Analog/Digital Simulation versus Actual

[RiDdLeR???]

Tanong ko lang mga masters  ...  Sorry for this unsound technique of electronics design via Trial and Error using simulators.  Mga students huwag gagayahin!  Trabahong tamad for someone who has very rusted basic electronics but its a quick jumpstart.

Question ko regarding the p-channel mosfet.  In the figure, based on the measured voltage drop accross the mosfet, there is around 17V developed and around 1.5A going through it when triggered via a 1KHz 25% duty cycle PWM.

In actual ba, ganun din ang mamemesure ng tunay na DMM.  What about actual power dissipation?  Will there be an actual power dissipation of 17V x 1.5A accross the mosfet?  The mosfet has an Rdson of around 100 milli ohm at 10V Vgs.  It has a Vgsth of around 2~4V. 

Lastly, I also noticed that increasing frequency w/o changing the duty cycle also increases the voltage developed accross the load resistor.  Is this normal in actual circuits?

[rdpzycho]

meron kayong scope captures nung gate-source at drain-source terminals sir?

bale ang nakikita nung voltmeter sa drain-source sir 'yung average voltage nung Vds, which is then roughly near 0.75 x 25V or 'yung time na off 'yung MOSFET.

ang magiging dissipation niya pa rin sir is 'yung current squared through 100mohm, kung naaabot 'yung 10V sa gate-source, of which I think naaabot naman dahil 'yung voltmeter sa gate-source is 2.901V which is 25% ng 11.6V.

with regards sa frequency, posibleng mangyari 'yun sir kung limited 'yung current ng turn-on at turn-off nung gate drive circuit. lalabas kasi na fixed time siya plus the duty cycle. kaya habang lumiliit 'yung time ng fixed duty cycle (increasing frequency) relative doon sa fixed na turn-on at turn-off time, tataas din ng pakonti-konti 'yung actual time na naka-ON 'yung MOSFET.

[RiDdLeR???]

Thanks master rd  ....subukan ko ng gawin sa actual

[rdpzycho]

mukhang 'yung turn off ang mabagal sir. merong mga rapid gate turn off circuits sir, bale, diode, resistor at transistor.

[RiDdLeR???]

Thanks again master rd  .... subukan ko muna gumamit ng lower capacity mosfet as the gate drive  ... may nabasa kasi ako na mas mabagal daw kapag bjt ang gamit.