Re: tda2002 - better replacements

From: Jess Askey <jess_at_askey.org>
Date: Sat Jun 09 2007 - 00:55:24 EDT

It looks like the LM1875 is meant for a split (+/-) supply while the old
TDA is meant for a single sided supply (+/ground). All the inputs are DC
isolated in the circuits but the output is not... it is connected to
ground on the LM1875 which is the same place you are have the (-Vee)
supply connected. The LM1875 expects a DC potential between Vee and the
output which you don't have. So, Im guessing that you are only getting
half the drive (the Vcc side) and it distorted and crappy? Or do you not
get anything at all?

Oh... looking the circuit again... the TDA drives the speaker through a
cap, the LM1875 does not have the filter cap (it is directly loaded).
So, that is the problem. Different output design. Someone else can
probably chime in here and give a more educated explanation of the
difference tho. :-)

andre wrote:
> I ordered in a couple LM1875T's which are 20w
> amplifiers in same package as the td's. Distortion is
> FAR lower and with the extra headroom, can keep any
> noise down low and still have volume was objective on
> AR-II's.
> But put them in and they didn't work. Pinout looks to
> be the same...anyone with any idea why they don't?
>
> TDA2002
> http://pdf1.alldatasheet.com/datasheet-pdf/view/54782/FAIRCHILD/TDA2002.html
>
> LM1875
> http://www.national.com/pf/LM/LM1875.html
>
> Is the voltage too low?
>
>
>
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Received on Sat Jun 9 00:56:26 2007

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