LME49720/LM4562 Popcorn Noise Update

[AnalogJoe]

Recently, someone on YouTube resurrected an age-old issue, namely, popcorn noise present in the LM4562/LME49720.

I used to believe that this was a fabrication process issue that TI resolved years ago. However, I am not so sure now. Although the user in the YouTube video did mention that the parts he has were bought years ago from Digikey.

It is my understanding that TI changed the fabrication process for this part from a 6'' to an 8'' wafer at some point in time. I don't know if this resolved or worsened the problem. As far as I can see, TI has not released any official statements about the status of this problem and whether they have solved it or not. All I've read on the TI forum is that they say they are looking into it and will come back with more information, that they cannot screen 100% of all parts being produced, and that it seems to be something inherent of the process required to produce these parts. They also have suggested to look at the BurrBrown OPA parts instead. They have never (as far as I can tell) released the promised results of their findings/solution on the TI forum, instead, their MO seems to be that they remain silent, and after the waters have calmed down, the threads are closed or left abandoned.

I saw Wayne posted over on the TI forum regarding popcorn noise in these parts almost a decade ago, and most of the other posts from users complaining about popcorn noise are at least 5-6 years old. Some users have complained that up to 50% of their batch exhibits popcorn noise. I was wondering if any of you have any recent information about this.

Is popcorn noise still an issue with these parts? Do you still use these parts or do you avoid them like the plague?

[mediatechnology]

I bought a couple of LEM49720 from Mouser a few months ago to test a modern lot and haven't gotten to it yet.

They recently moved a lot of legacy analog, including the 5532 and 5534, to a 300mm process and I expect that the LM49720 is also run on 300mm lines. I thought it was process-related too.

Even if the popcorn noise is resolved there's still the EMI problem.
I posted on the Audio Science Review Site about EMI and the popcorn: https://www.audiosciencereview.com/for ... st-1043604

I avoid the LME49720.
In the dual class-A headphone amp the LMEE49720 has lower THD than the OP2134 but the EMI problem is a deal killer.
In that circuit the "kink" in the 5532 phase/gain response requires over compensation so I defaulted to the OPA2134.

In my ULDO-Nacho oscillator with the -140 dBc THD I've found that the NJM5532 outperforms everything I've tried.
I haven't tried the OP1656 yet.

[AnalogJoe]

I read your post on the EMI issues of the 4562/49720. I think this part is just too unreliable and should be avoided.

So the 5534/5532 is also being affected? crap. That is a bummer. Nice to know that the Japanese are still making good 5532's.

I wonder if the LME49990 also suffered from popcorn noise. It is one of, if not the best of, the audio op-amps I've seen on paper. Yet, its lifetime was too short and it was retired years ago; I wonder why. It had 0.9 nV/rtHz, ultra-low distortion, and 22 V/usec SR. Almost too good to be true.

As for the OPA1656, I've only done simulations with several circuits using it, but it seems to be a superb opamp. Most of my current designs use the 1656. It has a CMOS input but with a noise voltage density comparable to some of the best BJT parts, amazing. It also has a large GBW product, and it seems to be very well behaved at high frequencies. It almost behaves like a dominant/single pole compensated opamp. Distortion is also extremely low. And the price is around the $2 mark.

I recently moved from my old place and haven't had the opportunity to set up my home lab. I've also been busy with other stuff.

[mediatechnology]

I find the TI 5532 and 5534 to be almost as good as the NJM5532 but it has a couple of dB more distortion in the ULDO0-Nacho oscillator. Not enough difference to matter in most circuits.

I do see a little bit of WiFi EMI rectification when its about 3 feet from the router and unshielded.