afbr-53d3 Avago Technologies, afbr-53d3 Datasheet - Page 5
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afbr-53d3
Manufacturer Part Number
afbr-53d3
Description
Rohs Compliant 850 Nm Vcsel 1x9 Fiber Optic Transceivers For Fibre Channel
Manufacturer
Avago Technologies
Datasheet
1.AFBR-53D3.pdf
(16 pages)
Electromagnetic Interference (EMI)
One of a circuit board designer’s foremost concerns is
the control of electromagnetic emissions from electronic
equipment. Success in controlling generated
Electromagnetic Interference (EMI) enables the designer
to pass a governmental agency’s EMI regulatory
standard; and more importantly, it reduces the
possibility of interference to neighboring equipment.
There are three options available for the AFBR-53D3 with
regard to EMI shielding which provide the designer with
a means to achieve good EMI performance. The EMI
performance of an enclosure using these transceivers is
dependent on the chassis design. Avago Technologies
encourages using standard RF suppression practices and
avoiding poorly EMI-sealed enclosures.
The first configuration is a standard AFBR-53D3 fiber
optic transceiver that has no external EMI shield. This
unit is for applications where EMI is either not an issue
for the designer, the unit resides completely inside a
shielded enclosure, or the module is used in a low
density, extremely quiet application.
The second configuration, option EZ, is for EMI shielding
applications where the position of the transceiver
module will extend outside the equipment enclosure.
The external metal shield of the transceiver helps locally
to terminate EM fields to the chassis to prevent their
emissions outside the enclosure. This metal shield
contacts the panel or enclosure on the inside of the
aperture on all but the bottom side of the shield and
provides a good RF connection to the panel. This option
can accommodate various panel or enclosure thickness,
i.e., .04 in. min. to 0.10 in. max. The reference plane for
this panel thickness variation is from the front surface
of the panel or enclosure. The recommended length for
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protruding the AFBR-53D3 EM transceiver beyond the
front surface of the panel or enclosure is 0.25 in. With
this option, there is flexibility of positioning the module
to fit the specific need of the enclosure design. (See
Figure 6 for the mechanical drawing dimensions of this
shield.)
The third configuration, option FZ, is for applications
that are designed to have a flush mounting of the
module with respect to the front of the panel or
enclosure. The flush-mount design accommodates a
large variety of panel thickness, i.e., 0.04 in. min. to 0.10
in. max. Note the reference plane for the flushmount
design is the interior side of the panel or enclosure. The
recommended distance from the centerline of the
transceiver front solder posts to the inside wall of the
panel is 0.55 in. This option contacts the inside panel or
enclosure wall on all four sides of this metal shield. See
Figure 8 for the mechanical drawing dimensions of this
shield.
The two designs are comparable in their shielding
effectiveness. Both design options connect only to the
equipment chassis and not to the signal or logic ground
of the circuit board within the equipment closure. The
front panel aperture dimensions are recommended in
Figures 7 and 9. When layout of the printed circuit board
is done to incorporate these metal-shielded transceivers,
keep the area on the printed circuit board directly under
the metal shield free of any components and circuit
board traces. For additional EMI performance advantage,
use duplex SC fiber-optic connectors that have low metal
content inside them. This lowers the ability of the metal
fiber-optic connectors to couple EMI out through the
aperture of the panel or enclosure.