MAX1947 19-3086 Rev 2 10/06 Low Input/Output Voltage Step-Up DC-DC Converter with RESET General Description Features The MAX1947 is a compact, high-efficiency, step-up DC- Low Input (0.7V) and Output (1.8V) Voltage DC converter that regulates output voltages from 1.8V to Capability 3.3V to power P/DSP cores, memory, and I/O rails in 1- Internal Synchronous Rectifier and 2-cell alkaline/NiMH/NiCd battery-powered systems. High 94% Efficiency It features an internal 800mA switch and synchronous rectifier to achieve up to 94% efficiency and to eliminate Fixed Output Voltages: 1.8V, 2.5V, 3V, and 3.3V the need for an external Schottky diode. Up to 2MHz Switching Allows Small External High-frequency switching (up to 2MHz) results in low Components and Low Output Ripple ripple and small external components, while automatic Automatic Pulse Skipping at Light Loads for pulse skipping at light loads reduces supply current to Extended Battery Life just 70A for extended battery life. Maxims proprietary Low 70A (typ) Operating Supply Current True Shutdown reduces supply current to just 2A (Measured at OUT) and fully discharges the output to ground. The convert- er is offered in fixed-output voltages of 1.8V, 2.5V, 3.0V, Low 2A Logic-Controlled Shutdown and 3.3V, requiring no feedback or compensation net- True Shutdown Fully Discharges Output to Ground work. A 75ms RESET output flag provides for power-on Uses Only Small Ceramic Capacitors reset (POR) and undervoltage detection. The MAX1947 is available in a space-saving 8-pin TDFN package. 75ms RESET Output Flag Applications Ordering Information MP3 Players, Pagers, and CD Players PKG PART TEMP RANGE PIN-PACKAGE PDAs and Organizers CODE Digital Still Cameras 8 TDFN 3mm x 3mm MAX1947ETAxy*-T -40C to +85C T833-1 8 TDFN 3mm x 3mm MAX1947ETAxy*+T -40C to +85C T833-1 Cordless Phones *xy represents the output voltage code (e.g., 18 =1.8V). Wireless Mice/Keyboards Standard output voltages include 3.3V (33), 3.0V (30), 2.5V Portable Medical Equipment (25), and 1.8V (18). Contact the factory for other output voltages in 100mV increments between 1.8V and 3.3V the minimum Other Battery-Powered Systems order quantity is 25,000 units. +Denotes lead-free package. Typical Application Circuit Pin Configuration V IN TOP VIEW 4.7H +0.7V TO +V OUT 2.2F RESET 1 8 BATT LX V OUT +1.8V, +2.5V, GND 2 7 OUT +3.0V, +3.3V BATT MAX1947 OUT GND 3 6 LX 10F MAX1947 SHDN 4 5 PGND SHDN PGND RESET TDFN 3mm x 3mm GND A SIGN WILL REPLACE THE FIRST PIN INDICATOR ON LEAD-FREE PACKAGES. True Shutdown is a trademark of Maxim Integrated Products, Inc. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLELow Input/Output Voltage Step-Up DC-DC Converter with RESET ABSOLUTE MAXIMUM RATINGS BATT, OUT, SHDN to GND ...................................-0.3V to +4.0V Operating Temperature Range ...........................-40C to +85C Junction Temperature......................................................+150C RESET to GND..........................................-0.3V to (V + 0.3V) OUT PGND to GND .......................................................-0.3V to +0.3V Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Switch Current (I , I , I ) (Note 1) .................-1A to +1A LX OUT PGND Continuous Power Dissipation (T = +70C) A 8-Pin TDFN (derate 24.4mW/C above +70C)..........................................................1951.2mW Note 1: LX has internal clamp diodes to PGND and OUT. Applications that forward bias these diodes should take care not to exceed the ICs package power-dissipation limits. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (V = 1.5V, T = -40C to +85C, unless otherwise noted. Typical values are at T = +25C.) (Note 2) BATT A A PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Startup Voltage R = 1k, T = +25C 0.8 0.95 V LOAD A Startup-Voltage Temperature -2.1 mV/C Coefficient Maximum Input Operating (Note 3) 3.6 V Voltage Minimum Input Operating Voltage 0.7 V MAX1947ETA18, I = 40mA 1.74 1.8 1.86 LOAD MAX1947ETA25, I = 32mA 2.42 2.5 2.58 LOAD Output Voltage V MAX1947ETA30, I = 25mA 2.9 3.0 3.1 LOAD MAX1947ETA33, I = 25mA 3.2 3.3 3.4 LOAD Load Regulation No load to full load 1.2 % MAX1947ETA18 160 273 MAX1947ETA25 130 214 V = 1V BATT MAX1947ETA30 100 185 Full-Load Output Current mA MAX1947ETA33 100 169 MAX1947ETA25 240 380 V = 1.8V BATT MAX1947ETA30 200 361 MAX1947ETA33 200 329 Supply Current into BATT No switching 2 4 A Supply Current into OUT No switching 70 110 A LX Switch Maximum On-Time 0.7 1 1.3 s LX Switch Minimum Off-Time 0.2 0.25 0.3 s V = 2.5V, 3.0V, 3.3V 3.6 4 4.6 Maximum On-Time to Minimum OUT s/s Off-Time Ratio V = 1.8V 3.0 4 4.6 OUT Frequency in Startup 650 kHz 2 MAX1947