tda2822m problems... - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 20th August 2010, 01:16 AM   #1
diyAudio Member
 
pat allen's Avatar
 
Join Date: Dec 2004
Location: Quebec
Default tda2822m problems...

Hi group, i would like some inputs about this:
i try to use their(ST) suggested bridged test circuit on a TDA2822m and i get very poor performance. It doesnt play bridged at all, one channel is barely getting anything out of it...if i ask the circuit to play a bit more it start to pop pop pop, and eventualy stop to work, i need to unpower it all.
There is no DC at the input, i have a 10uf decoupling cap (along with the 10k input resistor to gnd).

When i look at it it feels to me like a connection is missing, or a feedback from amp #1 to amp #2...
Each channels play OK in mono mode so it is not toasted.

This is meant to power up a white noise self unit for sleeping aid (dont ask further).
I got a bag of them for free and i thought i could use one in this project,
thanks for any inputs.
Attached Images
File Type: jpg test circuit.jpg (34.8 KB, 161 views)
__________________
Electronic engineer for automotive market.
  Reply With Quote
Old 20th August 2010, 01:57 AM   #2
diyAudio Member
 
pat allen's Avatar
 
Join Date: Dec 2004
Location: Quebec
i found this variation of the bridged circuit...
(i dont know if the image will show up)
Click the image to open in full size.
__________________
Electronic engineer for automotive market.
  Reply With Quote
Old 22nd August 2010, 05:40 PM   #3
diyAudio Member
 
Join Date: May 2008
The feedback should come through C1, which forms a voltage divider with C2. You should check C1, if you don't get any feedback on pin 5.

The amp in post #1 is AC coupled, the amp in post #2 is DC coupled. Depends on the value of the speakers, whether you want to try #2.
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 29th June 2013, 08:17 PM   #4
diyAudio Member
 
Join Date: Apr 2010
The circuit as shown on the data sheet does not work.


for mono bridge output:

You must put 100 uf on the output pins 1 &3 an connect them to the speaker for bridge output.

from pin 8 to pin 5 you should put a 10uf, +ve side on oin 8

from pin 5, 10uf to gound.

Pin 6 to ground

Input from pin 7

If you do not put the RC filter on the speakers, the cicuit will surely oscillate !
  Reply With Quote
Old 26th July 2013, 12:53 AM   #5
diyAudio Member
 
Join Date: Sep 2012
Location: Maine, Bangor-area
Quote:
Originally Posted by malti View Post
The circuit as shown on the data sheet does not work.


for mono bridge output:

You must put 100 uf on the output pins 1 &3 an connect them to the speaker for bridge output.

from pin 8 to pin 5 you should put a 10uf, +ve side on oin 8

from pin 5, 10uf to gound.

Pin 6 to ground

Input from pin 7

If you do not put the RC filter on the speakers, the cicuit will surely oscillate !
The bridge configuration according to the ST data sheets (schematic of post #1) worked fine for me, assembled on a socket board and 4.5VDC power supply.

How critical is the resistance value of the RC filter? I don't have 4.7 Ohm on hand, and I'd rather not parallel two 10 Ohm resistors that I do have on hand. Would 10 Ohm resistor in series with 0.1 microfarad cap be acceptable for the RC filter?

-Pete
  Reply With Quote
Old 26th July 2013, 09:47 PM   #6
PetruV is offline PetruV  Romania
diyAudio Member
 
Join Date: Dec 2012
Location: Bucuresti
yes it should work with 1-10 ohms
__________________
I know everything but do nothing
  Reply With Quote
Old 27th July 2013, 12:40 AM   #7
diyAudio Member
 
Join Date: Sep 2012
Location: Maine, Bangor-area
Quote:
Originally Posted by PetruV View Post
yes it should work with 1-10 ohms
Thank you! Of course I'd like to understand at least somewhat what is involved in designing such filters if you would care to explain.

-Pete
  Reply With Quote
Old 27th July 2013, 02:01 PM   #8
johnr66 is offline johnr66  United States
diyAudio Member
 
Join Date: Mar 2009
Quote:
Originally Posted by cT equals piD View Post
Thank you! Of course I'd like to understand at least somewhat what is involved in designing such filters if you would care to explain.

-Pete
Without getting into a long explanation, the series RC network connected to the output of the amplifier aids in HF stability. The engineer who designed or tested the circuit chose the values that kept the amplifier stable with various loads that may be connected since he doesn't know the characteristics of the load customer will actually use. It is best to stay with the datasheet recommendation but you can certainly adjust the values for your use as long as stability is not lost.

Many of the new low power ICs have been designed to remain stable without the RC circuit on the output. Lots of the car stereo BTL chips have done away with them.
  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
IE 8 problems lgreen Forum Problems 8 14th August 2010 09:10 PM
MiniWatt N3 problems, oscillation thumping and RF/motor problems. Destroyer OS. Tubes / Valves 18 6th July 2010 12:14 AM
TDA2822M amplifier circuit questions junkmail Chip Amps 2 22nd August 2007 10:39 PM
Problems Markz66mustang Car Audio 14 28th December 2004 06:04 AM


New To Site? Need Help?

All times are GMT. The time now is 05:45 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