lx1672| Datasheet

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LX1672
TM

Multiple Output LoadSHARETM PWM
P RODUCTION D ATA S HEET

DESCRIPTION

KEY FEATURES

WWW . Microsemi .C OM

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 voltagemode 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.

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

IMPORTANT: For the most current data, consult MICROSEMI's website: http://www.microsemi.com U.S Patents: 6,285,571,6,292,378

PRODUCT HIGHLIGHT
Refer to Typical Application for complete circuit. 12V 5V 3.3V I/O LX1672 Graphics Controller DDR Termination Memory Core ....

Memory Bus

DDR Memory

LX1672 LX1672

TA ( C) 0 to 70 0 to 70 0 to 70
Copyright 2000 Rev. 1.0, 2005-08-10

Switching Frequency (kHz) 300 500 600

PW

PACKAGE ORDER INFO Plastic TSSOP 28-Pin LX1672-03CPW LX1672-05CPW

LQ

Plastic MLPQ 38-Pin LX1672-03CLQ LX1672-06CLQ

RoHS Compliant / Pb-free Transition DC: 0518 RoHS Compliant / Pb-free Transition DC: 0512

NOTE: Available in Tape & Reel. Append the letters "TR" to the part number (i.e. LX1672-06CLQ-TR)

Microsemi
Integrated Products Division 11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

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lx1672 DATASHEET