UCC2882/-1
UCC3882/-1
Average Current Mode Synchronous Controller With 5-Bit DAC
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
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%.
(continued)
BLOCK DIAGRAM
UDG-97047-1
03/99
Powered by ICminer.com Electronic-Library Service CopyRight 2003
ETC [ ETC ]
