LTC1772B Constant Frequency Current Mode Step-Down DC/DC Controller in SOT-23 FEATURES DESCRIPTION n Burst Mode Operation Disabled for Lower Output The LTC 1772B is a constant frequency current mode Ripple at Light Loads step-down DC/DC controller providing excellent AC and n High Ef ciency: Up to 94% DC load and line regulation. The device incorporates an n High Output Currents Easily Achieved accurate undervoltage lockout feature that shuts down the n Wide V Range: 2.5V to 9.8V LTC1772B when the input voltage falls below 2.0V. IN n Constant Frequency 550kHz Operation The LTC1772B provides a 2.5% output voltage accuracy n Low Dropout: 100% Duty Cycle and consumes only 270A of quiescent current. In shut- n Output Voltage Down to 0.8V down, the device draws a mere 8A. n Current Mode Operation for Excellent Line and Load To further maximize the life of a battery source, the Transient Response n external P-channel MOSFET is turned on continuously Shutdown Mode Draws Only 8A Supply Current n in dropout (100% duty cycle). High constant operating Tiny 6-Lead TSOT-23 Package frequency of 550kHz allows the use of a small external inductor. APPLICATIONS The LTC1772B is available in a small footprint 6-lead n TSOT-23. One or Two Lithium-Ion-Powered Applications n Cellular Telephones For a Burst Mode operation enabled version of the n Wireless Devices LTC1772B, please refer to the LTC1772 data sheet. n Portable Computers L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n Distributed 3.3V, 2.5V or 1.8V Power Systems All other trademarks are the property of their respective owners. TYPICAL APPLICATION Ef ciency vs Load Current* V 100 IN 2.5V LTC1772 C1 TO 9.8V R1 95 Burst Mode 10F 0.03 OPERATION 10V 90 1 6 L1 I /RUN PGATE M1 TH 85 V 4.7H OUT 2.5V LTC1772B 10k LTC1772B 80 + C2A C2B 2A 2 5 GND V NON-Burst Mode D1 IN 47F 1F 3 4 220pF OPERATION 6V 10V 174k 75 V SENSE FB 70 C1: TAIYO YUDEN LMK325BJ106K-T 65 V = 3.6V IN C2A: SANYO 6TPA47M 80.6k V = 2.5V OUT C2B: AVX 0805ZC105KAT1A 60 D1: MOTOROLA MBRM120T3 10 100 1000 10000 L1: MURATA LQN6C-4R7 LOAD CURRENT (mA) M1: FAIRCHILD FDC638P 1772 F01a *OUTPUT RIPPLE WAVEFORMS FOR THE CIRCUIT R1: IRC LRC-LR1206-01-R030F OF FIGURE 1 APPEAR IN FIGURE 2. 1772 F01b Figure 1. High Ef ciency, High Output Current 2.5V/2A Regulator 1772bfa 1 EFFICIENCY (%)LTC1772B ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) Input Supply Voltage (V ) .........................0.3V to 10V TOP VIEW IN SENSE , PGATE Voltages ...............0.3V to (V + 0.3V) IN I /RUN 1 6 PGATE TH V , I /RUN Voltages............................... 0.3V to 2.4V FB TH GND 2 5 V IN PGATE Peak Output Current (<10s) ........................ 1A V 3 4 SENSE FB Storage Ambient Temperature Range.....65C to 150C S6 PACKAGE 6-LEAD PLASTIC TSOT-23 Operating Temperature Range (Note 2).... 40C to 85C T = 150C, = 230C/W JMAX JA Junction Temperature (Note 3) ............................ 150C Lead Temperature (Soldering, 10 sec) .................. 300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1772BES6 PBF LTC1772BES6 TRPBF LTVU 6-Lead Plastic TSOT Package 40C to 85C LTC1772BIS6 PBF LTC1772BIS6 TRPBF LTVU 6-Lead Plastic TSOT Package 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1772BES6 LTC1772BES6 TR LTVU 6-Lead Plastic TSOT Package 40C to 85C LTC1772BIS6 LTC1772BIS6 TR LTVU 6-Lead Plastic TSOT Package 40C to 85C 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. For more information on lead free part marking, go to: