LTC3403 1.5MHz, 600mA Synchronous Step-Down Regulator with Bypass Transistor FEATURES DESCRIPTIO n Dynamically Adjustable Output from 0.3V to 3.5V The LTC 3403 is a high efficiency monolithic synchro- n Very Low Quiescent Current: Only 20A nous buck regulator optimized for WCDMA power ampli- During Operation fier applications. The output voltage can be dynamically n 600mA Output Current programmed from 0.3V to 3.5V. At V > 3.6V an internal OUT n Internal P-Channel MOSFET Bypass Transistor bypass P-channel MOSFET connects V directly to V , OUT IN n High Efficiency: Up to 96% eliminating power loss through the inductor. Selectable n 1.5MHz Constant Frequency Operation forced continuous mode enables fast V response to the OUT n No Schottky Diode Required controlling input. n Low Dropout Operation: 100% Duty Cycle Supply current is only 20A in Burst Mode operation and n 2.5V to 5V Input Voltage Range drops to <1A in shutdown. The 2.5V to 5V input voltage n Drives Optional External P-Channel MOSFET range makes the LTC3403 ideally suited for single Li-Ion n Shutdown Mode Draws < 1A Supply Current battery-powered applications. 100% duty cycle provides n Current Mode Operation for Excellent Line and low dropout operation, extending battery life in portable Load Transient Response systems. n Overtemperature Protected n Available in 8-Lead 3mm 3mm DFN Package Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. U The internal synchronous switch increases efficiency and APPLICATIO S eliminates the need for an external Schottky diode. n WCDMA Cell Phone Power Amplifiers The LTC3403 is available in a low profile 8-lead 3mm n Wireless Modems 3mm DFN package. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. TYPICAL APPLICATIO 95 90 V = 3.6V IN 85 2.2H* V = 4.2V V V IN OUT IN 80 2.7V V SW 3 V REF IN V = 3.6V V = 4.2V C ** C IN IN TO 5V OUT 600mA IN LTC3403 75 4.7F 10F MODE GDR CER CER 70 V RUN OUT FORCED 65 REF CONTINUOUS OUTPUT GND MODE 60 WCDMA PROGRAMMING Burst Mode 3 RF PA DAC 55 OPERATION V = 1.8V OUT 50 *MURATA LQH32CN2R2M11 3403 F01a 0.1 1 10 100 1000 **TAIYO YUDEN JMK212BJ475MG TAIYO YUDEN JMK212BJ106MN OUTPUT CURRENT (mA) 3403 F01b Figure 1a. WCDMA Transmitter Power Supply Figure 1b. Efficiency vs Output Current 3403f 1 EFFICIENCY (%) U ULTC3403 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Input Supply Voltage (<300s) .................. 0.3V to 6V ORDER PART TOP VIEW Input Supply Voltage (DC) ....................... 0.3V to 5.5V NUMBER RUN, REF, MODE, V , GDR Voltages ..... 0.3V to V GDR 1 8 V OUT IN OUT LTC3403EDD SW Voltage .................................. 0.3V to (V + 0.3V) V 2 7 REF IN IN 9 P-Channel Switch Source Current (DC) ............. 800mA GND 3 6 MODE N-Channel Switch Sink Current (DC) ................. 800mA SW 4 5 RUN Peak SW Sink and Source Current ........................ 1.3A DD PART MARKING DD PACKAGE 8-LEAD (3mm 3mm) PLASTIC DFN Bypass P-Channel FET Source Current ...................... 1A EXPOSED PAD IS GND (PIN 9) LAAX Operating Temperature Range (Note 2) .. 40C to 85C MUST BE SOLDERED TO PCB T = 125C, = 43C/ W, = 3C/ W JMAX JA JC Junction Temperature (Note 3)............................ 125C Storage Temperature Range ................ 65C to 150C (DD Package) .................................... 65C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating temperature range, otherwise specifications are T = 25C. A V = 3.6V unless otherwise specified. IN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Regulated Output Voltage V = 1.1V, MODE = V l 3.23 3.3 3.37 V OUT REF IN V = 0.1V, MODE = V l 0.25 0.3 0.35 V REF IN V Output Voltage Line Regulation V = 2.5V to 5V l 0.1 0.4 %/V OUT IN I Peak Inductor Current V = 3V, V = 0.9V 0.70 1 1.25 A PK IN REF V Output Voltage Load Regulation 0.7 % LOADREG V Input Voltage Range l 2.5 5 V IN I Input DC Operating Current S Burst Mode Operation MODE = 0V, SW = Open 20 35 A Forced Continuous Mode Operation MODE = V , SW = Open 1.5 2.5 mA IN Shutdown V = 0V, V = 4.2V 0.1 1 A RUN IN f Oscillator Frequency V 0.25V l 1.2 1.5 1.8 MHz OSC REF V 0.1V 550 700 850 kHz REF V Bypass PFET Turn-Off Threshold V = 1.167 1.2 V REF REF Bypass PFET Turn-On Threshold V = 1.21 1.26 V REF R R of P-Channel FET I = 160mA, Wafer Level 0.3 0.4 PFET DS(ON) SW = 160mA, DD Package 0.4 I SW R R of N-Channel FET I = 160mA, Wafer Level 0.3 0.4 NFET DS(ON) SW I = 160mA, DD Package 0.4 SW R R of Bypass P-Channel FET I = 100mA, V = 3V, Wafer Level 0.15 0.18 BYPASS DS(ON) OUT IN I = 100mA, V = 3V, DD Package (Note 4) 0.20 OUT IN I SW Leakage V = 0V, V = 0V or 5V, V = 5V 0.01 1 A LSW RUN SW IN I Bypass PFET Leakage V = 0V, V = 5V, V = 0V 0.01 1 A LBYP OUT IN REF V RUN Threshold l 0.3 1 1.5 V RUN I RUN Input Current V = 2.5V or 0V l 0.01 1 A RUN RUN V MODE Threshold l 0.3 1.5 2 V MODE I MODE Input Current l 0.01 1 A MODE I REF Input Current l 0.01 1 A REF 3403f 2 U WWW