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For lower breakdown voltages, a power MOSFET is clearly the device to go for, in view of its higher efficiency, higher commutation speed and lower price.

Where should the line be drawn, upwards of which IGBTs take over as the preferable solution? What are the relevant decision criteria?

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The main criteria in choosing either IGBT or MOSFET are voltage rating, power losses (efficiency of the whole system) and of course the cost of the whole system. Choosing one over other may impact not only losses in the transistors but also the weight and cost of cooling, size of the complete product and also reliability so sometimes e.g. a weight constrain may force you to use MOSFET instead of IGBT.

If you look at this graph, you will see different areas, where each type of switch are typically used:

when to use IGBT or MOSFET graph

Choosing a particular device type depends on specific application and its requirements.

MOSFETs dominate in high frequency and low current applications because they can switch extremely fast and act as resistance when on.

Fast switching means they are used when the device has to be small as when you increase switching frequency you can reduce the size of passive filters.

The conduction losses are proportional to the square of drain current and therefore you cannot pass huge current through the structure.

They also have limited breakdown voltage and are typically used up to 600V.

IGBTs have higher breakdown voltage and conduction losses are approximately equal to Vf*Ic therefore you can use them in high current applications. They have limited switching speed therefore they are typically used in industrial applications where low switching frequency is not a problem (acoustical noise).

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  • \$\begingroup\$ This is such a great guide to power switching parts selection! Thank you, and where did you get that figure? \$\endgroup\$ – Bob Oct 10 '13 at 14:15
  • \$\begingroup\$ Google images, but I forgot to add the source :( \$\endgroup\$ – Szymon Bęczkowski Oct 10 '13 at 16:02
  • \$\begingroup\$ It's funny, I've never heard of MCT's, and I couldn't find a single source, but there they are: almost as good as IGBT's with more current handling. I wonder what happened to them? \$\endgroup\$ – Bob Oct 10 '13 at 16:15
  • \$\begingroup\$ Probably they died because of availability of high power (e.g. 1400A 1700V) IGBT modules. \$\endgroup\$ – Szymon Bęczkowski Oct 11 '13 at 6:53
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This question is really difficult to give a firm answer to. There are some jobs FETs simply can't do, and some jobs IGBTs simply can't do. If you're in a domain where both are possible solutions, you look at cost, including footprint and thermal management, and pick the cheaper one. In many cases (though not all), this will be a FET. But in a lot of cases, the decision is made for you simply by the application.

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