The US3033 IC combines a switching controller and a linear regulator controller all in a compact 8 pin surface mount package, providing a total solution for dual supply processor applications such as an Intel P55C TM, AMD K6TM, as well as Cyrix 6X86LTM and the M2TMprocessors. Typically in these applications a dual supply regulator converts 5V to 3.3V for I/O supply and a jumper programmable supply of 1.25V to 3.5V for CORE supply .The linear regulator controller portion in the US3033 is a programmable controller allowing flexibility for the I/O regulator and has a minimum of 50mA drive current capability designed to provide ample current for an external pass transistor. The IC uses an internal regulator generated from the 12V supply to power the controller as well as the 12V supply to drive the power MOSFET, allowing a low cost N channel MOSFET switch to be used. The IC also includes an error comparator for fast transient response, a precise voltage reference for setting the output voltage as well as a direct drive of the MOSFET for the minimum part count.