voltage differential drops below this point, the FET is turned off slowly. If the voltage between DCIN and CLP drops to less than –25mV, the input FET is turned off in less than 6µs to prevent significant reverse current from flowing back through the PFET, and the charger is disabled. Soft-Start Exiting the shutdown state enables the charger and releases the ITH pin. When enabled, switching will not begin until DCIN exceeds BAT by 500mV and ITH exceeds a threshold that assures initial current will be positive (about 5% to 25% of the maximum programmed current). To limit inrush current, soft-start delay is created with the compensation values used on the ITH pin. Longer soft-start times can be realized by increasing the filter capacitor on ITH, if reduced loop bandwidth is acceptable. The actual charge current at the end of soft-start will depend on which loop (current, voltage or adapter limit) is in control of the PWM. If this current is below that required by the ITH start-up threshold, the resulting charge current transient duration depends on loop compensation but is typically less than 100µs. 40123fb  LTC4012-3 operaTion LTC4012-3 WATCHDOG TIMER SYSTEM POWER TGATE PWM LOGIC 19 2 11 CLP BAT OSCILLATOR CLOCK S RD Q L1 BGATE 16 RIN RIN + + CC CA R1 CSP 15 + RSENSE VSENSE – – CSN PROG 14 13 RPROG – ICHRG CPROG EA Figure 1. PWM Circuit Diagram Bulk Charge When soft-start is complete, the LTC4012-3 begins sourcing the current programmed by the external components connected to CSP CSN and PROG. Some batteries may , require a small conditioning trickle current if they are heavily discharged. As shown in the Applications Information section, the LT4012-3 can address this need through a variety of low current circuit techniques on the PROG pin. Once a suitable cell voltage has been reached, charge current can be switched to a higher, bulk charge value. End of Charge and CHRG Output As the battery approaches the programmed output voltage, charge current will begin to decrease. The open-drain CHRG output can indicate when the current drops to 10% of its programmed full-scale value by turning off the strong pull-down (open-drain FET) and turning on a weak 25µA pull-down current. This weak pull-down state is latched until the part enters shutdown or the sensed current rises + – – – FROM ICL AMP 1.2085V VFB 9 LOOP COMPENSATION + ITH 12 4012-3 F01 to roughly C/6. C/10 indication will not be set if charge current has been reduced due to adapter input current limiting. As the charge current approaches 0A, the PWM continues to operate in full continuous mode. This avoids generation of audible noise, allowing bulk ceramic capacitors to be used in the application. Charge Current Monitoring When the LTC4012-3 is charging, the voltage on the PROG pin varies in direct proportion to the charge current. Referring to Figure 1, the nominal PROG voltage is given by: VPROG = ICHRG • RSENSE • RPROG + 11.67µA • RPROG RIN Voltage tolerance on PROG is limited by the charge current accuracy specified in the Electrical Characteristics table. Refer to the Applications Information section on programming charge current for additional details. 40123fb  LTC4012-3 operaTion Adapter Input Current Limit The LTC4012-3 can monitor and limit current from the input DC supply, which is normally an AC adapter. When the programmed adapter input current is reached, charge current is reduced to maintain the desired maximum input current. The ITH and PROG pins will reflect the reduced charge current. This limit function avoids overloading the DC input source, allowing the product to operate at the same time the battery is charging without complex load management algorithms. The battery will automatically be charged at the maximum possible rate that the adapter will support, given the application’s operating condition. The LTC4012-3 