Power Supply Impedance for Fieldbus

These modules were specially designed to provide appropriate impedance for fieldbus networks.

  • DF53 (4 ports)
  • DF98 (2 ports)

The purpose of this impedance is to implement an output circuit where the impedance is greater than 3 KΩ, and when assembling in parallel with two 100 Ω ±2% terminators, it results in 50 Ω line impedance approximately. This impedance can be implemented in a passive mode (50 Ω resistance in series with a 100 mH inductance) or in an active mode, through an impedance control circuit.

The fieldbus power supply impedance is a non-isolated, active impedance control device, in compliance with IEC 61158-2 standard. This device provides output impedance which, in parallel with the two bus terminators (a 100 Ω resistor in series with a 1 mF capacitor) required by the standard, results in a pure resistive line impedance for a broad frequency range. DF53 and DF98 were designed to work in non-hazardous areas.

Some Characteristics


24 to 32 Vdc +/- 10%


DF53: 340 mA per port
DF98: 500 mA per port

Maximum power dissipated

DF53: 2.26 W per port
DF98: 3.43 W per port


Operation: 0 to 60 ºC (32 to 140 ºF)
Storage: -30 to 70 ºC (-22 to 158 ºF)


260 g


39.9 x 137.0 x 141.5 mm
(1.57 x 5.39 x 5.57 in)