DS3181 Maxim Integrated Products, DS3181 Datasheet - Page 175

• Manufacturer Part Number: DS3181
• Description: Network Controller & Processor ICs DS3-E3 ATM-Packet PH Y with Built-in Line
• Manufacturer: Maxim Integrated Products

Specifications of DS3181

• Product: Framer
• Number Of Transceivers: 1
• Data Rate: 44.736 Mbps
• Supply Voltage (max): 3.465 V
• Supply Voltage (min): 3.135 V
• Supply Current (max): 280 mA
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Package / Case: TEBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DS3181/DS3182/DS3183/DS3184
10.10.7.4 Transmit G.751 E3 Overhead Insertion
Overhead insertion can insert any (or all) of the E3 overhead bits into the E3 frame. The FAS, A bit, and N bit can
be sourced from the transmit overhead interface (TOHCLK, TOH, TOHEN, and TOHSOF). The E3 overhead
insertion is fully controlled by the transmit overhead interface. If the transmit overhead data enable signal (TOHEN)
is driven high, then the bit on the transmit overhead signal (TOH) is inserted into the output data stream. Insertion
of bits using the TOH signal overwrites internal overhead insertion.
10.10.7.5 Transmit G.751 E3 AIS Generation
G.751 E3 AIS generation overwrites the data stream with AIS. If transmit AIS is enabled, the data stream (payload
and E3 overhead) is forced to all ones.
10.10.7.6 Receive G.751 E3 Frame Processor
The G.751 E3 frame format is shown in
Figure
10-43. FAS is the Frame Alignment Signal. A is the Alarm indication
bit used to indicate the presence of an alarm to the remote terminal equipment. N is the National use bit reserved
for national use.
10.10.7.6.1 Receive G.751 E3 Framing
G.751 E3 framing determines the G.751 E3 frame boundary. The frame boundary is found by identifying the frame
alignment signal (FAS), which has a value of 1111010000b. The framer is an off-line framer that updates the data
path frame counters when an out of frame (OOF) condition has been detected. The use of an off-line framer
reduces the average time required to reframe, and reduces data loss caused by burst error. The G.751 E3 framer
checks each bit position for the FAS. The frame boundary is set once the FAS is identified. Since, the FAS check is
performed one bit at a time, up to 1536 checks may be needed to find the frame boundary. The data path frame
counters are updated if an error free FAS is received for two additional frames, and an OOF condition is present, or
if a manual frame re-synchronization has been initiated.
10.10.7.6.2 Receive G.751 E3 Performance Monitoring
Performance monitoring checks the E3 frame for alarm conditions. The alarm conditions detected are OOF, LOF,
COFA, LOS, AIS, RUA1, and RAI. An Out Of Frame (OOF) condition is declared when four consecutive frame
alignment signals (FAS) contain one or more errors or at the next FAS check when a manual reframe is requested.
An OOF condition is terminated when three consecutive FASs are error-free or the G.751 E3 framer updates the
data path frame counters.
A Loss Of Frame (LOF) condition is declared by the LOF integration counter when it has been active for a total of T
ms. The LOF integration counter is active (increments count) when an OOF condition is present, it is inactive (holds
count) when an OOF condition is absent, and it is reset when an OOF condition is absent for T continuous ms. T is
programmable (0, 1, 2, or 3). An LOF condition is terminated when an OOF condition is absent for T continuous
ms.
A Change Of Frame Alignment (COFA) is declared when the G.751 E3 framer updates the data path frame
counters with a frame alignment that is different from the current data path frame alignment.
A Loss Of Signal (LOS) condition is declared when the HDB3 encoder is active, and it declares a LOS condition. A
LOS condition is terminated when the HDB3 encoder is inactive, or it terminates a LOS condition.
An Alarm Indication Signal (AIS) condition is declared when 4 or less zeros are detected in each of two consecutive
frame periods. An AIS condition is terminated when 5 or more zeros are detected in each of two consecutive frame
periods.
A Receive Unframed All 1’s (RUA1) condition is declared if in each of 4 consecutive 2047 bit windows, five or less
zeros are detected and an OOF condition is continuously present. A RUA1 condition is terminated if in each of 4
consecutive 2047-bit windows, six or more zeros are detected or an OOF condition is continuously absent.
A Remote Alarm Indication (RAI) condition is declared when four consecutive frames are received with the A bit
(first bit after the FAS) set to one. An RAI condition is terminated when four consecutive frames are received with
the A bit set to zero.
Only framing errors are accumulated. Framing errors are determined by comparing the FAS to its expected value.
The type of framing errors accumulated is programmable (OOF, bit, or word). An OOF error increments the count
whenever an OOF condition is first detected. A bit error increments the count once for each bit in the FAS that does
175