LTC3405 1.5MHz, 300mA Synchronous Step-Down Regulator in ThinSOT FEATURES DESCRIPTIO High Efficiency: Up to 96% The LTC 3405 is a high efficiency monolithic synchro- Very Low Quiescent Current: Only 20A nous buck regulator using a constant frequency, current During Operation mode architecture. Supply current during operation is 300mA Output Current at V = 3V only 20A and drops to <1A in shutdown. The 2.5V to IN 2.5V to 5.5V Input Voltage Range 5.5V input voltage range makes the LTC3405 ideally suited 1.5MHz Constant Frequency Operation for single Li-Ion battery-powered applications. 100% duty No Schottky Diode Required cycle provides low dropout operation, extending battery Low Dropout Operation: 100% Duty Cycle life in portable systems. 0.8V Reference Allows Low Output Voltages Switching frequency is internally set at 1.5MHz, allowing Shutdown Mode Draws <1A Supply Current the use of small surface mount inductors and capacitors. 2% Output Voltage Accuracy Current Mode Operation for Excellent Line and The internal synchronous switch increases efficiency and Load Transient Response eliminates the need for an external Schottky diode. Low Overtemperature Protected output voltages are easily supported with the 0.8V feed- TM Low Profile (1mm) ThinSOT Package back reference voltage. The LTC3405 is available in a low U profile (1mm) ThinSOT package. APPLICATIO S For new designs, refer to the LTC3405A data sheet. For Cellular Telephones fixed 1.5V and 1.8V output versions, refer to the Personal Information Appliances LTC3405A-1.5/LTC3405A-1.8 data sheet. Wireless and DSL Modems , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. Digital Still Cameras Protected by U.S. Patents, including 6580258, 5481178. MP3 Players Portable Instruments TYPICAL APPLICATIO 100 V = 3.6V IN 95 4.7H** V 90 IN 3 4 V * OUT 2.7V V SW IN 3.3V 22pF C TO 5.5V 85 IN LTC3405 2.2F + C V = 4.2V 1 OUT IN CER RUN 80 33F 6 5 MODE V FB 75 887k V = 5.5V IN GND 280k 70 2 3405 F01a 65 *V CONNECTED TO V FOR 2.7V < V < 3.3V OUT IN IN **MURATA LQH3C4R7M34 60 TAIYO YUDEN LMK212BJ225MG 0.1 1 10 100 1000 AVX TPSB336K006R0600 OUTPUT CURRENT (mA) 3405 F01b Figure 1a. High Efficiency Step-Down Converter Figure 1b. Efficiency vs Load Current 3405fa 1 EFFICIENCY (%) U ULTC3405 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Input Supply Voltage .................................. 0.3V to 6V ORDER PART TOP VIEW MODE, RUN, V Voltages ......................... 0.3V to V NUMBER FB IN SW Voltage .................................. 0.3V to (V + 0.3V) RUN 1 6 MODE IN LTC3405ES6 P-Channel Switch Source Current (DC) ............. 400mA GND 2 5 V FB SW 3 4 V IN N-Channel Switch Sink Current (DC) ................. 400mA Peak SW Sink and Source Current .................... 630mA S6 PACKAGE S6 PART MARKING 6-LEAD PLASTIC TSOT-23 Operating Temperature Range (Note 2) .. 40C to 85C T = 125C, = 250C/ W JMAX JA LTXQ Junction Temperature (Note 3)............................ 125C Storage Temperature Range ................ 65C to 150C Consult LTC Marketing for parts specified with wider operating temperature ranges. Lead Temperature (Soldering, 10 sec)................. 300C ELECTRICAL CHARACTERISTICS The 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 I Feedback Current 30 nA VFB I Peak Inductor Current V = 3V, V = 0.7V, Duty Cycle < 35% 375 500 625 mA PK IN FB V Regulated Feedback Voltage (Note 4) 0.784 0.8 0.816 V FB V Output Overvoltage Lockout V = V V 20 50 80 mV OVL OVL OVL FB V Reference Voltage Line Regulation V = 2.5V to 5.5V (Note 4) 0.04 0.4 %/V FB IN V Output Voltage Load Regulation 0.5 % LOADREG V Input Voltage Range 2.5 5.5 V IN I Input DC Bias Current (Note 5) S Pulse Skipping Mode V = 0.7V, Mode = 3.6V, I = 0A 300 400 A FB LOAD Burst Mode Operation V = 0.83V, Mode = 0V, I = 0A 20 35 A FB LOAD Shutdown V = 0V, V = 4.2V 0.1 1 A RUN IN f Oscillator Frequency V = 0.8V 1.2 1.5 1.8 MHz OSC FB V = 0V 210 kHz FB R R of P-Channel FET I = 100mA 0.7 0.85 PFET DS(ON) SW R R of N-Channel FET I = 100mA 0.6 0.90 NFET DS(ON) SW I SW Leakage V = 0V, V = 0V or 5V, V = 5V 0.01 1 A LSW RUN SW IN V RUN Threshold 0.3 1 1.5 V RUN I RUN Leakage Current 0.01 1 A RUN V MODE Threshold 0.3 1.5 2 V MODE I MODE Leakage Current 0.01 1 A MODE Burst Mode is a registered trademark of Linear Technology Corporation. Note 1: Absolute Maximum Ratings are those values beyond which the life Note 3: T is calculated from the ambient temperature T and power J A of a device may be impaired. dissipation P according to the following formula: D Note 2: The LTC3405E is guaranteed to meet performance specifications LTC3405: T = T + (P )(250C/W) J A D from 0C to 70C. Specifications over the 40C to 85C operating Note 4: The LTC3405 is tested in a proprietary test mode that connects temperature range are assured by design, characterization and correlation V to the output of the error amplifier. FB with statistical process controls. Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. 3405fa 2 U WWW