Weidmuller’s Active Diode Modules provide the function of a diode but do not actually contain a diode. Instead a MOSFET is configured to behave like a diode but with a significantly lower forward voltage drop. This means less power dissipation and a more efficient design.

Diodes are often connected to the output of a power supply to isolate the supply in the event of an internal failure. This is particularly common when multiple power supplies are connected in parallel for redundancy or increased capacity. If a component in one power supply fails in a short circuit condition it must be isolated so that it does not short the output of any of power supplies connected in parallel. A diode does this by preventing current to flow to the input of the failed power supply. Typical diodes introduce a voltage drop of approximately 0.7V or 0.3V in the case of Schottky diodes. This means between 0.3W and 0.7W per amp of load current applied to the power supply. This can contribute greatly to the ambient temperature within a control cabinet.

The Active Diode Modules replace the diode with a MOSFET and lower the voltage drop to 50mV maximum. This means 1.25W of power dissipation at 25A versus 7.5-17.5W when traditional diodes are used. The result is a cooler control cabinet and a higher ambient operating temperature for the Active Diode Modules.

Two versions are available – the Emphatec SigNext version is cULus approved for use in standard applications while the Emphatec DePro version is cCSAus approved for use in Class 1 Division 2 / Zone 2 hazardous locations.