The RT9228 is a 3-in-one power controller optimized for high-performance microprocessor and computer applications. The IC integrates a synchronous buck PWM controller, a linear regulator, and a linear controller as well as monitoring and protection functions into a 24-pin SOP package. The PWM controller regulates the microprocessor core voltage. The linear regulator provides power for the clock driver circuit and the linear controller regulates power for the GTL bus. The RT9228 features an Intel-compatible, TTL 5-bit programmable DAC that adjusts the core voltage from 2.1V to 3.5V in 0.1V increments and from 1.3V to 2.05V in 0.05V steps. The 5-bit DAC has a typical 1% tolerance. The linear regulator uses an internal drive device to provide 2.5V 2.5% output voltage. The linear controller drives an external N-Channel MOSFET or a low cost NPN bipolar transistor to provide 1.5V 2.5%. The RT9228 monitors all the output voltages. A Powergood signal is issued when the core voltage is within 10% of the DAC setting and the other levels are above their under-voltage levels. Additional build-in over-voltage protection for the core output uses the lower MOSFET to prevent output voltage above 115% of the DAC setting. The PWM over-current function monitors the output current using the voltage drop across the upper MOSFET's RDS(ON), which eliminates the need for a