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otherwise under any patent or patent rights of Analog Devices.
a
ADP3011
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
Analog Devices, Inc., 1998
5-Bit Programmable Synchronous
Switching Regulator Controller
for Pentium
II Processor
FEATURES
5-Bit Digitally Programmable 1.8 V to 3.5 V Output
Voltage
Dual N-Channel Synchronous Driver
High Efficiency
Current-Mode Operation
Short Circuit Protection
Power Good Output
Integrated Overvoltage Protection Crowbar
16-Lead SOIC Package
VRM 8.2 Compatible
APPLICATIONS
Desktop PC Power Supply for:
Pentium II Processor
Pentium Pro Processor
Pentium Processor
AMD–K6 Processor
VRM Modules
GENERAL DESCRIPTION
The ADP3011 is a highly efficient synchronous switching regu-
lator controller optimized for Pentium II Processor applications
where 5 V is stepped down to a digitally controlled output volt-
age between 1.8 V and 3.5 V. Using a 5-bit DAC to read a
voltage identification (VID) code directly from the processor,
the ADP3011 uses a current-mode constant off-time architec-
ture to generate its precise output voltage.
V
CC
SD
DRIVE1
SENSE+
SENSE–
DRIVE2
PGND
VID0–VID4
AGND
C
T
CMP
V
CC
+12V
1
m
F
22
m
F
R1
R2
150pF
5-BIT CODE
IRL3103
V
IN
+5V
+C
IN
10BQ015
L
2.5
m
H
IRL3103
+C
O
V
1.8V–3.5V
14A
R
6.7m
V
1nF
ADP3011
C
COMP
Figure 1. Typical Application
Pentium is a registered trademark of Intel Corporation.
All other trademarks are the property of their respective holders.
FUNCTIONAL BLOCK DIAGRAM
g
m
NONOVERLAP
DRIVE
IN
CROWBAR
12
14
13
15
SD
V
CC
DRIVE1 DRIVE2 PGND
V
REF
+ 15%
11
5
AGND
PWRGD
SENSE+
DELAY
V
REF
+ 5% V
REF
– 5%
7
SENSE–
2R
ADP3011
CMPI
DAC
CMP
1.20V
16
VID0
1
VID1
2
VID2
3
VID3
4
VID4
V
REF
V
T1
CMPT
V
T2
9
C
T
OFF-TIME
CONTROL
SENSE–
6
8
REFERENCE
R
10
S
R
Q
The ADP3011 drives two synchronous N-channel MOSFETS
at a switching frequency of 250 kHz. The constant off-time
architecture maintains constant inductor ripple current while
current-mode operation provides excellent line and load tran-
sient response. The operating current level is user program-
mable via an external current sense resistor.