TA8200 Chipamp

[kbeist]

I have a few of these and would like some help determining some items of intrest as to the original designs that I am thinking about using.
One item of intrest that I would like some clarification on is the Ripple filter implimented on two of these CA's. Could someone do a quick sim for me to determin the reason for such a circuit? I understand the reason for the RC filter (C2&R4 on pin #6), but from there backwards to the outputs (pins #7 & #12) is a unconvintional approach that I am in need of information on. Anyone that can help me on this would be appreciated.
As far as I can assess the RC ripple filter is phase compensated by the outputs via Q1. Yes/No??

[kbeist]

Oh. Crap. Sorry. The sch may help.

[sgrossklass]

Originally Posted by kbeist

As far as I can assess the RC ripple filter is phase compensated by the outputs via Q1. Yes/No??

Rather no. This setup would seem to generate a signal at the ripple filter pin that is lowpass filtered and out of phase with L+R, possibly in an attempt to increase ripple rejection. Toshiba's datasheet being as craptacular as they always are, I have no idea what exactly is going on inside the IC at pin 6. It doesn't seem to have a bootstrapped supply rail.

[kbeist]

Thank you sgrossklass for at least some light shed on this. I have added the other parts to the schematic to help shed a bit more info on the design.
(The nodes that are the outputs to the speakers actually go through a Hi-freq inductor and another RC filter before actually connecting to the speakers.)
Also I might add that I am kind-of reverse engineering this actual circuit so that I can reuse the better parts of it and throw away the other parts. Two of these CA's are from an older style CRT rear proj TV. Hense the Hi-freq attenuation on the inputs and outputs that I have not included for simplicity sake.

[sgrossklass]

The other stuff is a rail smoothing cap (C5), protection (clamping) diodes, a compensation (Zobel) network (R+C6/7) and output coupling caps (C3/4). Nothing terribly unusual there, most of these should be in the datasheet's example circuit as well. An inductor in the speaker line would not come entirely unexpected either, power amps commonly have parallel RL combos there.

If it performs well, you may want to reuse the entire PCB layout (as far as the amplifier is concerned, obviously). Good layouts are important.