LT3684 36V, 2A, 2.8MHz Step-Down Switching Regulator FEATURES DESCRIPTION n The LT 3684 is an adjustable frequency (300kHz to 2.8MHz) Wide Input Range: 3.6V to 34V Operating, monolithic buck switching regulator that accepts input 36V Maximum n voltages up to 34V (36V maximum). A high efficiency 2A Maximum Output Current n 0.18 switch is included on the die along with a boost Adjustable Switching Frequency: 300kHz to 2.8MHz n Schottky diode and the necessary oscillator, control and Low Shutdown Current: I < 1A Q n logic circuitry. Current mode topology is used for fast Integrated Boost Diode n transient response and good loop stability. The LT3684s Power Good Flag n high operating frequency allows the use of small, low cost Saturating Switch Design: 0.18 On-Resistance n inductors and ceramic capacitors resulting in low output 1.265V Feedback Reference Voltage n ripple while keeping total solution size to a minimum. Output Voltage: 1.265V to 20V n The low current shutdown mode reduces input supply Soft-Start Capability n current to less than 1A while a resistor and capacitor on Small 10-Pin Thermally Enhanced MSOP and the RUN/SS pin provide a controlled output voltage ramp (3mm 3mm) DFN Packages (soft-start). A power good flag signals when V reaches OUT 90% of the programmed output voltage. The LT3684 is APPLICATIONS available in 10-Pin MSOP and 3mm 3mm DFN packages with Exposed Pads for low thermal resistance. n Automotive Battery Regulation n L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Power for Portable Products Technology Corporation. All other trademarks are the property of their respective owners. n Distributed Supply Regulation n Industrial Supplies n Wall Transformer Regulation TYPICAL APPLICATION 3.3V Step-Down Converter Efficiency V IN V 90 OUT 4.5V TO 3.3V 34V 2A V BD IN 80 RUN/SS BOOST OFF ON 0.47F 4.7H 16.2k 70 V SW C 4.7F LT3684 60 RT 330pF PG BIAS 50 324k FB 60.4k V = 12V GND IN V = 3.3V 200k 22F 40 OUT L = 4.7H f = 800kHz 30 3684 TA01a 0 0.5 1 1.5 2 LOAD CURRENT (A) 3684 TA01b 3684fa 1 For more information www.linear.com/LT3684 EFFICIENCY (%)LT3684 ABSOLUTE MAXIMUM RATINGS (Note 1) V , RUN/SS Voltage .................................................36V Operating Temperature Range (Note 2) IN BOOST Pin Voltage ...................................................56V LT3684E ..............................................40C to 85C BOOST Pin Above SW Pin .........................................30V LT3684I ............................................. 40C to 125C FB, RT, V Voltage .......................................................5V Storage Temperature Range .................. 65C to 150C C BIAS, PG, BD Voltage ................................................30V Lead Temperature (Soldering, 10 sec) Maximum Junction Temperature .......................... 125C (MSE Only) .......................................................300C PIN CONFIGURATION TOP VIEW TOP VIEW BD 1 10 RT BD 1 10 RT BOOST 2 9 V BOOST 2 9 V C C SW 3 11 8 FB 11 SW 3 8 FB V 4 7 BIAS IN V 4 7 BIAS IN RUN/SS 5 6 PG RUN/SS 5 6 PG MSE PACKAGE 10-LEAD PLASTIC MSOP DD PACKAGE T = 125C, = 45C/W, = 10C/W JMAX JA JC 10-LEAD (3mm 3mm) PLASTIC DFN EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB T = 125C, = 45C/W, = 10C/W JMAX JA JC EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION