Over on YouTube [DENKI OTAKU] runs us by means of how a 4-pin MOSFET works and what the additional Kelvin supply pin does.
A typical MOSFET would possibly are available a 3-pin TO-247 package deal, however there are 4-pin variants which embody an additional pin for the Kelvin supply, also referred to as supply sense. These 4-pin packages are referred to as TO-247-4. The fourth pin supplies an extra supply for gate present return which might in flip reduce the impact of parasitic inductance on the gate-source when switching present, notably at excessive pace.
Within the video [DENKI OTAKU] makes use of his customized made testing board to analyze the efficiency traits of some 4-pin TO-247-4 MOSFETs versus their 3-pin TO-247 equivalents. Spoiler alert: the TO-247-4 MOSFETs have higher efficiency traits. The video takes a detailed take a look at the outcomes on the oscilloscope. The draw back is that because the switching pace will increase the ringing within the Vds waveform will increase, too. For those who’re switching to a 4-pin MOSFET from a 3-pin MOSFET in your design you will have to concentrate on this Vds overshoot and make lodging for it.
For those who’d wish to go deeper with MOSFET know-how take a look at Introduction To MOSFET Switching Losses and MOSFETs — The Hidden Gate.
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