A hybrid 4-in-1 DC?DC controller chip for a PC mainboard

Abstract

The DC–DC converter is a fundamental component of the personal computer (PC) mainboard and occupies a large part of its area. To increase the integration and reduce the cost of PC mainboards, a new hybrid 4-in-1 DC–DC power controller integrated circuit is designed, which integrates a programmable synchronous buck switching controller, a standard buck switching controller, a linear controller and a linear regulator with an on-chip MOS switch into one chip. It provides the complete solution of control, output adjustment, output monitoring and overcurrent/over-voltage protections for the four power supplies on a PC mainboard. The chip is designed and fabricated in the 1.7µm BiCMOS process. Test results of the established hybrid power system for PC mainboards show that the programmable synchronous switching regulator has fast transient response, small startup overshoot, high conversion efficiency and high precision of 0.8% under full load range. It meets the specifications of Intel's VRM8.4 design guidelines for the power supply of high-performance Pentium III central processing units. The standard switching regulator and the other two linear regulators also have high precision and small startup overshoots, they are suitable for providing voltages for the I/O, GTL bus and clock generator respectively on the PC mainboard.