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Why MOSFET is used as a power transistor on the aim-tti ql355tp
namster:
Hi ,
in most linear psu a BJT transistor is used as power transistor as i know the mosfet have many disavantage , so why on the aim-tti QL355 two mosfet are used ?
David Hess:
The major disadvantage used to be cost. For a given power rating, power MOSFETs used to cost more than bipolar transistors. But now I think economy of scale has made up for that.
The other disadvantage is high and less precise gate threshold voltage but that does not apply in an application like this where a higher supply voltage is available for the control circuits.
Seekonk:
Very low drive current is needed. Makes rest of circuitry cheaper.
David Hess:
--- Quote from: Seekonk on July 15, 2020, 11:13:40 pm ---Very low drive current is needed. Makes rest of circuitry cheaper.
--- End quote ---
High current drive is still required for good AC performance.
namster:
but is there any advantage in performance for using a more expensive transistor ? :-// , i think that a BJT power transistor like 2n3055 have better value for money in linear application ?
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