Optocouplers reject more noise

New single- and dual-channel optocouplers claim the industry's highest common-mode noise rejection rating, while providing high bandwidth with low power consumption.

Fairchild Semiconductor's new FOD0708 (single-channel) and FOD0738 (dual-channel) 15Mbaud optocouplers claim the industry's highest common-mode noise rejection (CMR) rating, while providing the high-bandwidth (15Mbit/s), low-power-consumption characteristics demanded by industrial control applications.

Fairchild's patented Optoplanar technology reduces package capacitance more than 30% compared with competing solutions.

This low package capacitance leads to a guaranteed 25kV/us minimum CMR rating that is 2.5x higher than the closest competitor, allowing the FOD07X8 series to operate in noisy industrial environments.

Unlike open collector bipolar-equivalent solutions, these optocouplers feature a push-pull detector that eliminates the need for a pull-up resistor and the power-consuming current it draws.

"Noise can cause data errors in industrial control environments, adversely affecting applications such as line receivers on an automated factory floor", said John Constantino, Manager of Fairchild's Optoelectronics Product Line.

"The FOD07X8 optocouplers offer our customers the industry's best available common-mode noise immunity to solve this problem".

"To address the other key requirements of the industrial market, we developed our new 15Mbaud optocouplers with a push-pull configuration that reduces power consumption without penalising bandwidth".

The electrical characteristics of the FOD07X8 product series are guaranteed beyond the full industrial temperature range (-40 to +100C).

Their performance makes these devices ideal for interfacing with microprocessors, peripheral I/O and other high-speed applications.

They are also well-suited for industrial networks such as Profibus, Fieldbus, DeviceNet and SDS.

The optocouplers' high-speed LED and a high-speed photodetector use Fairchild's proprietary 0.8um CMOS technology.

Compared with typical face-to-face optocoupler/LED combinations, the FOD07X8 devices employ a side-by-side Optoplanar configuration and integrated proprietary silicon design on the detector chip.

The resulting package capacitance enables these optocouplers to deliver excellent 50kV/us common-mode immunity when a 2kV (peak) pulse is applied.

These devices are available in a compact S0-8 package, with the dual-channel FOD0738 offering optimum mounting density.

They also offer a 2500V RMS isolation voltage rating and UL-certification for increased reliability.

The FOD0708 and FOD0738 are lead (Pb)-free products that meet or exceed the requirements of the joint IPC/JEDEC standard J-STD-020B and are compliant with the European Union now in effect.

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