RT9221

The RT9221 integrates a PWM controller and twolow-dropout linear regulators into a single chip. ThePWM controller provides the CPU core voltagecontrolled by a 5-bit DAC and the linear sectionregulates power for GTL bus, clock driver or othercircuits on motherboards. The PWM controllerprovides an adjustable Intel-compatible 1.3V~3.5Voutput voltage. The synchronous N-MOSFET driverwith 200 KHz switching frequency optimizes theefficiency, device size, and cost built-in overvoltageand current-limiting protection prevent the CPU fromdamage. Power-good signal is sent when the corevoltage is within ±10% of the setting point.

The linear section is a low dropout regulator whichdrives low cost NPN transistors to supply the 1.5Vand 2.5V regulated output power.