LX1671_06 Datasheet, PDF (1/21 Pages) Microsemi Corporation – Multiple Output LoadSHARE PWM

LX1671
TM
®
Multiple Output LoadSHARE™ PWM
PRODUCTION DATA SHEET
DESCRIPTION
The LX1671 is a highly integrated The additional outputs are capable of
power supply controller IC featuring supplying up to 5A (Linear Regulator
three PWM switching regulator stages Driver) and 15A (Switching Regulator)
with an additional onboard linear for I/O, memory, termination, and other
regulator driver.
supplies surrounding today’s micro-
Two of the constant frequency processor designs.
voltage-mode PWM phases can be Each PWM regulator output is
easily configured for a single Bi-Phase programmed via a simple voltage-divider
high current output or two in- network. The LX1671, utilizing
dependently regulated outputs. Each MOSFET R_DS(ON) impedance, monitors
phase incorporates a fully pro- current limit conditions, in each PWM
grammable soft-start sequence. This phase, without the use of expensive
versatility yields either three or four current sense resistors.
independently regulated outputs with The LX1671 was designed to give
full power sequencing capability giving design engineers maximum flexibility
system designers the ultimate with respect to the MOSFET supply.
flexibility in power supply design.
Each phase can utilize different supply
In Bi-Phase operation, the high voltages for efficient use of available
current (>30A) output can utilize supply rails. Additionally, when two
different supply rails allowing Forced phases are configured in Bi-Phase output,
Current Sharing^† from different the LoadSHARE^TM topology can be
sources. Power loss and noise, due to programmed via inductor ESR selection.
the ESR of the input capacitors, are There are three other methods that can
minimized by operating each PWM also be used with LoadSHARE^TM. These
output 180° out of phase. This other methods are presented in the theory
architecture also minimizes capacitor of operation section of this data sheet.
requirements while maximizing re-
gulator response.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
LoadSHARE is a Trademark of Microsemi Corporation
Protected by US Patents: 6,285,571 & 6,292,378
PRODUCT HIGHLIGHT
Refer to Typical
Application for
complete circuit.
DDR Termination
....
KEY FEATURES
ƒ Up to Four Independently
Regulated Outputs
ƒ Outputs As Low As 0.8V
Generated From An Internal 1%
Reference
ƒ Multiphase High Current Output
Reduces Required Capacitance
ƒ Integrated High Current MOSFET
Drivers
ƒ 300kHz High Frequency Operation
Minimizes External Component
Requirements
ƒ Independent Phase Programmable
Soft-Start and Power Sequencing
ƒ Adjustable Linear Regulator Driver
Output
ƒ No current-sense resistors
ƒ DDR Termination Compliant
APPLICATIONS/BENEFITS
ƒ Multi-Output Power Supplies
ƒ Video Card Power Supplies
ƒ PC Peripherals
ƒ Portable PC Processor and I/O
Supply
Memory Core
12V
5V
LX1671
Core
Graphics
Controller
Memory Bus
DDR Memory
3.3V
I/O
T_A (°C)
0 to 70
PACKAGE ORDER INFO
PW
Plastic TSSOP
38-Pin
LQ
Plastic MLPQ
38-Pin
RoHS Compliant / Pb-free Transition DC: 0518 RoHS Compliant / Pb-free Transition DC: 0512
LX1671CPW
LX1671CLQ
Note: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1671CPW-TR)
Copyright © 2000
Rev. 1.2b, 2006-02-13
Microsemi
Integrated Products, Power Management
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
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