ADP3155JRU 查看數據表（PDF） - Analog Devices
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ADP3155JRU
Analog Devices
ADP3155JRU Datasheet PDF : 14 Pages
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a 5-Bit Programmable Triple Power Supply
Controller for Pentium® III Processors
ADP3155
FEATURES
Active Voltage Positioning with Gain and Offset
Adjustment
Optimal Compensation for Superior Load Transient
Response
VRM 8.2, VRM 8.3 and VRM 8.4-Compliant
5-Bit Digitally Programmable 1.3 V to 3.5 V Output
Dual N-Channel Synchronous Driver
Two Onboard Linear Regulator Controllers
Total Output Accuracy ؎1% Over Temperature
High Efficiency, Current-Mode Operation
Short Circuit Protection
Overvoltage Protection Crowbar Protects Micro-
processors, with No Additional External Components
Power Good Output
TSSOP-20 Package
APPLICATIONS
Desktop PC Power Supplies for:
Pentium II and Pentium III Processor Families
AMD-K6 Processors
VRM Modules
GENERAL DESCRIPTION
The ADP3155 is a highly efficient synchronous buck switching
regulator controller optimized for converting the 5 V main sup-
ply into the core supply voltage required by the Pentium III and
other high performance processors. The ADP3155 uses an
internal 5-bit DAC to read a voltage identification (VID) code
directly from the processor, which is used to set the output
voltage between 1.3 V and 3.5 V. The ADP3155 uses a current-
mode, constant off-time architecture to drive two external N-
channel MOSFETs at a programmable switching frequency that
can be optimized for size and efficiency. It also uses a unique
supplemental regulation technique called active voltage position-
ing to enhance load transient performance.
Active voltage positioning results in a dc/dc converter that meets
the stringent output voltage specifications for Pentium II and
Pentium III processors, with the minimum number of output
capacitors and the smallest footprint. Unlike voltage-mode and
standard current-mode architectures, active voltage positioning
adjusts the output voltage as a function of the load current so
that it is always optimally positioned for a system transient.
The ADP3155 provides accurate and reliable short circuit pro-
tection and adjustable current limiting. It also includes an inte-
grated overvoltage crowbar function to protect the microprocessor
from destruction in case the core supply exceeds the nominal
programmed voltage by more than 15%.
Pentium is a registered trademark of Intel Corporation.
All other trademarks are the property of their respective holders.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
FUNCTIONAL BLOCK DIAGRAM
VCC DRIVE1 DRIVE2 PGND AGND PWRGD SENSE+ SENSE–
SD
CT
CMP
NONOVERLAP
DRIVE
VREF
+15%
DELAY
2R
CROWBAR
IN OFF
CMPI
VREF VREF
+5% –5%
S
Q
R
VT2
VT1
VREF
R
gm
CMPT
OFF-TIME VIN
CONTROL SENSE–
REFERENCE
VLDO2
FB2
ADP3155
DAC
1.20V
VLDO1
FB1
VID4 VID3 VID2 VID1 VID0
The ADP3155 contains two linear regulator controllers that are
designed to drive external N-channel MOSFETs. These linear
regulators are used to generate the auxiliary voltages (AGP,
GTL, etc.) required in most motherboard designs, and have
been designed to provide a high bandwidth load-transient re-
sponse. A pair of external feedback resistors sets each linear
regulator output voltage.
VCC +12V
VIN +5V
CIN
R1
22F 1F
SD VCC
+
DRIVE1
Q1
CCMMPP
R2
CCOMP VINLDO1
ADP3155
L RSENSE
QLDO1
VOLDO1
1F
VINLDO2
R3
R4
20k⍀
SENSE+
VLDO1
SENSE–
FB1
DRIVE2
1nF
Q2
QLDO2
VOLDO2
1F
R5
R6
20k⍀
PGND
VLDO2
150pF
FB2
CT
AGND
VID0–VID4
VO
1.3V TO
+ 3.5V
CO
5-BIT CODE
Figure 1. Typical Application
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., 1999
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