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How to choose a MOSFET

How to choose a MOSFET

An important consideration is whether there will be a radiator or not. in most cases, for devices capable of accepting the operation of a heat sink, a nominal continuous drain current about five times the continuous maximum.

For power mosfet, you choose it by following this sequence, in this order:

  • polarity of use (channel n or p)
  • maximum operating voltage
  • current maximum operating
  • maximum rdson (resistance drain – source when the channel is fully open).
  • maximum operating frequency
  • type of packaging (to-220, dpack, etc.)
  • manufacturer
  • price

you must first know the value of the nominal voltage of your application. If its high Voltages are suitable for power supply. Then check that the max. is chosen accordingly. check the merit (fom) for the mosfet. less of a better mosfet. rds (on) must be minimum to reduce conduction loss qg (tot), ie the total gate capacity must be lower for high frequency design if you are using it for an application of switching.

Choosing a mosfet is sometimes a daunting task. it’s all about compromise here and there. Here are the parameters to know. Break Voltage

vds – exceeds this limit and the MOSFET goes to kaboom and releases the magic smoke breakdown voltage

vgs. as above. it’s usually a +/- value.

Grid capacity – smaller will be better. if the capacity is large, you will need more power to charge it quickly enough. you may need to use a high current driver.

Enable / disable delay – the sooner the better. slow switching speeds result in power loss due to slow switching between cutoff and saturation states.

Rds (on) – on resistance – the smaller the better. decreased power loss and heat.

Package – depends on your application – to 220 or sot223 or sot 23 or dpak or d2pak.

Cost – as usual.


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