Isolation of digital signal communication between systems

Design engineers working in the field of industrial communications design need to transmit high-speed data over communication fieldbuses to sensitive controllers, ADCs, or sensors without the risk of loss.

Current solutions use two single-channel optocouplers, such as magnetic or capacitive coupling, or other technologies. However, these do not provide the required level of isolation and EMI immunity.

To help designers facing these challenges, Fairchild has developed the FOD8012, the industry's first full-duplex, bidirectional logic gate optocoupler featuring proven optical isolation as well as high noise immunity. This bidirectional optocoupler is ideal for inverters, factory automation, process control, and test and measurement instruments, as well as industrial fieldbus communications, programmable logic controllers, and servo control.

The FOD8012 supports isolated communication of digital signals between systems without ground loops or hazardous voltages. Unlike competing products with optical isolation clearances smaller than 0.1 mm, the FOD8012 features a minimum optical isolation clearance of 0.4 mm for proven reliability. It also features fast switching speeds of up to 15 Mbit/sec and utilizes Fairchild's proprietary Optoplanar® packaging technology and optimized IC design to achieve high Common Mode Improvement (CMR) of at least 20 kV/µs while operating in noisy industrial environments.

The high-speed logic gate optocoupler is combined with two aligned optical channels in a bidirectional configuration and comes in a small 8-pin package. Each optocoupler channel consists of a high-speed AIGaAs LED driven by a CMOS buffer IC coupled to a CMOS detector IC.

Additionally, the FOD8012 offers an extended industrial temperature range of -40ºC to +110ºC and a supply voltage of 3.3V or 5V to facilitate logic level transfer. The product's high isolation voltage is certified by UL1577 and IEC60747-5-2 to enhance reliability.

Fairchild helps customers drive innovation in their designs by developing solutions such as the FOD8012, which is part of a comprehensive portfolio of high-performance optocouplers. The FOD8012 provides the highest level of noise immunity from Fairchild's proprietary Optoplanar coplanar package technology. Optoplanar technology achieves reliable high-voltage isolation certified by UL1577 and IEC60747-5-2, while guaranteeing a stable insulation thickness of at least 0.4 mm.