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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
Programmable output from 1.3V to 3.5V using an
integrated 5-bit DAC
85% efficiency typical
Adjustable operation from 80KHz to 1MHz
Integrated Power Good and Enable functions
Overvoltage protection
Overcurrent protection
Drives N-channel MOSFETs
20 pin SOIC package
Meets Intel Pentium II specifications using minimum
number of external components
Applications
Power supply for Pentium
II
VRM for Pentium II processor
Programmable step-down power supply
Description
The RC5051 is a synchronous mode DC-DC controller IC
which provides an accurate, programmable output voltage
for all Pentium II CPU applications. The RC5051 uses a
5-bit D/A converter to program the output voltage from 1.3V
to 3.5V. The RC5051 uses a high level of integration to
deliver load currents in excess of 19A from a 5V source with
minimal external circuitry. Synchronous-mode operation
offers optimum efficiency over the entire specified output
voltage range, and the internal oscillator can be programmed
from 80KHz to 1MHz for additional flexibility in choosing
external components. An on-board precision low TC refer-
ence achieves tight tolerance voltage regulation without
expensive external components. The RC5051 also offers
integrated functions including Power Good, Output Enable,
over-voltage protection and current limiting.
Block Diagram
DIGITAL
CONTROL
+5V
1
16
20 19 18 17
8
2
3
9
7
12
13
4
5
–
+
1.24V
REFERENCE
5-BIT
DAC
65-5051-01
POWER
GOOD
OSC
PWRGD
VREF
VID0
VID1
VID2
VID4
VID3
ENABLE
–
+
–
+
–
+
+5V
VO
RC5051
+12V
RC5051
Programmable S ync hronous DC-DC Controller for
Low Voltage Mic roproc essors
Rev. 1.0.3
Pentium is a registered trademark of Intel Corporation.