HFBR-0527H

HFBR-0527H Datasheet


The traditional argument for using copper wire has always been that fiber optic solutions cost more, but Avago Technologies’ Versatile Link components now enable system designers to overcome cost barriers that have historically prevented the use of fiber optic cables in short distance applications. The HFBR-15X7Z LED transmitter and the HFBR-25X6Z receiver can be used with large diameter 1 mm plastic or 200 µm Hard Clad Silica HCSTM step index fibers to build unusually low cost data communication equipment. The fiber optic solution described in this application note can transmit data at rates up to for the same price as shielded twisted pair wire, but this unusually low cost optical data link has none of the disadvantages that are inherent to wire cables.

Part Datasheet
HFBR-0527H HFBR-0527H HFBR-0527H (pdf)
Related Parts Information
HFBR-0527P HFBR-0527P HFBR-0527P
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Fiber Optic Solutions for 125 MBd Data Communication Applications at Copper Wire Prices

Application Note 1066

Introduction

Fiber optic cables have historically been used when the distance is too long, or the data rate is too high, for the limited bandwidth of wire. Optical communication links are also favored when the environment through which the data will pass is electrically noisy, or when electromagnetic radiation from wire cables is a concern. Optical fibers have numerous technical advantages over conventional wire alternatives, but the cost of fiber optic solutions has always been higher until now.

The Inherent Disadvantages of Wire

Systems which must communicate are often connected to different reference potentials which are not necessarily zero volts, or in other situations ground references that are thought to be 0 V are electrically noisy. Metallic connections between systems with different ground potentials can be implemented by using the proper isolation and grounding techniques, but if these techniques are not strictly adhered to conductive cables will introduce conflicts between systems operating at different ground potentials. Data communication system designers must exercise caution to ensure that conductive cables do not exceed radiated noise limits established by the FCC, and cable installers need to route wire cables away from other power conductors that might couple electrical noise into the data by magnetic induction. Conventional wire transmission lines must also be terminated using a load resistor equal to the characteristic impedance of the metallic cable. This termination resistor must always be connected to the receiving end of every wire cable to ensure that pulses are not reflected back toward the data source causing interference with the transmitted data.

Fundamental Advantages of Optical Communication

Non-conductive optical cables have none of the traditional problems associated with wire. When using a fiber optic solution, system designers do not need to be concerned about environmental noise coupling into cables, or worry about whether there is a termination resistor at the end of the cable. Conflicts between systems with different reference potentials do not happen when using insulating fiber optic media because optical cables do not have conductors or shields that can be improperly grounded when the cables are installed or maintained. The fiber optic receiver is the only portion of the optical link which is sensitive to noise, and it can easily be protected because it is contained within the host system which is receiving the data. A simple power supply filter is usually sufficient to protect the fiber optic receiver from the host system’s electrical noise. Electrostatic shielding can be applied to the receiver if the host system is particularly noisy, but electrostatic shields are not needed in most applications if the circuit techniques recommended in this application note are used.

A Fiber Optic Solution at Wire Prices

The traditional argument for using copper wire has always been that fiber optic solutions cost more, but Avago Technologies’ Versatile Link components now enable system designers to overcome cost barriers that have historically prevented the use of fiber optic cables in short distance applications. The HFBR-15X7Z LED transmitter and the HFBR-25X6Z receiver can be used with large diameter 1 mm plastic or 200 µm Hard Clad Silica HCSTM step index fibers to build unusually low cost data communication equipment. The fiber optic solution described in this application note can transmit data at rates up to for the same price as shielded twisted pair wire, but this unusually low cost optical data link has none of the disadvantages that are inherent to wire cables.

