LT3477 3A, DC/DC Converter with Dual Rail-to-Rail Current Sense Fea T Descrip T n Dual 100mV Rail-to-Rail Current Sense Amplifiers The LT 3477 is a current mode, 3A DC/DC step-up converter n Wide Input Voltage Range: 2.5V to 25V with dual rail-to-rail current sense amplifiers and an internal n 3A, 42V Internal Switch 3A, 42V switch. It combines a traditional voltage feedback n High Efficiency Power Conversion: Up to 93% loop and two unique current feedback loops to operate n Drives LEDs in Boost, Buck-Boost or Buck Mode as a constant-current, constant-voltage source. Both cur- n Frequency Set by External Resistor: 200kHz to 3.5MHz rent sense voltages are set at 100mV and can be adjusted n Programmable Soft-Start independently using the I and I pins. Efficiency ADJ1 ADJ2 n Low V Switch: 0.3V at 2.5A of up to 93% can be achieved in typical applications. The CESAT n Capable of Positive and Negative Output Voltages LT3477 features a programmable soft-start function to (Boost, Inverting, SEPIC, Flyback) limit inductor current during start-up. Both inputs of the n Available in Thermally Enhanced 20-Lead error amplifier are available externally allowing positive (4mm 4mm) QFN and 20-Lead TSSOP Packages and negative output voltages (boost, inverting, SEPIC, Flyback). The switching frequency is programmable from 200kHz to 3.5MHz through an external resistor. a T Available in thermally enhanced 20-pin (4mm 4mm) n High Power LED Driver QFN and 20-pin TSSOP packages, the LT3477 provides a n DSL Modems complete solution for both constant-voltage and constant- n Distributed Power current applications. n Input/Output Current Limited Boost, SEPIC, , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Inverting, Flyback Converters All other trademarks are the property of their respective owners. n Constant-Voltage, Constant-Current Source Typical a T 330mA LED Driver With Open LED Protection Efficiency 10H 90 V IN 5V 3.3F 3.3F 85 200k I I SW SP1 SN1 80 V FBN IN I ADJ1 75 10k I ADJ2 70 LT3477 SHDN SHDN I SP2 65 0.3 60 V I C SN2 V R REF T 55 FBP GND SS 1k 330mA 50 0 0.1 0.2 0.3 0.4 33nF 22k I (A) OUT 4.7nF 3477 TA01b 3477 TA01a 3477fd 1 For more information www.linear.com/LT3477 EFFICIENCY (%) ion pplica ions pplica ion uresLT3477 (Note 1) a Te Maxi Mu M r a T SW Pin Voltage ........................................................ 42V Junction Temperature .......................................... 125C V , SHDN Pin Voltage ............................................. 25V Operating Temperature Range (Note 2) IN FBP, FBN Pin Voltage ................................................. 6V LT3477E ............................................... 40C to 85C V Pin Voltage......................................................... 6V LT3477I .............................................. 40C to 125C REF R , V , SS Pin Voltage ............................................... 6V Storage Temperature Range ...................65C to 125C T C I , I Pin Voltage ............................................ 25V Lead Temperature (Soldering, 10 sec) ADJ1 ADJ2 I , I , I , I Pin Voltage ...............................42V TSSOP .............................................................. 300C SP1 SP2 SN1 SN2 p in c F T TOP VIEW TOP VIEW V 1 20 NC IN R 2 19 NC 20 19 18 17 16 T SHDN 3 18 NC NC 1 15 I SP1 SS 4 17 SW NC 2 14 I SN2 V 5 16 SW C 21 V 3 21 13 I IN SP2 FBN 6 15 GND I R 4 12 ADJ1 T FBP 7 14 I SN1 SHDN 11 I 5 ADJ2 V 8 13 I REF SP1 6 7 8 9 10 I 9 12 I ADJ2 SN2 I 10 11 I ADJ1 SP2 UF PACKAGE FE PACKAGE 20-LEAD (4mm 4mm) PLASTIC QFN 20-LEAD PLASTIC TSSOP T = 125C, = 37C/W T = 125C, = 40C/W JMAX JA JMAX JA EXPOSED PAD (PIN 21) IS PGND (MUST BE SOLDERED TO PCB) EXPOSED PAD (PIN 21) IS PGND (MUST BE SOLDERED TO PCB) Der in F Ma T