POWER LOSS (mW) LTC3543 600mA Synchronous Step Down Buck Regulator with PLL, Soft-Start and Spread Spectrum FEATURES DESCRIPTION n 600mA Output Current The LTC 3543 is a high ef ciency monolithic synchronous n 2.5V to 5.5V Input Voltage Range current mode buck regulator. n 2.25MHz Constant-Frequency Operation, Spread The switching frequency is internally set at 2.25MHz, Spectrum or Synchronized PLL (1MHz to 3MHz) allowing the use of small surface mount inductors and n High Ef ciency: Up to 95% capacitors. In PLL mode, the LTC3543 can acquire fre- n 1A Peak Inductor Current quencies between 1MHz and 3MHz. Also, the LTC3543 n Very Low Quiescent Current: Only 45A During has spread spectrum capability providing a lower noise Burst Mode Operation regulated output, as well as low noise at the input. n No Schottky Diode Required n In Burst Mode operation, the supply current is only 45A, Low Dropout Operation: 100% Duty Cycle n dropping to <1A in shutdown. The 2.5V to 5.5V input Overtemperature Protected n voltage range makes the LTC3543 ideally suited for single Stable with Ceramic Capacitors n Li-Ion battery-powered applications. The 100% duty cycle Shutdown Mode Draws <1A Supply Current n provides a low dropout operation, extending the battery 2% Output Voltage Accuracy n life in portable systems. Burst Mode operation increases Current Mode Operation for Excellent Line and Load ef ciency at light loads, further extending battery life. Transient Response n Soft-Start The internal synchronous switch increases ef ciency and n Available in a Low Pro le (0.75mm) 2mm 3mm eliminates the need for an external Schottky diode. 6-Lead DFN Package L, LT, LTC, LTM, Linear Technology, Burst Mode 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, 6580258, 6304066, 6127815, 6498466, APPLICATIONS 6611131. n Portable Instruments n Cellular Phones TYPICAL APPLICATION Ef ciency and Power Loss vs Load Current 3.3H 100 1000 1.5V V OUT 2.5V TO 5.5V V SW IN V = 2.7V 1.5V 90 IN 10F 10pF 10F 300k 80 LTC3543 100 V = 4.2V IN 70 PWR EN RUN V FB 60 V = 3.6V MODE MODE CAP IN 50 10 200k GND 4nF 40 POWER LOSS 30 EXPOSED AT V = 3.6V IN 10 PAD 3543 TA01a 20 10 MODE = V m PULSE SKIP IN Burst Mode OPERATION ENABLED MODE = V m PULSE SKIP WITH SPREAD SPECTRUM FB 0 0.1 0.1 1 10 100 1000 MODE = GND m Burst Mode OPERATION MODE = EXTERNAL CLOCK m PLL LOAD CURRENT (mA) 3543 TA01b 3543fa 1 EFFICIENCY (%)LTC3543 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V Voltage ................................................... 0.3V to 6V IN RUN, V , MODE, CAP Voltages ...................0.3V to V FB IN SW 1 6 V IN SW Voltage ....................................0.3V to (V + 0.3V) IN 7 CAP 2 5 RUN Operating Temperature Range (Note 2).... 40C to 85C MODE 4 VFB 3 Junction Temperature (Note 3) ............................. 125C Storage Temperature Range ................... 65C to 125C DCB PACKAGE 6-LEAD (2mm s 3mm) PLASTIC DFN T = 125C, = 64C/W JMAX JA EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3543EDCB PBF LTC3543EDCB TRPBF LCCK 40C to 85C 6-Lead (2mm 3mm) Plastic DFN Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: