Seagate ST3600057SS Cheetah 15K.6 SAS Product Manual - Page 72
Differential signals, 5.2.1, Eye masks, 5.2.1.1, Eye masks overview, Table 27, LED drive signal,
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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 27 for the output characteristics of the LED drive signals. Table 27: LED drive signal State LED off, high LED on, low Test condition 0 V ≤ VOH ≤ 3.6 V IOL = 15 mA Output voltage -100 µA < IOH < 100 µA 0 ≤ VOL ≤ 0.225 V 9.5.2 Differential signals The drive SAS differential signals comply with the intra-enclosure (internal connector) requirements of the SAS standard. Table 28 defines the general interface characteristics. Table 28: General interface characteristics Characteristic Bit rate (nominal) Unit interval (UI)(nominal) Impedance (nominal, differential ) Transmitter transients, maximum Receiver transients, maximum Units Mbaud ps ohm V V 1.5 Gbps 1,500 666.6 100 ± 1.2 ± 1.2 3.0 Gbps 3,000 333.3 100 ± 1.2 ± 1.2 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 10-12 of the jitter population. The random content of the total jitter population has a range of ± 7 standard deviations. 68 Cheetah 15K.6 SAS Product Manual, Rev. B