[Richtek]

General Description
The RT9221 integrates a PWM controller and two low-dropout linear regulators into a single chip. The PWM controller provides the CPU core voltage controlled by a 5-bit DAC and the linear section regulates power for GTL bus, clock driver or other circuits on motherboards.

Features
• Provides 3 Regulated Voltages
• N-MOSFET Driver for High Efficiency Switching Section
• Power-good, Over-voltage, and Currentlimiting Protection for Switching Section
• 1.5V and 2.5V Fixed Output Voltage for Linear Section
• Linear Section Uses Low Cost NPN Transistor as Power Device
• TTL-compatible 5-bit DAC Core Output Voltage

Applications
• Power Supply for Pentium, Pentium ProTM, Pentium IITM, Power PCTM, K6TM, 6×86TM, and AlphaTM Microprocessors
• High-power 5V to 3.xV DC-DC Regulators
• Low-voltage Distributed Power Supplies
• Programmable Power Supplies