Seagate ST973451SS, ST936751SS General interface characteristics, Eye masks Eye masks overview

Table 16 defines the general interface characteristics.

Table 16: General interface characteristics

Characteristic	Units	1.5 Gbps	3.0 Gbps
Bit rate (nominal)	Mbaud	1,500	3,000
Unit interval (UI)(nominal)	ps	666.6	333.3
Impedance (nominal, differential )	ohm	100	100
Transmitter transients, maximum	V	± 1.2	± 1.2
Receiver transients, maximum	V	± 1.2	± 1.2

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 10-12of the total jitter population has a range of ± 7 standard deviations.

time limits on the signal at the compliance of the jitter population. The random content

9.5.2.1.2Receive eye mask

Figure 16 describes the receive eye mask. This eye mask applies to jitter after the application of a single pole high-pass frequency-weighting function that progressively attenuates jitter at 20 dB/decade below a frequency of ((bit rate) / 1.667).

Absolute amplitude (in V)

Z2

Z1

0 V

-Z1

-Z2

0 X1 X2 1-X1 1

1-X2

Normalized time (in UI)

Figure 16. Receive eye mask

Verifying compliance with the limits represented by the receive eye mask should be done with reverse channel traffic present in order that the effects of crosstalk are taken into account.

60 Savvio 15K SAS Product Manual, Rev. B