XRT75L02 datasheet(10/50 Pages) EXAR

10 / 50 page

XRT75L02

REV. 1.0.3

TWO CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH JITTER

CLOCK INTERFACE

PIN #

SIGNAL NAME

TYPE

DESCRIPTION

E3CLK

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.

DS3CLK

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-1CLK/ 12M

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.

SFM_EN

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

CLKOUT_0

CLKOUT_1

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:

This clock output is only available in SFM mode.

The maximum drive capability for the clockouts is 16 mA.

CLKOUT_EN

Clock Output Enable in Single Frequency Mode:

Tie this pin “High” to enable the output clocks via the CLKOUT pins.

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