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What is the body diode of the power MOSFET?
Unlike virtually every other active device, the power MOSFET is unusual in that its schematic symbol includes a parasitic device – the body diode. The body diode is intrinsic to the device’s structure.
Why do MOSFETs conduct when V GS = 0?
MOSFETs have an extremely useful property; that is, when V GS =0, they still conduct in reverse. They do this because they have a parasitic diode between source and drain called an intrinsic body diode.
Can a IGBT conduct in reverse as a MOSFET?
When learning power electronics, we all discovered that MOSFETs can conduct in reverse (because they have a body diode) and IGBTs can’t (because they don’t). Because “reverse current path with gate off” is kind of a mouthful, we all got accustomed to just referring to this effect as a “body diode.”
When does third quadrant operation occur in power MOSFET?
Third-quadrant operation for power MOSFET is common in C-DC buck converters, where current conduction occurs nder relatively low current, the on-state characteristics for sufficient large current, and therefore sufficient large VDON. When VDONapproaches the forward drop voltage of the body diode, the body diode starts to conduct.
How is the bipolar transistor used in a MOSFET?
Discreet power MOSFETs also feature a parasitic bipolar transistor, but the metallization connecting the source and body regions — also an explicit feature of the schematic symbol — shorts the base-emitter junction. This prevents the bipolar device from turning on under all but the most extreme conditions.
A Schottky diode connected in parallel to the body diode will conduct with a lower forward voltage, preventing the body PN junction from becoming forward biased. The Schottky diode is a majority-carrier device and exhibits no recombination.
Which is an example of a MOSFET topologies?
Many of the most common power MOSFET applications involve devices, in either half- or full-bridge configurations, driving inductive loads. Buck-converter topologies are a typical example. The high-side FET operates with a duty cycle D approximately equal to A typical buck converter topology.