15

IDT77V106L25

Da ta

Da ta

Da ta

Data

Da ta

Data

SW ITCH

Lo op Tim ing M od e

L oop Tim ing M od e

Loo p Timing Mode

Line Car d 2

Line Car d 3

Line Ca rd 4

CLK

CLK

CL K

RX

RX

RX

TX

TX

TX

TX

RX

No rm al M ode

Line Ca rd 1

OS C

1

2

3

4

5

Figure 15

Figure 15. Test Setup for Loop Timing Jitter Measurements

Loop Timing Jitter Specification

Line Rate

Data Rate

Min.

Typ.

Max.

Note

Mbps

Mbps

32

25.6

—

100 ps

—

Using 32Mhz OSC

64

51.2

—

100 ps

—

Using 64Mhz OSC

The waveforms below show some of the measurements taken with the set-up in Figure 15. Using the formula above, the jitter specification was derived.

For example, at data rate 25.63 Mbps, jitter added going through Line Card 3 is 1.5ns - 1.4ns (as shown in the waveform below).

TABLE 2 — LOOP TIMING JITTER