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www.fairchildsemi.com
Features
Programmable output from 2.1V to 3.5V using integrated
4-bit DAC
87% efficiency
Oscillator frequency adjustable from 200KHz to 1MHz
On-chip Power Good function
Excellent transient response
Over-Voltage Protection
Short Circuit Protection
Precision trimmed low TC voltage reference
16 pin SOIC package
Meets Intel Pentium
Pro VRM specifications using
minimum number of external components
Applications
Programmable power supply for Pentium Pro and
Pentium-based CPU motherboards
VRM module for Pentium Pro CPU
Programmable power supply for high current
microprocessors
Description
The RC5042 is a non-synchronous DC-DC controller IC
which provides an accurate, programmable output for
Pentium Pro CPU applications. Using an integrated 4-bit
DAC to accept a voltage identification (VID) code directly
from the CPU, the RC5042 can generate precise output volt-
ages between 2.1V and 3.5V in 100mV increments. Output
load currents in excess of 12A can be delivered using mini-
mal external circuitry. The RC5042 is designed to operate in
a standard PWM control mode under heavy load conditions
and in PFM control mode while supplying light loads for
optimal efficiency. An on-board precision low TC voltage
reference eliminates the requirement for external compo-
nents in order to achieve tight voltage regulation. The Pen-
tium Pro CPU is continuously protected by an integrated
Power Good function, which sends an active-low interrupt
signal to the CPU in the event that the output voltage is out
of tolerance. The internal oscillator can be programmed to
operate over a range of 200KHz to 1MHz to allow flexibility
in choosing external components.
Block Diagram
DIGITAL
CONTROL
–
+
1.24V
REFERENCE
4-BIT
DAC
65-5042-01
POWER
GOOD
OSCILLATOR
RC5042
PWRGD
VID0
VID1
VID2
VID3
–
+
–
+
–
+
VIN
VO
VREF
+5V
RC5042
Programmable DC-DC Converter
Rev. 1.3.1