10
Figure 8. Recommended Panel Mounting
Package footprint and front panel considerations
The Avago Technologies transceivers comply with the
circuit board “Common Transceiver Footprint” hole pattern
dened in the current multisource agreement which de-
ned the 2 x 10 package style. This drawing is reproduced
in Figure 7 with the addition of ANSI Y14.5M compliant di-
mensioning to be used as a guide in the mechanical layout
of your circuit board. Figure 8 shows the front panel dimen-
sions associated with such a layout.
Eye Safety Circuit
For an optical transmitter device to be eye-safe in the event
of a single fault failure, the transmit-ter must either main-
tain eye-safe operation or be disabled.
The HFCT-5914ATLZ is intrinsically eye safe and does not
require shut down circuitry.
Signal Detect
The Signal Detect circuit provides a de-asserted out-
put signal when the optical link is broken (or when the
remote transmitter is OFF). The Signal Detect thresh-
old is set to transition from a high to low state be-
tween the minimum receiver input optical power and
-30 dBm avg. input optical power indicating a denite opti-
cal fault (e.g. unplugged connector for the receiver or trans-
mitter, broken ber, or failed far-end transmitter or data
source). The Signal Detect does not detect receiver data
error or error-rate. Data errors can be determined by signal
processing oered by upstream PHY ICs.
Electromagnetic Interference (EMI)
One of a circuit board designer’s foremost concerns is
the control of electromagnetic emissions from electron-
ic equipment. Success in controlling generated Elec-
tromagnetic Interference (EMI) enables the designer to
pass a governmental agency’s EMI regulatory standard
and more importantly, it reduces the possibility of in-
terference to neighboring equipment. Avago Technolo-
gies has designed the HFCT-5914ATL to provide good
EMI performance. The EMI performance of a chassis
is dependent on physical design and features which
help improve EMI suppression. Avago Technologies en-
courages using standard RF suppression practices and
avoiding poorly EMI-sealed enclosures.
Avago Technologies’ Gbe LC transceivers have nose
shields which provide a convenient chassis connection
to the nose of the transceiver. This nose shield im-
proves system EMI performance by eectively closing
o the LC aperture.
Localized shielding is also improved by tying the four metal
housing package grounding tabs to signal ground on the
PCB. Though not obvious by inspection, the nose shield
and metal housing are electrically separated for customers
who do not wish to directly tie chassis and signal grounds
together. Figure 8 shows the recommended positioning of
the transceivers with respect to the PCB and faceplate.
15.24
(0.6)
DIMENSIONS IN MILLIMETERS (INCHES)
1. FIGURE DESCRIBES THE RECOMMENDED FRONT PANEL OPENING FOR A LC OR SG SFF TRANSCEIVER.
2. SFF TRANSCEIVER PLACED AT 15.24 mm (0.6) MIN. SPACING.
14.22 ±0.1
(0.56 ±0.004)
DETAIL A
TOP OF PCB
1
(0.039)
A
SOLDER POSTS
15.75 MAX. 15.0 MIN.
(0.62 MAX. 0.59 MIN.)
SECTION B - B
15.24
(0.6)
B
10.16 ± 0.1
(0.4 ± 0.004)
