XRT75L00D Datasheet, PDF (13/92 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER

REV. 1.0.2
CLOCK INTERFACE
PIN #
44
SIGNAL NAME
ExClk/12M
9
SFM_EN
39
CLK_OUT
XRT75L00D
E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
TYPE
I
I
O
DESCRIPTION
Clock Input (34.368 MHz or 44.736 MHz or 51.84 MHz ± 20 ppm):
Based on the mode selected, provide the appropriate reference clock signal.
If the XRT75L00D is configured for Single Frequency Mode with the SFM_EN
tied “High”, then provide a 12.288 MHz ± 20 ppm clock and depending on the
mode, the correct frequency is generated internally by the clock synthesizer..
Single Frequency Enable:
Tie this pin “High” to select the single frequency mode. When enabled, a single
frequency clock, 12.288 MHz is input through the ExClk input pin and the inter-
nal clock synthesizer generates the appropriate clock frequency.
NOTE: This pin is internally pulled down.
Clock out put:
When the Single Frequency Mode is selected, a low jitter clock will be out put.
The frequency of this clock depends on whether the XRT75L00D is configured
in E3 or DS3 or STS-1 mode.
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