LTC3406B-2 2.25MHz, 600mA Synchronous Step-Down TM Regulator in ThinSOT FEATURES DESCRIPTIO High Efficiency: Up to 96% The LTC 3406B-2 is a high efficiency monolithic synchro- 600mA Output Current at V = 3V nous buck regulator using a constant frequency, current IN 2.5V to 5.5V Input Voltage Range mode architecture. Supply current with no load is 350A, 2.25MHz Constant Frequency Operation dropping to <1A in shutdown. The 2.5V to 5.5V input No Schottky Diode Required voltage range makes the LTC3406B-2 ideally suited for Low Dropout Operation: 100% Duty Cycle single Li-Ion battery-powered applications. 100% duty Low Quiescent Current: 350A cycle capability provides low dropout operation, extend- 0.6V Reference Allows Low Output Voltages ing battery life in portable systems. PWM pulse skipping Shutdown Mode Draws < 1A Supply Current mode operation provides very low output ripple voltage for Current Mode Operation for Excellent Line and noise sensitive applications. Load Transient Response The switching frequency is internally set at 2.25MHz, allow- Overtemperature Protected ing the use of tiny surface mount inductors and capacitors. Low Profile (1mm) SOT-23 Package The internal synchronous switch increases efficiency and U eliminates the need for an external Schottky diode. Low APPLICATIO S output voltages are easily supported with the 0.6V feedback Cellular Telephones reference voltage. The LTC3406B-2 is available in a low pro- Personal Information Appliances file (1mm) SOT-23 package. Refer to LTC3406 for appli- Wireless and DSL Modems cations that require Burst Mode operation. Digital Still Cameras , LTC and LT are registered trademarks of Linear Technology Corporation. MP3 Players Burst Mode is a registered trademark of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. Portable Instruments Protected by U.S. Patents, including 6580258, 5481178. TYPICAL APPLICATIO High Efficiency Step-Down Converter Efficiency vs Load Current 100 V = 1.8V OUT 2.2H* V V OUT IN T = 25C 90 A 1.8V 2.7V V SW IN 600mA TO 5.5V 10F 80 4.7F 22pF CER CER LTC3406B-2 70 1M V = 3.6V IN RUN V 60 FB V = 2.7V IN GND 499k 50 40 3406B TA01a 30 20 V = 4.2V IN 10 0.1 1000 1 10 100 OUTPUT CURRENT (mA) 3406B TA01b sn3406b2 3406b2fs 1 EFFICIENCY (%) U ULTC3406B-2 UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) Input Supply Voltage .................................. 0.3V to 6V ORDER PART TOP VIEW NUMBER RUN, V Voltages ..................................... 0.3V to V FB IN SW Voltage (DC) ......................... 0.3V to (V + 0.3V) RUN 1 5 V FB IN LTC3406B-2ES5 GND 2 P-Channel Switch Source Current (DC) ............. 800mA SW 3 4 V IN N-Channel Switch Sink Current (DC) ................. 800mA S5 PART MARKING Peak SW Sink and Source Current ........................ 1.3A S5 PACKAGE 5-LEAD PLASTIC TSOT-23 Operating Temperature Range (Note 2) .. 40C to 85C T = 125C, = 250C/ W, = 90C/ W JMAX JA JC LTAGH Maximum Junction Temperature (Notes 3, 6) ..... 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. V = 3.6V unless otherwise specified. A IN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS I Feedback Current 30 nA VFB V Regulated Feedback Voltage (Note 4) T = 25C 0.5880 0.6 0.6120 V FB A (Note 4) 0C T 85C 0.5865 0.6 0.6135 V A (Note 4) 40C T 85C 0.5850 0.6 0.6150 V A V Reference Voltage Line Regulation V = 2.5V to 5.5V (Note 4) 0.04 0.4 %/V FB IN V Output Overvoltage Lockout V = V V , LTC3406B 20 50 80 mV OVL OVL OVL FB I Peak Inductor Current V = 3V, V = 0.5V or V = 90%, 0.75 1 1.25 A PK IN FB OUT Duty Cycle < 35% 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 V = 0.5V or V = 90% 350 500 A FB OUT Shutdown V = 0V, V = 4.2V 0.1 1 A RUN IN f Oscillator Frequency V = 0.6V or V = 100% 1.8 2.25 2.7 MHz OSC FB OUT V = 0V or V = 0V 310 kHz FB OUT R R of P-Channel FET I = 100mA 0.4 0.5 PFET DS(ON) SW R R of N-Channel FET I = 100mA 0.35 0.45 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 Note 1: Absolute Maximum Ratings are those values beyond which the life Note 4: The LTC3406B-2ES5 is tested in a proprietary test mode that of a device may be impaired. connects V to the output of the error amplifier. FB Note 2: The LTC3406B-2ES5 is guaranteed to meet performance Note 5: Dynamic supply current is higher due to the gate charge being specifications from 0C to 70C. Specifications over the 40C to 85C delivered at the switching frequency. operating temperature range are assured by design, characterization and Note 6: This IC includes overtemperature protection that is intended to correlation with statistical process controls. protect the device during momentary overload conditions. Junction Note 3: T is calculated from the ambient temperature T and power temperature will exceed 125C when overtemperature protection is active. J A dissipation P according to the following formula: Continuous operation above the specified maximum operating junction D temperature may impair device reliability. LTC3406B-2ES5: T = T + (P )(250C/W) J A D sn3406b2 3406b2fs 2 U WWW