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The MOSFETs And The Amp again

I found it doesn't work. Well it will work but not do what I want it to do. I had to make a fairly major design change.

At this point whatever polarity of MOSFETs doesn't matter. but in the circu it that WILL work when the voltare across it goes reverse of course the int ernal diode will conduct.

However one thing is hard to fix, the Vgs will be up, as if driving the thi ng. Now that doesn't matter to it working because it is in reverse voltage,

What concerns me is if will damage the MOSFET.

For example, you got negative (to the MOSFET) bias Vds, but you got drive v otage on the gate, VGD.

There will not be alot of current VDS but I don't like the wrong voltages o n shit. Just like many drive optimization circuits even to a bipolar, some are potentially damaging to the E-B junction. For example some will put a n egative voltage on the base of an NPN for fast turnoff. that ocld possibly be too much. Many exceed the reverse Vbe rating but are fine because the du ration is so short.

I am just avoiding trouble. This design has never been dome before and I do not want to find out things the hard way.

Reply to
Jeff Urban
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o. I had to make a fairly major design change.

cuit that WILL work when the voltare across it goes reverse of course the i nternal diode will conduct.

hing. Now that doesn't matter to it working because it is in reverse voltag e,

votage on the gate, VGD.

on shit. Just like many drive optimization circuits even to a bipolar, som e are potentially damaging to the E-B junction. For example some will put a negative voltage on the base of an NPN for fast turnoff. that ocld possibl y be too much. Many exceed the reverse Vbe rating but are fine because the duration is so short.

do not want to find out things the hard way.

When the drain is reverse biased the voltage to the source is limited to a diode drop. Typically the gate doesn't care much about the polarity of thi s voltage unless there are protection zeners, but even then the voltage is enough to allow operation.

I don't know anything about your circuit but it is not uncommon to use two FETs in series with sources connected to prevent conduction of the body dio de. I don't think I've ever seen this in an amp, but amps don't typically get reverse biased.

--

Rick C. 

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Reply to
Rick C

I like to avoid trouble too but I'm not sure "trouble" is the appropriate middle name for you. Maybe "danger"? Jeff "Danger" Urban? That sounds pretty cool

Reply to
bitrex

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