LX1672 Datasheet, PDF (1/20 Pages) Microsemi Corporation – Multiple Output LoadSHARE PWM

LX1672
®
Multiple Output LoadSHARE™ PWM
TM
PRELIMINARY DATA SHEET
DESCRIPTION
The LX1672 is a highly integrated This patented approach also gives
power supply controller IC featuring system designers maximum flexibility with
two PWM switching regulator stages respect to MOSFET supply. Each phase
with an additional onboard linear can utilize different supply voltages, for
regulator driver.
efficient use of available supplies, while
The two constant frequency voltage- programming the ratio of current pulled
mode PWM phases can be easily from each using one of three methods (see
configured as a single Bi-Phase high application section).
current output, two independently The LX1672 incorporates fully
regulated outputs, or as a DDR memory programmable soft-start sequencing
I/O supply with a tracking DDR capabilities. Each output can be
termination voltage supply. Power loss configured to come up in any order
and noise, due to the ESR of the input necessary as required by the application.
capacitors, are minimized by operating The LX1672 features an additional
each PWM output 180° out of phase. Linear Regulator Driver output, which
This architecture also minimizes when coupled with an inexpensive
capacitor requirements while MOSFET is capable of supplying up to 5A
maximizing regulator response.
for I/O, memory, and other supplies
In bi-phase operation, the high surrounding today’s micro-processor
current output utilizes a patented current designs.
sharing architecture, called Forced Each regulator voltage output is
Current Sharing^†, to allow accurate programmed via a simple voltage-divider
current sharing without the use of network. The LX1672, utilizing MOSFET
expensive current sense resistors.
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
LoadSHARE is a Trademark of Microsemi Corporation
PRODUCT HIGHLIGHT
KEY FEATURES
ƒ Up to Three Independently
Regulated Outputs
ƒ DDR Termination Compliant
ƒ Bi-phase Current Sharing
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, 500KHz and 600KHz
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
APPLICATIONS/BENEFITS
ƒ Multi-Output Power Supplies
ƒ Video Card Power Supplies
ƒ DDR, VDDQ and Termination
Supply
ƒ PC Peripherals
ƒ Portable PC Processor and I/O
Supply
Refer to Typical
Application for
com plete circuit.
DDR Term ination
....
Mem ory Core
12V
5V
3.3V
LX1672
Graphics
Controller
Memory Bus
DDR Mem ory
I/O
T_A (°C)
0 to 70
0 to 70
0 to 70
Switching
Frequency (kHz)
300
500
600
PACKAGE ORDER INFO
Plastic TSSOP
PW _28-Pin
RoHS Compliant / Pb-free Transition DC: 0518
LX1672-03CPW
LX1672-05CPW
Plastic MLPQ
LQ _38-Pin
RoHS Compliant / Pb-free Transition DC: 0512
LX1672-03CLQ
LX1672-06CLQ
NOTE: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1672-06CLQ-TR)
Copyright © 2000
Rev. 0.3m, 2005-04-12
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
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