TAN-007 Datasheet, PDF (1/4 Pages) Exar Corporation – XR-T5683 Operation at 10.1 Mbps

...the analog plus company^TM
TAN-007
XR-T5683 Operation
at 10.1 Mbps
INTRODUCTION
The purpose of this application note is to present an
example circuit, illustrating how to operate the XR-T5683
device at 10.1 Mbps. This note shows the results of
measurements made on the XR-T5683 at a 10.1 Mbps
data rate. Hardware used for this evaluation was a slightly
modified board designed for 8.448 Mbps E2 service. The
only change to the circuit, which is shown in Figure 1,
involved lowering the LC clock extraction circuit tuning
capacitor value.
Circuit Details
LC Tank Circuit:
L1 - Schott Corporation Part Number
67146440, 5µH nominal, Q ~ 90
C7 - 33 pF
R7 - 15 kΩ
Note
Circuit actually resonates at 10.1 MHz due to stray capacitance.
Transformers
The input and output transformers are both Pulse
Engineering type PE-65835. The input unit is connected
as a 1:2 step-up and the output as a 2:1 step-down.
Measurement Results
June 1997-3
The oscilloscope photographs given in Figure 2 shows
XR-T5683 operation at 10.1 Mbps.
Photos A and B show the receive-side timing relationship
between the input signals as measured at the transformer
primary, the recovered clock (RCLK), and the dual-rail
data (RPOS and RNEG). Photo A is for a repetitive 1010
pattern while photo B uses a pseudo-random sequence.
Photo C has an expanded horizontal scale that more
clearly shows the received data (RPOS) to recovered
clock (RCLK) timing relationship.
Photo D is the transmitter output for all ones data. The
pulse amplitude shown in this picture is approximately 1V
peak because the measurement was made with the
output transformer secondary connected to the
oscilloscope 50Ω input through a 75Ω to 50Ω matching
pad that had 5.6 dB loss.
CONCLUSION
These measurements show that in the circuit tested, the
XR-T5683, the Pulse Engineering transformers, and the
Schott timing inductor are all functional at 10.1 Mbps.
Rev. 1.04
E1994
EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 z [phone] z FAX [phone]
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