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Old 13th June 2005, 11:42 PM   #1
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Default URGENT! Dead Time Needed for Discrete Gate Driver

Hello all!

I have one week to finish my graduation project but there is a problem; shoot through

so i need a dead time circuit to overcome that effect

Please do not offer an external series gate resistor shunted by a reverse biased because of bad rise and fall times of output signal

Thanks in advance!
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Old 14th June 2005, 04:41 AM   #2
MOER is offline MOER  United States
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Default Dead time

We designed a class D amplifier using discrete drivers for Nakamichi.
Your triangle wave signal drive line is the only place that you can place it

basically you run a comparator with a + and - theshold and only when the threshhold is exceeded can the output fets conduct.

The circuit is on an old MSdos printout so I need a fax to send to you

Regards



Stephen Mantz

Zed Audio Corporation

www.zedaudio.com
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Old 14th June 2005, 05:25 AM   #3
IVX is offline IVX  Russian Federation
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try the voltage bias for comparators to unbalance them, though res+diode not so bad idea too (just 3% more loses, or so)
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Old 14th June 2005, 05:31 AM   #4
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I once did within an old design of mine what Stepen is talking of. I once posted it on this forum. Maybe I can find it again. It was a complementary design so you'd have to watch out for the comparator input polarities.

Regards

Charles
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Old 14th June 2005, 05:41 AM   #5
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Here we go:

http://www.diyaudio.com/forums/showt...684#post194684


Regards

Charles
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Old 14th June 2005, 05:48 AM   #6
Pierre is offline Pierre  France
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Perhaps this can help: increase the rising time of the mosfets but leaving the turn off as fast as possible:
Instead of putting a resistor in series with each gate, put it connected to the NPN driver transistor. This way, when it activates, it passes current to the gate with the resistor in series (turn on), but when the PNP driver activates, it removes charge from the gate with no resistor in series.

Hope this helps.
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Old 14th June 2005, 06:02 AM   #7
R Dijk is offline R Dijk  Norway
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search forum i good: http://www.diyaudio.com/forums/showt...747#post429747

Here comparator drives drivers. drigvers trigger level for on/off and delayed on can bee made, it also makes it easier to make it self osscilating. In the tread the driver trigger level is also dealt with. Graduate ?
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