The LTC1553 is a high power, high efficiency switching regulator controller optimized for 5V or 12V input to 1.8V3.5V output applications. It features a digitally programmable output voltage, a precision internal reference and an internal feedback system that provides output accuracy of 1.5% at room temperature and typically 2% over-temperature, load current and line voltage shifts. The LTC1553 uses a synchronous switching architecture with two external N-channel output devices, providing high efficiency and eliminating the need for a high power, high cost P-channel device. Additionally, it senses the output current across the on-resistance of the upper N-channel FET, providing an adjustable current limit without an external low value sense resistor. The LTC1553 free-runs at 300kHz and can be synchronized to a faster external clock if desired. It includes all the inputs and outputs required to implement a power supply conforming to the Intel Pentium II Processor VRM 8.2 DC/DC Converter Specification.