Optimally Compensated Active Voltage Positioning
with Gain and Offset Adjustment (ADOPT™) for
Superior Load Transient Response
Complies with VRM 8.4 Specifications with Lowest
4-Bit Digitally Programmable 1.3 V to 2.05 V Output
N-Channel Synchronous Buck Driver
Two On-Board Linear Regulator Controllers
Total Accuracy ؎0.8% Over Temperature
High Efficiency Current-Mode Operation
Short Circuit Protection
Power Good Output
Overvoltage Protection Crowbar Protects Micro-
processors with No Additional External Components
Core Supply Voltage Generation for:
Intel Pentium® III
Synchronous Buck Controllers
FUNCTIONAL BLOCK DIAGRAM
The ADP3159 and ADP3179 are highly efficient output syn-
chronous buck switching regulator controllers optimized for
converting a 5 V main supply into the core supply voltage
required by high-performance processors. These devices use an
internal 4-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 2.05 V. They use a current mode,
constant off-time architecture to drive two N-channel
MOSFETs at a programmable switching frequency that can be
optimized for regulator size and efficiency.
The ADP3159 and ADP3179 also use a unique supplemental
regulation technique called Analog Devices Optimal Position-
ing Technology (ADOPT) to enhance load transient
performance. Active voltage positioning results in a dc/dc con-
verter that meets the stringent output voltage specifications
for high-performance processors, with the minimum number
VID3 VID2 VID1 VID0
of output capacitors and 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 it is always optimally positioned for a system tran-
sient. The devices also provide accurate and reliable short
circuit protection and adjustable current limiting. They also
include an integrated overvoltage crowbar function to protect
the microprocessor from destruction in case the core supply
exceeds the nominal programmed voltage by more than 20%.
The ADP3159 and ADP3179 contain two fixed-output volt-
age linear regulator controllers that are designed to drive
external N-channel MOSFETs. The outputs are internally
fixed at 2.5 V and 1.8 V in the ADP3159, while the ADP3179
provides adjustable output, which is set using an external
resistor divider. These linear regulators are used to generate
the auxiliary voltages (AGP, GTL, etc.) required in most moth-
erboard designs, and have been designed to provide a high
bandwidth load-transient response.
The ADP3159 and ADP3179 are specified over the commercial
temperature range of 0°C to 70°C and are available in a 20-lead
ADOPT is a trademark of Analog Devices, Inc.
Pentium is a registered trademark of Intel Corporation.
Celeron is a trademark of Intel Corporation.
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 that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
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© Analog Devices, Inc., 2001