TAN-007
...the analog plus
company TM
XR-T5683 Operation
at 10.1 Mbps
June 1997-3
INTRODUCTION
Measurement Results
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.
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.
Circuit Details
LC Tank Circuit:
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.
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.
CONCLUSION
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.
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
1994
EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 (510) 668-7000 FAX (510) 668-7017
1
TAN-007
SCHOTT 67146440
VCC
GND
L1
1
3
R4
C3
0.1uF
C10
0.1uF
C7
6
TBIAS
PE-65835
T1 10
3
8
RING
RX INPUT
5
TIP
6
2
5
RNEG
RCLK
TX DATA TNEG
INPUTS TCLK
12
16
OUTPUTS
8
RCLK
PE-65835
XR-T5683
TXDAT+
17
RX DATA
VCC
0.1uF
TPOS
TVCC
TPOS
R2 46.4
18
8
T2 1
3
15
6
5
13
TXDAT-
TCLK
PDC RGND TGND
1
1
7
4
Figure 1. XR-T5683 Circuit Diagram
Rev. 1.04
2
10
R3 46.4
C6
0.1uF
TNEG
C1
0.1uF
C4
0.1uF
RNEG 10
RXDATA+
BIAS
C8
22uF
RPOS
U1
3
C2
+
4 9
TE RVCC
RPOS 11
RXDATA-
R1
300
C9
0.1uF
C5
0.1uF
RING
TX OUT
TIP
TAN-007
Pin 10
(RNEG)
Pin 11
(RPOS)
Pin 10
(RNEG)
Pin 11
(RPOS)
Pin 8
(RCLK)
Pin 8
(RCLK)
Input Signal
Input Signal
(At Input
Trans. Primary)
B. 215 - 1 Length AMI Encoded
Pseudorandom Data
A. 1010 Data
Pin 11
(RPOS)
Pin 8
(RCLK)
C. 1010 Data
D. 1111 Data, Transmit Output
(Transformer output measured through 5.6dB
75Ω to 50Ω Pad terminated with 50Ω)
Figure 2. XR-T5683 Operating at 10.1 Mbps
Rev. 1.04
3
TAN-007
NOTICE
EXAR Corporation reserves the right to make changes to the products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any circuits described herein, conveys no license under any patent or other right, and makes no representation that the circuits are
free of patent infringement. Charts and schedules contained here in are only for illustration purposes and may vary
depending upon a user’s specific application. While the information in this publication has been carefully checked;
no responsibility, however, is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or
malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly
affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation
receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized; (b) the
user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances.
Copyright 1994 EXAR Corporation
Datasheet June 1997
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
Rev. 1.04
4