can only limit input current by reducing charge current, and in this case the charger uses nonsynchronous PWM operation to prevent boosting if the average charge current falls below about 25% of the maximum programmed current. Note that the ICL indicator output becomes active (low) at an adapter input current level just slightly less than that required for the internal amplifier to begin to assert control over the PWM loop. Charger Status Indicator Outputs The LTC4012-3 open-drain indicator outputs provide valuable information about the IC’s operating state and can be used for a variety of purposes in applications. Table 1 summarizes the state of the indicator outputs as a function of LTC4012-3 operation. ON TOP FET OFF ON BOTTOM FET OFF THRESHOLD SET BY ITH VOLTAGE 4012-3 F02 Table 1. LTC4012-3 Open-Drain Indicator Outputs CHRG Off On 25µA On 25µA ICL Off Off Off On On CHARGER STATE No DC Input (Shutdown) or Reverse Current Bulk Charge Low Current Charge or Initial DCIN – BAT 100) at 10µA levels. Low gain NPNs will increase programming errors. Q1 must be a matched NPN pair. Since RF has been reduced in value by half, the capacitor value of CF should double to 0.22µF to remain effective at filtering out any noise. If you wish to reduce RCL power dissipation for a given current limit, the programming equation becomes:  5 • 2.49k  100mV –   R1   = ILIM In many notebook applications, there are situations where two different ILIM values are needed to allow two different power adapters or power sources to be used. In such cases, start by setting RLIM for the high power ILIM configuration and then use Figure 7 to set the lower ILIM value. To toggle between the two ILIM values, take the three ground connections shown in Figure 7, combine them into one common connection and use a small-signal NFET (2N7002) to open or close that common connection to circuit ground. When the NFET is off, the circuit is defeated (floating) allowing ILIM to be the maximum value. When the NFET is on, the circuit will become active and ILIM will drop to the lower set value. Monitoring Charge Current The PROG pin voltage can be used to indicate charge current where 1.2085V indicates full programmed current (1C) and zero charge current is approximately equal to RPROG • 11.67µA. PROG voltage varies in direct proportion to the charge current between this zero-current (offset) value and 1.2085V. When monitoring the PROG pin voltage, using a buffer amplifier as shown in Figure 8 will minimize charge current errors. The buffer amplifier may be powered from the INTVDD pin or any supply that is always on when the charger is on. INTVDD 17 LTC4012-3 PROG 13 0.125 • VCLP  150mV  fPWM •  – IMAX   RSENSE  For C-grade parts, a reasonable starting point for setting ripple current is ∆IL = 0.4 • IMAX. For I-grade parts, use ∆IL = 0.2 • IMAX only if the IC will actually be used to charge batteries over the wider I-grade temperature range. The voltage compliance of internal LTC4012-3 circuits also imposes limits on ripple current. Select RIN (in Figure 1) to avoid average current errors in high ripple designs. The following equation can be used for guidance: R RSENSE • ∆IL • ∆IL ≤ RIN ≤ SENSE 50µA 20µA 40123fb  LTC4012-3 applicaTions inForMaTion RIN should not be less than 2.37k or more than 6.04k. Values of RIN greater than 3.01k may cause some reduction in programmed current accuracy. Use these equations and guidelines, as represented in Table 5, to help select the correct inductor value. This table was developed for C-grade parts to maintain maximum ∆IL near 0.6 • IMAX with fPWM at 550kHz and VBAT = 0.5 • VCLP (the point of maximum ∆IL), assuming that inductor value could also vary by 25% at IMAX. For I-grade parts, reduce maximum ∆IL to less than 0.4 • IMAX, but only if the IC will actually be used to charge batteries over the