PCM Repeater. XR-C277 Datasheet

XR-C277 Repeater. Datasheet pdf. Equivalent


Exar XR-C277
XR-C277
Low-Voltage PCM Repeater
GENERAL DESCRIPTION
The XR-C277 is a monolithic repeater circuit for Pulse-
Code Modulated (PCM) telephone systems. It is designed to
operate as a regenerative repeater at 1.544 Megabits per
second (Mbps) data rate on T1-type PCM lines. It is pack-
aged in a hermetic 16-Pin CERDIP package and is designed
to operate over a temperature range of -40°C to +85°C. It
contains all the basic functional blocks of a regenerative
repeater system, including Automatic Line Build-Out
(ALBO) and equalization, and is insensitive to reflections
caused by cable discontinuities.
The key feature of the XR-C277 is its ability to operate
with low supply voltage (6.3 volts and 4.3 volts) with a
supply current of less than 13 mA. Compared to conven-
tional repeater designs using discrete components, the
XR-C277 monolithic repeater IC offers greatly improved
reliability and performance, along with significant savings
in power consumption and system cost.
The XR-C277-5F is an improved version of XR-C277 with
an internal feedback that improved the phase gain margin
which enables the system to be more stable and less sensi-
tive to PC board layouts.
Other versions of the XR-C277-5F are XR-C277-F and XR-
C277-Fl. XR-C277-F is an AC tested device of XR-C277-
5F at 2Mbit while XR-C277-F L is the equivalen at 1.544
Mbit.
FEATURES
Contains all the Active Components of a PCM Repeater
Low-Voltage Operation (6.3 volts)
Low-Power Dissipation (13 mAl
On-Chip ALBO Port
High-Current Outp ut Drivers
Increased Reliability over Discrete Designs
2 Megabit Operation Capability
Pin-Compatible with XR-C240
ABSOLUTE MAXIMUM RATINGS
Storage Temperature
-65°C to +150o C
Operating Temperature
-40°C to +85°C
Supply Voltage
-0.5 to +10 V
Input Voltage (Except Pin 1,16)
-0.5 to +7 V
Input Voltage (Pin 1,16)
-0.5 to +0.5 V
Data Output Voltage (Pin 8,9)
20V
Voltage Surge (Pin 2,3,8,9) (10 msec only)
50V
SYSTEM DESCRIPTION
The XR-C277 contains all the active circuits required to
build one side of a T1 or 2 M bitls PCM repeater. T1 is the
FUNCTIONAL BLOCK DIAGRAM
ALBO
OUTPUT
lJPREAMP
INPUTS
I
PREAMP
OUTPUTS \
ANALOG
GROUND
GND
(+1 DRIVER
OUTPUT
most widely used PCM transm ission system, operating at
1.544 M bit/s. It can operate on either pulp or plastic insu-
lated twisted pair cables. Although the cable gauge may
vary the total cable loss should not exceed 36 dB at 772
kHz. For a 22 gauge pulp insulated cable and a bit error
rate (BER) of less than 10-6 the max allowable repeater to
repeater spacing is about 6300 feet.
Bipolar PCM signal is attenuated and dispersed in time as
it travels along a transmission cable. This signal, when re-
ceived, is amplified and reconstructed by the preamplifier
automatic line build out (ALBO), clock and data threshold
detector circuits contained within the XR-C277. Amplitude
equalization and frequency spectrum shaping is achieved
through the variable impedance of the ALBO port and its
associated ALBO network.
Incoming pulse stream is full wave rectified and timing
information is extracted by the clock threshold detector.
Clock recovery is then achieved by pUlsing a tank circuit
tuned to 1.544 MHz. Either injection locking or pulsed
tank type clock extraction are possible with the XR-C277.
By grounding Pin 13, the circuit works in the injection
lock mode. Floating (open) Pin 13 switches the XR-C277
to an pulse tank mode. The oscillator's sinusoidal waveform
is amplified and phase shifted by 90 degrees with the help
of a capacitor between Pins 11 and 12.
Data is sampled and stored in the output data latches by
an internally generated sampling pulse. Buffer drivers are
then enabled to produce precisely timed output pulses
whose width and time of occurence are controlled by the
regenerated clock signal.
2-32


XR-C277 Datasheet
Recommendation XR-C277 Datasheet
Part XR-C277
Description Low-Voltage PCM Repeater
Feature XR-C277; XR-C277 Low-Voltage PCM Repeater GENERAL DESCRIPTION The XR-C277 is a monolithic repeater circuit.
Manufacture Exar
Datasheet
Download XR-C277 Datasheet




Exar XR-C277
XR-C277
ELECTRICAL CHARACTERISTICS
Test Conditions: +25°C, V++ = 6.3V ±5%, V+ = 4.4V ±5%, unless specified otherwise.
PARAMETERS
LIMITS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
Supply Current
IA
IB
Total Current
3.5 mA Measured at Pin 10
7.5 mA Measured at Pin 15
8 11 13 mA (lc + IB)
Preamplifier
Input Offset Voltage
Input Bias Current
Voltage Gain
Prea!11P Output Swing
High Swing
Low Swing
Output DC Level
44
3.45
1.25
2.47
1.5
0.3
48
3.6
1.4
2.55
15
4
51
3.75
1.55
2.72
mV
fJA
dB
V
V
V
Measured at Pins 2 and 3
Measured at Pins 2 and 3
Single-ended Gain
Measured at Pins 4 and 5
Maximum Voltage Swing
Minimum Voltage Swing
A LBO Section
ALBO "Off" Voltage
ALBO "On" Voltage
ALBO "On Voltage
ALBO Threshold
Differential Threshold
ALBO "On" Impedance
ALBO "Off" Impedance
0.6
1.2
1.35
-75
20
10
0.87
1.5
1.50
5
50
75
1.1
2.1
1.65
+75
10
mV
V
V
V
mV
fl
kfl
Measured from Pin 1 and 16 to
Ground
Measured at Pin 1
Measured at Pin 16
Measured Differentially
Across Pins 4 and 5
Threshold Difference for
Polarity Reversal at Pins 4 and 5
Measured at Pin 1
Measured at Pin 1
Comparator Thresholds
Clock Threshold
68 73 78 % % of ALBO Threshold
Data Threshold
47 50 53 % % of ALBO Threshold
Clock Extractor
Oscillator Current
Tank Drive Impedance
Recommended OSC. 0
linjection/IOSC.
10
100
6.0
14
50
7
Output Driver
Low Output Voltage
0.65
0.75
Output "Off" Current
Output Pulse
Max. Pulse Width Error
Rise'Time
Full Time
I
APPLICATIONS
5
PCM Repeater for Tl Systems
PCM Repeater for 2 M Bit/s Systems
20 fJA
kfl
7.5
Ratio of Current 01 B to
Current in 01A
0.95
100
V
fJA
Measured at Pins 8 and 9
IL=15mA
Vout = 20V
±30 n sec
80 n sec
80 n sec
ORDERING INFORMATION
Part Number
XR-C277
XR-C277-5F
XR-C277-F
XR-C277-FL
2-33
Package
Ceramic
Ceramic
Ceramic
Ceramic
Operating Temperature
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
_40° C to +85° C





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