Power supply requirement for Class D amp. - diyAudio
Go Back   Home > Forums > Amplifiers > Class D
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 28th December 2008, 09:37 PM   #1
diyAudio Member
e_fortier's Avatar
Join Date: May 2001
Location: Canada
Default Power supply requirement for Class D amp.

Hi all,

I need some guidance to properly size a linear transformer for a very near future power amp. (will be built during the X-mas vacation)

Class D IC would be TDA8920BTH from Philips that runs at about
+- 27Vdc (from a +-20Vac Xtrm), implementation would be to use each stereo IC as BTL therefore power output would be 138W at 8 ohm per channel (based on spec sheet)

I have not done many Class D power amp so I'd like to know how much VA would be required per channel, would a +- 20Vac, 5A (200VA) sufficient..or do I require more power (VA) like a typical AB power amp.

Any help or rule of thumb to size the power xtrm would be welcome.

  Reply With Quote
Old 29th December 2008, 04:48 PM   #2
diyAudio Member
Join Date: Dec 2003
Location: Munich
For 138W class D a 200VA transformer is easily strong enough. But take care with your e-caps.
There is no evident reason to reduce their value vs. class AB. The rail sagging is also happening in class D and can lead to undesired early clipping, similar as it can happen in class AB if the caps are to small.
Furtheron most class D amps have less PSRR than class AB.
  Reply With Quote
Old 29th December 2008, 10:19 PM   #3
diyAudio Member
e_fortier's Avatar
Join Date: May 2001
Location: Canada

I will then buy either 2 x 200VA or a 400VA to power both channel.

  Reply With Quote


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
Understanding DC power requirement for amplifier board macpaulster Digital Line Level 11 4th January 2009 08:15 AM
Output Inductor Power Requirement gearheadgene Class D 6 28th February 2007 03:47 PM
Power supply requirement help araven Power Supplies 1 8th August 2006 07:26 PM
DC-DC Power converter for Class T amp power supply? rtalk Class D 2 7th December 2004 04:02 AM
Minimum power requirement Seville Multi-Way 3 3rd December 2001 01:15 PM

New To Site? Need Help?

All times are GMT. The time now is 08:21 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2