3.0 Applications
CX28331/CX28332/CX28333
3.1 PCB Design Considerations for CX2833i
Single/Dual/Triple E3/DS3/STS-1 Line Interface Unit
3.1.2 Impedance Matching
It is critical that traces around the transformers and matching resistors be kept to a
minimum length and, in the following cases, the trace impedance be matched to
75 Ω with a ±10% tolerance:
•
•
The impedance from the BNC connector to the transformer
The impedance from the transformer to the matching resistors
3.1.3 Other Passive Parts
The reference design uses the Pulse T3001 extended temperature range 1:1
transformer for the coupling of the BNC connector to the device.
The ferrite beads used to decouple the receive- and transmit-VDD pins on all
analog input VDD pins are type 2508056017Y0 from Fair-Rite Products
Corporation. The bulk capacitor used for where the power enters the board
should be a tantulum–type capacitor, the recommended value and type is a 220 µf
tantulum capacitor.
3.1.4 IBIS Models
IBIS (Input/Output Buffer Interface Specification) models for the
CX28331/CX28332/CX28333-1x and -3x are available from Conexant’s web site
(www.conexant.com).
3.1.5 Recommended Vendors
Product: Transformers
Pulse
Corporate Office
Product: Ferrite Beads
America
Address:
Fair-Rite Products Corp.
P.O. Box J
12220 World Trade Drive
San Diego, CA 92128
858-674-8100
One Commercial Row
Wallkill, NY 12589
914-895-2055
Telo:
Fax:
Telo:
Web site:
858-674-8262
www.Fair-Rite.com
Northern Asia
Pulse
3F-4, No. 81, Sec. 1
Hsin Tai Wu Road
Hsi-Chih
Tapei Hsien, Taiwan
R.O.C.
Telo:
886-2-26980228
886-2-26980948
Product: Crystals
Northern Europe
Pulse
Crystek Corp.
1S2 Huxley Road
The Surrey Research Park
Guildford, Surrey GU2 5RE
United Kingdom
12730 Commonwealth Drive
Fort Myers, FL 33913
800-237-3061
Telo:
Fax:
941-561-1025
Telo:
Fax:
44-1483-401700
44-1483-401701
E-mail:
Web site:
sales@crystek.com
www.crystek.com
3-2
Conexant
100985A
CONEXANT [ CONEXANT SYSTEMS, INC ]
