AIC1573

AIC1573 5-bit DAC, Synchronous PWM Power Regulator with Simple PWM Power Regulator, LDO And Linear Controller n FEATURES l l n DESCRIPTION The AIC1573 combines two PWM voltage mode controllers and two linear controllers as well as the monitoring and protection functions in this chip. One PWM controller regulates the microprocessor core voltage with a synchronous rectified buck converter. The second PWM controller provides AGP bus 1.5V or 3.3V power with a standard buck converter. Two linear controllers regulate power for the 1.5V GTL bus and 1.8V power for the chip set core voltage and/or cache memory circuits. An integrated 5 bit D/A converter that adjusts the microprocessor core voltage from 2.1V to 3.5V in 0.1V increments and from 1.3V to 2.05V in 0.05V increments. The second PWM controller for AGP bus power is selectable by means of SELECT pin status for 1.5V or 3.3V with 3% accuracy. Two linear controllers drive with external N-channel MOSFETs to provide 1.5V±3% and fixed output voltage 1.8V±3%. This chip monitors all the output voltages. Power Good signal is issued when the core voltage is within ±10% of the DAC setting and the other levels are above their under-voltage levels. Over-voltage protection for the core output uses the lower Nchannel MOSFET to prevent output voltage above 116% of the DAC setting. The PWM over-current function monitors the output current by using the voltage drop across the upper MOSFET’s RDS(ON), eliminating the need for a current sensing r...