AMD
5 .5 In t e rfa c in g t o Fib e r Op t ic Tra n s m it t e rs /Re c e ive rs
The TAXlchip set can be used in conjunction with optical components and optical fiber
to form a simple fiber optic communication link. Optical transmission has many advan-
tages over conventional electrical transmission. These include: immunity to EMI/RFI,
low attenuation, electrical isolation, data security, and wide bandwidth. Because of these
features, use of optical fiber as the serial media will result in optimum performance of
the TAXIchip set link. Depending on the type of fiber and the optical components used,
TAXI links using optical fiber can cover distances of up to several kilometers.
Figure 5-6 shows a block diagram of a complete TAXI fiber optic link. The optical
components transmitters and receivers can be obtained from one of the sources listed in
Appendix A of this manual. The interface between the TAXlchips and the optical
components will be the subject of this section.
Fig u re 5 -6
TAXl-Ba s e d Fib e r Op t ic Lin k
Data Command
8,
9,
10
4,
3,
2
Fiber Optic Transmitter
Optical
Source
Source:
Driver
LED or
Laser Diode
Electronics
Am7968
Transmitter
Optical
Connectors
Transceiver
TAXI /Optical
Interface
Fiber
Optic
Cable
Fiber Optic Receiver
Am7969
Receiver
Optical
Detector:
PIN or
Avalanche
Photodiode
Receiver
Electronics
8,
9,
4,
3,
2
10
Data Command
12330E-13
5 .5 .1 DC-Co u p le d TAXl-Fib e r Op t ic Tra n s c e ive r In t e rfa c e
When passing data between the TAXIchip set and an optical module, care must be
taken to assure that the logic levels of the TAXIchip set and the optical components are
matched. If the supply voltages of the optical components do not match those of the
TAXIchip set, then the logic levels will probably differ and the interface will require AC
coupling to isolate these different levels. However, if the power supply requirements
match those of the TAXIchip set (i.e. VCC = +5 V, VEE = GND) and if the two components
are connected to the same power and ground planes, a DC coupled interconnection
may be sufficient.
66
TAXIchip Integrated Circuits Technical Manual
AMD [ AMD ]
