LT3436 3A, 800kHz Step-Up Switching Regulator DESCRIPTIO FEATURES Constant 800kHz Switching Frequency The LT 3436 is an 800kHz monolithic boost switching Wide Operating Voltage Range: 3V to 25V regulator. A high efficiency 3A, 0.1 switch is included on High Efficiency 0.1/3A Switch the die together with all the control circuitry required to 1.2V Feedback Reference Voltage complete a high frequency, current-mode switching regu- 2% Overall Output Voltage Tolerance lator. Current-mode control provides fast transient re- Uses Low Profile Surface Mount External sponse and excellent loop stability. Components New design techniques achieve high efficiency at high Low Shutdown Current: 11A switching frequencies over a wide operating range. A low Synchronizable from 1MHz to 1.4MHz dropout internal regulator maintains consistent perfor- Current-Mode Control mance over a wide range of inputs from 24V systems to Li- Constant Maximum Switch Current Rating Ion batteries. An operating supply current of 1mA main- at All Duty Cycles* tains high efficiency, especially at lower output currents. Available in a Small Thermally Enhanced Shutdown reduces quiescent current to 11A. Maximum TSSOP-16 Package switch current remains constant at all duty cycles. Syn- U chronization capability allows an external logic level signal APPLICATIO S to increase the internal oscillator from 1MHz to 1.4MHz. DSL Modems Full cycle-by-cycle switch current limit protection and ther- Portable Computers mal shutdown are provided. High frequency operation al- Battery-Powered Systems lows the reduction of input and output filtering components Distributed Power and permits the use of tiny chip inductors. The LT3436 is available in an exposed pad, 16-pin TSSOP package. , LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protectd by U.S. Patents including 6535042, 6611131, 6498466 TYPICAL APPLICATIO Efficiency vs Load Current 5V to 12V Boost Converter 90 V = 5V IN 3.9H V = 12V OUT 85 B220A OUTPUT INPUT 12V V V IN SW 80 5V 0.9A OPEN LT3436 4.7F 90.9k OR CERAMIC 75 HIGH SHDN FB = ON V SYNC GND C 70 22F 10k 10nF CERAMIC 1% 470pF 65 4.7k 60 MAXIMUM OUTPUT CURRENT IS SUBJECT TO THERMAL DERATING. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 3436 TA01 LOAD CURRENT (A) 3436 TA01b 3436fa 1 EFFICIENCY (%) U ULT3436 ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) TOP VIEW ORDER PART NUMBER Input Voltage .......................................................... 25V GND 1 16 GND Switch Voltage ......................................................... 35V V 2 15 NC IN LT3436EFE SHDN Pin ............................................................... 25V SW 3 14 SYNC SW 4 13 V C FB Pin Current ....................................................... 1mA 17 GND 5 12 FB SYNC Pin Current .................................................. 1mA GND 6 11 SHDN FE PART MARKING Operating Junction Temperature Range (Note 2) NC 7 10 NC GND 8 9 GND LT3436E .......................................... 40C to 125C 3436EFE FE PACKAGE Storage Temperature Range ................ 65C to 150C 16-LEAD PLASTIC TSSOP EXPOSED PAD IS GND (PIN 17), Lead Temperature (Soldering, 10 sec)................. 300C MUST BE SOLDERED TO PCB T = 125C, = 45C/W, JMAX JA = 10C/W JC(PAD) Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T = 25C. V = 15V, V = 0.8V, SHDN, SYNC and switch open unless otherwise noted. A IN C PARAMETER CONDITION MIN TYP MAX UNITS Recommended Operating Voltage 325 V Maximum Switch Current Limit 346 A Oscillator Frequency 3.3V < V < 25V 640 800 960 kHz IN Switch On Voltage Drop I = 3A 330 550 mV SW V Undervoltage Lockout (Note 3) 2.47 2.6 2.73 V IN V Supply Current I = 0A 1 1.3 mA IN SW V Supply Current/I I = 3A 15 mA/A IN SW SW Shutdown Supply Current V = 0V, V = 25V, V = 25V 11 25 A SHDN IN SW 45 A Feedback Voltage 3V < V < 25V, 0.4V < V < 0.9V 1.182 1.2 1.218 V IN C 1.176 1.224 V FB Input Current 0 0.2 0.4 A FB to V Voltage Gain 0.4V < V < 0.9V 150 350 C C FB to V Transconductance I = 10A 500 850 1300 Mho C VC V Pin Source Current V = 1V 85 120 165 A C FB V Pin Sink Current V = 1.4V 70 110 165 A C FB V Pin to Switch Current Transconductance 4.8 A/V C V Pin Minimum Switching Threshold Duty Cycle = 0% 0.3 V C V Pin 3A I Threshold 0.9 V C SW Maximum Switch Duty Cycle V = 1.2V, I = 350mA 85 90 % C SW V = 1.2V, I = 1A 80 % C SW SHDN Threshold Voltage 1.28 1.35 1.42 V SHDN Input Current (Shutting Down) SHDN = 60mV Above Threshold 7 10 13 A SHDN Threshold Current Hysteresis SHDN = 100mV Below Threshold 4 7 10 A SYNC Threshold Voltage 1.5 2.2 V SYNC Input Frequency 1 1.4 MHz SYNC Pin Resistance I = 1mA 20 k SYNC 3436fa 2 U W U U WWW