Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th April 2006, 08:43 AM   #1
diyAudio Member
 
Join Date: Apr 2006
Location: Kingston
Default Wiring the IR2011 Correctly

Hi everyone...This is my first time building an amp so any help would be really appreciated. I tried searching the forum but I couldn't find any posts to help me out.

I got the pwm signal(both inverted and noninverted and both correctly level shifted to -15V low to -10 V high) to correctly propagate to the ir2011 mosfet driver. But the waveform from the ir2011 feeding the mosfets seem to be incorrect. The ir2011 is wired as shown below in the schematic.
Click the image to open in full size.
I am uncertain as to why the the high side mosfet waveform is the way it is. I thought the signal should be just the inverted version of the low side mosfet waveform. The attached picture shows the output from the oscilloscope. The top waveform input to the mosfet attached to the +15V rail and the bottom is attached to the -15 rail. Any help would be deeply Appreciated. Thanks.
Click the image to open in full size.
  Reply With Quote
Old 6th April 2006, 09:55 AM   #2
Account Disabled
 
Join Date: Feb 2004
Send a message via AIM to classd4sure Send a message via MSN to classd4sure
You're starving it man!!

Ditch R20, R21, you're not using 50Vdc rails here, seriously not needed.

Then make sure you've some method to to allow pre charge of bootstrap to occure. Hint here, try tying a ~4.7K from Vs to -15.

You'll then need a delay before enabling oscillation, or do like IR and kick the low side mosfet on first.. see the circuit they use for that "start up circuit".

That should get something happening. You'll probably want to increase the bootstrap cap in value to at least 1 to 10uF according to what others had good luck with.

Try that and see what smokes,
Chris
  Reply With Quote
Old 6th April 2006, 10:26 AM   #3
Pierre is offline Pierre  France
Banned
 
Join Date: Nov 2004
Location: Paris
R20 is likely causing no problems, at most a 0.5V reduction in the chip's VCC, not enough to do harm. R21 is not necessary, I would leave it out.
For the bootstrap cap, I would recommend 1uF.

In order to measure the upper mosfet gate drive, tie the oscilloscope GND to source of M1 and the tip to its gate. Be sure that your oscilloscope GND is isolated from the PSU's GND or you will effectively be shorting the output to GND and... bang!
  Reply With Quote
Old 6th April 2006, 10:40 AM   #4
Account Disabled
 
Join Date: Feb 2004
Send a message via AIM to classd4sure Send a message via MSN to classd4sure
Quote:
Originally posted by Pierre
R20 is likely causing no problems, at most a 0.5V reduction in the chip's VCC, not enough to do harm.

It would really do little harm to take it out too I'd imagine. In this case .. without seeing the rest of the circuit, there's no idea if he's holding inputs low for a short time before "enabling" them or just letting it rip. Since 0V is the only precharge path we may as well speed it up, the diode will take it.
  Reply With Quote
Old 9th April 2006, 09:00 PM   #5
diyAudio Member
 
Join Date: Apr 2006
Location: Kingston
Thanks guys. I removed the 4.7 ohm resister, added capacitors to the +/-15 rails and changed the diode to MURS120. I originally used a fast response diode but i think this one is much better. And now it's working perfectly. I'm building on breadboard so the output is a bit noisely but I'm still amazed at how good it sounds it definately packs a pretty good puch. I also have one more question. I connected the rails to +/- 15 just to test out the circuit, should i put the 4.7 ohm resister back when i connect the circuit to +/- 50 rail. Thanks.
Niroshan

P.S. I will post the completed schematics of the entire circuit very soon.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to correctly use WinISD Zero D Subwoofers 30 22nd December 2013 09:21 PM
Am I using Unibox correctly? zimjj Multi-Way 0 7th February 2009 11:26 PM
IR2011 Gate Driver smartsabby Class D 1 27th February 2008 04:20 AM
dv/dt turn on with ir2011 simulation oldroborg Class D 5 20th December 2005 07:39 PM
Are we looking at distortion correctly? mashaffer Solid State 24 14th July 2004 03:04 AM


New To Site? Need Help?

All times are GMT. The time now is 09:11 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2