wider I-grade temperature range. In that case, a good starting point can be found by multiplying the inductor values shown in Table 5 by a factor of 1.6 and rounding up to the nearest standard value. Table 5. Minimum Typical Inductor Values VCLP 20V 20V 20V 20V L1 (Typ) ≥10µH ≥20µH ≥28µH ≥5.1µH ≥10µH ≥14µH ≥3.4µH ≥6.8µH ≥9.5µH ≥2.5µH ≥5.1µH ≥7.1µH TGATE BOOST Supply Use the external components shown in Figure 11 to develop a bootstrapped BOOST supply for the TGATE FET driver. A good set of equations governing selection of the two capacitors is: C1 = 20 • QG , C2 = 20 • C1 4.5V where QG is the rated gate charge of the top external NFET with VGS = 4.5V. The maximum average diode current is then given by: ID = QG • 665kHz To improve efficiency by increasing VGS applied to the top FET, substitute a Schottky diode with low reverse leakage for D1. PWM jitter has been observed in some designs operating at higher VIN/VOUT ratios. This jitter does not substantially affect DC charge current accuracy. A series resistor with a value of 5Ω to 20Ω can be inserted between the cathode of D1 and the BOOST pin to remove this jitter, if present. A resistor case size of 0603 or larger is recommended to lower ESL and achieve the best results. BOOST 20 LTC4012-3 INTVDD 17 SW 18 IMAX 1A 1A 1A 2A 2A 2A 3A 3A 3A 4A 4A 4A RSENSE 100mΩ 100mΩ 100mΩ 50mΩ 50mΩ 50mΩ 33mΩ 33mΩ 33mΩ 25mΩ 25mΩ 25mΩ RIN 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k 3.01k RPROG 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k 26.7k D1 1N4148 C2 2µF C1 0.1µF L1 TO RSENSE To guarantee that a chosen inductor is optimized in any given application, use the design equations provided and perform bench evaluation in the target application, particularly at duty cycles below 20% or above 80% where PWM frequency can be much less than the nominal value of 550kHz. 4012-3 F11 Figure 11. TGATE Boost Supply 40123fb  LTC4012-3 applicaTions inForMaTion FET Selection Two external power MOSFETs must be selected for use with the charger: an N-channel power switch (top FET) and an N-channel synchronous rectifier (bottom FET). Peak gate-to-source drive levels are internally set to about 5V. Consequently, logic-level FETs must be used. In addition to the fundamental DC current, selection criteria for these MOSFETs also include channel resistance RDS(ON), total gate charge QG , reverse transfer capacitance CRSS , maximum rated drain-source voltage BVDSS and switching characteristics such as td(ON/OFF). Power dissipation for each external FET is given by: PD(TOP) = VBAT • IMAX 2 • (1+ δ∆T) RDS(ON) VCLP + k • VCLP 2 • IMAX • CRSS • 665kHz PD(BOT) The synchronous (bottom) FET losses are greatest at high input voltage or during a short circuit, which forces a low side duty cycle of nearly 100%. Increasing the size of this FET lowers its losses but increases power dissipation in the LTC4012-3. Using asymmetrical FETs will normally achieve cost savings while allowing optimum efficiency. Select FETs with BVDSS that exceeds the maximum VCLP voltage that will occur. Both FETs are subjected to this level of stress during operation. Many logic-level MOSFETs are limited to 30V or less. The LTC4012-3 uses an improved adaptive TGATE and BGATE drive that is insensitive to MOSFET inertial delays, td(ON/OFF), to avoid overlap conduction losses. Switching characteristics from power MOSFET data sheets apply only to a specific test fixture, so there is no substitute for bench evaluation of external FETs in the target application. In general, MOSFETs with lower inertial delays will yield higher efficiency. Diode Selection A Schottky diode in parallel with the bottom FET and/or top FET in an LTC4012-3 application clamps SW during the non-overlap times between conduction of the top and bottom FET switches. This prevents the body diode of the MOSFETs from forward