Hello guys,
I am working on an buck converter project. I realized something weird while doing this project.
My input voltage Vin is 15V and PWM is 0-15V. I am using IRF520N mosfet. On the 100% pwm signal, I expect Vd(voltage accross diode) to be approximately 15V. But I am getting 10.8V. I found the reason. It is because of the threshold voltage of the mosfet which is 4V. Output of the mosfet goes up until 10.8V and then stops there because after that voltage Vgs becomes less then threshold voltage. (Let me be more clear. Vgate-ground =15V, Vsource-ground =10.8V. Vgs=15-10.8=4.2V. )
I thing it is weird. Isn't it? If I want 30V buck converter, I have to build a 0-34V PWM and find a mosfet which can be max Vgs 34V (Because first time when we fire the system Vsource-ground=0V).
I am wondering if I do something wrong. I attached a general buck converter schematic, in case. i appreciate if anybody could help.
Thank you.
I am working on an buck converter project. I realized something weird while doing this project.
My input voltage Vin is 15V and PWM is 0-15V. I am using IRF520N mosfet. On the 100% pwm signal, I expect Vd(voltage accross diode) to be approximately 15V. But I am getting 10.8V. I found the reason. It is because of the threshold voltage of the mosfet which is 4V. Output of the mosfet goes up until 10.8V and then stops there because after that voltage Vgs becomes less then threshold voltage. (Let me be more clear. Vgate-ground =15V, Vsource-ground =10.8V. Vgs=15-10.8=4.2V. )
I thing it is weird. Isn't it? If I want 30V buck converter, I have to build a 0-34V PWM and find a mosfet which can be max Vgs 34V (Because first time when we fire the system Vsource-ground=0V).
I am wondering if I do something wrong. I attached a general buck converter schematic, in case. i appreciate if anybody could help.
Thank you.
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