XRT75L02 View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'XRT75L02' PDF : 50 Pages View PDF
xr
REV. 1.0.3
XRT75L02
TWO CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER
CLOCK INTERFACE
PIN #
SIGNAL NAME
66
E3CLK
63
DS3CLK
60 STS-1CLK/ 12M
99
SFM_EN
80
CLKOUT_0
46
CLKOUT_1
45
CLKOUT_EN
TYPE
I
I
I
I
O
I
DESCRIPTION
E3 Clock Input (34.368 MHz ± 20 ppm):
If any of the channels is configured in E3 mode, a reference clock 34.368 MHz
is applied on this pin.
NOTE: In single frequency mode, this reference clock is not required.
DS3 Clock Input (44.736 MHz ± 20 ppm):
If any of the channels is configured in DS3 mode, a reference clock 44.736
MHz. is applied on this pin.
NOTE: In single frequency mode, this reference clock is not required.
STS-1 Clock Input (51.84 MHz ± 20 ppm):
If any of the channels is configured in STS-1 mode, a reference clock 51.84
MHz is applied on this pin..
In Single Frequency Mode, a reference clock of 12.288 MHz ± 20 ppm is con-
nected to this pin and the internal clock synthesizer generates the appropriate
clock frequencies based on the configuration of the channels in E3, DS3 or
STS-1.
Single Frequency Mode Enable:
Tie this pin “High” to enable the Single Frequency Mode. A reference clock of
12.288 MHz ± 20 ppm is applied. This offers the flexibility of using a low cost
reference clock and configures the board for either E3 or DS3 or STS-1 without
the need to change any components on the board.
In the Single Frequency Mode (SFM) an output clock is provided for each chan-
nel if the CLKOUT_EN bit is set or CLKOUT_EN pin tied “High”.
Tie this pin “Low” if single frequency mode is not selected. In this case, the
appropriate reference clocks must be provided.
NOTE: This pin is internally pulled down
Clock output for channel 0
Clock output for channel 1
Low jitter clock is output for each channel based on the mode selection
(E3,DS3 or STS-1) if the CLK_EN_n bit is set in the control register or
CLKOUT_EN pin is tied “High”.
This eliminates the need for a separate clock source for the framer.
NOTES:
1. This clock output is only available in SFM mode.
2. The maximum drive capability for the clockouts is 16 mA.
Clock Output Enable in Single Frequency Mode:
Tie this pin “High” to enable the output clocks via the CLKOUT pins.
8
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