eorex
EM44AM1684LBA
On-Die Termination (ODT)
ODT (On-Die Termination) is a new feature on DDR2 components that allows a DRAM to turn on/off
termination resistance for each UDQ, LDQ, UDQS, UDQS, LDQS, LDQS, UDM and LDM signal via the ODT
control pin for x16 configuration, where UDQS and LDQS are terminated only when enabled in the EMRS(1)
by address bit A10 = 0.
The ODT feature is designed to improve signal integrity of the memory channel by allowing the DRAM
controller to independently turn on/off termination resistance for any or all DRAM devices.
The ODT function can be used for all active and standby modes. ODT is turned off and not supported in Self-
Refresh mode.
ODT Function
Switch sw1 or sw2 is enabled by the ODT pin. Selection between sw1 or sw2 is determined by “Rtt
(nominal)” in EMRS(1) address bits A6 & A2. Target Rtt = 0.5 * Rval1 or 0.5 * Rval2.
The ODT pin will be ignored if the EMRS(1) is programmed to disable ODT.
Jul. 2006
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