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What causes MOSFETs to burn?
MOSFETs boast a high input gate resistance while the current flowing through the channel between the source and drain is controlled by the gate voltage. However, if not appropriately handled and protected, the high input impedance and gain can also lead to MOSFET damage caused by over voltage or too-high current.
Are transistors MOSFETs?
Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is a kind of Field Effect Transistor (FET) that consists of three terminals – gate, source, and drain. In a MOSFET, the drain is controlled by the voltage of the gate terminal, thus a MOSFET is a voltage-controlled device.
What is the difference between a MOSFET and transistor?
The BJT is a bipolar junction transistor whereas MOSFET is a metal oxide semiconductor field-effect transistor. BJT’s are used for low current applications, whereas MOSFET is used for high power applications. Nowadays, in analog and digital circuits, MOSFETs are treated to be more commonly used than BJTS.
What kind of voltage does a MOSFET need to fail?
For example, a suitably high voltage applied between the gate and source (VGS) will break down the MOSFET gate oxide. Gates rated at 12 V will likely succumb at about 15 V or so; gates having a 20-V rating typically fail at around 25 V.
What happens when transistors overlap in a MOSFET?
Here, if the control signals to the MOSFETs overlap, the transistors will effectively short-circuit the supply. This is known as a shoot-through condition. When it arises, any supply decoupling capacitors discharge rapidly through both MOSFETs during every switching transition, causing short but large current pulses.
What happens when you run a direct short on a MOSFET?
A common outcome of a direct short is a melting of the die and metal, eventually opening the circuit. For example, a suitably high voltage applied between the gate and source (VGS) will break down the MOSFET gate oxide.
Why do transistors drop in Q1 / Q3?
A minor issue with both circuits is that the Base-Emitter voltage drop in Q1/Q3 increases power loss in those transistors and reduces the voltage available to the motor. In a low power device this loss may be acceptable, but it can easily be eliminated by using PNP transistors (switched on by the same Base current as Q4/Q2).