AIC1574

The AIC1574 combines a synchronous voltage mode controller with three linear controller as well as the monitoring and protection functions in this chip. The PWM controller regulates the microprocessor core voltage with a synchronous rectified buck converter.The three linear controllers regulate power for the 1.5V or 3.3V AGP bus power for AIC1574, the 1.5V GTL bus and the 1.8V power for the chip set core voltage and/or cache memory circuits.An integrated 5 bit D/A converter that adjusts the core PWM output voltage from 2.1V to 3.5V in 0.1V increments and from 1.3V to 2.05V in 0.05V increments.

The linear controller for AGP bus power is selectable by TTL-compatible SELECT pin status for 1.5V or 3.3V with ±3% accuracy. The other two linear controller provide 1.5V±3% and 1.8V±3% or adjustable output voltage by means of external divided resistor based on FIX pin status. AIC1574 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 resistor.