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 27 for the output characteristics of the LED drive signals.
Table 27: | LED drive signal |
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State |
| Test condition | Output voltage |
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LED off, high |
| 0 V ≤ VOH ≤ 3.6 V | |
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LED on, low |
| IOL = 15 mA | 0 ≤ VOL ≤ 0.225 V |
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9.5.2Differential signals
The drive SAS differential signals comply with the
Table 28 defines the general interface characteristics.
Table 28: General interface characteristics
Characteristic | Units | 1.5 Gbps | 3.0 Gbps |
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Bit rate (nominal) | Mbaud | 1,500 | 3,000 |
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Unit interval (UI)(nominal) | ps | 666.6 | 333.3 |
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Impedance (nominal, differential ) | ohm | 100 | 100 |
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Transmitter transients, maximum | V | ± 1.2 | ± 1.2 |
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Receiver transients, maximum | V | ± 1.2 | ± 1.2 |
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9.5.2.1Eye masks
9.5.2.1.1Eye masks overview
The eye masks are graphical representations of the voltage and point. The time values between X1 and (1 - X1) cover all but
time limits on the signal at the compliance of the jitter population. The random content
68 | Cheetah 15K.6 SAS Product Manual, Rev. B |