GS2985 datasheet(25/45 Pages) SEMTECH

25 / 45 page

GS2985 Multi-Rate SDI Reclocker with Equalization &

De-emphasis

Data Sheet

36663 - 5

July 2012

25 of 45

Proprietary & Confidential

cycles through the data rates and starts over if that data rate is not found (see Figure 4-3).

A “search algorithm” cycles through the supported data rates until lock is achieved, as

shown in Figure 4-3 below.

Figure 4-3: GS2985 Automatic Mode Search Algorithm

In MANUAL mode, the SS[1:0] pins become inputs and the data rate can be programmed.

In this mode, the search algorithm is disabled and the GS2985's PLL will only lock to the

data rate selected in accordance with Table 4-8.

4.11 SD/HD Indication

The SD/HD signal indicates the output data rate of the device and can be connected to

the SD/HD input pin of dual slew rate cable drivers such as the GS2988.

When this signal is HIGH, the data rate is 270Mb/s. This signal is LOW for all other data

rates.

This signal is also LOW when the device is operating in bypass mode (Auto-bypass and

User-bypass).

The SD/HD signal is LOW when the device is not locked.

Power up

270Mb/s

1485Mb/s

2970Mb/s

*Note: the search algorithm does not necessarily begin with 270Mb/s.

Table 4-8: Data Rate Indication/Selection Bit Pattern

SS[1:0]

Data Rate (Mb/s)

Reserved

270

1485 or 1485/1.001

2970 or 2970/1.001

GS2985 Datasheet(PDF) 25 Page - Semtech Corporation