On Sat, May 10, 2025 at 09:42 PM, <guilhermesouzam01@...> wrote:
... in our example, the power supply voltage is 5V. But what if our power supply is much higher, say around 300V? The MOSFET needs a gate-to-source voltage (Vgs) that is higher than the source (Vs) to turn on. So, if we keep using a 10V PWM signal referenced to ground, it wouldn¡¯t work properly.
I¡¯ve been researching this, and I came across the bootstrap driver technique. Is this commonly used in such high-voltage applications? Or is there another configuration we should use in this scenario?
What you said is correct.? There are probably a few ways to make it work.? I am not an expert on the ways to do that.
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What you need is to apply the gate drive signal as a differential voltage between the gate and source of the pull-up FET.? For simulations (not real circuits), you can easily do that by connecting the PULSE voltage source between the gate and source pins instead of ground.? For real circuits, sometimes a miniature transformer can isolate the signal from ground, and connect it between gate and source instead.? If a transformer doesn't work, there are isolation ICs as well as opto-isolators that perform a similar function.? Also, many ICs are designed for driving MOSFETs and have internal circuits to bootstrap the signal that goes to the FET's gate pin.? I don't know if those can accommodate as much as 300 V.? But transformers can, and signal isolating ICs probably can.
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Depending on the waveforms and a few other things, it might even work to use a capacitor to AC-couple and level-shift the voltage for the gate pin.
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Andy
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