UCC2882/-1

UCC3882/-1

03/99

FEATURES

• Combined DAC/Voltage Monitor and PWM

with Synchronous Rectification Functions

• 5-Bit Digital-to-Analog (DAC) Converter

• 1% DAC/Reference Combined Accuracy

• Compatible with 5V and 12V Systems and

12V-only Systems

• Low Offset Current Sense Amplifier

• Programmable Oscillator Frequency Practical

to 700kHz

• Foldback Current Limiting

• Overvoltage and Undervoltage Fault Windows

• 2Ω Totem Pole Outputs with Programmable

Dead Times to Eliminate Cross-Conduction

• Chip Disable Function

Average Current Mode Synchronous Controller With 5-Bit DAC

BLOCK DIAGRAM

UDG-97047-1

DESCRIPTION

The UCC3882 combines high precision reference and voltage

monitoring circuitry with average current mode PWM synchro-

nous rectification controller circuitry to power high-end micropro-

cessors 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 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/ref-

erence combination is better than 1%. Undervoltage lockout cir-

cuitry 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 ex-

ceeds its designed value by more than 17.5%.

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