VRM8.5 Dual PWM and Dual Linear Power System Controller

The ISL6523A provides the power control and protection for four output voltages in high-performance microprocessor and computer applications. The IC integrates two PWM controllers and two linear controllers, as well as the monitoring and protection functions into a 28-pin SOIC package. One PWM controller regulates the microprocessor core voltage with a synchronous-rectified buck converter. The second PWM controller supplies the computer system’s AGTL+ 1.2V bus power with a standard buck converter. The linear controllers regulate power for the 1.5V AGP bus and the 1.8V power for the chipset core voltage and/or cache memory circuits.

Features
• Provides 4 Regulated Voltages
    - Microprocessor Core, AGTL+ Bus, AGP Bus Power,
        and North/South Bridge Core
• Drives N-Channel MOSFETs
• Linear Regulator Drives Compatible with both MOSFET
    and Bipolar Series Pass Transistors
• Simple Single-Loop Control Designs
    - Voltage-Mode PWM Control
• Fast PWM Converter Transient Response
    - High-Bandwidth Error Amplifiers
    - Full 0% to 100% Duty Ratios
• Excellent Output Voltage Regulation
    - Core PWM Output . . . . . . . . . . ±1% Over Temperature
    - All Other Outputs . . . . . . . . . . . . . ±3% Over Temperature
• VRM8.5 TTL-Compatible 5-Bit DAC Microprocessor Core
    Output Voltage Selection
    - Wide Range . . . . . . . . . . . . . . . . . . . . 1.050V to 1.825V
• Power-Good Output Voltage Monitors
    - Separate delayed VTT Power Good
• Overcurrent Fault Monitors
    - Switching Regulators Do Not Require Extra Current
        Sensing Elements, Use MOSFET’s rDS(ON)
• Small Converter Size
    - Constant Frequency Operation
    - 200kHz Internal Oscillator

Applications
• Motherboard Power Regulation for Computers