UCC3882-1

This IC is intended to be used in a high performance power supply to power the Pentium^® II or a similar processor. Figure 1 shows a typical power supply application circuit which converts +5V to lower voltages required by the Pentium^® II Processor.

The UCC3882 combines high precision reference and voltage monitoring circuitry with average current mode PWM synchronous rectification controller circuitry to power high-end microprocessors with a minimum of external components. The UCC3882 converts 5V or 12V to an adjustable output ranging from 1.8VDC to 2.05VDC in 50mV steps and 2.1VDC to 3.5VDC in 100mV steps with 1% DC system accuracy.

The UCC3882 DAC output voltage is directly compatible with Intel's 5-bit VID code (Table 1) which covers 1.3V to 2.05V in 50mV steps and 2.1V to 3.5V in 100mV steps. The accuracy of the DAC/reference combination is better than 1%. Undervoltage lockout circuitry assures the correct logic states at the outputs during power up and power down. The overvoltage and undervoltage comparators monitor the system output voltage and indicate when it rises above or falls below its designed value by more than 9%. A second overvoltage comparator digitally forces GATEHI off and GATELO on when the system output voltage exceeds its designed value by more than 17.5%.