SC1401

HIGH PERFORMANCE SYNCHRONOUS BUCK CONTROLLER WITH LDO FOR PORTABLE POWER November 21, 2000 SC1401 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC1401 is a synchronous buck regulator designed to power the latest generation microprocessors in battery operated systems. The SC1401 may be used to provide both the I/O and core voltages utilizing synchronous rectification for the core supply voltage and an LDO N-Channel MOSFET controller for the I/O supply voltage. A 1.25 volt reference allows lower output voltages required by today’s portable microprocessors. The synchronous buck regulator is capable of achieving efficiencies up to 95%. The gate drive circuitry can deliver 2.0A peak currents, allowing the use of N-channel MOSFETs for lower switching and conduction losses. A digital soft start is provided to ensure orderly start up of the power supply without the need for external components. At light load in power save mode, the controller changes mode of operation by missing gate drive cycles, thus reducing gate drive current and improving efficiency. A logic high on PSAVE disables the power saving mode thus reducing noise. The SC1401 is fabricated in a high performance BiCMOS process. This process reduces the power dissipation in low current and shutdown operation modes and improves efficiency. The LDO controller is a high performance positive voltage regulator designed to provide a low noise power source to the microprocessor peripherals by dri...