POWER LOSS (W) LTC3605 15V, 5A Synchronous Step-Down Regulator FEATURES DESCRIPTION n High Efficiency: Up to 96% The LTC 3605 is a high efficiency, monolithic synchronous n 5A Output Current buck regulator using a phase lockable controlled on-time n 4V to 15V V Range constant frequency, current mode architecture. PolyPhase IN n Integrated Power N-Channel MOSFETs operation allows multiple LTC3605 regulators to run out of (70m Top and 35m Bottom) phase while using minimal input and output capacitance. n Adjustable Frequency 800kHz to 4MHz The operating supply voltage range is from 15V down to n PolyPhase Operation (Up to 12 Phases) 4V, making it suitable for dual lithium-ion battery inputs n Output Tracking as well as point of load power supply applications from n 0.6V 1% Reference Accuracy a 12V or 5V rail. n Current Mode Operation for Excellent Line and Load The operating frequency is programmable from 800kHz to Transient Response 4MHz with an external resistor. The high frequency capabil- n Shutdown Mode Draws Less Than 15A Supply ity allows the use of small surface mount inductors. For Current switching noise sensitive applications, it can be externally n Available in 24-Pin (4mm 4mm) QFN Package synchronized from 800kHz to 4MHz. The PHMODE pin allows user control of the phase of the outgoing clock signal. The unique constant frequency/controlled on-time APPLICATIONS architecture is ideal for high step-down ratio applications n Point of Load Power Supply that are operating at high frequency while demanding n Portable Instruments fast transient response. Two internal phase-lock loops n Distributed Power Systems synchronize the internal oscillator to the external clock n Battery-Powered Equipment and also servos the regulator on-time to lock on to either the internal clock or the external clock if its present. L, LT, LTC, LTM, PolyPhase, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5847554, 6580258, 6304066, 6476589, 6774611. TYPICAL APPLICATION Efficiency and Power Loss High Efficiency 1MHz, 5A Step-Down Regulator 100 10 V = 12V V = 3.3V IN OUT V 90 f = 1MHz IN 4V TO 15V 22F 80 PV SV 2 IN IN 70 CLKOUT INTV 1 CC V = 1.2V OUT 2.2F 60 CLKIN BOOST 50 PGOOD 0.1F 1H LTC3605 V 40 V = 3.3V OUT OUT SW V = 1.2V 3.3V OUT 0 30 V 11.5k ON 47F V RUN FB 20 IN 2 ITH 2.55k 10 RT 16k 0 0.1 PGND 10 100 1000 10000 162k 220pF OUTPUT CURRENT (mA) 3605 TA01a 3605 TA01b 3605fc 1 EFFICIENCY (%)LTC3605 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW PV , SV , SW Voltage .............................. 0.3V to 15V IN IN SW Transient Voltage ................................. 2V to 17.5V BOOST Voltage .......................... 0.3V to PV + INTV IN CC 24 23 22 21 20 19 RUN Voltage ............................................. 0.3V to SV IN RT 1 18 PV IN V Voltage ............................................... 0.3V to SV PHMODE 2 17 PV ON IN IN INTV Voltage .......................................... 0.3V to 3.6V MODE 3 16 SW 25 CC PGND FB 4 15 SW ITH, RT, CLKOUT, PGOOD Voltage ......... 0.3V to INTV CC TRACK/SS SW 5 14 CLKIN, PHMODE, MODE Voltage .......... 0.3V to INTV CC ITH 6 13 SW TRACK/SS, FB Voltage .......................... 0.3V to INTV CC 7 8 9 10 11 12 Operating Temperature Range (Note 2)..40C to 125C Junction Temperature (Note 5) ............................. 125C Storage Temperature Range ...................65C to 125C UF PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN T = 125C, = 37C/W JMAX JA EXPOSED PAD (PIN 25) IS PGND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3605EUF PBF LTC3605EUF TRPBF 3605 40C to 85C 24-Lead (4mm 4mm) Plastic QFN LTC3605IUF PBF LTC3605IUF TRPBF 3605 40C to 125C 24-Lead (4mm 4mm) Plastic QFN 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: