Unitrode UCC3882
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 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.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 BLOCK DIAGRAM
DESCRIPTION
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 m...