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參數(shù)資料
| 型號： | XR-T7288 |
| 廠商： | Exar Corporation |
| 英文描述： | CEPT1 Line Interface |
| 中文描述： | CEPT1線路接口 |
| 文件頁數(shù)： | 15/24頁 |
| 文件大小： | 293K |
| 代理商： | XR-T7288 |
XR-T7288
15
Rev. 1.01
Alarms
An independent loss-of-clock (LOC) output is provided so
that loss of clock is detected when the shutdown option is
in effect. LOS and LOC can be wire-ORed to produce a
single alarm.
A bipolar violation output is included if HDB3 = 0, giving an
alarm (VIO) each time a violation occurs (two or more
successive 1s on a rail). The violation alarm output is
held in a latch for one cycle of the internal clock (RClk). In
the HDB3 mode, HDB3 code violations are detected and
an alarm is produced.
An alarm test pin (ALMT) is provided to test the alarm
outputs, LOS, LOC and VIO. Clearing this pin forces the
alarm outputs to the alarm state without affecting data
transmission.
HDB3 Option
The XR-T7288 device contains an HDB3 encoder and
decoder (for single-rail mode only, i.e., SD/DR = 0) that
can be selected by setting the HDB3 pin. This allows the
encoder to substitute a zero-substitution code for four
consecutive 0s detected in the data stream, as illustrated
in Table 6 A “V” represents a violation of the HDB3 code,
and a “B” represents a bipolar pulse of correct polarity.
The decoder detects the zero-substitution code and
reinserts four 0s in the data stream.
Case 1:
Preceding mark has a polarity opposite the
polarity of the preceding violation and is not a violation
itself.
Case 2:
Preceding mark has a polarity the same as the
polarity of the preceding violation or is a violation itself.
Case 1
Case 2
Before HDB3
0000
0000
After HDB3
000V
B00V
Table 6. HDB3 Substitution Code
Blue Signal (AIS) Generators
There are two blue signal (AIS) generators in this device.
One (RBC = 1) substitutes an all-1s signal on RDATA
output (SR/DR = 0) or RPDATA and RNDATA (SR/DR = 1)
toward the terminal equipment. The other (TBC = 1)
substitutes a bipolar, all-1s signal for the bipolar data out
of the transmit converter which can be used to keep line
repeaters active.
Loopback Paths
The XR-T7288 device has three independent loopback
paths that are activated by clearing the respective control
inputs, LP1, LP2 or LP3. Loopback 1 bridges the data
stream from the transmit converter (transmit converter
included) to the input of the receive converter. This
maintenance loop includes most of the internal circuitry.
Loopback 2 provides a loopback of data and recovered
clock from the bipolar inputs (T1, R1) to the bipolar
outputs of the transmit converter (T2, R2). The receive
front end, receive PLL, and transmit driver circuitry are all
exercised. The loop can be used to isolate failures
between systems. TBC = 1 overrides this function.
Loopback 3 loops the data stream as in loopback 1 but
bypasses the transmit and receive converters. The blue
signal (AIS) can be transmitted to the line when in this
loopback. Loopbacks 2 and 3 can be operated
simultaneously to provide transmission loops in both
directions.
Current Pulses
With all other pins grounded, current pulses of maximum
value and time widths are allowed on the T1/R1 and
T2/R2 pins without damaging the device, as shown in
Table 7 Also, to help ensure long-term reliability, the
average value of a current-pulse train is specified.
Pin
Max Value
Width
1
μ
s to 1s
1
μ
s to 1s
Avg Value
T1, R1
20 mA
6 mA
T2, R2
200 mA
40 mA
Table 7. Maximum Allowable Current
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| XR-T7295E-1EIP | INTEGRATED LINE RECEIVER |
| XRT7295E | INTEGRATED LINE RECEIVER |
| XR-T7295E-1EIW | INTEGRATED LINE RECEIVER |
| XR-T7295E | INTEGRATED LINE RECEIVER |
| XR-T7295IP | DS3/Sonet STS-1 Integrated Line Receiver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| XRT7288IP | 制造商:Exar Corporation 功能描述: 制造商:Exar Corporation 功能描述:DATACOM, PCM TRANSCEIVER, PDIP28 |
| XR-T7288IP | 制造商:EXAR 制造商全稱:EXAR 功能描述:CEPT1 Line Interface |
| XRT7288IW | 制造商:EXAR 制造商全稱:EXAR 功能描述:CEPT1 Line Interface |
| XR-T7288IW | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:PCM Transceiver |
| XR-T7295 | 制造商:EXAR 制造商全稱:EXAR 功能描述:DS3/Sonet STS-1 Integrated Line Receiver |
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