LTC3633A-2/LTC3633A-3 Dual Channel 3A, 20V Monolithic Synchronous Step-Down Regulator FEATURES DESCRIPTION n 3.6V to 20V Input Voltage Range The LTC 3633A-2 is a high efficiency, dual-channel mono - n 3A Output Current per Channel lithic 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 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 Available in (4mm 5mm) QFN-28 and 28-Lead the on-time of the internal one-shot timer to match the TSSOP Packages frequency of the internal clock or an applied external clock. APPLICATIONS The LTC3633A-2 can select between forced continuous mode and high efficiency Burst Mode operation. The n Distributed Power Systems LTC3633A-2 and LTC3633A-3 differ in their output volt- n Battery Powered Instruments age sense range (refer to Table 1 in the Operation section n Point of Load Power Supplies for a description of the entire LTC3633A product family). L, LT, LTC, LTM, Burst Mode, 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 vs Load Current V IN 6V TO 20V 100 47F PV PV SV IN2 IN1 IN Burst Mode x2 90 OPERATION RUN1 INTV CC 80 RUN2 ITH1 2.2F LTC3633A-2 70 ITH2 RT 60 MODE/SYNC 50 PHMODE 40 TRACKSS2 TRACKSS1 PGOOD2 PGOOD1 30 BOOST2 BOOST1 20 1.5H 1H 0.1F 0.1F V V OUT2 OUT1 V = 5V SW2 SW1 10 OUT 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 3633a23 TA01b 3633a23 TA01a 3633a23fb For more information www.linear.com/LTC3633A-2 1 EFFICIENCY (%)LTC3633A-2/LTC3633A-3 ABSOLUTE MAXIMUM RATINGS (Note 1) PV , PV , SV ...................................... 0.3V to 20V RUN1 ............................................. 0.3V to SV + 0.3V IN1 IN2 IN IN PGOOD1, PGOOD2, V , V ................. 0.3V to 18V RUN2 ......................................................... 0.3V to 20V ON1 ON2 BOOST1, BOOST2 ...................................... 0.3V to 23V Operating Junction Temperature Range BOOST1-SW1, BOOST2-SW2 ................... 0.3V to 3.6V (Notes 3, 4) ............................................ 40C to 125C 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 V , V , PHMODE................. 0.3V to INTV + 0.3V FB1 FB2 CC PIN CONFIGURATION TOP VIEW TOP VIEW 1 V ITH1 28 ON1 2 SW1 TRACKSS1 27 3 SW1 V 26 FB1 28 27 26 25 24 23 4 PV PGOOD1 25 PGOOD1 1 22 PV IN1 IN1 5 PV PHMODE PHMODE 24 2 21 PV IN1 IN1 6 SV RUN1 3 20 SV RUN1 23 IN IN MODE/SYNC 4 19 BOOST1 7 BOOST1 MODE/SYNC 22 29 29 PGND PGND RT 5 18 INTV 8 INTV CC RT 21 CC RUN2 6 17 BOOST2 9 BOOST2 RUN2 20 SGND 7 16 PV IN2 10 PV SGND 19 IN2 PGOOD2 8 15 PV IN2 11 PV PGOOD2 18 IN2 9 10 11 12 13 14 12 SW2 V 17 FB2 13 SW2 TRACKSS2 16 14 V ITH2 15 ON2 UFD PACKAGE FE PACKAGE 28-LEAD (4mm 5mm) PLASTIC QFN 28-LEAD PLASTIC TSSOP T = 125C, = 43C/W JMAX JA T = 125C, = 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 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3633AEUFD-2 PBF LTC3633AEUFD-2 TRPBF 633A2 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AIUFD-2 PBF LTC3633AIUFD-2 TRPBF 633A2 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AEFE-2 PBF LTC3633AEFE-2 TRPBF LTC3633AFE-2 28-Lead Plastic TSSOP 40C to 125C LTC3633AIFE-2 PBF LTC3633AIFE-2 TRPBF LTC3633AFE-2 28-Lead Plastic TSSOP 40C to 125C LTC3633AEUFD-3 PBF LTC3633AEUFD-3 TRPBF 633A3 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AIUFD-3 PBF LTC3633AIUFD-3 TRPBF 633A3 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3633AEFE-3 PBF LTC3633AEFE-3 TRPBF LTC3633AFE-3 28-Lead Plastic TSSOP 40C to 125C LTC3633AIFE-3 PBF LTC3633AIFE-3 TRPBF LTC3633AFE-3 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. 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