Serious: Switching Mode Power Supply

[Sherif8]

Dear all,

I'm working on some project which requires 100v converted from 9v, so i called the basic idea of Boost converter.

The circuit is quiet simple, i use IRF540NS switched from PWM (Pulse Value 3.3v, Pulse Width 278us, Period 300us)

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I used TI application note **broken link removed** to calculate the values of the coil and the output capacitor using the equations 5,6 and 12, 13.
The inputs are: Vout = 100, Iout(max) = 5mA
After all, L = 148mH and Cout = 511uF

The simulation output is 10v not 100v!!!

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Any help please?!

 

[FvM]

I expect, that the strange combination of transistor and diode ratings is only a simulation thing. No step-up action probably happens because the transistor is never turned on with 3.3 V. Review the datssheet.

 

[Sherif8]

@FVM Thanks a lot!! That really helped, i changed the pulsed value to 5v and it lastly settled on 100v, have no idea how it did pass me!!

 

[betwixt]

I wuld use a higher rated diode than the 1N4148 - it can only withstand 100V peak and you are probably giving it quite a bit more!

Brian.