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P
PRELIMINARY INFORMATION
describes products that are not in full production at the time of printing. Specifications are based on design goals
and limited characterization. They may change without notice. Contact Fairchild Semiconductor for current information.
www.fairchildsemi.com
Features
Drives N-Channel MOSFET
Operates From +5V or +12V V
CC
Bias
Operates from +5V Power Input
Simple Single-Loop Control Design
- Voltage-Mode PWM Control
Fast Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Ratio
Excellent Output Voltage Regulation
-
±
1.5% Over Line Voltage and Temperature
4 Bit Digital-to-Analog Output Voltage Selection
- Wide Range - 2.0VDC to 3.5VDC
- 0.1V Binary Steps
Power-Good Output Voltage Monitor
Over-Voltage and Over-Current Fault Monitors
- Does Not Require Extra Current Sensing Element, uses
MOSFET’s R
DS(ON)
Small Converter Size
- Constant Frequency Operation
- 200kHz Free-Running Oscillator Programmable from
50kHz to 1MHz
Block Diagram
Applications
Power Supply for Pentium
, Pentium
Pro, PowerPC
and Alpha Microprocessors
High-Power 5V to 3.xV DC-DC Regulators
Low-Voltage Distributed Power Supplies
Description
The RC5039 provides complete control and protection for a
DC-DC converter optimized for high-performance micropro-
cessor applications. It is designed to drive an N-Channel
MOSFET in a standard buck topology. The RC5039 inte-
grates all of the control, output adjustment, monitoring and
protection functions into a single package.
The RC5039 includes a 4-Input Digital-to-Analog Converter
(DAC) that adjusts the output voltage from 2.0VDC to
3.5VDC in 0.1V increments. The precision reference and
voltage-mode regulator hold the selected output voltage to
within
±
1.5% over temperature and line voltage variations.
D/A
CONVERTER
(DAC)
OSCILLATOR
SOFT-
START
REFERENCE
POWER-ON
RESET (POR)
115%
110%
90%
INHIBIT
PWM
COMPARATOR
ERROR
AMP
VCC
PGOOD
SS
PWM
GND
VSEN
OCSET
VID0
VID1
VID2
VID3
FB
COMP
DACOUT
OVER-
VOLTAGE
+
-
OVER-
CURRENT
CLOGIC
BOOT
UGATE
PHASE
200
μ
A
10
μ
A
4V
+
-
+
-
+
-
+
-
+
-
RT/OVP
Alpha is a trademark of Digital Equipment Corporation.
Pentium is a registered trademark of Intel Corporation.
PowerPC is a trademark of IBM.
RC5039
Programmable DC-DC Converter
for P55C, K 6, and M2 proc essors
Rev. 0.9.2