URGENT! Dead Time Needed for Discrete Gate Driver

defragmenter · 13th June 2005, 11:42 PM

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!

MOER · 14th June 2005, 04:41 AM

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

IVX · 14th June 2005, 05:25 AM

try the voltage bias for comparators to unbalance them, though res+diode not so bad idea too (just 3% more loses, or so)

phase_accurate · 14th June 2005, 05:31 AM

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

phase_accurate · 14th June 2005, 05:41 AM

Here we go:

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

Regards

Charles

Pierre · 14th June 2005, 05:48 AM

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.

R Dijk · 14th June 2005, 06:02 AM

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 ?

14th June 2005, 04:41 AM	#2
MOER diyAudio Member Join Date: Aug 2003 Location: SIMI VALLEY CA	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

14th June 2005, 05:25 AM	#3
IVX diyAudio Member Join Date: Jul 2003 Location: Everywhere (Buddhist's context)	try the voltage bias for comparators to unbalance them, though res+diode not so bad idea too (just 3% more loses, or so) __________________ Best regards, E1.

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14th June 2005, 05:31 AM	#4
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	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

14th June 2005, 05:41 AM	#5
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	Here we go: http://www.diyaudio.com/forums/showt...684#post194684 Regards Charles

14th June 2005, 05:48 AM	#6
Pierre Banned Join Date: Nov 2004 Location: Paris	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.

14th June 2005, 06:02 AM	#7
R Dijk diyAudio Member Join Date: Mar 2005 Location: i live here	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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