The cheap simple ClassD - Page 3 - diyAudio
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 24th October 2005, 12:06 PM   #21
Account Disabled
 
Join Date: Feb 2004
Send a message via AIM to classd4sure Send a message via MSN to classd4sure
Quote:
Originally posted by classd4sure
Sorry, what's on page 5 exactly?

Nevermind, it's the Sony amp you mentioned, thanks for posting it. It's very simple.
  Reply With Quote
Old 24th October 2005, 12:20 PM   #22
TroelsM is offline TroelsM  Denmark
diyAudio Member
 
TroelsM's Avatar
 
Join Date: May 2003
Location: AARHUS. DK
The RD's on the gates are pretty standard. The "Xtra" deadtime is a lot easy'ere to trim to get very short deadtime.

Totem-pole? Please explain?

In the sim the freq is approx 250kz, but that is a function of the delay in the inverters and therefore the freq in the real-world sch could be a lot different.

Im using PSpice.

TroelsM
  Reply With Quote
Old 24th October 2005, 12:48 PM   #23
nitrate is offline nitrate  United Kingdom
diyAudio Member
 
nitrate's Avatar
 
Join Date: Jun 2005
Location: England, Lancashire
Quote:
Totem-pole? Please explain?
Hi,

The totem pole i'm referring to is Q1/Q3 and Q4/Q5. They are arranged in a configuration known as 'totem-pole'. It is a standard way of driving at low frequencys and works well but i've never seen one working above 100KHz, the low switching times and crow bar current will cause havock. Talking of speed if you want more you will find changing the gates for TTL instead of Cmos will speed things up, the waveform of TTL gates are much sharper as well. Unfortunatly you must use them at a max of 5V, this complicates things a little.

Have fun,
Mad.P
__________________
The perfect amplifier is a piece of wire with gain....
  Reply With Quote
Old 24th October 2005, 12:52 PM   #24
TroelsM is offline TroelsM  Denmark
diyAudio Member
 
TroelsM's Avatar
 
Join Date: May 2003
Location: AARHUS. DK
Aha. Got it. Why should it not work above 100Hz? I have used it in an amp running at 500Khz and the waveforms were pretty decent.

Any links/Pdf's on the problems you talk about? I would like to learn more about it. After sll its a somewhat important part of the Sch..

TroelsM
  Reply With Quote
Old 24th October 2005, 02:20 PM   #25
Kenshin is offline Kenshin  China
diyAudio Member
 
Kenshin's Avatar
 
Join Date: Jan 2005
Location: China
1.You can't use the same 40106 chip for high side and low side...

2.Simple design, probably I would begin to use N channel since this.
What's the actual ton/toff of high side?

3.why so many filters in the japanese amp TA-N88 ?
  Reply With Quote
Old 24th October 2005, 02:45 PM   #26
diyAudio Member
 
Join Date: May 2002
Location: Switzerland
Quote:
3.why so many filters in the japanese amp TA-N88 ?
Years ago everybody thought that even the tiniest bit of ripple had to be "ironed out" in order to reach audio nirvana.
Only within the last 10 years there was a paradigm change in that reasonable amaounts of ripple aren't regarded as disturbing as a filter of high order itself.

Regards

Charles
  Reply With Quote
Old 24th October 2005, 03:32 PM   #27
nitrate is offline nitrate  United Kingdom
diyAudio Member
 
nitrate's Avatar
 
Join Date: Jun 2005
Location: England, Lancashire
Greet's

I don't know if anyone has ever written a paper about the pro's and con's of totem pole drivers, I'm sure somewere somebody has LOL. I'm just going off my own experience in trying to use them in these kinds of amps. Alos i have not seen any practical designs that use them, pity really as they are so simple

Mad.P
__________________
The perfect amplifier is a piece of wire with gain....
  Reply With Quote
Old 24th October 2005, 04:37 PM   #28
TroelsM is offline TroelsM  Denmark
diyAudio Member
 
TroelsM's Avatar
 
Join Date: May 2003
Location: AARHUS. DK
Nitrate: What kind of problems are you referring to? If you could explain which transistors you have used and what the problems were maybe we could find and/or solve some of the problems?

I'm guessing that a lot of discrete drivers have failed because of very poor PCB-layouts with dozen of nH trace-inductance and slow transistors.

Kenshin: No, you're absolutely right. Im going to use a separate 40106 for the highside. The Sch is only a sim-model. Some of the inverters might not be used and I hav'nt figured out how many 40106 I'll need in total.

I would like some more input on the post-filter-feedback but maybe I'll build the powerstage and examine the switching of the driver and Mosfet. If those parts are working well then I guess that a LOT of people will be very interested in the design.

TroelsM
  Reply With Quote
Old 25th October 2005, 02:29 AM   #29
TroelsM is offline TroelsM  Denmark
diyAudio Member
 
TroelsM's Avatar
 
Join Date: May 2003
Location: AARHUS. DK
Default Better driver-curcuit

I Have siulated the performance of the totempole-driver but i cant find any serious faults with it. I tried to ad a lot of parasitic inductance but it only made things a wee bit worse.

-But anyhow i decided to try another driver-curcuit in the simulator. Two different schematics are added to this post. The top-schem is a little faster at turn-on because off the "kick/boost" from the C1, R2-connection around Q2. The timeconstant is so small that C1/R2 are only conducting the first 100nS of the switching action but the give a good kick to turn Q1 on faster.

C1/R2 does the "AC" switching and Q2 does the DC-switching...?

Both Curcuits seems to work fine, but they will be harder to implement with leaded components as there are more componets in the critical loop driving the gate.

Comments? Ideas?

Sim-results will be in the next post.

TroelsM
Attached Images
File Type: png newdriver.png (23.2 KB, 536 views)
  Reply With Quote
Old 25th October 2005, 02:39 AM   #30
TroelsM is offline TroelsM  Denmark
diyAudio Member
 
TroelsM's Avatar
 
Join Date: May 2003
Location: AARHUS. DK
Default Sim-Res.

Here's the sim-results. The sim's are done without any parasitic/PCB-inductance.

M1 are clearly turned on faster and the loss (area under curve) is therefore smaller. Not a big difference but it's there.

The inverters in the sch might have to be made up off 2-4 inverters in parralel.

TroelsM

EDIT: just tried the totempole-driver from my original-schematic. It gives the same switch-times and losses as the best of the two "new ones". The Totem-pole is, as i mentioned before, a lot simpler to implement though.

I would like to try both in the real world, but Im not shure when I'll get near a scope' again..

TroelsM
Attached Images
File Type: png newdriversim.png (25.5 KB, 421 views)
  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
Simple/cheap DAC? Znyper Digital Source 9 15th January 2008 08:52 AM
Simple and cheap sparkle Solid State 33 14th May 2004 05:19 PM
simple, cheap, 6L6 amp? help trespasser_guy Tubes / Valves 54 22nd March 2003 02:03 AM


New To Site? Need Help?

All times are GMT. The time now is 08:38 AM.


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