
IBM42F10SNNAA20
IBM42F12SNNAA20
SFF-1063/1250N-SW PTH Serial Optical Transceiver Design & Layout Guide
optxcvr.fm
July 2000
Page 1
Introduction
The SFF-1063/1250N-SW is a small form factor
(SFF), plated through hole-type (PTH) serial optical
transceiver for use at distances up to 1804.6ft/550m
in high data rate applications including Fibre Chan-
nel Arbitrated Loop (FC-AL) and Gigabit Ethernet.
The transceiver receives serial optical signals and
converts them into serial electrical signals. Con-
versely, it also receives serial electrical signals and
retransmits them as optical signals.
The transceiver uses 850nm short-wavelength light
emitted by a vertical cavity surface emitter laser
(VCSEL) and operates at 1.063Gbps
(IBM42F10SNNAA20) in Fibre Channel applications
and at 1.250Gbps (IBM42F12SNNAA20) in Gigabit
Ethernet applications. The transceiver conforms to
ANSI Fibre Channel specification FC-0 for short-
wavelength operation (100-M5-SN-I) and conforms
to draft 2 of the IEEE 802.3z 1000 Base-SX stan-
dard. The transceiver works with industry-standard
“8b/10b” serializer/deserializer modules and incorpo-
rates circuits optimized for the 8b/10b protocol.
The transceiver uses outgoing and incoming fiber
channel paths. The preferred fiber optic medium is
50/125mm multimode, duplex (dual) optical fiber
cable. A 62.5/125mm multimode fiber can be substi-
tuted for shorter linking distances. Single-mode
10/125mm single-mode fiber should not be used. A
duplex LC-style miniature connector is used for the
fiber optic input, a direct follow-on to the duplex SC-
style connector that has long been used with IBM
GBIC products. However, the LC connector has
been in service long enough to prove its reliability.
The transceiver is a Class 1 laser-safe product.
Under normal operation, optical power is at eyesafe
levels. Cables can be connected and disconnected
while the transceiver is in operation.
This application note should be used in conjunction
with IBM engineering specification
1063/1250 MBd
Small Form Factor Transceiver with Signal Detect,
available from the IBM Microelectronics web site at:
Special Design ConsiderationsAs noted in the following paragraphs, the transceiver
requires design considerations different from that of
previous industry transceiver devices, namely the
GBIC and the 1x9.
Vcc Supply
In contrast to the IBM GBIC, which requires 5Vdc
and has internally connected receiver and transmit-
ter power pins, the transceiver requires 3.3Vdc for
receive and transmit power, which is applied at pins
2 and 6 (Rx Power and Tx Power) of the transceiver,
respectively (Figure 1). Pins 2 and 6 may be tied
together or fed separately, however better isolation
between transmit and receive signals can be
obtained with separate power feeds.
Logic Levels
The transceiver is compatible with 3-volt PECL logic
technology for high speed transmit and receive inter-
faces, and is compatible with 3-volt open-collector
TTL technology for low speed logic lines.
AC Coupling
To ensure AC coupling between the transceiver and
the host logic or SERDES module, a DC blocking
capacitor is required in series with each of the two
high speed input lines and each of the two high
speed output lines.
Split-Chassis Grounds
The transceiver chassis is divided into two electri-
cally isolated halves:
1. The half near the optical fiber is electrically float-
ing and must be connected to chassis ground
(pins CA and CB) for best electrical shielding.
2. The half near the signal pins is electrically con-
nected to logic ground inside the transceiver.
Pins SC through SF are electrically connected to
pins 1 and 7 inside the SFF transceiver and
should be connected to the host logic ground.
See
Grounding Considerations
on page 3 for
more information.