LT3510 Monolithic Dual Tracking 2A Step-Down Switching Regulator FEATURES DESCRIPTION n Wide Input Range: 3.1V to 25V The LT 3510 is a dual current mode PWM step-down n Two Switching Regulators with 2A Output Capability DC/DC converter with two internal 2.5A switches. Inde- n Independent Supply to Each Regulator pendent input voltage, feedback, soft-start and power n Adjustable/Synchronizable Fixed Frequency good pins for each channel simplify complex power Operation from 250kHz to 1.5MHz supply tracking/sequencing requirements. n Antiphase Switching Both converters are synchronized to either a common n Outputs Can be Paralleled external clock input or a resistor programmable xed n Independent, Sequential, Ratiometric or Absolute 250kHz to 1.5MHz internal oscillator. At all frequencies, a Tracking Between Outputs 180 phase relationship between channels is maintained, n Independent Soft-Start and Power Good Pins reducing voltage ripple and component size. Programmable n Enhanced Short-Circuit Protection frequency allows for optimization between ef ciency and n Low Dropout: 95% Maximum Duty Cycle external component size. n Low Shutdown Current: <10A n Minimum input-to-output voltage ratios are improved 20-Lead TSSOP Package with Exposed Leadframe by allowing the switch to stay on through multiple clock cycles, only switching off when the boost capacitor needs APPLICATIONS recharging, resulting in ~95% maximum duty cycle. n DSP Power Supplies Each output can be independently disabled using its own n Disc Drives soft-start pin, or by using the SHDN pin the entire part can n DSL/Cable Modems be placed in a low quiescent current shutdown mode. n Wall Transformer Regulation n The LT3510 is available in a 20-lead TSSOP package with Distributed Power Regulation n exposed leadframe for low thermal resistance. PCI Cards L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION 3.3V and 1.8V Dual 2A Step-Down Converter with Output Tracking V IN Ef ciency 12V 4.7F V V 100 IN1 IN2 61.9k V = 3.3V OUT SHDN R /SYNC V = 5V T OUT 90 BST1 BST2 80 4.7H 3.3H 0.47F 0.47F SW1 SW2 70 V = 2.5V V = 1.8V OUT OUT PMEG4005 PMEG4005 B360A B360A 60 LT3510 50 IND1 IND2 V V OUT1 OUT2 40 3.3V 1.8V V V OUT1 OUT2 2A 2A 47F 100F 30 24.9k 10k PG1 PG2 20 FB1 FB2 V = 12V IN V V I = 0A OUT2 C1 C2 10 FREQUENCY = 500kHz 470pF 470pF SS/TRACK1 SS/TRACK2 0 GND 0 0.5 1 1.5 2 8.06k 10pF 40.2k 40.2k 47pF 8.06k LOAD CURRENT (A) 0.1F 3510 TA01b 3510 TA01a 3510fe 1 EFFICIENCY (%)LT3510 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V , SHDN, PG1/2 ...................................... 25V/0.3V IN1/2 V 1 20 BST1 IN1 SW1/2 .................................................................... V IN1/2 SW1 2 19 SS/TRACK1 BST1/2 ........................................................... 35V/0.3V IND1 3 18 V C1 BST1/2 Pins Above SW1/2 ........................................25V V 4 17 FB1 OUT1 IND1/2 .....................................................................4A PG1 5 16 R /SYNC T 21 V ........................................................ V /0.3V OUT1/2 IN1/2 PG2 6 15 SHDN FB1/2, SS1/2, R /SYNC ............................................ 5.5V T V 7 14 FB2 OUT2 V ......................................................................1mA C1/2 IND2 8 13 V C2 Operating Junction Temperature Range SW2 9 12 SS/TRACK2 LT3510EFE (Notes 2, 8) ..................... 40C to 125C V 10 11 BST2 IN2 LT3510IFE (Notes 2, 8) ...................... 40C to 125C FE PACKAGE Storage Temperature Range ................... 65C to 150C 20-LEAD PLASTIC TSSOP T = 125C, = 45C/W, = 10C/W JMAX JA JC(PAD) Lead Temperature (Soldering, 10 sec) .................. 300C EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3510EFE PBF LT3510EFE TRPBF LT3510FE 20-Lead TSSOP 40C to 125C LT3510IFE PBF LT3510IFE TRPBF LT3510FE 20-Lead TSSOP 40C to 125C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3510EFE LT3510EFE TR LT3510FE 20-Lead TSSOP 40C to 125C LT3510IFE LT3510IFE TR LT3510FE 20-Lead TSSOP 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. For more information on lead free part marking, go to: