All about ultrafast diodes app note from IXYS. Link here (PDF)
During the last 10 years, power supply topology has undergone a basic change. Power supplies of all kinds are now constructed so that heavy and bulky 50/60 Hz mains transformers are no longer necessary. These transformers represented the major part of volume and weight of a traditional power supply. Today they have been replaced with smaller and lighter transfomers, whose core materials now consist of sintered ferrites instead of iron laminations and which can operate up to 250 kHz. For the same power rating, high frequency operation significantly reduces the weight and volume of the transformer. This development has been significantly influenced by new, fast switching power transistors, such as MOSFETS or IGBTs, working at high blocking voltages (VCES > 600 V).
Apart from the characteristics of the transitor switches, the on-state and dynamic characteristics of the free wheeling diodes have a significant impact on the power loss, the efficiency and the degree of safety in operation of the whole equipment. They also play a decisive role when it comes to increasing the efficiency of a SMPS and to reduce the losses of an inverter, which clearly mandates that ultrafast diodes be used. The ultrafast diodes described here embrace all characteristics of modern epitaxial diodes, such as soft recovery, low reverse recovery current IRM with short reverse recovery times.
An app note from IXYS about choosing the right diode for efficiency and cost. Link here (PDF)
Great efforts have been made to improve power switches – MOSFETs and IGBTs – to decrease forward voltage drop and as well as to decrease turn-off energy. In switching inductive loads, the turn-on losses depend strongly of the behavior of the companion free-wheeling diode and now form the major part of over-all power losses. New developments like series connected diodes in a single package can greatly improve a given design. This paper shows how to choose the optimum diode using the specific example of a PFC circuit.
Some examples of power MOSFETS application from this app note from IXYS Corporation. Link here (PDF)
Applications like electronic loads, linear regulators or Class A amplifiers operate in the linear region of the Power MOSFET, which requires high power dissipation capability and extended Forward Bias Safe Operating Area (FBSOA) characteristics. Such mode of operation differs from the usual way of using Power MOSFET, in which it functions like an “on-off switch” in switched-mode applications. In linear mode, the Power MOSFET is subjected to high thermal stress due to the simultaneous occurrence of high drain voltage and current resulting in high power dissipation. When the thermo-electrical stress exceeds some critical limit, thermal hot spots occur in the silicon causing the device to fail
IXYS Corporation’s N-Channel power MOSFET selection and application. Link here (PDF)
Applications like constant current sources, solid-state relays, telecom switches and high voltage DC lines in power systems require N-channel Depletion-mode power MOSFET that operates as a normally “on” switch when the gate-to-source voltage is zero (VGS=0V). This paper will describe IXYS latest N-Channel Depletion power MOSFETs and their application advantages to help designers to select these devices in many industrial applications.
Chossing the right power semiconductor for an application, a technical note from IXYS. Link here
This application note is intended to show how to choose the appropriate rating of a power semiconductor component for a known application using the specifications given in the datasheet. The explanations have been kept sufficiently general to be applicable to all common power circuits. However, for the sake of concreteness, they focus on IXYS IGBT modules and discretes respectively with or without diode. Proceeding as described in the following enables the designer to gain all necessary information from the data sheets for the most economic selection of power semiconductors.