XRT5997 Datasheet, PDF(20/37 Page) Exar Corporation – Seven-Channel E1 Line Interface Unit

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XRT5997 Datasheet, PDF (20/37 Pages) Exar Corporation – Seven-Channel E1 Line Interface Unit

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XRT5997

TxPOS_x

TxNEG_x

TClk_x

tSU

tHO

Figure 2. Illustration on how the XRT5997 Device Samples the data on

the TxPOS_x and TxNEG_x input pins

In general, if the XRT5997 device samples a â1â on the

TxPOS_x input pin, then the âTransmit Sectionâ of the

device will ultimately generate a positive polarity pulse

via the TTIP_x and TRing_x output pins (across a 1:2

transformer). Conversely, if the XRT5997 device

samples a â1â on the âTxNEG_xâ input pin, then the

âTransmit Sectionâ of the device will ultimately gener-

ate a negative polarity pulse via the TTIP_x and TRing_x

output pins (across a 1:2 transformer).

1.2.1 Operating the Transmitter in the

âClocklessâ Mode

The user can configure a given channel (within the

XRT5997 device) to operate in the âClocklessâ mode by

doing the following:

â¢ Not applying a clock signal to the TxClk_x input,

and either pulling this pin to VDD or letting it float.

â¢ By applying RZ (Return to Zero) data to the

TxPOS_x and TxNEG_x input pins, as illustrated

below.

Rev. 1.0.0

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