General Description
The APW6021 provides the power control and protection for four output voltages in high-performance, graphics intensive microprocessor and computer applications. The IC integrates voltage-mode PWM controller and three linear controllers, as well as the monitoring and protection functions into a 28-pin SOIC package. The PWM controller regulates the microprocessor core voltage with a synchronous-rectified buck converter. The linear controllers regulate the computer system’s AGP 1.5V or 3.3V bus power, the 1.5V GTL bus power, and the 1.8V power for the North/South Bridge core voltage and/or cache memory circuits.

Functional
• 4 Regulated Voltages are provided
    • Microprocessor Core (1.3V to 3.5V)
    • AGP Bus (1.5V or 3.3V)
    • Memory (1.8V)
    • GTL Bus (1.5V)
• Linear Controllers Drives with both MOSFET and Bipolar Series Pass Transistors
• Fixed or Externally Resistor-Adjustable Linear Outputs (FIX Pin)
• Simple Single-Loop Control Design
• Voltage-Mode PWM Control
• Fast PWM Converter Transient Response
    • High-Bandwidth Error Amplifier
    • Full 0% to 100% Duty Ratio
• Excellent Output Voltage Regulation
    • Core PWM Output: ± 1% Over Temperature
    • Other Outputs: ± 3% Over Temperature
• TTL-Compatible 5- Bit DAC Microprocessor Core Output Voltage Selection
    • Wide Range - 1.3VDC to 3.5 VDC
• Power-Good Output Voltage Monitor
• Over-Voltage and Over-Current Fault Monitors
    • Switching Regulator Does Not Require Extra Current Sensing Element, Uses MOSFET’s rDS(ON)
• Small Converter Size
    • Constant Frequency Operation
    • 200kHz Free-Running Oscillator; Program mable From 50kHz to Over 1MHz