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the solution turned out being to increase the resistance between the mosfet driver and mosfet... the lower impedance worked at lower voltage but now the high voltage
i gave the resonant drive a try
it seems that at 500khz and 3nf load that the inductance needed to make it osciallate from say 100 t 500V is so small that even the copper wires have larger inducance.
ill copy in some screen shots of pspice.
and i did do this on the breadboard though too and...
im not against trying this out.
can you help me understand this a little better.
an inductor matched to transducer (simialar to capactior) in series?
is there a link or something, or anotehr term you can use (maybe buck converter?) im not getting a lot of google hits on this.
i do remember doing...
DC on the ultrasound transducer is probably not desirable.
the ultrasound trandcuer is piezoelectic
it strains when voltage is applied and there is a practical limit to how much strain occurs.
so if too much DC is present, there is less strain that can occur it gets hit with an electrical square...
hi all.
I previously built a mosfet driver which drove a N/P array at 120V at 500Khz to 1Mhz.
The device work well but I need more power.
This is for an ultrasound cleaning driver.
Ideally I need something that can drive 200 minimum volts into a capactive load (10nf) while switching at 300 to...
keith, thanks
i think there is a simuliation model for cadence that is free.
i usually just use that.
but there are no models for the chips in use
have to really have very mathced switching speedings for it to be of any value as it is very high precision.
i know about how the reference makes...
sunnyskyguy, i saw your posts
Im going to try this stuff tomorrow when im infront of the circuits.
It is impedance matched somewhat
Its very small impedance matching network with this load though.
I did the computations via smith chart and came out with mostly real resistances and the matching...
40000 posts, incredible.:shock:
Im on a unrelated BB with 12000, I can appreciate your dedication
sorry, there is a balance with trying to be concise and providing enough information.
In this case, the circuit should be driving an ultrasound transducer, a piezoelectric element which can be...
i really appreciate your time barry
the caps are for DC biasing.
the half bridge is configured to switch from 0 to 60V
but i can also switch -60 to +60V .
so the caps help configure independent biasing of each gate in reference to the supply by blocking the DC.
i lowered teh 10k resistance...
barry,
yes, there is big capacitance.
there is only one 10k resistor, the other is 100ohm.
changing the 10k to a smaller value, ie 220ohm does not fix the problem.
there does not appear to be a problem with a time constant, it switches very fast.
I have 3 function generators, and tried them...
hello all,
Im having problem with a half bridge.
The sides seem to be fighting which is generating heat.
The isolated section of circuit causing the problems is a mosfet driver (IDD614) and matched N and P mosfet array (FMP26)
It is being driven from a function generator with 5V peak to peak...
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