HFBR-15X7Z/25X6Z Distance and Data Rate Capabilities

Various distances and data rates are possible when the shows the performance possible with 1 mm diam-

HFBR-15X7Z and HFBR-25X6Z components are used with eter plastic fiber. The HFBR-15X7Z/25X6Z components can
large-core step index fibers. At low data rates, the distances be used with standard 1 mm plastic cables to build 20 m
achievable are determined by the sensitivity of the receiver, links which are capable of transmitting data at a rate of 125
cable attenuation, and the amount of light which the LED MBd. When low loss plastic fiber is used, distances of 25 m
can launch into the fiber core. As data rate increases, fiber bandwidth will begin
the dis1 shows

DATA RATE, SYMBOLS/SEC, MBd

DATA RATE, SYMBOLS/SEC, MBd
data link can be and how fast the data can be transmitted. that a distance of 100 m is typically possible at rates as low

The distance60data rate curves shown in Figures 1 and 2 are 6u0sed with 200 µm diameter hard clad silica HCS fiber.
provided to allow designers to quickly determine if HFBR15X7Z and H4F0BR-25X6Z can be used with large-core optical
4S0ubstantial increases in cable length are possible when using 200 µm HCSTM fiber since it has a much lower opti-
fibers to meet their system requirements. Figure 1 shows cal attenuation than plastic fiber. Figure 2 indicates
tAhveagdois’sta1nmce2ms0
and data rates that can plastic fibers and Figure
be achieved with 2 shows what can
2t0hat data rates are typically possible with 125 m lengths of 200 µm HCSTM fiber when using the transceiver
be accomplished when using Avago’s 200 µm hard clad recommended in this publication. Distances of can
as d1u,0e0t0o HCSTM cable.
the shaded portions of and Figure The fiber
optic transceiver shown in this publication was optimized
for operation at 125 MBd. Greater distances can be achieved
at data rates less than 125 MBd by optimizing the trans-
mitter and receiver circuits for operation at lower speeds. HCS is a registered trademark of OFS.
180 140
100 80 60
40 RECOMMENDED

OPERATING REGION

TYPICAL PERFORMANCE AT 25 C
System designers can quickly determine if the HFBR-15X7Z and HFBR-25X6Z will meet their needs by ordering the HFBR-0527Z. The HFBR-0527Z is a completely assembled
demo board for the transceiver shown in Figure When using plastic fiber order the HFBR-0527P, and when using 200 µm HCSTM fibers specify the HFBR-0527H. The test fixture in is also available as the HFBR-0319. The HFBR-0319 is a fully assembled test fixture. This test fixture adapts any fiber optic transceiver with a 1x9 footprint to test equipment with -5 V ECL inputs and outputs. The HFBR-0527 and the HFBR-0319 minimize the effort needed to design new products which use fiber optic data links. The HFBR-0527 and the HFBR-0319 provide a high level of technical support. This high level of technical assistance drastically reduces the time needed to develop and market new products which utilize the fundamental advantages of optically isolated data communication.
1 x 10-3
1 x 10-5
1 x 10-7
1 x 10-9

CLOCK DELAY, ns

Figure Typical BER vs. Clock Delay at 125 MBd with 20 m of 1 mm Plastic Fiber
1 x 10-3
1 x 10-5 5439-15
1 x 10-7
1 x 10-9

CLOCK DELAY, ns

Figure Typical BER vs. Clock Delay at 125 MBd with 100 m of 200 µm HCSTM Fiber

Conclusion

The HFBR-15X7Z and HFBR-25X6Z components can be
used with large core fibers and inexpensive optical con-
nectors to build exceptionally low cost digital fiber optic
links. When these Versatile Link components are used with
1 mm plastic, or 200 µm HCSTM fibers, digital data links that
are comparable with the cost of shielded twisted pair wire
9-16
can easily be implemented. The HFBR-15X7Z and HFBR-
25X6Z provide designers with a short haul data communi-
cation solution that costs the same as shielded twisted pair
wire, but this low cost fiber optic solution has none of the
grounding and electromagnetic compatibility problems
inherent in metallic cables.

Table Parts List for Circuit Shown in Figure 8

Designator

Part Type

C8 1mm Plastic
43 pF

C8 200HCS
120 pF

MC10H116FN

TL431CD

CB70-1812

R8 1mm Plastic

R9 1mm Plastic

R8 200HCS
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Datasheet ID: HFBR-0527H 520305