XRT59L921IB Exar Corporation, XRT59L921IB Datasheet - Page 27

• Manufacturer Part Number: XRT59L921IB
• Description: 21 CHANNEL E1 LIU
• Manufacturer: Exar Corporation

Specifications of XRT59L921IB

• Lead Free Status / RoHS Status: Contains lead / RoHS Compliant

REV. 1.2.1
indicator. In particular, the XRT59L921 will declare a LOS, between 10 and 255 UI (or E1 bit-periods) after the
actual time the LOS condition occurred. Further, the XRT59L921 will clear the LOS indicator within 10 to 255
UI after restoration of the incoming line signal.
behavior, in response to first, the Loss of Signal event and then afterwards, the restoration of the signal.
The LOSMute feature is included in the XRT59L921 such that when the input signal to a receiver is too low or
is lost. The LOS_n pin will toggle "High" and at the same time the RPOS_n and RNEG_n outputs are muted to
a "Zero" state to prevent output data chattering.
The purpose of the Receive Output Interface block is to interface directly with the Receiving Terminal
Equipment. The Receive Output Interface block outputs the data (which has been recovered from the incoming
line signal) to the Receive Terminal Equipment via the RxPOS_n and RxNEG_n output pins.
If the Receive Sections of the XRT59L921 has received a Positive-Polarity pulse, via the RTIP_n and RRing_n
input pins, then the Receive Output Interface will output a pulse via the RxPOS_n output pins.
Similarly, if the Receive Sections of the XRT59L921 has received a Negative-Polarity pulse, via the RTIP_n
and RRing_n input pins, then the Receive Output Interface will output a pulse via the RxNEG_n output pins.
N
Each channel (within the XRT59L921) permits the user to shut off the Transmit Driver within their respective
Transmit Section. This feature can come in handy for system redundancy design considerations or during
diagnostic testing. The user can activate this feature by connecting the TxClk_n input pin to a logic “0” (e.g.,
GND) and continue to apply data via the TxPOS_n and TxNEG_n input pins.
F
R
2.6
2.7
3.0 SHUTTING OFF THE TRANSMITTER
OTE
IGURE
ESTORATION OF THE
RxIN
: The Receive Output Interface block does not supply a recovered clock. This device is intended to be used in those
LOS Output Pin
applications, where the Clock Recovery circuit is realized in an ASIC solution.
14. T
LOS Mute Description
The Receive Output Interface block
HE
B
EHAVIOR OF THE
S
IGNAL
0 UI
Actual Occurrence
of LOS Condition
LOS O
G.775 Compliance
10 UI
UTPUT
LOS Declaration
Time Range for
I
NDICATOR
Figure 14
TWENTY-ONE CHANNEL E1 LINE INTERFACE UNIT
25
255 UI
Line Signal
is Restored
,
IN RESPONSE TO THE
illustrates the LOS Declaration and Clearance
0UI
G.775 Compliance
10 UI
L
OSS OF
S
IGNAL
Time Range for
LOS Clearance
XRT59L921
255 UI
,
AND THE