biasing and storing charge, which could reduce efficiency as much as 1%. One or both diodes can be omitted if the efficiency loss can be tolerated. A 1A Schottky is generally a good size for 3A chargers due to the low duty cycle of the non-overlap times. Larger diodes can actually result in additional efficiency (transition) losses due to larger junction capacitance. Loop Compensation and Soft-Start The three separate PWM control loops of the LTC4012-3 can be compensated by a single set of components attached between the ITH pin and GND. As shown in the typical LTC4012-3 application, a 6.04k resistor in series with a capacitor of at least 0.1µF provides adequate loop compensation for the majority of applications. (VCLP – VBAT) • IMAX 2 • (1+ δ∆T)RDS(ON) = VCLP where δ is the temperature dependency of RDS(ON), ∆T is the temperature rise above the point specified in the FET data sheet for RDS(ON) and k is a constant inversely related to the internal LTC4012-3 top gate driver. The term (1 + δ ∆T) is generally given for a MOSFET in the form of a normalized RDS(ON) curve versus temperature, but δ of 0.005/°C can be used as a suitable approximation for logic-level FETs if other data is not available. CRSS = ∆QGD /∆VDS is usually specified in the MOSFET characteristics. The constant k = 2 can be used in estimating top FET dissipation. The LTC4012-3 is designed to work best with external FET switches with a total gate charge at 5V of 15nC or less. For VCLP < 20V, high charge current efficiency generally improves with larger FETs, while for VCLP > 20V, top gate transition losses increase rapidly to the point that using a topside NFET with higher RDS(ON) but lower CRSS can actually provide higher efficiency. If the charger will be operated with a duty cycle above 85%, overall efficiency is normally improved by using a larger top FET. 40123fb  LTC4012-3 applicaTions inForMaTion The LTC4012-3 can be soft-started with the compensation capacitor on the ITH pin. At start-up, ITH will quickly rise to about 0.25V, then ramp up at a rate set by the compensation capacitor and the 40µA ITH bias current. The full programmed charge current will be reached when ITH reaches approximately 2V. With a 0.1µF capacitor, the time to reach full charge current is usually greater than 1.5ms. This capacitor can be increased if longer start-up times are required, but loop bandwidth and dynamic response will be reduced. INTVDD Regulator Output Bypass the INTVDD regulator output to GND with a low ESR X5R or X7R ceramic capacitor with a value of 0.47µF or larger. The capacitor used to build the BOOST supply (C2 in Figure 11) can serve as this bypass. Do not draw more than 30mA from this regulator for the host system, governed by IC power dissipation. Calculating IC Power Dissipation The user should ensure that the maximum rated junction temperature is not exceeded under all operating conditions. The thermal resistance of the LTC4012-3 package (θJA) is 37°C/W, provided the Exposed Pad is in good thermal contact with the PCB. The actual thermal resistance in the application will depend on forced air cooling and other heat sinking means, especially the amount of copper on the PCB to which the LTC4012-3 is attached. The following formula may be used to estimate the maximum average power dissipation, PD (in watts), of the LTC4012-3, which is dependent upon the gate charge of the external MOSFETs. This gate charge, which is a function of both gate and drain voltage swings, is determined from specifications or graphs in the manufacturer’s data sheet. For the equation below, find the gate charge for each transistor assuming 5V gate swing and a drain voltage swing equal to the maximum VCLP voltage. Maximum LTC4012-3 power dissipation under normal operating conditions is then given by: PD = DCIN(3mA + IDD + 665kHz(QTGATE + QBGATE)) – 