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3. What is the current that will flow through the device? The first two numbers in the part number give a rough indication of the usable current.

For hard switching applications, the usable frequency vs current graph is helpful in determining whether a device will fit the application. Differences between datasheet test conditions and the application should be taken into account, and an example of how to do this will be given later.

For soft switching applications, the IC2 rating could be used as a starting point.

4. What is the desired switching speed? If the answer is "the higher, the better", then a Punch-Through (PT) device is the best choice for you. Again, the usable frequency vs current graph can help answer this question for hard switching applications.

Answers to the following set of burning questions will be helpful to determine which insulated gate bipolar transistor (IGBT) is appropriate for the particular application. The differences between Non Punch-Through (NPT) and Punch-Through (PT) devices as well as terms and graphs will be explained later.

1. What is the operating voltage? The highest voltage that the insulated gate bipolar transistor (IGBT) has to block should be less than 80% of the VCES rating.

2. Is it hard or soft switched?
Generally, a Punch-Through (PT) device is better suited for soft switching due to reduced tail current. But a Non Punch-Through (NPT) device will also work here. 

5. The additional PN junction adds a diode-like voltage drop to the device.

At lower blocking voltage ratings, this additional diode-like voltage drop means that an insulated gate bipolar transistor (IGBT) would have a higher on-state voltage drop. As the voltage rating of the device increases, the advantage of the reduced N- drift region resistance overcomes the penalty of this diode drop and the overall on-state voltage drop is lower (the crossover is around 400 V blocking rating). Thus insulated gate bipolar transistors (IGBTs) are rarely used where the blocking voltage requirement is below 600 V.

1. The additional PN junction blocks reverse current flow.

This means that unlike the MOSFET, IGBTs cannot conduct in the reverse direction. In bridge circuits where reverse current flow is needed an additional diode (a freewheeling diode) is placed in parallel with the insulated gate bipolar transistor (IGBT) to conduct current in the opposite direction. This penalty isn't as severe as first assumed though, because at the higher voltages where insulated gate bipolar transistor (IGBT) usage dominates, discrete diodes are of significantly higher performance than the body diode of a MOSFET.

2. The reverse bias rating of the N- drift region to collector P+ diode is usually only of tens of volts. So if the circuit application applies a reverse voltage to the insulated gate bipolar transistor (IGBT), an additional series diode must be used.

If you are professional in this field, you will know that the industry trend is for insulated gate bipolar transistors (IGBTs) to replace power MOSFETs except in very low current applications. So I think it's useful for us to understand the structure of IGBT.

This additional p+ region creates a cascade connection of a PNP bipolar junction transistor with the surface n-channel MOSFET. This cascade connection results in a significantly lower forward voltage drop compared to a conventional MOSFET in higher blocking voltage rated devices.

As the blocking voltage rating of both MOSFET and insulated gate bipolar transistor (IGBT) devices increases, the depth of the n- drift region must increase, meanwhile, the doping must decrease, thus resulting in roughly square relationship increase in forward conduction loss compared to blocking voltage capability of the device.

Insulated gate bipolar transistor (IGBT) is a three-terminal power semiconductor device. It's noted for high efficiency and fast switching. In many modern appliances in the industry, such as electric cars, trains, variable speed refrigerators, air-conditioners and stereo systems, insulated gate bipolar transistor (IGBT) switches electric power with switching amplifiers.

Insulated gate bipolar transistor (IGBT) combines the simple gate-drive characteristics of the MOSFETs with the high-current and low–saturation-voltage capability of bipolar transistors by combining an isolated gate FET for the control input, and a bipolar power transistor as a switch, in a single device. Insulated gate bipolar transistors (IGBTs) displaced power bipolar transistors as the device of choice for high current and high voltage applications.