[sdiy] Happenin' new opamp

[rsdio at audiobanshee.com]

Thanks for the link, Tim. I am a fan of Texas Instruments' op-amps, especially the Burr Brown family (isn't that where OPA comes from?). I've investigated the OPA1662 / OPA1664 as well as the OPA1641 / OPA1642 / OPA1644, but had not seen the OPA167x before.

I don't know whether I can find the citation now, but I remember reading that through-hole chips actually have more problems than SMT. The reason given is that the through-holes themselves introduce inductance that affects the performance of the circuit. SMT chips suffer from stray capacitance, but only if there is a power plane directly under the SMT pads. You can avoid the unintended capacitance in SMT designs by voiding the power plane under the pads; in contrast, there is no way to avoid the unintended inductance of through-hole designs because those pins have to go through the PCB.

I seem to recall someone mentioning non-plated holes and soldering both sides of through-hole parts - component side and solder side - in order to avoid the inductance, but that is not a design-for-manufacturing technique that average folks can afford (it effectively requires manual soldering).

Anyway, I have no qualms about SMT designs. I have my doubts that I'll ever run into circuit that literally sounds "bad" because there aren't pins going through the PCB. I mean, the working parts of the chip - the die - are exactly the same for both packages.

Brian


On May 23, 2017, at 2:14 PM, "Jarno Verhoeven at ziggo.nl" <jarno.verhoeven at ziggo.nl> wrote:
> I don't think I'll ever finish that stick of DIP TL074's I bought a while back, do love quad SMT opamps, nice n compact :-)
>  
> > Op 23 mei 2017 om 21:30 schreef Tim Ressel <timr at circuitabbey.com>:
> > Writing to say the OPA1678 from TI is a pretty nice little amp. Low 
> > noise, low distortion, low bias current, low cost. Is a dual; OPA1679 is 
> > a quad. SMT only, sad to say, but that be the times we live in.
> > 
> > http://www.ti.com/lit/ds/symlink/opa1678.pdf