Fairchild FEBFOD8012-RS485 User Manual
User Guide for
FEBFOD8012_RS485
Evaluation Board
Bi-Directional Logic Gate Optocoupler
Provides Proven and Reliable Isolation to
the RS485 Interface
Featured Fairchild Product:
FOD8012
Direct questions or comments
about this evaluation board to:
“Worldwide Direct Support”
Fairchild Semiconductor.com
© 2012 Fairchild Semiconductor Corporation FEBFOD8012_RS485 • Rev. 1.0.0
Table of Contents
1. Introduction ............................................................................................................................... 3
1.1. Description ....................................................................................................................... 3
2. Photographs............................................................................................................................... 4
3. Printed Circuit Board ................................................................................................................ 4
3.1. Board Setup and Operation .............................................................................................. 5
3.2. Test Procedures and Conditions ....................................................................................... 5
4. Schematic .................................................................................................................................. 6
5. Scope Shots ............................................................................................................................... 7
6. Conclusion ................................................................................................................................ 8
7. Revision History ....................................................................................................................... 9
© 2012 Fairchild Semiconductor Corporation 2 FEBFOD8012_RS485 • Rev. 1.0.0
This user guide supports the evaluation kit for the FOD8012. It should be used in
conjunction with the FOD8012 datasheet as well as Fairchild’s application notes and
technical support team. Please visit Fairchild’s website at www.fairchildsemi.com.
1. Introduction
The FOD8012 is an industry-first, full-duplex, bi-directional, logic-gate optocoupler with
high noise immunity as well as proven and reliable optical isolation. It is highly
integrated with two optically coupled channels arranged in a bi-directional configuration
illustrated in Figure 1. The FOD8012 is housed in a compact 8-pin small outline package.
Each optocoupler channel consists of a high-speed AIGaAs LED driven by a CMOS
buffer IC coupled to a CMOS detector IC.
Figure 1. 3-Dimensional Illustration of the Internal Die Set of Fairchild’s Optoplanar®
1.1. Description
The FOD8012 supports isolated communication between systems of digital signals
without conducting ground loops or hazardous voltages. Unlike competitive devices,
which provide less than 0.1 mm optical isolation gap, the FOD8012 features a 0.4 mm
(minimum) optical isolation gap for proven, reliable isolation. The device also features a
fast switching speed, up to 15Mbit/sec, and uses Fairchild’s Optoplanar
technology and optimized IC design to achieve high Common Mode Rejection (CMR) of
20 kV/μs minimum, allowing the device to operate in noisy industrial environments.
Additionally, the FOD8012 offers an extended industrial temperature range of -40°C to
+110ºC and a 3.3 V or 5.0 V supply voltage to facilitate logic level translation. The
device’s high isolation voltage is certified by UL1577 and DIN_EN/IEC60747-5-2 for
increased reliability.
Package Construction
®
packaging
© 2012 Fairchild Semiconductor Corporation 3 FEBFOD8012_RS485 • Rev. 1.0.0
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