XR-T5683A Datasheet, PDF (4/12 Pages) Exar Corporation – PCM Line Interface Chip

XR-T5683A
ELECTRICAL CHARACTERISTICS (CONT’D)
Parameters
AC Electrical Characteristics (Cont’d)
Transmitter Section
Pulse Width at 8.448MHz
Output Rise Time
Output Fall Time
Output Pulse Imbalance
Min.
53
Typ. Max.
65
12
25
12
25
2.5
Unit Conditions
ns Measured at Pin 13 & 15, See Figure 6
ns See Figure 5
ns See Figure 5
ns At 50% Output Level
Specifications are subject to change without notice
Notes
Bold face parameters are covered by production test and guaranteed over operating temperature range.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . +20V
Storage Temperature . . . . . . . . . . . . . . -65°C to +150°C
SYSTEM DESCRIPTION
The incoming bipolar PCM signal which is attenuated and
distorted by the cable is applied to the threshold
comparator and the peak detector. The peak detector
generates a DC reference for the threshold comparator
for data and clock extraction. An external tank circuit
tuned to the appropriate frequency is added for the later
operation. The clock signal, data (+) and data (-) all go
through a similar level shifter to be converted into TTL
level to be compatible for digital processing.
In the transmit direction, the output drivers consist of two
identical TTL inputs with open collector output stages.
The maximum low level current these output stages can
sink is 40mA. With full width data (NRZ) applied to the
inputs together with a synchronized clock, the output will
generate a bipolar signal when driving a center-tapped
transformer. A block diagram of the XR-T5683A is shown
in Figure 1.
The clock recovery uses an external tank circuit. The
receive data will create an excitation for the tank circuitry
which in turn will create a recovered, received clock
(RCLK).
Rev. 2.01
4