LTC3633A/LTC3633A-1 Dual Channel 3A, 20V Monolithic Synchronous Step-Down Regulator FEATURES DESCRIPTION n 3.6V to 20V Input Voltage Range The LTC 3633A is a high efficiency, dual-channel monolithic n 3A Output Current per Channel synchronous buck regulator using a controlled on-time, n Up to 95% Efficiency current mode architecture, with phase lockable switching n Low Duty Cycle Operation: 5% at 2.25MHz frequency. The two channels can run 180 out of phase to n Selectable 0/180 Phase Shift Between Channels relax the requirements for input and output capacitance. The n Adjustable Switching Frequency: 500kHz to 4MHz operating supply voltage range is from 3.6V to 20V, making n External Frequency Synchronization it suitable for lithium-ion battery stacks as well as point of n Current Mode Operation for Excellent Line and load power supply applications from a 12V or 5V supply. Load Transient Response The operating frequency is programmable from 500kHz to n 0.6V Reference Allows Low Output Voltages 4MHz with an external resistor and may be synchronized n User Selectable Burst Mode Operation or Forced to an external clock signal. The high frequency capabil- Continuous Mode Operation ity allows the use of small surface mount inductors and n Output Voltage Tracking and Soft-Start Capability capacitors. The unique constant frequency/controlled on- n Short-Circuit Protected time architecture is ideal for high step-down ratio applica- n Overvoltage Input and Overtemperature Protection tions that operate at high frequency while demanding fast n Power Good Status Outputs transient response. An internal phase locked loop servos n LTC3633: 16V Absolute Maximum V IN the on-time of the internal one-shot timer to match the n LTC3633A: 20V Absolute Maximum V , Pin Compatible IN frequency of the internal clock or an applied external clock. with LTC3633 n The LTC3633A can select between forced continuous mode Low Profile (4mm 5mm) QFN-28 and 28-Lead and high efficiency Burst Mode operation. The LTC3633A TSSOP Packages and LTC3633A-1 differ in their output voltage sense range APPLICATIONS (refer to Table 1 in the Operation section for a description of the entire LTC3633A product family). n Distributed Power Systems L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks n Battery Powered Instruments of Linear Technology Corporation. All other trademarks are the property of their respective n owners. Protected by U.S. Patents including 5481178, 5847554, 6580258, 6304066, 6476589, Point of Load Power Supplies 6774611. TYPICAL APPLICATION Efficiency vs Load Current V IN 6V TO 20V 100 47F Burst Mode V V IN2 IN1 RUN1 INTV CC x2 90 OPERATION RUN2 ITH1 2.2F 80 ITH2 LTC3633A 70 RT MODE/SYNC 60 PHMODE 50 V2P5 40 TRACKSS2 TRACKSS1 30 PGOOD2 PGOOD1 BOOST2 BOOST1 20 1.5H 1H 0.1F 0.1F V V V = 5V OUT2 OUT1 OUT 10 SW2 SW1 5V AT 3A 3.3V AT 3A V = 12V V = 3.3V IN OUT V V ON2 ON1 0 0.001 0.01 0.1 1 10 V V FB2 FB1 SGND PGND LOAD CURRENT (A) 73.2k 45.3k 22F 10k 10k 22F 3633a TA01b 3633a TA01a 3633a1fb For more information www.linear.com/LTC3633A 1 EFFICIENCY (%)LTC3633A/LTC3633A-1 ABSOLUTE MAXIMUM RATINGS (Note 1) V , V ................................................... 0.3V to 20V V , V , PHMODE................. 0.3V to INTV + 0.3V IN1 IN2 FB1 FB2 CC PGOOD1, PGOOD2, V , V ................. 0.3V to 18V RUN1, RUN2 .................................... 0.3V to V + 0.3V ON1 ON2 IN BOOST1, BOOST2 ...................................... 0.3V to 23V Operating Junction Temperature Range BOOST1-SW1, BOOST2-SW2 ................... 0.3V to 3.6V (Notes 2, 3) ............................................ 40C to 125C V2P5, INTV , TRACKSS1, TRACKSS2 ...... 0.3V to 3.6V Storage Temperature Range ................... 65C to 150C CC ITH1, ITH2, RT, MODE/SYNC ........ 0.3V to INTV + 0.3V CC PIN CONFIGURATION TOP VIEW TOP VIEW ITH1 1 28 V ON1 TRACKSS1 2 27 SW1 V 3 26 SW1 FB1 28 27 26 25 24 23 PGOOD1 4 25 V PGOOD1 1 22 IN1 V IN1 PHMODE 5 24 V PHMODE 2 21 V IN1 IN1 RUN1 3 20 BOOST1 RUN1 6 23 BOOST1 MODE/SYNC 4 19 INTV MODE/SYNC 7 22 INTV CC 29 CC 29 PGND PGND RT 5 18 V2P5 RT 8 21 V2P5 RUN2 6 17 BOOST2 RUN2 9 20 BOOST2 7 16 SGND V IN2 SGND 10 19 V IN2 PGOOD2 8 15 V IN2 PGOOD2 11 18 V IN2 9 10 11 12 13 14 V 12 17 SW2 FB2 TRACKSS2 13 16 SW2 ITH2 14 15 V ON2 UFD PACKAGE FE PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN 28-LEAD PLASTIC TSSOP T = 125C, = 43C/W T = 125C, = 30C/W JMAX JA JMAX JA EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 29) IS PGND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3633AEUFD PBF LTC3633AEUFD TRPBF 3633A 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AIUFD PBF LTC3633AIUFD TRPBF 3633A 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AEFE PBF LTC3633AEFE TRPBF LTC3633AFE 28-Lead Plastic TSSOP 40C to 125C LTC3633AIFE PBF LTC3633AIFE TRPBF LTC3633AFE 28-Lead Plastic TSSOP 40C to 125C LTC3633AEUFD-1 PBF LTC3633AEUFD-1 TRPBF 633A1 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AIUFD-1 PBF LTC3633AIUFD-1 TRPBF 633A1 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AEFE-1 PBF LTC3633AEFE-1 TRPBF LTC3633AFE-1 28-Lead Plastic TSSOP 40C to 125C LTC3633AIFE-1 PBF LTC3633AIFE-1 TRPBF LTC3633AFE-1 28-Lead Plastic TSSOP 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: