HFBR-53D3 查看數據表（PDF） - HP => Agilent Technologies

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HFBR-53D3

1 x 9 Fiber Optic Transceivers for Fibre Channel

HP => Agilent Technologies 

5

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

HFBR-53D3 and two for the

HFCT-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.

Agilent encourages using

standard RF suppression

practices and avoiding poorly

EMI-sealed enclosures.

The first configuration is a

standard HFBR-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

HFCT-53D3 is not available for

use without an external shield.

The second configuration, option

EM, is for EMI shielding

applications where the position of

the transceiver module will

extend outside the equipment

enclosure. The metallized plastic

package and integral 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 protruding the

HFBR/HFCT-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

FM, 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 flush-

mount 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 metallized 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.

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