Question about Rds(on) of a power MOSFET

Discussion in 'General Electronics Chat' started by hunterage2000, Feb 16, 2016.

  1. hunterage2000

    Thread Starter Active Member

    May 2, 2010
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    Can someone tell how Rds(on) of a power MOSFET is calculated when operated as a switch?
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    We simply check the value in data sheet for a given MOSFET.
     
  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    It isn't calculated. It is stated on the datasheet, usually under specific conditions such as a 10 V drive signal and a stated pulse width.

    ak
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    How fast is this thing switching?

    If just every so often than Rds on times source current is a decent estimation of device power.

    Switch that sucker on and off fast, as is done in a switching power supply, and the losses are dominated by switching losses as the device goes off to on (minority) and on to off (mostly).

    These are due to the short period when the device voltage is increasing but the load current is still on. It is but a brief period but they do add up.
     
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