TDA7273 (for car audio) -- purpose of output caps

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Here's a link to the ST datasheet for this device [a TDA for car audio].

With respect to the TDA7372 datasheet schematic below...

tda7372.gif


....
A while back, a mild debate arose elsewhere as to what function(s) the OUTPUT CAPS serve (2200uF, C9-12 in schema above).

Are they to BLOCK DC

...and/or ...

(as contended by another) "all push pull stages that operate only on a single rail power supply utilize a SERIES capacitor in series with the speaker, which acts a a voltage source during the negative half cycle." ?

In other words, can one REMOVE the 1000uF caps?
 
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yep, the output at idle sits at half the psu voltage. to block this DC the caps are used.
edit* by mistake i was thinking this chip has BTL mode too, but i see it is not easyli done. so you should not remove the capacitors.
otherwise you get an unhappy speaker.

"all push pull stages that operate only on a single rail power supply utilize a SERIES capacitor in series with the speaker, which acts a a voltage source during the negative half cycle." this statemant is incomplete , and at first glance looks to be.. not so clever.
however , you "could" if you want to, (but you don't have to, and should not want to since its pointless) consider that for the "negative part" of the sine wave at outut you can sortha assume the capacitor as a kind of voltage source. its not "wrong" to do so, its just... better to look at what it actually does and go by that. witch is blocking dc.
allso does not need to be push-pull output.
 
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Yeah -- that el cheapo TDA is used in low-end card radios (class B, I think).

For some reason, I was getting confused with more-respected LM3886 Gainclone that uses +/- PS and no limiting blocking caps on the output:

lm3886-amplifier-gainclone-circuit-diagram.jpg


EDIT:
I looked at the LM3886 datasheet a little more carefully and saw an option for a SINGLE POWER SUPPLY [PDF, pg. 6].
That schema seems more complex than the DUAL-SUPPLY setup.
I have no idea what industry (auto, budget home stereo, etc.) prefers what option. The parts count seem similar??
 
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To use those output caps (in a single-supply design) is ... ugghhh :(
Even with boutique caps you'll get issues with temperature, electrolyte drying up (over time).
Maybe many car (or car audio) manuf's think the driver will trade in the vehicle before these caps wear out ;)
 
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