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www.fairchildsemi.com
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.
Features
Current Sensing is achieved using MOSFET R
DS(ON)
Programmable output from 1.3V to 3.5V using an
integrated 5-bit DAC
85% efficiency typical at full load
Adjustable operation from 50KHz to 1MHz
Integrated Power Good and Enable/Soft Start functions
Overvoltage protection pin controls external SCR
Short circuit protection with current limiting
Drives N-channel MOSFETs
20 pin SSOP and SOIC package
Meets Intel Pentium II specifications using minimum
number of external components
On board LDO for GTL termination
On board LDO for Clock power supply
TTL Compatible inputs
Applications
Power supply for Pentium
II
VRM for Pentium II processor
Programmable step-down power supply
Block Diagram
Description
The RC5056 is a synchronous mode DC-DC controller IC
which provides an accurate, programmable output voltage
for all Pentium II CPU applications. The RC5056 uses a
5-bit D/A converter to program the output voltage from 1.3V
to 3.5V. The RC5056 uses a high level of integration to
deliver load currents in excess of 17A 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 50KHz 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 RC5056 also offers
integrated functions including Power Good, Output Enable/
Soft Start, over-voltage protection and current limiting. The
linear regulator is also specified at 1% precision.
D/A
CONVERTER
(DAC)
OSCILLATOR
SOFT-
REFERENCE
POWER-ON
115%
110%
90%
INHIBIT
COPWM
EAMP
VCC
PGOOD
13
23
16
2
15
14
17
18
12
20
1
5
6
7
8
9
11
10
19
3
4
SS
OVP
PWM
GNDA
OPAMP1
VSEN
OCSET
VID0
VID1
FB
COMP
OVP/RT
GATE1
FB1
DACOUT
VREF
VOVER-
+
-
COVER-
CLOGIC
UGATE
PHASE
LGATE
PGND
200
μ
A
10
μ
A
4V
+
-
+
-
+
-
+
-
+
-
+
-
65-5056-01
RC5056
Programmable S ync hronous DC-DC Converter
Controller for Low Voltage Mic roproc essors and
V tt Linear Regulator
Pentium is a registered trademark of Intel Corporation.
Rev. 0.9.0