HYS72T64400HFD Datasheet, PDF (15/42 Pages) Qimonda AG – 240-Pin Fully-Buffered DDR2 SDRAM Modules

Internet Data Sheet
HYS72T[64/128/256]4[00/20]HFD–[3S/3.7]–A
3.3.4
Peak Theoretical Channel Throughput
An FB-DIMM channel transfers read completion data on the
Northbound data connection. 144 bits of data are transferred
for every Northbound data frame. This matches the 18-byte
data transfer of an ECC DDR DRAM in a single DRAM
command clock. A DRAM burst of 8 from a single channel or
a DRAM burst of four from two lock stepped channels
provides a total of 72 bytes of data (64 bytes plus 8 bytes
ECC). The FB-DIMM frame rate matches the DRAM
command clock because of the fixed 6:1 ratio of the FB-DIMM
channel clock to the DRAM command clock. Therefore, the
Northbound data connection will exhibit the same peak
theoretical throughput as a single DRAM channel. For
example, when using DDR2 533 DRAMs, the peak theoretical
bandwidth of the Northbound data connection is 4.267
GB/sec. Write data is transferred on the Southbound
command and data connection, via Command+Wdata
frames. 72 bits of data are transferred for every
Command+Wdata frame. Two Command+Wdata frames
match the 18-byte data transfer of an ECC DDR DRAM in a
single DRAM command clock. A DRAM burst of 8 transfers
from a single channel, or a burst of 4 from two lock-step
channels provides a total of 72 bytes of data (64 bytes plus 8
bytes ECC). When the frame rate matches the DRAM
command clock, the Southbound command and data
connection will exhibit one half the peak theoretical
throughput of a single DRAM channel. For example, when
using DDR2 533 DRAMs, the peak theoretical bandwidth of
the Southbound command and data connection is 2.133
GB/sec. The total peak theoretical throughput for a single FB-
DIMM channel is defined as the sum of the peak theoretical
throughput of the Northbound data connection and the
Southbound command and data connection. When the frame
rate matches the DRAM command clock, this is equal to 1.5
times the peak theoretical throughput of a single DRAM
channel. For example, when using DDR2 533 DRAMs, the
peak theoretical throughput of a single DDR2-533 channel
would be 4.267 GB/sec., while the peak theoretical
throughput of the entire FB-DIMM PC4200F channel would
be 6.4GB/sec.
3.4
Hot-add
The FB-DIMM channel does not provide a mechanism to
automatically detect and report the addition of a new DIMM
south of the currently active last DIMM. It is assumed the
system will be notified through some means of the addition of
one or more new DIMMs so that specific commands can be
sent to the host controller to initialize the newly added
DIMM(s) and perform a Hot-Add Reset to bring them into the
channel timing domain. It should be noted that the power to
the DIMM socket must be removed before a “hot-add” DIMM
is inserted or removed. Applying or removing the power to a
DIMM socket is a system platform function.
3.5
Hot-remove
In order to accomplish removal of DIMMs the host must
perform a Fast Reset sequence targeted at the last DIMM that
will be retained on the channel. The Fast Reset re-establish
the appropriate last DIMM so that the Southbound Tx outputs
of the last active DIMM and the Southbound and Northbound
outputs of the DIMMs beyond the last active DIMM are
disabled. Once the appropriate outputs are disabled the
system can coordinate the procedure to remove power in
preparation for physical removal of the DIMM if needed. It
should be noted that the power to the DIMM socket must be
removed before a “hot-add” DIMM is inserted or removed.
Applying or removing the power to a DIMM socket is a system
platform function.
3.6
Hot-replace
Hot replace of DIMM is accomplished through combining the Hot-Remove and Hot-Add process.
Rev. 1.2, 2006-11
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03292006-GUME-ERC3