5-Bit Programmable Synchronous Switching Regulator Controller for Pentium II Processor

The LTC1553 is a high power, high efficiency switching regulator controller optimized for 5V or 12V input to 1.8V-3.5V 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.

Applications

* Power Supply for Pentium II, SPARC, ALPHA and PA-RISC Microprocessors

* High Power 5V or 12V to 1.8V-3.5V Regulators

* 5-Bit Digitally Programmable 1.8V to 3.5V Fixed Output Voltage

* Provides All Features Required by the Intel Pentium® II Processor VRM 8.2 DC/DC Converter Specification

* Flags for Power Good, Over-Temperature and Overvoltage Fault

* 19A Output Current Capability from a 5V or 12V Supply

* Dual N-Channel MOSFET Synchronous Driver

* Initial Output Accuracy: ±1.5%

* Excellent Output Accuracy: ±2% Typ Over Line, Load and Temperature Variations

* High Efficiency: Over 95% Possible

* Adjustable Current Limit Without External Sense Resistors

* Fast Transient Response

* Available in 20-Lead SSOP and SW Packages