XRT75R12DIB-F Exar Corporation, XRT75R12DIB-F Datasheet - Page 98

• Manufacturer Part Number: XRT75R12DIB-F
• Description: Peripheral Drivers & Components (PCIs) 12 Channel 3.3V-5V temp -45 to 85C
• Manufacturer: Exar Corporation

Specifications of XRT75R12DIB-F

• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3.3 V to 5 V
• Package / Case: TBGA-420
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

XRT75R12D
TWELVE CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT WITH SONET DESYNCHRONIZER
In general, the role/purpose of the POH bytes is to fulfill the following functions.
The role of the POH bytes is beyond the scope of this data sheet and will not be discussed any further.
Now that we have defined the STS-1 SPE, we can now describe how a DS3 signal is mapped into an STS-1
SPE. As mentioned above, the STS-1 SPE is basically an 87 byte column x 9 row structure of data. The very
first byte column (e.g., in all 9 bytes) consists of the POH (Path Overhead) bytes. All of the remaining bytes
within the STS-1 SPE is simply referred to as "user" or "payload" data because this is the portion of the STS-1
signal that is used to transport "user data" from one end of the SONET network to the other. Telcordia GR-253-
CORE specifies the approach that one must use to asynchronously map DS3 data into an STS-1 SPE. In
short, this approach is presented below in
F
8.2.1.2
IGURE
To support error detection within the STS-1 SPE
To support the transmission of various alarm conditions such as RDI-P (Path - Remote Defect Indicator) and
REI-P (Path - Remote Error Indicator)
To support the transmission and reception of "Path Trace" Messages
42. I
LLUSTRATION OF THE
Mapping DS3 data into an STS-1 SPE
9 Rows
1 Byte
B3
C2
G1
G1
H4
H4
B3
C2
F2
Z3
Z4
Z5
F2
Z3
Z4
Z5
J1
J1
B
YTE
S
TRUCTURE OF THE
Figure
Payload (or User) Data
43.
94
87 Bytes
86 Bytes
STS-1 SPE
REV. 1.0.3