MAX777L

19-0186; Rev 2; 7/96 NUAL KIT MA ATION U EET L H A S V E TA WS DA FOLLO Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters ____________________________Features o 1V to 4.5V Input Guarantees Start-Up Under Load o Up to 210mA Output o Load Fully Disconnected in Shutdown o 82% Efficiency o Output in Regulation with Input Voltage above Output Voltage o Internal 1A Power Switch and Active Rectifier o Adjustable Current Limit Allows Low-Cost Inductors o 190µA No Load Supply Current o 20µA Shutdown Supply Current o 3V/3.3V (MAX778L), 5V (MAX777L), and Adjustable (MAX779L) Output Voltage _______________General Description The MAX777L/MAX778L/MAX779L are pulse-skipping DC-DC converters that step up from low-voltage inputs (1V guaranteed). They require only three external components—an inductor (typically 22µH) and two capacitors. The MAX777L delivers a 5V output, the MAX778L generates pin-selectable voltages of 3.0V or 3.3V, and the MAX779L output can be adjusted from 2.5V to 6V through an external resistive divider. The devices include an Active RectifierTM that eliminates the need for an external catch diode, and permits regulation even when the input is greater than the output. Also, unlike those in other step-up converters, the MAX777L/MAX778L/MAX779L’s Active RectifierTM turns off in the shutdown mode, disconnecting the output from the source. This eliminates the current drain associated with conventional step-up converters when off or in shutdown. High...