Low Noise SMPS Switch - High Power Applications

432

04:32:53

A High Power Low Noise SMPS Mosfet Switch used for driving high current loads!  It’s quite fast and has very small noise and delay between switching transitions!

**IMPORTANT -How To Start The Oscillations**

*Simply shake your phone to inject noise, then adjust the time scale to be closer to real time till the oscillations start, (then set the time scale back to original position, otherwise you may see much more noise than there really is).*

The SMPS action greatly improves efficiency and reduces heat v.s. using 2 parallel Mosfets with DC bias.  The PWM signal that’s used to drive the 2 mosfets is cancelled out since they are 180° out of phase; when one mosfet turns off, the other turns on and visa-versa so the output always remains high, until the SPST switch is closed, which will cause the amplifiers driving the two mosfets to be cut-off by pulling the gates high.  This concept/approach can be further improved for even higher power applications by dividing the PWM signal into more than just 2 phases, such as 3,4 or 5 phases, where each Mosfet will now be conducting for a much shorter period of time while having an off time that is much greater than its on time to allow it to cool down more, the total power of the load will thus be equally divided across each mosfet, and the output still cancels out.

published 2 years ago

mikey5869

2 years ago

What is the point in this circuit? It doesnt regulate or change the voltage

Issacsutt

2 years ago

Basically in an ideal world there’s no difference between this approach and just using 2 transistors in parallel with DC bias. But in a practical world, there is huge differences, because you pretty much will never be able to equally divid the current between the two, because any very slight differences in temperature, biasing, or junction resistances will result in one transistor conducting slightly more than the other, which will exponentially get worse and cause the one conducting the most current to completely smoke and burn out first, with the other one very quickly and inevitably enduring the same, since now it will have 100% of the power flowing through it which it certainly could not handle by itself! By driving each transistor with a 50% duty cycle and in 180° phase difference, only one will be on at a time and while the other is able to cool off, and this will switch every 1/2 period. Unless you use 3,4, or 5 or more transistors, with, respectively, 120°, 90°, and 72° phase splits. Or same as 33.333…%, 25%, and 20% duty cycles.

Issacsutt

2 years ago

By the way, I checked out your published circuits, lots of nice designs! Surprised I’ve never seen you here before, and you’ve had the app longer than me. What qualifications do you have if you don’t mind me asking, just curious?

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