TDA2822M issues

[ben7]

I am having some trouble with a TDA2822M mini amp that I built. The outputs are pulsing at about once a second. I have soldered individual wires to each ground to eliminate possible ground loops. The output decoupling caps are 1800uF. The speakers are 8Ω 1W. I have a zobel network (4R7 and 0.1uF) on each output. The supply voltage to the chip is a rock steady 10v. Why the heck could this be happening?

It seems that one output has half the supply voltage on it. The other pulses from 0 to 1v. Could this chip be fried? I measure each output pin to ground and to positive rail. No noticeable shorts.

I also checked for solder bridges and found none.

-Ben

 

[mvs sarma]

There are two versions of TDA2822. one is 16 pin and second with 8 pins. which chip did you use? please try to give 9V supply, if 8pin chip.

At times the lay out issues cause that pulsing problem. STmicro has given tentative pcb layout for their 16 pin chip. perhaps you could also fine similar artwork for the 8 pin.

 

[ben7]

There are two versions of TDA2822. one is 16 pin and second with 8 pins. which chip did you use? please try to give 9V supply, if 8pin chip.

At times the lay out issues cause that pulsing problem. STmicro has given tentative pcb layout for their 16 pin chip. perhaps you could also fine similar artwork for the 8 pin.

It does the same thing with a lower supply voltage.

It is a TDA2822M as stated.

I even tried a decoupling cap on the power pins, but no change.

 

[mvs sarma]

if you had followed a sch and pcb artwork, try to upload so that we could discuss to overcome the defect

 

[ben7]

if you had followed a sch and pcb artwork, try to upload so that we could discuss to overcome the defect

It's the same circuit as in the datasheet.

https://www.e-dan.co.uk/electronics/TDA2822.GIF

 

[mvs sarma]

please see how the datasheet indicates the artwork. as the pcb overlay is dull, watch keenly look for Fig3 , there in, for a stereo amplifier model.
https://www.electro-tech-online.com/custompdfs/2012/09/TDA2822M_datasheet.pdf

the pcb has been tried to be made of Eagle. PDF of solder and overlay are shown attached.
the sch is as per datasheet and even the artwork follows their pattern.

 

[audioguru]

The TDA2822M is a little guy (8-pins DIL low power stereo amplifier).
Since your supply voltage was too high then you fried it.
Its DC output is supposed to be at half the supply voltage. One channel of yours is too low and it goes up and down. Maybe a part inside gets too hot then quits until it cools then it gets hot again and cools and hot and cool over and over.

 

[ben7]

The TDA2822M is a little guy (8-pins DIL low power stereo amplifier).
Since your supply voltage was too high then you fried it.
Its DC output is supposed to be at half the supply voltage. One channel of yours is too low and it goes up and down. Maybe a part inside gets too hot then quits until it cools then it gets hot again and cools and hot and cool over and over.

Yeah, now it gets extremely hot, and no oscillation. Must be fried.

Howcome I used too high a supply voltage? The data sheet says 15v max!

 

[mvs sarma]

you can use upto 15V provided that the load is around 32 Ohms each channel. As the load reduces to say 4 ohms, datasheet suggests low voltages. like 3, 4.5 or 6V only.