7A, Very Low Dropout Regulator

The LT1580 is a 7A low dropout regulator designed to power the new generation of microprocessors. The dropout voltage of this device is 100mV at light loads rising to just 540mV at 7A. To achieve this dropout, a second low current input voltage 1V greater than the output voltage, is required. The device can also be used as a single supply device where dropout is comparable to an LT1584.

Several other new features have been added to the LT1580. A remote SENSE pin is brought out. This feature virtually eliminates output voltage variations due to load changes. Typical load regulation, measured at the SENSE pin, for a load current step of 100mA to 7A is less than 1mV.

The LT1580 has fast transient response, equal to the LT1584. On fixed voltage devices, the ADJ pin is brought out. A small capacitor on the ADJ pin further improves transient response.

This device is ideal for generating processor supplies of 2V to 3V on motherboards where both 5V and 3.3V supplies are available.

Applications

* Microprocessor Supplies

* Post Regulators for Switching Supplies

* High Current Regulators

* 5V to 3.XXV for Pentium® Processors Operating at 90MHz to 166MHz and Beyond

* 3.3V to 2.9V for Portable Pentium Processor

* Power PC™ Series Power Supplies

* Low Dropout, 540mV at 7A Output Current

* Fast Transient Response

* Remote Sense

* 1mV Load Regulation

* Fixed 2.5V Output and Adjustable Output

* No Supply Sequencing Problems in Dual Supply Mode