Analog Devices Inc.

The MAX1630–MAX1635 are buck-topology, step-down,switch-mode, power-supply controllers that generatelogic-supply voltages in battery-powered systems. Thesehigh-performance, dual/triple-output devices include on-boardpower-up sequencing, power-good signaling withdelay, digital soft-start, secondary winding control, low-dropoutcircuitry, internal frequency-compensation networks,and automatic bootstrapping.Up to 96% efficiency is achieved through synchronousrectification and Maxim's proprietary Idle Mode™ controlscheme. Efficiency is greater than 80% over a 1000:1load-current range, which extends battery life in system-suspendor standby mode. Excellent dynamic responsecorrects output load transients caused by the latestdynamic-clock CPUs within five 300kHz clock cycles.Strong 1A on-board gate drivers ensure fast externalN-channel MOSFET switching.These devices feature a logic-controlled and synchronizable,fixed-frequency, pulse-width-modulation (PWM)operating mode. This reduces noise and RF interferencein sensitive mobile communications and pen-entry applications.Asserting the active-low SKIP pin enables fixed-frequencymode, for lowest noise under all load conditions.The MAX1630–MAX1635 include two PWM regulators,adjustable from 2.5V to 5.5V with fixed 5.0V and 3.3Vmodes. All these devices include secondary feedbackregulation, and the MAX1630/MAX1632/MAX1633/MAX1635 each contain 12V/120mA linear regulators. TheMAX1631/MAX1634 include a secondary feedback input(SECFB), plus a control pin (STEER) that selects whichPWM (3.3V or 5V) receives the secondary feedback signal.SECFB provides a method for adjusting the secondarywinding voltage regulation point with an externalresistor divider, and is intended to aid in creating auxiliaryvoltages other than fixed 12V.The MAX1630/MAX1631/MAX1632 contain internal outputovervoltage and undervoltage protection features.ApplicationsDesktop CPU Local DC-DC ConvertersNotebook and Subnotebook ComputersPDAs and Mobile Communicators