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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 and Output Enable functions
Excellent transient response
Over-Voltage Protection
Short Circuit Protection
Precision trimmed low TC voltage reference
20 pin SOIC package
Meets Intel Pentium
Pro VRM specifications using
minimum number of external components
Applications
Programmable power supply for Pentium
Pentium
based CPU motherboards
VRM module for Pentium
Programmable power supply for high current
microprocessors
Pro and
Pro CPU
Description
The RC5040 is a synchronous mode 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 RC5040 can generate precise output
voltages between 2.1V and 3.5V in 100mV increments.
Output load currents in excess of 12A can be delivered using
minimal external circuitry. The RC5040 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
components in order to achieve tight voltage regulation.
The Pentium 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
ENABLE
4-BIT
DAC
65-5040-01
POWER
GOOD
OSCILLATOR
RC5040
PWRGD
VID0
VID1
VID2
VID3
–
+
–
+
–
+
VIN
VO
VREF
+5V
RC5040
Programmable S ync hronous DC-DC Converter
Rev. 1.3.1