LOSS (W) LTC3545/LTC3545-1 Triple 800mA Synchronous Step-Down Regulator2.25MHz FEATURES DESCRIPTION Three 800mA Outputs The LTC 3545/LTC3545-1 are triple, high efficiency, High Ef ciency: Up to 95% monolithic synchronous buck regulators using a constant 2.25V to 5.5V Input Voltage Range frequency, current mode architecture. The regulators op- Low Ripple (<20mV ) Burst Mode Operation erate independently with separate run pins. The 2.25V to P-P I : 58A 5.5V input voltage range makes the LTC3545/LTC3545-1 Q 2.25MHz Constant Frequency Operation or well suited for single Li-Ion battery-powered applications. Synchronizable to External 1MHz to 3MHz Clock Low ripple pulse skip mode or high ef ciency Burst Mode Power Good Indicators Ease Supply Sequencing operation is externally selectable. PWM pulse skip mode 0.6V Reference Allows Low Output Voltages operation provides very low output ripple voltage while Current Mode Operation/Excellent Transient Response Burst Mode operation increases ef ciency at low output Low Pro le 16-Lead 3mm 3mm QFN Package loads. Switching frequency is internally set to 2.25MHz, or the APPLICATIONS switching frequency can be synchronized to an external Smart Phones 1MHz to 3MHz clock. Power good indicators easily allow Wireless and DSL Modems power on sequencing between the three regulators. Digital Still Cameras The internal synchronous switches increase ef ciency and Portable Instruments eliminate external Schottky diodes. Low output voltages are Point of Load Regulation supported with the 0.6V feedback reference voltage. L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LTC3545-1 replaces the SYNC/MODE function with a Protected by U.S. Patents including 6580258, 5481178, 6127815, 6498466, 6611131. third PGOOD pin and forces Burst Mode operation. TYPICAL APPLICATION High Ef ciency Triple Step-Down Converter with Power Sequencing Ef ciency and Loss vs Load Current V IN 2.25V TO 5.5V 100 1 C5 C4 10F 10F 90 GNDA PGND 80 L2 R8 R7 0.1 70 1.5H 500k 500k V PV IN IN V OUT2 RUN1 SW2 1.2V 60 C7 PGOOD1 20pF 50 0.01 RUN2 V FB2 40 R4 C2 PGOOD2 R3 10F 30 226k 226k 0.001 RUN3 LTC3545 20 V = 2.5V IN SYNC/MODE V = 3.6V L1 L3 10 IN V = 4.2V 1.5H 1.5H IN V 0 0.0001 V OUT1 OUT3 SW1 SW3 1.8V 1.5V 0.0001 0.001 0.01 0.1 1 C6 C8 20pF 20pF LOAD CURRENT (A) C1 C3 3545 TA01b V V T = 25C A FB1 FB3 10F 10F V = 2V OUT R2 R6 R1 GNDA PGND R5 Burst Mode OPERATION 255k 200k 511k 301k f = 2.25MHz OSC SINGLE CHANNEL 3545 TA01 35451fb 1 EFFICIENCY (%)LTC3545/LTC3545-1 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage .................................... 0.3V to 6V N-Channel Sink Current (DC) (Note 8) .....................1.1A RUNx, PGOODx ............................. 0.3V to (V + 0.3V) Peak SW Sink and Source Current (Note 8) .............1.3A IN V , SYNC/MODE ........................ 0.3V to (V + 0.3V) Operating Junction Temperature Range FBx IN SWx .............................................. 0.3V to (V + 0.3V) (Note 2) .............................................40C to 125C IN P-Switch Source Current (DC) (Note 8) ...................1.1A Storage Temperature Range ...................65C to 125C PIN CONFIGURATION LTC3545 LTC3545-1 TOP VIEW TOP VIEW 16 15 14 13 16 15 14 13 SW1 1 12 V SW1 1 12 V FB2 FB2 PGOOD1 2 11 V PGOOD1 2 11 V FB3 FB3 17 17 RUN2 RUN3 3 10 RUN2 3 10 RUN3 PGOOD2 4 9 SYNC/MODE PGOOD2 4 9 PGOOD3 5 6 7 8 5 6 7 8 UD PACKAGE UD PACKAGE 16-LEAD (3mm s 3mm) PLASTIC QFN 16-LEAD (3mm s 3mm) PLASTIC QFN T = 125C, = 55C/W T = 125C, = 55C/W JMAX JA JMAX JA EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3545EUD PBF LTC3545EUD TRPBF LCSR 16-Lead (3mm 3mm) Plastic QFN 40C to 125C LTC3545IUD PBF LTC3545IUD TRPBF LCSR 16-Lead (3mm 3mm) Plastic QFN 40C to 125C LTC3545EUD-1 PBF LTC3545EUD-1 TRPBF LDDP 16-Lead (3mm 3mm) Plastic QFN 40C to 125C LTC3545IUD-1 PBF LTC3545IUD-1 TRPBF LDDP 40C to 125C 16-Lead (3mm 3mm) Plastic QFN Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: