DAC To The Future! | AD5791 Linearity Calibrator

- github.com/NNNILabs/AD5791-Li...
- aisler.net/
- www.analog.com/media/en/techn...
- www.eevblog.com/forum/metrolo...
- www.analog.com/media/en/analo...
- www.analog.com/media/en/techn...
- / @sahko123
- github.com/macaba/Nuts/tree/m...
- www.printables.com/model/7462...
- github.com/raspberrypi/pico-e...
Special thanks to / marcoreps for helping me characterize the DAC.

[@dmytroengineering]

How dare you question the audiophoolery!

[@NNNILabs]

Am I cutting into your profit margins too much? ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⠟⠛⠛⠛⠋⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠙⠛⠛⠛⠿⠻⠿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⠋⠀⠀⠀⠀⠀⡀⠠⠤⠒⢂⣉⣉⣉⣑⣒⣒⠒⠒⠒⠒⠒⠒⠒⠀⠀⠐⠒⠚⠻⠿⠿⣿⣿⣿⣿⣿⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⠏⠀⠀⠀⠀⡠⠔⠉⣀⠔⠒⠉⣀⣀⠀⠀⠀⣀⡀⠈⠉⠑⠒⠒⠒⠒⠒⠈⠉⠉⠉⠁⠂⠀⠈⠙⢿⣿⣿⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⠇⠀⠀⠀⠔⠁⠠⠖⠡⠔⠊⠀⠀⠀⠀⠀⠀⠀⠐⡄⠀⠀⠀⠀⠀⠀⡄⠀⠀⠀⠀⠉⠲⢄⠀⠀⠀⠈⣿⣿⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⠋⠀⠀⠀⠀⠀⠀⠀⠊⠀⢀⣀⣤⣤⣤⣤⣀⠀⠀⠀⢸⠀⠀⠀⠀⠀⠜⠀⠀⠀⠀⣀⡀⠀⠈⠃⠀⠀⠀⠸⣿⣿⣿⣿ ⣿⣿⣿⣿⡿⠥⠐⠂⠀⠀⠀⠀⡄⠀⠰⢺⣿⣿⣿⣿⣿⣟⠀⠈⠐⢤⠀⠀⠀⠀⠀⠀⢀⣠⣶⣾⣯⠀⠀⠉⠂⠀⠠⠤⢄⣀⠙⢿⣿⣿ ⣿⡿⠋⠡⠐⠈⣉⠭⠤⠤⢄⡀⠈⠀⠈⠁⠉⠁⡠⠀⠀⠀⠉⠐⠠⠔⠀⠀⠀⠀⠀⠲⣿⠿⠛⠛⠓⠒⠂⠀⠀⠀⠀⠀⠀⠠⡉⢢⠙⣿ ⣿⠀⢀⠁⠀⠊⠀⠀⠀⠀⠀⠈⠁⠒⠂⠀⠒⠊⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡇⠀⠀⠀⠀⠀⢀⣀⡠⠔⠒⠒⠂⠀⠈⠀⡇⣿ ⣿⠀⢸⠀⠀⠀⢀⣀⡠⠋⠓⠤⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠄⠀⠀⠀⠀⠀⠀⠈⠢⠤⡀⠀⠀⠀⠀⠀⠀⢠⠀⠀⠀⡠⠀⡇⣿ ⣿⡀⠘⠀⠀⠀⠀⠀⠘⡄⠀⠀⠀⠈⠑⡦⢄⣀⠀⠀⠐⠒⠁⢸⠀⠀⠠⠒⠄⠀⠀⠀⠀⠀⢀⠇⠀⣀⡀⠀⠀⢀⢾⡆⠀⠈⡀⠎⣸⣿ ⣿⣿⣄⡈⠢⠀⠀⠀⠀⠘⣶⣄⡀⠀⠀⡇⠀⠀⠈⠉⠒⠢⡤⣀⡀⠀⠀⠀⠀⠀⠐⠦⠤⠒⠁⠀⠀⠀⠀⣀⢴⠁⠀⢷⠀⠀⠀⢰⣿⣿ ⣿⣿⣿⣿⣇⠂⠀⠀⠀⠀⠈⢂⠀⠈⠹⡧⣀⠀⠀⠀⠀⠀⡇⠀⠀⠉⠉⠉⢱⠒⠒⠒⠒⢖⠒⠒⠂⠙⠏⠀⠘⡀⠀⢸⠀⠀⠀⣿⣿⣿ ⣿⣿⣿⣿⣿⣧⠀⠀⠀⠀⠀⠀⠑⠄⠰⠀⠀⠁⠐⠲⣤⣴⣄⡀⠀⠀⠀⠀⢸⠀⠀⠀⠀⢸⠀⠀⠀⠀⢠⠀⣠⣷⣶⣿⠀⠀⢰⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣧⠀⠀⠀⠀⠀⠀⠀⠁⢀⠀⠀⠀⠀⠀⡙⠋⠙⠓⠲⢤⣤⣷⣤⣤⣤⣤⣾⣦⣤⣤⣶⣿⣿⣿⣿⡟⢹⠀⠀⢸⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣧⡀⠀⠀⠀⠀⠀⠀⠀⠑⠀⢄⠀⡰⠁⠀⠀⠀⠀⠀⠈⠉⠁⠈⠉⠻⠋⠉⠛⢛⠉⠉⢹⠁⢀⢇⠎⠀⠀⢸⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣦⣀⠈⠢⢄⡉⠂⠄⡀⠀⠈⠒⠢⠄⠀⢀⣀⣀⣰⠀⠀⠀⠀⠀⠀⠀⠀⡀⠀⢀⣎⠀⠼⠊⠀⠀⠀⠘⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⣄⡀⠉⠢⢄⡈⠑⠢⢄⡀⠀⠀⠀⠀⠀⠀⠉⠉⠉⠉⠉⠉⠉⠉⠉⠉⠁⠀⠀⢀⠀⠀⠀⠀⠀⢻⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⣦⣀⡈⠑⠢⢄⡀⠈⠑⠒⠤⠄⣀⣀⠀⠉⠉⠉⠉⠀⠀⠀⣀⡀⠤⠂⠁⠀⢀⠆⠀⠀⢸⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⣦⣄⡀⠁⠉⠒⠂⠤⠤⣀⣀⣉⡉⠉⠉⠉⠉⢀⣀⣀⡠⠤⠒⠈⠀⠀⠀⠀⣸⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣷⣶⣤⣄⣀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣰⣿⣿⣿ ⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⣶⣶⣶⣶⣤⣤⣤⣤⣀⣀⣤⣤⣤⣶⣾⣿⣿⣿⣿⣿

[@matjesmeister2403]

The next Marco Reps! ;) Looking forward to more videos

[@NNNILabs]

Thanks! When I started narrating my videos back in 2018, Marco Reps was my 'idol', so maybe I finally succeeded in my goal for this channel!?😵‍💫

[@tiagoferreira086]

Definitely Marco Reps inspired! :) but he also is original on his presentation format, some other channels try to be an exact copy of famous channels, mostly Great Scott's one.

[@NNNILabs]

@@tiagoferreira086 Somehow, even if you try to copy someone else's presentation style, you end up adding your own 'uniqueness' to it, so it ends up being somewhat original😄

[@jimmy2drinks]

Jim Williams application notes are fantastic. Warmth & humour where you'd never expect to see it.

[@NNNILabs]

For sure! He takes you by the hand and reveals all of his secrets so you can learn too😄

[@jimmy2drinks]

Also: subbed.

[@coxfuture]

This channel is criminally undersubscribed. Marco Reps had better watch his back :D

[@NNNILabs]

Ironically it was Reps himself who helped me characterize the DAC😆

[@larkop6504]

Wow, really interesting video. Went over my head but have to learn eventually, hopefully via osmosis.

[@NNNILabs]

I don't think I know what I'm doing most of the time🤪

[@kavithasudhakar7376]

Very well explains 👏 Amazing 👏

[@kcasc_hd]

For additional tests you could use another meter to monitor the Zener Voltage or the Vrefs of the DAC directly, that way you could get as many sources of error out of the way as possible

[@NNNILabs]

That's a good idea! I guess you could get an idea of drift by getting a second opinion...kinda beats the point of having a standalone calibrator, but I guess when you get down to the sub-ppm level you really need the help🤔

[@screen-protector]

Great project.

[@NNNILabs]

Thanks, glad you liked it!

[@vmiguel1988]

Good job

[@NNNILabs]

Thanks!

[@lorforlinux]

Nice video!

[@NNNILabs]

Thank you! Hope you enjoyed watching!

[@hardwareful]

5:28 [Homer Simpson voice] D'oh!

[@NNNILabs]

Could say the same when I destroyed an LM399 by connecting it the wrong way because I didn't pay attention to the pin number marking🤪 That was 2022, maybe I am more careful now...?

[@uditkotnis7531]

Is that Doctor Pyta's multilexer?

[@NNNILabs]

It's this one: github.com/c-lan/low-temf-scanner

[@victorman2227]

Nice intuitive explanation of a R2R DAC! Very impessive results too. Looking forward to the Jim Williams DAC video. What about a PWM DAC? The RP2040 can output 16 bit PWM with a max frequency of about 1.3 kHz. There are some designs where 2 PWM channels are combined to get 32 bit of resolution. The linearity is going to be worse of course.

[@NNNILabs]

You'll have to thank ADI for doing all the hard work on the DAC, I just followed the instructions in the datasheet😅 PWM DACs are actually used in all the highest-end calibrators, and a friend of mine recently designed one that achieved ±0.1ppm INL...I hope I'll get a chance to feature it in a later DAC video. Regarding the RP2040 PWM - I've put some thought into this as well, it's not just PWM resolution, but there are other factors like jitter that can influence INL. Combining two 16-bit PWM channels to get 32 bits is also something I've considered, but of course, there's some nuance to that, for example the resistors you use to combine the PWM channels need to be very well matched. Of course, the workaround to that is having a few bits overlap so you can do some kind of gain calibration to line up the two channels (misalignment might influence INL again!). Jim Williams did something similar in AN-86 by combining two 16-bit DACs with 4 bit overlap to get a 24-bit DAC. Yet another thing to consider is ripple, you'd need a very good filter that is also DC accurate to achieve sub-LSB ripple. So many things to think about...enough yapping! The Jim Williams ADC is definitely something I'm looking forward to showcase. Spoiler alert - I was able to achieve single-digit ppm INL (±10V range)!

[@fletcherreder6091]

465B, nice scope

[@NNNILabs]

Indeed, I wish I could get the focus right, plus I need to take it apart and fix some of the crusty switches...not that much of a repair person 😅

[@fletcherreder6091]

@@NNNILabs Ah, yeah, especially if it's the drum switches. I haven't found the focus on these to be super super sharp; some kind of trade-off for bandwidth I guess. I might have to steal that technique for improving INL ;)

[@NNNILabs]

@@fletcherreder6091 Feel free to do so! Just make sure that whatever you are calibrating can hold that INL😅

[@Cuprum88]

Now make it with a FPGA

[@NNNILabs]

☠

[@apurvathak]

Loved your manhattan style prototype .Can I know where are you located.I want to connect with you

[@NNNILabs]

You can get in touch on Discord, same tag

[@ivolol]

Stop choosing picos with switching regs! Even the chinesium RP2040 boards are better because they put a linear one in instead 🤣

[@HoorGuvLabs]

how about: pro pico

[@NNNILabs]

There was a certain Pro Pico video that I collaborated on recently 😉