5IDD where: IDD = Average external INTVDD load current, if any QTGATE = Gate charge of external top FET in Coulombs QBGATE = Gate charge of external bottom FET in Coulombs PCB Layout Conciderations To prevent magnetic and electrical field radiation and high frequency resonant problems, proper layout of the components connected to the LTC4012-3 is essential. Refer to Figure 12. For maximum efficiency, the switch node rise and fall times should be minimized. The following PCB design priority list will help insure proper topology. Layout the PCB using this specific order. 1. Input capacitors should be placed as close as possible to switching FET supply and ground connections with the shortest copper traces possible. The switching FETs must be on the same layer of copper as the input capacitors. Vias should not be used to make these connections. 2. Place the LTC4012-3 close to the switching FET gate terminals, keeping the connecting traces short to produce clean drive signals. This rule also applies to IC supply and ground pins that connect to the switching FET source pins. The IC can be placed on the opposite side of the PCB from the switching FETs. SWITCH NODE L1 VIN CIN HIGH FREQUENCY CIRCULATING PATH RSENSE COUT D1 VBAT + BAT ANALOG GROUND GND SWITCHING GROUND 4012 F12 SYSTEM GROUND Figure 12. High Speed Switching Path 40123fb  LTC4012-3 applicaTions inForMaTion 3. Place the inductor input as close as possible to the switching FETs. Minimize the surface area of the switch node. Make the trace width the minimum needed to support the programmed charge current. Use no copper fills or pours. Avoid running the connection on multiple copper layers in parallel. Minimize capacitance from the switch node to any other trace or plane. 4. Place the charge current sense resistor immediately adjacent to the inductor output, and orient it such that current sense traces to the LTC4012-3 are not long. These feedback traces need to be run together as a single pair with the smallest spacing possible on any given layer on which they are routed. Locate any filter component on these traces next to the LTC4012-3, and not at the sense resistor location. 5. Place output capacitors adjacent to the sense resistor output and ground. 6. Output capacitor ground connections must feed into the same copper that connects to the input capacitor ground before connecting back to system ground. 7. Connection of switching ground to system ground, or any internal ground plane, should be single-point. If the system has an internal system ground plane, a good way to do this is to cluster vias into a single star point to make the connection. 8. Route analog ground as a trace tied back to the LTC4012-3 GND pin and paddle before connecting to any other ground. Avoid using the system ground plane. A useful CAD technique is to make analog ground a separate ground net and use a 0 Ω resistor to connect analog ground to system ground. 9. A good rule of thumb for via count in a given high current path is to use 0.5A per via. Be consistent when applying this rule. 10. If possible, place all the parts listed above on the same PCB layer. 11. Copper fills or pours are good for all power connections except as noted above in Rule 3. Copper planes on multiple layers can also be used in parallel. This helps with thermal management and lowers trace inductance, which further improves EMI performance. 12. For best current programming accuracy, provide a Kelvin connection from RSENSE to CSP and CSN. See Figure 13 for an example. 