2006 Fairchild Semiconductor Corporation
1
www.fairchildsemi.com
March 2006
FAN5031 Rev. 1.0.1
F
AN5031 8-Bit Pr
ogrammab
le
,
2 to 4 Phase
,
Sync
hr
onous Buc
k Contr
oller
FAN5031
8-Bit Programmable, 2 to 4 Phase, Synchronous Buck
Controller
Features
Selectable 2, 3, or 4 phase operation at up to 1MHz
per phase
7.7mV worst-case differential sensing error over
temperature
Active current balancing between the output phases
Power good and Crowbar blanking supports on-the-fly
VID code changes
0.5V to 1.6V output
Fully compliant to both Intel's VR10 and VR11
specifications
Selectable VR10 extended (7 bit) and VR11 (8 bit)
VID tables
Programmable soft start ramp
Programmable short circuit protection and latch-off
delay
Applications
Desktop PC/Server processor power supplies for
existing and next generation Intel processors
VRM modules
Description
The FAN5031 device is a multi-phase buck switching
regulator controller, that is optimized to convert a 12V
input supply to the processor core voltage required by
high performance Intel processors. It has an internal 8-bit
DAC that converts a digital voltage identification (VID)
code, that is sent from the processor, to set the output
voltage between 0.5V and 1.6V in 6.25 mV steps. It out-
puts a PWM signals to external MOSFET drivers that, in
turn, drive the switching power MOSFETs. The switching
frequency of the design is easily programmable by a
single resistor value and the number of phases can be
programmed to support 2, 3, or 4 phase applications.
The FAN5031 also includes programmable no-load off-
set and droop functions to adjust the output voltage as a
function of the load current, as required by the Intel spec-
ifications. The FAN5031 also provides an accurate and
reliable short circuit protection function with an adjust-
able over current set-point.
The FAN5031 is specified over the commercial tempera-
ture range of 0C to +85C and is available in a 40-lead
MLP package.
Ordering Information
*Lead free part
Part Number
Temperature
Range Package
Type
Packing
Method
Quantity per
Reel
FAN5031MPX*
0C to 85C
MLP-40
Tape and Reel
3,000
3
www.fairchildsemi.com
FAN5031 Rev. 1.0.1
F
AN5031 8-Bit Pr
ogrammab
le
,
2 to 4 Phase
,
Sync
hr
onous Buc
k Contr
oller
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY
ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT
CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.
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The following are registered and unregistered trademarks Fairchild Semiconductor owns or is authorized to use and is
not intended to be an exhaustive list of all such trademarks.
LIFE SUPPORT POLICY
FAIRCHILDS PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF FAIRCHILD SEMICONDUCTOR CORPORATION.
As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant into
the body, or (b) support or sustain life, or (c) whose
failure to perform when properly used in accordance
with instructions for use provided in the labeling, can be
reasonably expected to result in significant injury to the
user.
2. A critical component is any component of a life
support device or system whose failure to perform can
be reasonably expected to cause the failure of the life
support device or system, or to affect its safety or
effectiveness.
PRODUCT STATUS DEFINITIONS
Definition of Terms
Datasheet Identification
Product Status
Definition
Advance Information
Preliminary
No Identification Needed
Obsolete
This datasheet contains the design specifications for
product development. Specifications may change in
any manner without notice.
This datasheet contains preliminary data, and
supplementary data will be published at a later date.
Fairchild Semiconductor reserves the right to make
changes at any time without notice in order to improve
design.
This datasheet contains final specifications. Fairchild
Semiconductor reserves the right to make changes at
any time without notice in order to improve design.
This datasheet contains specifications on a product
that has been discontinued by Fairchild semiconductor.
The datasheet is printed for reference information only.
Formative or
In Design
First Production
Full Production
Not In Production
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