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Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers
« Last post by xvr on Today at 09:21:45 am »> You said i should put a zenner diode .
did you meen in parralel to the power supply?
No. In series with R2 in my schematic
As for temperature raise, it calaculated as power, dissipated in MOSFET multiplayed by Temperature resistance (55W/C by your calculations). Power dissipation is I^2*Rdson
Graph in question shows changes of Temperature resistance via pulse characteristics.
Tja & Tjc are temperature resistancies from chip junction to ambient (this is case of bare chip in air) and for chip junction to case (this is variant of chip attached to ideal heatsink)
As you understand there is no such thing as ideal heatsink, so in later case you shoul add Temperature resistance of heatsink itself to Tjc to get real value
did you meen in parralel to the power supply?
No. In series with R2 in my schematic
As for temperature raise, it calaculated as power, dissipated in MOSFET multiplayed by Temperature resistance (55W/C by your calculations). Power dissipation is I^2*Rdson
Graph in question shows changes of Temperature resistance via pulse characteristics.
Tja & Tjc are temperature resistancies from chip junction to ambient (this is case of bare chip in air) and for chip junction to case (this is variant of chip attached to ideal heatsink)
As you understand there is no such thing as ideal heatsink, so in later case you shoul add Temperature resistance of heatsink itself to Tjc to get real value