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PDF XRT82D20 Data sheet ( Hoja de datos )
| Número de pieza | XRT82D20 | |
| Descripción | SINGLE CHANNEL E1 LINE INTERFACE UNIT | |
| Fabricantes | Exar Corporation | |
| Logotipo |  |
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XRT82D20
APRIL 2001
SINGLE CHANNEL E1 LINE INTERFACE UNIT
REV. 1.0.7
GENERAL DESCRIPTION
The XRT82D20 is a fully integrated, single channel,
Line Interface Unit (Transceiver) for 75 Ω or 120 Ω E1
(2.048 Mbps) applications. The LIU consists of a
receiver with adaptive data slicer for accurate data
and clock recovery and a transmitter which accepts
either single or dual-rail digital inputs for signal
transmission to the line using a low- impedance
differential line driver. The LIU also includes a crystal-
less jitter attenuator for clock and data smoothing
which, depending on system requirements, can be
selected in either the transmit or receive path.
Coupling the XRT82D20 to the line requires trans-
formers on both the Receiver and Transmitter sides,
and supports both 120 Ω balanced and 75 Ω unbal-
anced interfaces. The receiver can be capacitive
coupled to for cost reduction
FEATURES
• Complete E1 (CEPT) line interface unit
• Generates transmit output pulses that are compli-
ant with the ITU-T G.703 Pulse Template for
2.048Mbps (E1) rates
• On-Chip Pulse Shaping for both 75 Ω and 120 Ω
Line Drivers
• Clock Recovery and Selectable Crystal-less Jitter
attenuator
• Compliant with ETS300166 Return Loss
• Compliant with the ITU-T G.823 Jitter Tolerance
Requirements
• Remote, Local and Digital Loop backs
• Declares and Clears LOS per ITU-T G.775
• Logic Inputs accept either 3.3V or 5.0V levels
• - 400C to 850C Temperature Range
• Low Power Dissipation; 145mW with 120 Ω or
160mW with 75 Ω typical
• +3.3V or +5V Supply Operation
• Pin Compatible with the XRT7288
APPLICATIONS
• PDH Multiplexers
• SDH Multiplexers
• Digital Cross-Connect Systems
• DECT (Digital European Cordless Telephone) Base
Stations
• CSU/DSU Equipment
• Test Equipment
FIGURE 1. BLOCK DIAGRAM OF THE XRT82D20
TClk
TPOS
TNEG
RClk
RPOS
RNEG
HDB3
Encoder
MUX
Digital
Loopback
Remote
Loopback
HDB3
Decoder
MUX
Tx Pulse
Shaper
Line
Driver
Jitter Attenuator
Data &
Timing
Recovery
LOS
Detect
Data
Slicer
Local
Loopback
Peak
Detector
Timing
Generator
TTIP
TRing
RLOS
RTIP
RRing
MClk
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com
1 page  
XRT82D20 SINGLE CHANNEL E1 LINE INTERFACE UNIT
áç
REV. 1.0.7
PIN DESCRIPTIONS
PIN #
1
SYMBOL
RLOS
2 ClkLOS
3 TNEG/CODE
4 RNEG/LCV
5 RClk
6 RPOS/RData
7 TClk
8 TPOS/TData
9 LLoop
10 RLoop
11 DLoop
TYPE
O
O
I
O
O
O
I
I
I
I
I
DESCRIPTION
Receiver Loss of Signal: This pin toggles Low to indicate the loss of
signal at the receive inputs.
Receiver Loss of Clock: With MuteRx=1, this pin will toggle low to indi-
cate a loss of clock has occurred when the receive signal is lost
(RLOS=0). When RLOS=0, no transitions occur on RClk, RPOS/RData
and RNEG outputs.
Transmitter Negative Data Input/Coding Select: With Jitter Attenuator
enabled (pin 18=1), input activity on this pin determines whether the
device is configured to operate in single-rail or dual-rail mode. With n-rail
transmit data applied to this pin, the device is automatically configured to
operate in dual-rail mode for both transmit input and receive output.
If this pin is tied high for more than 16 clock cycles, the device is config-
ured to operate in single-rail mode with HDB3 encoding and decoding
functions enabled.
If this pin is tied low for more than 16 clock cycles, the device is config-
ured to operate in single-rail mode with AMI encoding and decoding
functions enabled. (internal pull-down).
Receive Negative Data/Line Code Violation Output:
If the device is configured in Dual-rail mode with n-rail data applied to pin
3, then the receive negative data will be output through this pin.
If the device is configured in Single-rail mode and operate with HDB3
coding enabled, HDB3 code violation will be detected and cause this pin
to go high.
If the device is configured in Single-rail mode and with AMI coding
selected, every bipolar violation will be reported at this pin.
Receive Clock:
Output receive clock signal to the terminal equipment.
Receive Positive/ Data Output:
In Dual-rail mode, this signal is the p-rail receive output data. In Single-
rail mode, this signal is the receive output data.
Transmitter Clock Input:
Input clock signal (2.048 MHz ± 50ppm)
Transmit Positive / Data Input:
In Dual-rail mode, this signal is the p-rail transmit input data. In Single-rail
mode, this signal is the transmit input data.
Local Loop back enable (active low):
Tie this pin low to enable analog Local Loop-back.In local loop-back
mode, transmit output data is looped back to the input of the
receiver.Input signal at RTIP and RRing are ignored. Local Loop-back
has priority over Remote and Digital Loop-back mode. See Section 2.2
for more details. (internal pull-down).
Remote Loop Back Enable (active low):
Connect this pin to ground to enable Remote Loop-back. In Remote
Loop-back mode, transmit data at TPOS/TData and TNEG are ignored.
See Section 2.2 for more details. (internal pull-down).
Digital Loop Back enable (active low):
Connect this pin to ground to enable Digital Local Loop-back.In Digital
loop-back mode, transmit input data after the encoder is looped back to
the jitter attenuator (if selected) and to the receive decoder. Input data at
RTIP and RRing are ignored in this mode. (internal pull-up). In this
mode, the XRT82D20 can operate only as a jitter attenuator.
3
5 Page 
XRT82D20 SINGLE CHANNEL E1 LINE INTERFACE UNIT
REV. 1.0.7
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TABLE 6: DC ELECTRICAL CHARACTERISTICS
Ta = 25°C, Vdd=3.3V ± 5% or 5V ± 5% unless otherwise specified
PARAMETER
SYMBOL
MIN
TYP
Input High Voltage
Input Low Voltage
Output High Voltage @IOH=5mA (See Note)
VDD=3.3V
VDD=5.0v
Output Low Voltage @ IOL=5mA (See Note)
VDD=3.3V
VDD=5.0v
Input Leakage Current (except input pins with pull-up
resistors)
Input Capacitance
Output Load Capacitance
VIH
VIL
VOH
VOL
IL
CI
CO
2.0 3.3 or 5.0
0.5 0
-
2.4
2.4
-
0
0
-0
-5
--
NOTE: All Digital output pins except pin 1 and pin 2, which
typically source 20µA at VOH and sink -4mA at VOL
ABSOLUTE MAXIMUM RATINGS
Storage Temperature
Operating Temperature
Supply Voltage
-65 to 150°C
-40 to 85°C
-0.5V to +5.5V
MAX
5.5
0.8
VDD
VDD
0.4
0.4
10
UNIT
V
V
V
V
uA
20 pF
20 pF
9
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| PDF Descargar | [ Datasheet XRT82D20.PDF ] | |
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