TXC-03453BROG Transwitch Corporation, TXC-03453BROG Datasheet - Page 12

• Manufacturer Part Number: TXC-03453BROG
• Manufacturer: Transwitch Corporation

Specifications of TXC-03453BROG

• Screening Level: Industrial
• Package Type: BGA
• Lead Free Status / Rohs Status: Compliant

September 2003
TL3M
TXC-03453B
PRELIMINARY TXC-03453B-MB, Ed. 3
Control bits are provided which enable line AIS to be sent when either a loss of signal or input clock failure is
detected. A control bit also enables the microprocessor to send line AIS, independent of alarms. Separate NRZ
data (RnNRD) and clock (RnNRC) output signals are also provided which may be used for monitoring.
The line signal is connected to the Stuff/Sync block. This block basically consists of a FIFO into which the data
is written from the line and is read out by a SDH/SONET clock which is either derived from the Add bus (i.e.,
Add bus timing), or from the Drop bus (i.e., Drop bus timing). The stuffing algorithm for the DS3 signal uses one
set of five control bits (C-bits) with one stuffing opportunity bit (S-bit) for frequency justification per subframe
(nine subframes). The E3 format uses five pairs of control bits (C1 and C2 bits) to control two stuff opportunity
bits (S1 and S2) per subframe (one subframe per three rows for a total of three subframes per frame). FIFO
underflow and overflow alarm indications are provided. Should an underflow or overflow condition occur, the
FIFO will immediately reset to a preset value. The FIFO also tracks an incoming line signal having an average
frequency deviation as high as ± 20 ppm, and can simultaneously accept the signal with up to 5 UI peak-to-
peak jitter (where 1 UI = 1/f).
The Build block formats the data bits into either a SONET STS-3 STS-1 SPE format (see Figure 4) or an STM-
1 VC-4 TUG-3 format (see Figure 5). The STS-1 format has two stuff columns and payload plus a column of
POH bytes, while the TUG-3 format consists of the payload, plus a column of POH bytes and H1/H2 pointer
bytes. The TUG-3 pointer bytes define the start of the J1 POH byte within the TUG-3. A fixed pointer value of
6800 hex is used as the initial value when building a TUG-3 format. There are two levels of pointer movements
in the TUG-3 build process. In either drop or add timing, the transmit pointer value will increment or decrement
when there is an STM-1 VC-4 increment or decrement based on the relative position of the J1 pulse in the
C1J1. The pointer movement for the TUG-3s will be in the opposite direction. This feature can be disabled.
POH 8R 8R RRC 5I 200I 8R 8R CCRRRRRR 208I 8R 8R CCRROORS
1
2
3
Figure 4. SONET AU-3/STS-1 SPE Build Format
DS3 44.736 Mbit/s Subframe Format (1 of 9)
AU-3/STS-1 SPE Format (87 x 9)
30 31
B3
C2
G1
H4
F2
Z3
Z4
Z5
J1
1
DATA SHEET
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30
32
59
59 60
87
1
9
61
208I
87