What parameters need to check for the selection of Power MOSFET in the Power supply?
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In MOSFET selection, 1. Maximum drain-source voltage, 2. Peak current, 3. Loss due to the ON-resistance (Ron), 4. Maximum allowable power dissipation 5. Lowest input capacitance possible to avoid long delays and to minimize in-rush current which can be very high initially but lessens as the capacitoRead more
In MOSFET selection,
See less1. Maximum drain-source voltage,
2. Peak current,
3. Loss due to the ON-resistance (Ron),
4. Maximum allowable power dissipation
5. Lowest input capacitance possible to avoid long delays and to minimize in-rush current which can be very high initially but lessens as the capacitor charges
RDS(ON) parameters RDS(ON) means “resistance between drain and source in conduction.” MOSFETs are generally used as a better alternative to power transistors and are used for high-current–switching applications. If this parameter is lower, it means that the MOSFET loses less energy, according to OhmRead more
RDS(ON) parameters
RDS(ON) means “resistance between drain and source in conduction.” MOSFETs are generally used as a better alternative to power transistors and are used for high-current–switching applications. If this parameter is lower, it means that the MOSFET loses less energy, according to Ohm’s law, and results in higher energy efficiency and produces less heat. The designer should choose a component model with the lowest possible RDS(ON) value. when the MOSFET is conducted, the RDS(ON) can be calculated with the formula: RDS(ON) = V(DS) / I(D)
Input (Ciss) and output (Coss) capacitance parameters
The “gate,” the oxide layer, and the relative connection on the MOSFET body works, in effect, like a small capacitor. As soon as the “gate” is subjected to a voltage, this virtual capacitor begins to charge. Charging takes time, and therefore, there is a delay in the on state. The designer should choose a MOSFET with the lowest possible input capacitance to avoid long delays. If using a MOSFET with a direct connection to an MCU output pin, the “gate” should be connected via an external resistor to prevent unwanted results. Regarding the SiC model used, its capacitive parameters are as follows:
Input capacitance (Ciss): At VDS = 100 V, VGS = 0 V, F = 100 kHz — 1,500 pF
Output capacitance (Ciss): At VDS = 100 V, VGS = 0 V, F = 100 kHz — 104 pF
Parameters related to switching speed
MOSFETs are particularly suitable for fast-switching applications. The higher the frequency, the smaller the transformers must be, but the transmitted noise increases. In parameters that link the component to the switching speed are as follows:
Turn-on delay time (tdon): 25 ns
See lessRise time (tr): 14 ns
Turn-off delay time (tdoff): 54 ns
Fall time (tf): 11 ns