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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 resis-
tor are external to the drive. See Table 14 for the output characteristics of the LED drive signals.
Table 14:
LED drive signal
State
LED off, high
LED on, low
9.5.2
Differential signals
The drive SAS differential signals comply with the intra-enclosure (internal connector) requirements of the SAS
standard.
Table 15 defines the general interface characteristics.
Table 15:
General interface characteristics
Characteristic
Bit rate (nominal)
Unit interval (UI)(nominal)
Impedance (nominal, differential )
Transmitter transients, maximum
Receiver transients, maximum
9.5.2.1
Eye masks
9.5.2.1.1
Eye masks overview
The eye masks are graphical representations of the voltage and time limits on the signal at the compliance
point. The time values between X1 and (1 - X1) cover all but 10
of the total jitter population has a range of ± 7 standard deviations.
64
Test condition
≤
≤
0 V
VOH
3.6 V
I
= 15 mA
OL
Output voltage
-100 µA < I
< 100 µA
OH
≤
≤
0
V
0.225 V
OL
Units
1.5 Gbps
Mbaud
1,500
ps
666.6
ohm
100
± 1.2
V
± 1.2
V
-12
of the jitter population. The random content
Cheetah 15K.6 SAS Product Manual, Rev. A
3.0 Gbps
3,000
333.3
100
± 1.2
± 1.2
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