
PENTIUM
652 MITCHELL ROAD NEWBURY PARK CA 91320
®
PROCESSOR P55C
VOLTAGE REGULATOR MODULE
MP55C
October 27, 1997
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION:
The MP54C/MP55C series of power modules are low
noise (no EMI), economical linear DC:DC converters
with an integral connector conforming to Intel Corporation’s Voltage Regulator Module specification for the
Pentium
Outstanding features include internal current limiting
and thermal shutdown, providing full device protection
against load faults and thermal overstress. The MP55C
is designed to power split voltage plane microprocessors requiring 3.3V V
ways supplied directly from a 3.3V input; either the
main system power supply or a low dropout regulator
on the motherboard. The CPU core can be supplied
either from the 3.3V main supply to reduce heat dissipation (MP55C-3.3) or the 5V main power supply
(MP55C-5). The MP55C-3.3 still requires a few mA of
5V power for control circuitry. The MP55C-3.3 will not
be available for CPU core voltages higher than 2.8V.
Please contact Semtech for availability.
®
Processor.
and 2.xV V
I/O
CORE
. The V
I/O
is al-
FEATURES:
• Integral VRM header connector
• Input voltage 5V ± 5%
• 2.8 ± 0.1V output for CPU core power
• 3.3V passes through the I/O power plane
• Maximum output current 6A
• Input power voltage:
5V ± 5% for MP55C-5 or
3.3V for MP55C-3.3
• Low noise, no EMI
ORDERING INFORMATION:
DEVICE Input (V) Output (V)
MP55C-5-2.8 5.0 2.8
MP55C-5-2.5 5.0 2.5
MP55C-3.3-2.8 3.3 2.8
APPLICATIONS:
• Pentium
®
Processor P55C, Cyrix 6x86 and
AMD5K86 power supplies
MP55C-3.3-2.7 3.3 2.7
MP55C-3.3-2.5 3.3 2.5
ELECTRICAL CHARACTERISTICS
PARAMETER SYMBOL MIN TYP MAX UNITS
Output Voltage
Output Current I
Line Regulation
Load Regulation
Dropout voltage (MP55C-5)
(MP55C-3.3)
Current Surge Limit I
Quiescent Current I
Temperature Coefficient T
Temperature Stability T
RMS Output Noise
Ripple Rejection Ratio R
Linear Airflow Requirements
(ambient temperature 55°C)
NOTES:
(1) Low duty cycle pulse testing with Kelvin connections required.
(2) Bandwidth of 10 Hz to 10 kHz.
(1)
2.8V version V
O
2.7 2.8 3.0 V
2.7V version 2.6 2.7 2.8
2.5V version 2.4 2.5 2.6
6.0 A
1.3 V
(1)
(1)
REG
REG
O
V
(LINE)
(LOAD)
D
0.015 0.2 %
0.1 0.4 %
1.2
0.40
S
Q
C
(2)
S
V
N
A
0.5
100
7.5 A
12 16 mA
0.005 %/°C
0.5 %
0.003 %V
72 dB
m/s
ft/min
O
Pentium is a registered trademark of Intel Corporation. AMD5K86 is a trademark of Advanced Micro Devices. 6x86 is a trademark of Cyrix.

October 27, 1997
652 MITCHELL ROAD NEWBURY PARK CA 91320
PENTIUM
®
PROCESSOR P55C
VOLTAGE REGULATOR MODULE
MP55C
INPUT AND OUTPUT CONNECTIONS
Pin No. Row A Row B Pin No.
1 V
2 V
SS
SS
3 ND V
4 V
I/O
V
SS
V
SS
I/O
V
I/O
1
2
3
4
5 +3.3V +3.3V 5
6 +3.3V +3.3V 6
7 V
8 V
9 V
10 V
CORE
CORE
SS
CORE
V
V
V
V
CORE
CORE
CORE
CORE
7
8
9
10
11 PWR GOOD RES 11
12 SENSE DISABLE 12
13 V
SS
V
SS
13
14 +5.0V +5.0V 14
15 +5.0V +5.0V 15
A B
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
VRM
PCB
End view of VRM connector
(viewed from motherboard side)
VOLTAGE REGULATOR MODULE CONNECTOR PIN REFERENCE
Pin Name I/O Function Notes
+3.3V Input +3.3V Supply Connected directly to V
MP55C-3.3: Main Power Input
+5.0V Input +5.0V Supply
V
V
V
CORE
I/O
SS
Output Voltage Regulator Module Output 2.8V output for CPU core
Output CPU I/O power connection. Tied to 3.3V input (V
Input Ground Reference Ground
DISABLE Input When driven high, this input will disable the
Voltage Regulator Module output and the
output of the module will float.
PWR GOOD Output Power Good is driven low when the VRM
output is not within valid levels.
SENSE Input Sense is provided for the regulator to correct
for voltage drops across the connector and
motherboard powerplane.
RES Input Formerly UPVRM# Tied to output.
ND Not connected
MP55C-5: Main power input
MP55C-3.3: Bias for regulator control
Not connected
Not connected
MP55C-5: Not connected
MP55C-3.3: Connected
CC3
I/O
)
.

October 27, 1997
652 MITCHELL ROAD NEWBURY PARK CA 91320
MECHANICAL DIMENSIONS
PENTIUM
®
PROCESSOR P55C
VOLTAGE REGULATOR MODULE
MP55C
Dimension Inches Millimeters
A 2.575 65.4
B 1.8 45.7
C 0.8 20.3
D 1.6 40.6
E 0.24 6.1
B
2
B
3
B
5
0.42 10.7
0.15 3.8
0.5 12.7
INPUT VOLTAGE CONFIGURATIONS
MP55C-3.3
Uses 3.3V input (from main system power supply) for
conversion to CPU core voltage. Lowest dropout at 4A
is 0.35V; VCORE higher than 2.8V must use MP55C-5.
Component size and location
for illustration only
MP55C-5
Uses 5V for main power and 3.3V for V
. 3.3V can be
I/O
supplied by a low dropout regulator such as an
EZ1085. 5V is supplied by main system power supply.
A few milliamps of power at 5V is necessary for control
circuit bias.