DS3170N+ Maxim Integrated Products, DS3170N+ Datasheet - Page 90

• Manufacturer Part Number: DS3170N+
• Description: IC TXRX DS3/E3 100-CSBGA
• Manufacturer: Maxim Integrated Products

Specifications of DS3170N+

• Function: Single-Chip Transceiver
• Interface: DS3, E3
• Number Of Circuits: 1
• Voltage - Supply: 3.135 V ~ 3.465 V
• Current - Supply: 120mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-LBGA
• Includes: DS3 Framers, E3 Framers, HDLC Controller, On-Chip BERTs
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power (watts): -

DS3170 DS3/E3 Single-Chip Transceiver
Once all of the E3 overhead bits have been overwritten, the data stream is passed on to error insertion. If frame
generation is disabled, the incoming E3 signal is passed on directly to error insertion. Frame generation is
programmable (on or off).
10.6.7.3 Transmit G.751 E3 Error Insertion
Error insertion inserts framing errors into the frame alignment signal (FAS). The type of error(s) inserted into the
FAS is programmable (errored FAS bit or errored FAS). An errored FAS bit is a single bit error in the FAS. An
errored FAS is an error in all ten bits of the FAS (a value of 0000101111b is inserted in the FAS). Framing error(s)
can be inserted one error at a time, or in four consecutive frames. The framing error insertion number (single or
four) is programmable.
Single error insertion mode inserts an error at the next opportunity when requested. The multi-error insertion mode
inserts the indicated number of errors at the next opportunities when requested. I.e., a single request will cause
multiple errors to be inserted. The requests can be initiated by a register bit(TSEI) or by the manual error insertion
input (TMEI). The error insertion initiation type (register or input) is programmable. The insertion of each particular
error type is individually enabled.
Once all error insertion has been performed, the data stream is passed on to overhead insertion.
10.6.7.4 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.
10.6.7.5 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.
10.6.7.6 Receive G.751 E3 Frame Processor
The G.751 E3 frame format is shown in
Figure
10-16. 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.
10.6.7.6.1 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 resynchronization has been initiated.
10.6.7.6.2 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 FAS’s 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.
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