POWER LOSS (W) LTC3634 15V Dual 3A Monolithic Step-Down Regulator for DDR Power FEATURES DESCRIPTION n 3.6V to 15V Input Voltage Range The LTC 3634 is a high efficiency, dual-channel monolithic n 3A Output Current per Channel synchronous step-down regulator which provides power n Up to 95% Efficiency supply and bus termination rails for DDR1, DDR2, and n Selectable 90/180 Phase Shift Between Channels DDR3 SDRAM controllers. The operating input voltage n Adjustable Switching Frequency: 500kHz to 4MHz range is 3.6V to 15V, making it suitable for point-of-load n VTTR = V /2 = V Reference power supply applications from a 5V or 12V input, as well DDQ TT n 1.6% Accurate VTTR at 0.75V as various battery powered systems. n Optimal V Range: 0.6V to 3V OUT The V regulated output voltage is equal to VDDQIN 0.5. TT n 10mA Buffered Output Supplies V Reference Voltage REF An on-chip buffer capable of driving a 10mA load pro- n Current Mode Operation for Excellent Line and Load vides a low noise reference output (VTTR) also equal to Transient Response VDDQIN 0.5. n External Clock Synchronization n The operating frequency is programmable and synchro- Short-Circuit Protected n nizable from 500kHz to 4MHz with an external resistor. Input Overvoltage and Overtemperature Protection n The two channels can operate 180 out-of-phase, which Power Good Status Outputs n relaxes the requirements for input and output capacitance. Available in (4mm 5mm) QFN-28 and Thermally The unique controlled on-time architecture is ideal for Enhanced 28-Lead TSSOP Packages powering DDR applications from a 12V supply at high switching frequencies, allowing the use of smaller external components. APPLICATIONS n DDR Memory Power Supplies The LTC3634 is offered in both 28-pin 4mm 5mm QFN L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode and PolyPhase are registered and 28-pin exposed pad TSSOP packages. trademarks and Hot Swap is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5847554, 6580258, 6476589, 6774611. TYPICAL APPLICATION V IN Efficiency and Power Loss 3.6V TO 15V 47F vs Load Current V V IN2 IN1 2 100 2.0 RUN1 BOOST1 V = 12V IN 0.1F RUN2 1.5H 90 1.8 V DDQ LTC3634 INTV SW1 CC 80 1.6 1.8V/3A 2.2F PHMODE V ON1 70 1.4 100F MODE/SYNC VDDQIN 24.3k 2 V DDQ 60 1.2 V FB1 V (SINKING CURRENT) TT RT 12.1k 50 1.0 V (SOURCING CURRENT) TT ITH1 BOOST2 324k 40 0.8 0.1F 0.82H 26.4k V TT 30 0.6 SW2 0.9V/3A 560pF V FB2 20 0.4 100F V ON2 10 0.2 V 4 REF ITH2 VTTR 0.9V 0 0 SGND PGND 18k 0 0.5 1 1.5 2 2.5 3 0.01F 3634 TA01a LOAD CURRENT (A) 910pF 3634 TA01b 3634fc 1 For more information www.linear.com/LTC3034 EFFICIENCY (%)LTC3634 (Note 1) ABSOLUTE MAXIMUM RATINGS V , V ................................................... 0.3V to 16V SW Source and Sink Current (DC) (Note 3) ................3A IN1 IN2 V , V Transient (Note 2) ....................................18V Operating Junction Temperature Range (Notes 4, 5, 8) IN1 IN2 PGOOD1, PGOOD2, V , V ................. 0.3V to 16V LTC3634E, LTC3634I ......................... 40C to 125C ON1 ON2 VTTR, INTV , TRACKSS, VDDQIN .......... 0.3V to 3.6V LTC3634H .......................................... 40C to 150C CC ITH1, ITH2, RT, MODE/SYNC .....0.3V to INTV + 0.3V LTC3634MP ....................................... 55C to 150C CC V , V , PHMODE ..................0.3V to INTV + 0.3V Storage Temperature Range ..................65C to 150C FB1 FB2 CC BOOST1-SW1, BOOST2-SW2 .................... 0.3V to 3.6V Lead Temperature BOOST1, BOOST2 ....................................0.3V to 19.6V (Soldering, 10 sec, TSSOP Package) .....................260C RUN1, RUN2 .................................... 0.3V to V + 0.3V IN PIN CONFIGURATION TOP VIEW TOP VIEW ITH1 1 28 V ON1 TRACKSS 2 27 SW1 V 3 26 SW1 FB1 28 27 26 25 24 23 PGOOD1 4 25 V IN1 PGOOD1 1 22 V IN1 PHMODE 5 24 V IN1 PHMODE 2 21 V IN1 RUN1 6 23 BOOST1 RUN1 3 20 BOOST1 MODE/SYNC 7 22 INTV CC 29 MODE/SYNC 4 19 INTV 29 CC PGND PGND RT 8 21 VTTR RT 5 18 VTTR RUN2 9 20 BOOST2 RUN2 6 17 BOOST2 SGND 10 19 V 7 16 IN2 SGND V IN2 PGOOD2 11 18 V PGOOD2 8 15 V IN2 IN2 9 10 11 12 13 14 V 12 17 SW2 FB2 VDDQIN 13 16 SW2 ITH2 14 15 V ON2 UFD PACKAGE FE PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN 28-LEAD PLASTIC TSSOP T = 150C, = 43C/W JMAX JA T = 150C, = 25C/W JMAX JA EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB 3634fc 2 For more information www.linear.com/LTC3034 V V FB2 FB1 VDDQIN TRACKSS ITH2 ITH1 V V ON2 ON1 SW2 SW1 SW2 SW1