Seagate ST3450802SS ユーザーズマニュアル
62
Cheetah NS 10K.2 SAS Product Manual, Rev. C
9.5.2.5
Receiver characteristics
The drive receiver is A.C. coupled. The receive network terminates the TxRx connection by a 100 ohm equiva-
lent impedance as specified in table 29.
lent impedance as specified in table 29.
The receiver operates within a BER of 10
-12
when a SAS signal with valid voltage and timing characteristics is
delivered to the compliance point from a 100 ohm source. The received SAS signal are considered valid if it
meets the voltage and timing limits specified in table 26.
meets the voltage and timing limits specified in table 26.
Additionally the receiver operates within the BER objective when the signal at a receiving phy has the addi-
tional sinusoidal jitter present that is specified in table 28 and the common mode signal V
tional sinusoidal jitter present that is specified in table 28 and the common mode signal V
CM
over frequency
range F
CM
as specified in table 24. The jitter tolerance is shown in Figure 16 for all Rx compliance points in a
TxRx connection. The figure given assumes that any external interference occurs prior to the point at which the
test is applied. When testing the jitter tolerance capability of a receiver, the additional 0.1 UI of sinusoidal jitter
may be reduced by an amount proportional to the actual externally induced interference between the applica-
tion point of the test and the input to the receiving phy. The additional jitter reduces the eye opening in both
voltage and time.
test is applied. When testing the jitter tolerance capability of a receiver, the additional 0.1 UI of sinusoidal jitter
may be reduced by an amount proportional to the actual externally induced interference between the applica-
tion point of the test and the input to the receiving phy. The additional jitter reduces the eye opening in both
voltage and time.
9.6
SAS-2 Specification compliance
Seagate SAS-2 drives are entirely compatible with the latest SAS-2 Specification (T10/1760-D) Revision 16.
The most important characteristic of the SAS-2 drive at 6Gb/s is that the receiver is capable of adapting the
equalizer to optimize the receive margins. The SAS-2 drive has two types of equalizers:
equalizer to optimize the receive margins. The SAS-2 drive has two types of equalizers:
1.
A Decision Feedback Equalizer (DFE) which utilizes the standard SAS-2 training pattern transmitted dur-
ing the SNW-3 training gap. The DFE circuit can derive an optimal equalization characteristic to compen-
sate for many of the receive losses in the system.
ing the SNW-3 training gap. The DFE circuit can derive an optimal equalization characteristic to compen-
sate for many of the receive losses in the system.
2.
A Feed Forward Equalizer (FFE) optimized to provide balanced receive margins over a range of channels
bounded by the best and worst case channels as defined by the relevant ANSI standard.
bounded by the best and worst case channels as defined by the relevant ANSI standard.
9.7
Additional information
Please contact your Seagate representative for SAS electrical details, if required.
For more information about the Phy, Link, Transport, and Applications layers of the SAS interface, refer to the
Seagate SAS Interface Manual, part number 100293071.
Seagate SAS Interface Manual, part number 100293071.
For more information about the SCSI commands used by Seagate SAS drives, refer to the Seagate SCSI
Commands Reference Manual, part number 100293068.
Commands Reference Manual, part number 100293068.