LT3514 Triple Step-Down Switching Regulator with 100% Duty Cycle Operation FEATURES DESCRIPTION n Wide Input Voltage Range: 3.2V to 36V The LT 3514 consists of three buck regulators (2A, 1A, (40V Transient) 1A output current). The device has a wide operating input n Three Outputs: 2A, 1A, 1A range of 3.2V to 36V. An on-chip boost regulator allows n 100% Duty Cycle Operation each channel to operate up to 100% duty cycle. The LT3514 n Resistor-Programmed Constant Frequency is designed to minimize external component count and n Short-Circuit Robust results in a simple and small application circuit. n Wide SYNC Range: 350kHz to 2.2MHz The LT3514 operates robustly in fault conditions. Cycle- n Anti-Phase Switching Reduces Ripple by-cycle peak current limit and catch diode current limit n Feedback Voltage: 800mV sensing protect the IC during overload conditions. Ther- n Independent Run/Soft-Start Pins mal shutdown protects the power switches at elevated n Shutdown with UVLO temperatures. Soft-start helps control the peak inductor n Internal Compensation current during startup. n Thermal Shutdown n The LT3514 also features output voltage tracking and Tiny 28-Lead (4mm 5mm) Thermally Enhanced sequencing, programmable frequency, programmable QFN Package n undervoltage lockout, and a power good pin to indicate 24-Lead Exposed Pad TSSOP when all outputs are in regulation. The LT3514 has one fewer channel (CH2) than the LT3504, APPLICATIONS and has one channel (CH3) that outputs 2A instead of 1A. n Automotive Battery Regulation The LT3514 in QFN is pin compatible with the LT3504. The n Industrial Control Supplies LT3504 provides four 1A outputs. n Wall Transformer Regulation L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks n Distributed Supply Regulation of Linear Technology Corporation. All other trademarks are the property of their respective owners. TYPICAL APPLICATION LT3514 Start-Up and Shutdown Waveform. V (Top Trace) Is Ramped Triple Buck Regulator IN from OV Up to 8V and Then Back Down 3.3H to 0V. The Other Three Traces Are the SKY SW1 1.8V/1A Output Voltages of All Three Channels 100pF SW5 12.7k 22F 1F DA1 10.2k 10H LT3514 FB1 V 1V/DIV V IN IN 4.7H 5.4V TO 20V V IN 5V CHANNEL BEGINS 1F SW3 3.3V/2A TRANSIENT TO 40V V 100% DC OPERATION IN 2 47pF EN/UVLO 31.6k 47F 3.3V CHANNEL BEGINS CH4 1V/DIV DA3 10.2k 100% DC OPERATION PG PG FB3 8.2H CH3 1V/DIV RUN/SS1 UVLO = ~2.9V SW4 5V/1A RUN/SS3 PARTS SHUTS 22pF OFF RUN/SS4 53.6k 22F CH1 1V/DIV DA4 47nF 10.2k RT/SYNC FB4 18.2k GND 1MHz 3514 TA01b 100ms/DIV 3514 TA01a 3514fa For more information www.linear.com/LT3514 1LT3514 ABSOLUTE MAXIMUM RATINGS (Note 1) PG .............................................................................25V EN/UVLO ...................................................................40V Operating Junction Temperature Range (Notes 2, 7) EN/UVLO Pin Above V ..............................................5V IN LT3514EUFD ...................................... 40C to 125C V ............................................................................40V IN LT3514IUFD ....................................... 40C to 125C SKY ...........................................................................46V LT3514EFE ......................................... 40C to 125C SW5 ..........................................................................47V LT3514IFE .......................................... 40C to 125C RUN/SS .......................................................................6V LT3514HFE ......................................... 40C to 150C FB ...............................................................................6V Storage Temperature Range .................. 65C to 150C RT/SYNC .....................................................................6V PIN CONFIGURATION TOP VIEW TOP VIEW V 1 24 SKY IN NC 2 23 SW5 28 27 26 25 24 23 DA3 3 22 GND NC 1 22 NC NC 2 21 FB3 SW3 4 21 PG DA3 3 20 FB1 SW3 5 20 FB3 SW3 4 19 FB4 29 SW1 6 19 FB1 25 GND GND SW1 5 18 GND DA1 7 18 FB4 DA1 6 17 RT/SYNC SW4 8 17 RT/SYNC SW4 7 16 EN/UVLO DA4 9 16 EN/UVLO DA4 8 15 RUN/SS3 NC 10 15 RUN/SS3 9 10 11 12 13 14 V 11 14 RUN/SS1 IN V 12 13 RUN/SS4 IN FE PACKAGE UFD PACKAGE 24-LEAD PLASTIC TSSOP 28-LEAD (4mm 5mm) PLASTIC QFN = 33C/W JA = 43C/W EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB JA EXPOSED PAD (PIN 29) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3514EUFD PBF LT3514EUFD TRPBF 3514 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LT3514IUFD PBF LT3514IUFD TRPBF 3514 40C to 125C 28-Lead (4mm 5mm) Plastic QFN LT3514EFE PBF LT3514EFE TRPBF LT3514FE 24-Lead Plastic TSSOP 40C to 125C LT3514IFE PBF LT3514IFE TRPBF LT3514FE 24-Lead Plastic TSSOP 40C to 125C LT3514HFE PBF LT3514HFE TRPBF LT3514FE 24-Lead Plastic TSSOP 40C to 150C 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: