Diotec Semiconductor AG

Efficient Thermal Management in Power Factor Correction Circuits

Power factor correction is an essential part of modern industrial power supplies, especially in helping to improve power quality and reducing harmonic distortion.

Boost PFC topologies are popular in applications that need efficient AC/DC conversion, such as industrial power supplies, telecommunication equipment and high-power electronic systems.

The selection of semiconductors with suitable voltage, current and switching characteristics is only one part of the engineering challenge, when designing these circuits. Effective thermal management is equally important, as power losses in switching devices and rectifier diodes generate heat that must be dissipated to ensure reliable operation.

In a conventional boost PFC circuit, the MOSFET drain is usually connected to the boost diode's anode. However, the MOSFET's mounting tab is typically connected to its drain, while the diode's mounting tab is connected to its cathode, effectively mounting both devices directly onto the same electrically conductive heatsink. This configuration can result in an unintended electrical connection.

To prevent this, conventional designs often require additional insulating pads or other electrical isolation measures. These components increase assembly complexity and introduce additional thermal resistance between the semiconductor and the heatsink.

Fully Isolated Package for Simplified Heatsink Integration

Diotec Semiconductor addresses this challenge with the ERJ3006, a 600 V ultrafast rectifier diode that is rated for 30 A and housed in a fully isolated ITO-220AC package.

Unlike rectifiers with electrically connected mounting tabs, the ERJ3006 provides electrical isolation between its internal semiconductor connections and the external mounting surface. This advantage allows the device to be mounted onto a common heatsink without requiring a separate insulating pad for the diode.

The integrated isolation can simplify mechanical assembly, reduce the number of additional mounting components and eliminate the thermal resistance associated with an external insulating interface. This approach offers greater flexibility in heatsink design and component placement. However, any MOSFET sharing the heatsink must still be appropriately isolated where required.

Fast Recovery and Low Forward Voltage for Efficient Power Conversion

In addition to its isolated package, Diotec’s ERJ3006 offers electrical characteristics suited to high-frequency power conversion.

The device allows for a reverse recovery time of less than 50 ns, helping reduce reverse recovery effects during switching transitions. In boost PFC circuits, fast diode recovery is particularly important because a reverse recovery current can contribute to additional switching losses and electrical stress in the MOSFET.

The ERJ3006 by Diotec also provides a forward voltage drop below 1.7 V at a forward current of 30 A at 25 °C. This characteristic helps limit conduction losses and supports efficient power conversion.

Key Technical Features

• Repetitive reverse voltage (VRRM): 600 V

• Forward current rating: 30 A

• Reverse recovery time (trr): less than 50 ns

• Forward voltage (VF): below 1.7 V at 30 A at 25 °C

• Fully isolated ITO-220AC package

• No additional insulating pad required for the diode when mounted on a suitable common heatsink

Diotec Semiconductor Supports Efficient Industrial Power Supply Design

For power electronics engineers, the ERJ3006 offers a combination of fast switching characteristics and simplified thermal integration. Its fully isolated package can reduce assembly complexity while supporting effective heat dissipation in boost PFC circuits.

For technical buyers and procurement teams, the integrated isolation also provides an opportunity to reduce the number of separate insulation components required during assembly, potentially simplifying manufacturing processes.

By combining fast reverse recovery with low forward voltage and integrated package isolation, Diotec provides a practical rectifier solution for designers seeking to balance electrical performance, thermal management and assembly requirements.