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 25th June 2009, 01:23 PM   #421
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
Mike, looking at the Lepai board pin 22 and 25 are connected with only one cap feeding them both. You might be able to just connect all the overshoot diodes to the same location (going to 22,25). On the other board I have pin 22 and 25 are kept separate, also they have there own capacitor supplying them and each pair of overshoot diodes go to each.

col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 25th June 2009, 01:43 PM   #422
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
the overshoot diodes might not work because pin 22 and 25 are connected. what happens if voltage from OUTP1 and OUTM1 is returned to pin22 instead of pin 25?



col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 25th June 2009, 02:08 PM   #423
diyAudio Member
 
MikeHunt79's Avatar
 
Join Date: Aug 2003
Location: Bristol, UK
Quote:
Originally posted by col
the overshoot diodes might not work because pin 22 and 25 are connected. what happens if voltage from OUTP1 and OUTM1 is returned to pin22 instead of pin 25?



col.
I see what you are saying now... Pins 22, 25, and 27 are all hooked up to VDD, they're all on the same PCB trace, resistance is 0 ohms between them, meaning it's best to connect the diodes straight to the pins, but it doesn't really matter if you get VDD from somewhere else AFAIK.

In this case I used VDD for the diodes from near where the power cap is, as it was easier because of the board layout.

for the other two pins I used pins 25 and 27 as the source of VDD...

I'm just about to wire in a Fault LED, then I'll trying powering it up and see if anything happens.
  Reply With Quote
Old 25th June 2009, 02:18 PM   #424
zog666 is offline zog666  Australia
diyAudio Member
 
Join Date: May 2009
I'm another happy Lepai owner, just saying hi!

I can be lazy as mine right now as mine already masterfully modded by Col!

anyway, its being held in reserve right now until the right set of matching speakers for it fall into my lap.

Good to have this resource all you peoples getting the most of it!
  Reply With Quote
Old 25th June 2009, 05:28 PM   #425
diyAudio Member
 
Join Date: May 2006
Hi,

I just purchased a Lepai today, I should get it in 7 to 10 days. I had to get one to check it out. The price is sure right for getting a TA2020 chip amp!

I've got the TA2020 bug with all of these cheap TA2020 Amps out there now! I just received my HLLY TA2020 yesterday!!! Check it out on the other thread. So far it's VERY NICE!

Can't wait to get the Lepai now and see how it sounds. I am also really interested to check out the bass control.

Marc
  Reply With Quote
Old 25th June 2009, 11:54 PM   #426
diyAudio Member
 
MikeHunt79's Avatar
 
Join Date: Aug 2003
Location: Bristol, UK
Quote:
Originally posted by MikeHunt79

I see what you are saying now... Pins 22, 25, and 27 are all hooked up to VDD, they're all on the same PCB trace, resistance is 0 ohms between them, meaning it's best to connect the diodes straight to the pins, but it doesn't really matter if you get VDD from somewhere else AFAIK.

In this case I used VDD for the diodes from near where the power cap is, as it was easier because of the board layout.

for the other two pins I used pins 25 and 27 as the source of VDD...

I'm just about to wire in a Fault LED, then I'll trying powering it up and see if anything happens.
Powered up and everything appears to work ok.

I guess I won't really know until I try it in the car with 14.4v input.

Pic:
Click the image to open in full size.
  Reply With Quote
Old 25th June 2009, 11:57 PM   #427
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
just quoting this from the TA2020 evaluation board datasheet. It's not elaborated so well on the TA2020 chip datasheet:

"The figure below is the Tripath TA2020-020 evaluation board. The most critical components on the board are the power supply decoupling capacitors. Capacitors, C674 and C451, must be placed right next to pins 22 (VDD2) and 19 (PGND2) as shown. Similarly, capacitors, C673 and C451B, must be placed right next to pins 25 (VDD1) and 28 (PGND1) as shown. These power supply decoupling capacitors not only help reject power supply noise, but more importantly, absorb voltage spikes on the VDD pins caused by overshoots of the outputs of the amplifiers.

Similarly, schottky diodes, D1, D2, D3 and D4, minimize overshoots with respect to VDD and schottky diodes, D702, D703, D704 and D728, minimize undershoots with respect to power ground. For maximum effectiveness, these diodes must be located close to the output pins and returned to their respective VDD or PGND pins. Diodes D1, D2, D3 and D4 are only required for applications where VDD>13.5V. Voltage overshoots can also be caused by output inductor flyback during high current switching events such as shorted outputs or driving low impedances at high levels. If these capacitors and diodes are not close enough to the pins, electrical overstress to the part can occur, possibly resulting in permanent damage to the TA2020-020."

col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 26th June 2009, 01:09 AM   #428
diyAudio Member
 
MikeHunt79's Avatar
 
Join Date: Aug 2003
Location: Bristol, UK
Thanks for the info Col, I was only going by the info on the TA2020 datasheet.

I'll have a look at the Eval board datasheet and also the amp6basic schematic and double check everything along with the decoupling caps.

Also, I noticed a 14V zener on the board today, I'm going to check how much voltage the TA2020 gets with an input voltage of 14.4v as I could be doing this mod for no reason...
  Reply With Quote
Old 1st July 2009, 03:36 AM   #429
msj965 is offline msj965  United States
diyAudio Member
 
Join Date: Feb 2009
Default Need help on lepai

Hello
Just wanna ask how can I eliminate the humming noise on my lepai.I just change the 2x10uf to 2.2uf 250v,Is this the reason why it is making the noise?

Thanks
  Reply With Quote
Old 1st July 2009, 07:10 AM   #430
diyAudio Member
 
Lostcause's Avatar
 
Join Date: Aug 2005
Location: NW UK
Default Re: Need help on lepai

Quote:
Originally posted by msj965
Hello
Just wanna ask how can I eliminate the humming noise on my lepai.I just change the 2x10uf to 2.2uf 250v,Is this the reason why it is making the noise?

Thanks
Hi msj965
Humming? Sounds like a grounding issue.
Look earlier on in the thread for reference to this.
There are wires grounding the pots that may have dry solder joints or have become detached.
Also the case doesn't like being 'earthed' on earlier models (UK plugs 3rd pin). If it's sat on another metal case i.e. your CDP the grounding of that case can affect it.

It's definately not the input capacitors

Hope that helps
  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
New ta2020 pcb'S ArjenShenzhen Vendor's Bazaar 98 14th November 2012 11:39 AM
Ta2020 Bengali Class D 0 29th September 2007 05:28 AM
Eb-ta2020 opentop Class D 16 30th May 2005 07:42 AM


New To Site? Need Help?

All times are GMT. The time now is 12:15 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