DDR TERMINATION REGULATOR
DESCRIPTION
The UTC UR5596 is a linear bus termination regulator and
designed to meet JEDEC SSTL-2(Stub-Series Terminated Logic)
specifications for termination of DDR-SDRAM. It also can be
used in SSTL-3 or HSTL (High-Speed Transceiver Logic)
scheme. The device contains a high-speed OP AMP to provide
excellent response to the load transients, and can deliver 1.5A
continuous current and transient peaks up to 3A in the application
as required for DDR-SDRAM termination.
The UTC UR5596 also incorporates a VSENSE pin to provide
superior load regulation and a VREF output as a reference for the
chipset and DIMMs. Besides, an active low shutdown (SHDN) pin
provides Suspend To RAM (STR) functionality. When SHDN is
pulled low the VTT output will tri-state providing a high impedance
output, but, VREF will remain active. A power savings advantage
can be obtained in this mode through lower quiescent current.
Regarding the output, VTT is capable of sinking and sourcing
current while regulating the output voltage equal to VDDQ/2. The
output stage has been designed to maintain excellent load
regulation while preventing shoot through. The UTC UR5596 also
incorporates two distinct power rails that separates the analog
circuitry from the power output stage. This allows a split rail
approach to be utilized to decrease internal power dissipation and
permits UTC UR5596 to provide a termination solution for DDRII
SDRAM.
FEATURES
* 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 protection
APPLICATION CIRCUIT
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