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The Ready LED Out signal is designed to pull down the cathode of an LED. The anode is attached to the proper +3.3 volt
supply through an appropriate current limiting resistor. The LED and the current limiting resistor are external to the drive. See
Table 19 for the output characteristics of the LED drive signals.
Table 19 LED drive signal
S
TATE
LED off, high
LED on, low
11.5.2 Differential signals
The drive SAS differential signals comply with the intra-enclosure (internal connector) requirements of the SAS standard.
Table 20 defines the general interface characteristics
Table 20 General interface characteristics
C
HARACTERISTIC
Bit rate (nominal)
Unit interval (UI)(nominal)
Impedance (nominal, differential )
Transmitter transients, maximum
Receiver transients, maximum
11.6
SAS-2 S
PECIFICATION 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:
1. A Decision Feedback Equalizer (DFE) which utilizes the standard SAS-2 training pattern transmitted during the SNW-3
training gap. The DFE circuit can derive an optimal equalization characteristic to compensate 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.
11.7
A
DDITIONAL 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.
For more information about the SCSI commands used by Seagate SAS drives, refer to the Seagate SCSI Commands
Reference Manual, part number 100293068.
S
10K.5 SAS P
AVVIO
RODUCT
T
EST CONDITION
≤
≤
0 V
VOH
3.6 V
I
= 15 mA
OL
U
NITS
Mbaud
ps
ohm
V
V
M
, R
. J
ANUAL
EV
O
UTPUT VOLTAGE
-100 μA < I
< 100 μA
OH
≤
≤
0
V
0.225 V
OL
1.5G
/
3.0G
/
B
S
B
S
1,500
3,000
666.6
333.3
100
100
± 1.2
± 1.2
± 1.2
± 1.2
6.0G
/
B
S
6,000
166.6
100
± 1.2
± 1.2
65
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