POWER LOSS (W) LTC3618 Dual 4MHz, 3A Synchronous Buck Converter for DDR Termination Fea T Descrip T n DDR Power Supply, Termination and Reference The LTC 3618 is a dual synchronous step-down regulator n High Efficiency: Up to 94% using a current mode, constant-frequency architecture. It n Dual Outputs with 3A Output Current Capability provides a complete DDR solution with an input voltage n 2.25V to 5.5V Input Voltage Range range from 2.25V to 5.5V. n 1% Output Voltage Accuracy The output of the first step-down regulator offers a high n V Output Voltage Down to 0.5V TT accuracy V supply. A buffered reference generates DDQ n Shutdown Current 1A VTTR at 50% of VDDQIN and drives loads up to 10mA. n VTTR = VDDQIN/2, V = VTTR FB2 The second regulator generates the DDR termination volt- n Adjustable Switching Frequency Up to 4MHz age (V ) equal to VTTR. Both regulators are capable of TT n Internal or External Compensation delivering 3A of load current at 1MHz switching frequency. n Selectable 0/90/180 Phase Shift Between Channels n The operating frequency is externally programmable up to Internal or External Soft-Start for V , Internal DDQ 4MHz, allowing the use of small surface mount inductors. Soft-Start for V TT n 0, 90, or 180 of phase shift between the two channels Power Good Status Outputs n can be selected to minimize input current ripple. For Low Profile 4mm 4mm QFN-24 and TSSOP-24 switching noise-sensitive applications, the LTC3618 can Packages be synchronized to an external clock up to 4MHz. a T The LTC3618 is offered in leadless 24-pin 4mm 4mm QFN and thermally enhanced 24-pin TSSOP packages. n DDR Memory n L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Supports DDR, DDR2, and DDR3 Standards Technology Corporation. All other trademarks are the property of their respective owners. n Tracking Supplies Protected by U.S. Patents, including 5481178, 6498466, 6580258, 6611131. Typical a T V IN Efficiency and Power Loss vs Load Current 3.3V 100F 100 10 SV PV PV IN IN1 IN2 VDDQIN 90 V = 1.8V RUN1 DDQ 1H V DDQ 80 TRACK/SS1 SW1 1.8V/3A 70 47F 1 422k PGOOD1 60 LTC3618 ITH1 FB1 V = 0.9V TT 50 210k RT 40 MODE/SYNC 392k 1H V 0.1 TT 30 SW2 0.9V/3A PHASE 47F 20 RUN2 10 FB2 PGOOD2 0 0.01 ITH2 0.01 0.1 1 10 V DDQ V = LOAD CURRENT (A) VTTR REF 3618 TA01b 2 SGND PGND 3618 TA01a 0.01F 3618fc 1 For more information www.linear.com/LTC3618 EFFICIENCY (%) ion pplica ions pplica ion uresLTC3618 a T e Maxi Mu M r a T (Notes 1, 10) PV , PV Voltages .................................. 0.3V to 6V Operating Junction Temperature IN1 IN2 SV Voltage ................................................ 0.3V to 6V Range (Note 2) ....................................... 40C to 125C IN SW1 Voltage .............................0.3V to (PV + 0.3V) Storage Temperature.............................. 65C to 150C IN1 SW2 Voltage ..............................0.3V to (PV + 0.3V) Lead Soldering Temperature (TSSOP) ..................300C IN2 RUN1 Voltage .............................. 0.3V to (SV + 0.6V) Reflow Peak Body Temperature (QFN) ..................260C IN All Other Pins ............................................... 0.3V to 6V p c F T TOP VIEW TOP VIEW 1 24 MODE/SYNC PHASE 2 23 ITH1 FB2 24 23 22 21 20 19 3 22 FB1 ITH2 FB1 1 18 PGOOD1 4 21 TRACK/SS1 VDDQIN ITH1 2 17 VTTR 5 20 SV SGND IN 25 MODE/SYNC 3 16 PGOOD2 6 19 PV 25 PV IN2 IN1 PGND PGND PHASE 4 15 RT 7 18 PV PV IN2 IN1 FB2 5 14 RUN1 8 17 SW1 SW2 ITH2 6 13 RUN2 9 16 SW1 SW2 7 8 9 10 11 12 10 15 PGOOD1 RUN2 11 14 VTTR RUN1 12 13 PGOOD2 RT FE PACKAGE UF PACKAGE 24-LEAD PLASTIC TSSOP 24-LEAD (4mm 4mm) PLASTIC QFN T = 125C, = 33C/W T = 125C, = 46.9C/W JMAX JA JMAX JA EXPOSED PAD (PIN 25) IS PGND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 25) IS PGND, MUST BE SOLDERED TO PCB o r D i n F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3618EFE PBF LTC3618EFE TRPBF LTC3618FE 24-Lead Plastic TSSOP 40C to 125C LTC3618IFE PBF LTC3618IFE TRPBF LTC3618FE 24-Lead Plastic TSSOP 40C to 125C LTC3618EUF PBF LTC3618EUF TRPBF 3618 24-Lead (4mm 4mm) Plastic QFN 40C to 125C LTC3618IUF PBF LTC3618IUF TRPBF 3618 24-Lead (4mm 4mm) Plastic QFN 40C to 125C 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: