2. The RCD termination

The traditional solution to properly match each line of the bus consists of the use of several discrete

resistances, capacitors and small schottky diodes. For a 16-bit bus, this requires 48 discrete components.

SGS-THOMSON offers an innovating solution with a monolithic structure using ASD

The ASD

device. The RCD16-47B reduces component cost and assembly cost, saves board space and improves

reliability.

The simulation illustrates the signal distortion produced by line reflection at the end of the line when such a

termination is used.

The resistor provides the path termination for PCB track, thus resulting in low reflection phenomena.

The capacitor of 33 pF blocks DC currents while acting as a short circuit during signal transitions, and

holds the bus at the last logic level. It reduces power consumption and avoids excessive current.

The small Schottky diode clamps the negative remaining undershoots which can result from impedance

mismatch. This damps negative voltages and prevents the logic signal from rising above the logic level

’0’ threshold after a falling edge.

The RCD termination provides optimal solution compared to all other termination techniques.

(*) ASD

™ = Apllicaion Specific Discretes.

RCD16-47B

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