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Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Thu Jan 28, 2021 11:03 pm
by emrr
Interesting. I’ll have to revisit the previous enhanced versions, TL207x I think.

Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Wed Jan 05, 2022 10:51 pm
by georgeonthenet
I am testing my first SOT-23-8 TL072H parts and it's "interesting".

TI's data sheet(updated December 2021) that covers ALL of the TL072s is clear as mud in some areas. One being noise. Under the "H" version and "switching" it shows a whopping 37nV input noise density, however... they also list the "H" version elsewhere at the usual 18nV. Typo? It seems to be. I haven't set up a proper test yet to pin down the noise to the nV, but what I am seeing is about 3db more noise than a TL072C DIP using a 40 db inverting amplifier.

TI also claims that this is simply an upgraded version of the old 72 and is not CMOS. So then what sort of magic is giving beautiful rail to rail outputs?

Another very interesting point is that they lowered the distortion from 0.003% to 0.00012%! I will certainly give that a close look.

Also the tiny package makes my mind wander through all sorts of possibilities. From what I can tell so far, it will indeed work very well for many applications and I have already started to breadboard my latest version of the DBX 200 VCA that I use for guitar applications where it works VERY well. I may be able to get my VCA down to about $0.25(maybe less) in semiconductors and actually be about the size of a quarter. Maybe a wide 14 pin DIP size.

Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Fri Jan 07, 2022 8:14 am
by mediatechnology
Thanks for the info.
Where did you find inventory?

Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Fri Jan 07, 2022 4:05 pm
by georgeonthenet
Digikey has/had them. These days you never for how long of course.

The testing I have done so far looks noisy, but... the Ein for these measures in at exactly 18nV as do some of my very old TL072s, however... my latest TL072C DIPs measure in at 10nV! Under what circumstance the new ones would have the 37 nV found in one particular area of the datasheet is a mystery.

All of my old and new 5532s measure exactly on spec which gives me confidence that my measurement setups(I use 3 to get a consensus) are all telling the truth. It looks like I have been spoiled by quiet 72s lately and I didn't know it. My old parts date back to the 80s and some even older. Also my audio noise recordings that I use to show the relative noise of various op amps reveals that my recently purchased TL072C stock is indeed strangely quiet. I also have some insanely noisy LF353s from the 80s for reference.

My distortion rig is also showing that the THD for these 72H specimens are indeed around 0.00012%, however not +N. I think that even an Audio Precision would confirm that. I have seen this before. This is likely among the many suspected errors/typos in the datasheet. The latest revision of the datasheet is December 2021 so they may be working on it. The part is pretty new.

So what to make of the new 72? I am finding that where vintage 72 noise can be tolerated, they are pretty impressive. I do suspect that there is CMOS in there, but so far I haven't found any confirmation of that from TI. If they are getting that rail to rail performance from BJTs, that is pretty impressive. I think that I will be using the new 72 for low gain or hybrid circuits where the noise is of no consequence.

Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Thu Jan 13, 2022 3:58 pm
by emrr
thanks for the update on these

Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Fri Jan 14, 2022 12:36 pm
by mediatechnology
The datasheet is confusing showing the same simplified diagram as the standard TL07x series but I doubt that's the case.

With the OPA1612 (bipolar) and OPA1642 (FET) products they use a common emitter output stage (PNP on top) to get near rail-to-rail output.

The output saturation numbers for the TL07xH and the OPA1612 are similar - they may have grafted a new bipolar output stage onto the H series.

Re: The TL071, TL072 and TL074 "H" Next Generation Enhanced Versions

Posted: Fri Jan 14, 2022 10:55 pm
by georgeonthenet
My latest observations revealed a very sharp rise in distortion at approximately a p/n junction from the rail. Indeed this sounds like something similar to what you describe. Also the negative rail does this at about 700 mV and the positive closer to 600 mV.

They apparently have a different type of BJT output that gets closer to the rail and has much lower impedance. In fact, when driving 1K loads the old 72s have quite the rise in output impedance under 100 hz or so and in some of my circuits this causes a significant rise in 60 hz noise compared to a 072H, 5532 or an OPA1678 etc.. I was always aware of the rise in THD in 72s when loaded heavily, but never gave much thought to the low frequency impedance issue.

Also I discovered that the TL072H is only super low distortion when the the rails are high. As the supply voltage drops there's a rather startling spike in the distortion residual that brings the THD up to some pretty mediocre levels eventually. That said, at +/- 15V my gear bottomed out at 0.0003%. This part may not be the choice for 5 volt use is all.