PRODUCTION D
TA SHEET
Microsemi
Integrated Products Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 1
Copyright © 2000
Rev. 1.0, 2005-08-10
WWW.Microsemi .COM
LX1672
Multiple Output LoadSHARE™ PWM
TM
®
DESCRIPTION
The LX1672 is a highly integrated
power supply controller IC featuring
two PWM switching regulator stages
with an additional onboard linear
regulator driver.
The two constant frequency voltage-
mode PWM phases can be easily
configured as a single Bi-Phase high
current output, two independently
regulated outputs, or as a DDR memory
I/O supply with a tracking DDR
termination voltage supply. Power loss
and noise, due to the ESR of the input
capacitors, are minimized by operating
each PWM output 180° out of phase.
This architecture also minimizes
capacitor requirements while
maximizing regulator response.
In bi-phase operation, the high
current output utilizes a patented current
sharing architecture, called Forced
Current Sharing
†
, to allow accurate
current sharing without the use of
expensive current sense resistors.
This patented approach also gives
system designers maximum flexibility with
respect to MOSFET supply. Each phase
can utilize different supply voltages, for
efficient use of available supplies, while
programming the ratio of current pulled
from each using one of three methods (see
application section).
The LX1672 incorporates fully
programmable soft-start sequencing
capabilities. Each output can be
configured to come up in any order
necessary as required by the application.
The LX1672 features an additional
Linear Regulator Driver output, which
when coupled with an inexpensive
MOSFET is capable of supplying up to 5A
for I/O, memory, and other supplies
surrounding today’s micro-processor
designs.
Each regulator voltage output is
programmed via a simple voltage-divider
network. The LX1672, utilizing MOSFET
RDS(ON) impedance, monitors maximum
current limit conditions, in each PWM
phase without the use of expensive current
sense resistors.
IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com
†
U.S
Patents: 6,285,571,6,292,378
KEY FEATURES
Up to Three Independently
Regulated Outputs
DDR Termination Compliant
Bi-phase Current Sharing
Outputs As Low As 0.8V
Generated From An Internal 1%
Reference
Multiphase High Current Output
Reduces Required Capacitance
Integrated High Current MOSFET
Drivers
300KHz, 500KHz and 600KHz
High Frequency Operation
Minimizes External Component
Requirements
Independent Phase Programmable
Soft-Start and Power Sequencing
Adjustable Linear Regulator Driver
Output
No current-sense resistors
APPLICATIONS/BENEFITS
Multi-Output Power Supplies
Video Card Power Supplies
DDR, VDDQ and Termination
Supply
PC Peripherals
Portable PC Processor and I/O
Supply
PRODUCT HIGHLIGHT
Memory Bus
....
DDR Termination
Memory Core
12V
3.3V
I/O
Graphics
Controller
DDR MemoryLX1672
Refer to Typical
Application for
complete circuit.
5V
PACKAGE ORDER INFO
PW
Plastic TSSOP
28-Pin
LQ
Plastic MLPQ
38-Pin T
A
(°C)
Switching
Frequency (kHz)
RoHS Compliant / Pb-free Transition DC: 0518 RoHS Compliant / Pb-free Transition DC: 0512
0 to 70 300
LX1672-03CPW LX1672-03CLQ
0 to 70 500
LX1672-05CPW
0 to 70 600
LX1672-06CLQ
NOTE: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1672-06CLQ-TR)
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X
X
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