LP2997 DDR-II Termination Regulator
June 2004
LP2997
DDR-II Termination Regulator
General Description
The LP2997 linear regulator is designed to meet the JEDEC
SSTL-18 specifications for termination of DDR-II memory.
The device contains a high-speed operational amplifier to
provide excellent response to load transients. The output
stage prevents shoot through while delivering 500mA con-
tinuous current and transient peaks up to 900mA in the
application as required for DDR-II SDRAM termination. The
LP2997 also incorporates a V
SENSE
pin to provide superior
load regulation and a V
REF
output as a reference for the
chipset and DIMMs.
An additional feature found on the LP2997 is an active low
shutdown (SD) pin that provides Suspend To RAM (STR)
functionality. When SD is pulled low the V
TT
output will
tri-state providing a high impedance output, but, V
REF
will
remain active. A power savings advantage can be obtained
in this mode through lower quiescent current.
Features
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Source and sink current
Low output voltage offset
No external resistors required
Linear topology
Suspend to Ram (STR) functionality
Low external component count
Thermal Shutdown
Available in SO-8, PSOP-8 packages
Applications
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DDR-II Termination Voltage
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SSTL-18 Termination
Typical Application Circuit
20109418
漏 2004 National Semiconductor Corporation
DS201094
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