13. It is important to minimize parasitic capacitance on the CSP and CSN pins. The traces connecting these pins to their respective resistors should be as short as possible. DIRECTION OF CHARGING CURRENT RSENSE 4012 F13 TO CSP RIN TO CSN RIN Figure 13. Kelvin Sensing of Charge Current 40123fb  LTC4012-3 package DescripTion (Reference LTC DWG # 05-08-1710 Rev A) UF Package 20-Lead Plastic QFN (4mm × 4mm) 0.70 ±0.05 4.50 ± 0.05 3.10 ± 0.05 2.00 REF 2.45 ± 0.05 2.45 ± 0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ± 0.10 PIN 1 TOP MARK (NOTE 6) 2.00 REF 2.45 ± 0.10 0.75 ± 0.05 R = 0.05 TYP BOTTOM VIEW—EXPOSED PAD R = 0.115 TYP PIN 1 NOTCH R = 0.20 TYP OR 0.35 45° CHAMFER 19 20 0.40 ± 0.10 1 2 4.00 ± 0.10 2.45 ± 0.10 (UF20) QFN 01-07 REV A 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING IS PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-1)—TO BE APPROVED 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.25 ± 0.05 0.50 BSC 40123fb  LTC4012-3 revision hisTory REV B DATE 3/10 DESCRIPTION I-Grade Part Added. Reflected Throughout the Data Sheet (Revision history begins at Rev B) PAGE NUMBER 1 to 28 40123fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.  LTC4012-3 Typical applicaTion 12.6V 4 Amp Charger FROM ADAPTER 15V AT 4A Q5 C1 0.1µF D1 R1 3k R 7 4 R2 10k INFET CHRG DCIN CLP CLN BOOST 3 2 1 20 19 D3 R15 0* C5 0.1µF Q2 R7 25m R8 5.1k C8 10µF D5 POWER TO SYSTEM D6 18V ZENER Q4 C4 0.1µF OR R14 100k 5 GND BULK CHARGE TGATE LTC4012-3 18 SW 17 INTVDD 8 16 ICL BGATE TO/FROM 6 MCU SHDN 21 GND 12 ITH 15 CSP C2 0.1µF R4 14 6.04k CSN 11 BAT 13 10 PROG FBDIV C3 R5 4.7nF 26.7k 9 VFB R6 Q1 53.6k D4 C6 2µF R9 3.01k R11 25m Q3 L1 4.7µH TO POWER SYSTEM LOAD WHEN ADAPTER IS NOT PRESENT, USE SCHOTTKY DIODE D5 OR THE COMBINATION OF R14, R2 D6 AND Q4 D3: CMDSH-3 D4: MBR230LSFT1 Q1: 2N7002 Q2, Q3: Si7218DN Q4, Q5: Si7423DN L1: 1HLP-2525CZER4R7M11 *: SEE TGATE BOOST SUPPLY IN APPLICATIONS INFORMATION R10 3.01k R12 294k R13 31.2k C10 10pF C9 10µF + 12.6V Li-Ion BATTERY 40123 TA03 relaTeD parTs PART NUMBER LTC4006 LTC4007 LTC4008/LTC4008-1 DESCRIPTION Small, High Efficiency, Fixed Voltage, Lithium-Ion Battery Chargers with Termination High Efficiency, Programmable Voltage, Lithium-Ion Battery Charger with Termination High Efficiency, Programmable Voltage/Current Battery Chargers High Efficiency, Multichemistry Battery Charger High Efficiency, Multi Chemistry Battery Chargers with PowerPath Control Standalone Linear NiMH/NiCd Fast Charger 2.6A Low Loss Idea Diode Low Loss PowerPath Controllers Dual 2.6A, 2.5V to 5.5V Ideal Diodes 36V, Low Loss PowerPath Controller for Large PFETs Dual Low Loss PowerPath Controllers COMMENTS Complete Charger for 3- or 4-Cell Li-Ion Batteries, AC Adapter Current Limit and Thermistor Sensor, 16-pin SSOP Package Complete Charger for 3- or 4-Cell Li-Ion Batteries, AC Adapter Current Limit, Thermistor Sensor and Indicator Outputs Constant-Current/Constant-Voltage Switching Regulator, Resistor Voltage/Current Programming, Thermistor Sensor and Indicator Outputs, AC Adapter Current Limit (Omitted on 4008-1) Constant-Current/Constant-Voltage Switching Regulator in a 20-Lead QFN Package, AC Adapter Current Limit, Indicator Outputs Constant-Current/Constant-Voltage Switching Regulator in a 20-Lead QFN Package, AC Adaptor Current Limit PFET Input Ideal Diode Control, 3 Indicator Outputs Complete NiMH/NiCd Charger in a Small 16-Pin Package, No Sense Resistor or Blocking Diode Required No External MOSFET, Automatic Switching Between DC sources, 140mΩ On Resistance in ThinSOTTM package Very Low Loss Replacement for Power Supply ORing Diodes Using Minimal External Complements, Operates up to 28V (36V for HV) Low Loss Replacement for ORing Diodes, 100mΩ On Resistance Low Loss Replacement for ORing Diodes, Operates up to 36V Low Loss Replacement for ORing Diodes, Operates up to 36V, Drives Large PFETs, Programmable, Autonomous Switching 40123fb LT 0610 REV B • PRINTED IN USA LTC4009/LTC4009-1 LTC4009-2 LTC4012/LTC4012-1 LTC4012-2 LTC4060 LTC4411 LTC4412/LTC4412HV LTC4413 LTC4414 LTC4416  Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com  LINEAR TECHNOLOGY CORPORATION 2009