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 8th March 2006, 10:18 AM   #1
zilog is offline zilog  Sweden
diyAudio Member
 
Join Date: Oct 2005
Default UcD and SMPS

How sensitive is the UcD scheme to voltage bus ripple / frequency beating from a SMPS?
  Reply With Quote
Old 8th March 2006, 10:27 AM   #2
diyAudio Member
 
Join Date: Sep 2003
Location: -
Default Re: UcD and SMPS

Quote:
Originally posted by zilog
How sensitive is the UcD scheme to voltage bus ripple / frequency beating from a SMPS?
Not very much. We have a customer who have tested and other OEM Class-D module, and the UcD was more stable on the SMPS.

Besides this I have heard an UcD400 with a SMPS and the sound was impressive. So a good SMSP + UcD is a nice combination....

Jan-Peter
  Reply With Quote
Old 8th March 2006, 10:48 AM   #3
zilog is offline zilog  Sweden
diyAudio Member
 
Join Date: Oct 2005
I plan to use a DIY-SMPS with an inductive switched voltage balancer to get rid of rail pumping effects. Is the UcD so insensitive to frequency beating on the voltage lines that I dont even need to keep the SMPS and the voltage balancer synchronized? (Would save much trouble to let smps and balancer have their own oscillators with whatever frequency they like and thus avoid needing to pass gate drive signals over the isolation barrier)
  Reply With Quote
Old 8th March 2006, 12:00 PM   #4
diyAudio Member
 
Join Date: Apr 2004
Location: BE/NL/RW/ZA
Indeed there should be no reason to synchronise the voltage balancer. Quite apart from the fact that UcD amplifiers are self-oscillating and hence variable frequency, so you couldn't synchronise anything to it even if you wanted.

Simply grab a scope and look at the disturbances caused by the amplifier itself. If your voltage balance circuit isn't noisier than that you're safe.
  Reply With Quote
Old 8th March 2006, 12:15 PM   #5
zilog is offline zilog  Sweden
diyAudio Member
 
Join Date: Oct 2005
Apart from stability issues - how much of the supply rail noise will be visible on the UcD output?

I have a 1 uH/2200uF (also serves as tank for the output switches) filter on each rail to prevent the UcD channels from conducting high frequency disturbance between each other and keep HF current ripple local to each channel, but nothing more. Added to this will be the LC-filter of the SMPS, values still do be decided upon.

My greatest worry is that some harmonic of the SMPS+balancer+UcD switching will come through the LC filter of the UcD and end up in the audible range (the switches will conduct all noise during their on-time)
  Reply With Quote
Old 8th March 2006, 12:51 PM   #6
diyAudio Member
 
Join Date: Apr 2004
Location: BE/NL/RW/ZA
The same filter that takes care of preventing any HF noise from the UcD power stage getting out into the power rails is equally effective at stopping noise from the power supply getting into the amplifier. The error control system (the bit that's actually called UcD) takes care of remaining noise.

Again, keep in mind that multiple UcD modules on one supply don't bother eachother, so as long as your circuit doesn't cause more noise than a UcD amplifier module, you're safe.
  Reply With Quote
Old 8th March 2006, 01:25 PM   #7
ghemink is offline ghemink  Netherlands
diyAudio Member
 
Join Date: Jun 2004
Location: Japan
Quote:
Originally posted by zilog
I plan to use a DIY-SMPS with an inductive switched voltage balancer to get rid of rail pumping effects. Is the UcD so insensitive to frequency beating on the voltage lines that I dont even need to keep the SMPS and the voltage balancer synchronized? (Would save much trouble to let smps and balancer have their own oscillators with whatever frequency they like and thus avoid needing to pass gate drive signals over the isolation barrier)

Do you have some link that describes the "inductive switched voltage balancer" as described above? More people maybe interested in this.

Best regards

Gertjan
  Reply With Quote
Old 8th March 2006, 01:30 PM   #8
diyAudio Member
 
Join Date: Apr 2004
Location: BE/NL/RW/ZA
Any half bridge power stage driven by a *fixed* duty cycle and its "output" (after the inductor of course) shorted to ground will do.
  Reply With Quote
Old 8th March 2006, 01:30 PM   #9
zilog is offline zilog  Sweden
diyAudio Member
 
Join Date: Oct 2005
Quote:
Originally posted by ghemink



Do you have some link that describes the "inductive switched voltage balancer" as described above? More people maybe interested in this.

Best regards

Gertjan

I got this in another thread,
http://www.diyaudio.com/forums/attac...amp=1141781588
  Reply With Quote
Old 8th March 2006, 02:47 PM   #10
ssanmor is offline ssanmor  Spain
diyAudio Member
 
Join Date: Jan 2002
Location: Madrid
I am a bit surprised about why people really cares so much about bus supply pumping. IMHO it is not a problem in practice.
I have been testing a lot of class-D amplifiers at quite high power levels (up to 1300W in bridge-mode) with reasonable capacitance in the (linear) PSU (2x20000uF or so) and NEVER had any problems with bus pumping, even with large power at low frequency (_BIG_ PA subwoofers)
???

With a SMPS you won't have problems either if it is regulated and is properly designed, I bet you definitely don't need the switched voltage balancer. Our SPS80 PSU (that is being produced and will become available in a month or so :-) performs very well in this aspect too and you won't see the rails increasing. It has 6600uF per rail output capacitance.

Perhaps Ghemink can also tell us his experience, as he did some deep tests with a SMPS on audio amplifiers, and the PSU he used (K6 SMPS) had very low output capacitance (2x470uF per rail if I recall ok).

Any comments?
  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
Smps a2005r2003 Power Supplies 19 11th August 2011 06:19 AM
SMPS for B+ from PC PS jkeny Tubes / Valves 1 10th February 2007 07:52 PM
Smps Juani_12-5 Car Audio 8 20th January 2007 09:15 AM
Smps rinox Power Supplies 0 2nd September 2005 10:05 PM
Need help on car SMPS DFI Car Audio 16 18th June 2004 05:59 AM


New To Site? Need Help?

All times are GMT. The time now is 07:19 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