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Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

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Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#11

Post by magicalhippo »

Richi's Lab[1] also contains a large number of pictures and analysis of decapped ICs. He's also documented his decapping process[2] which uses an oven rather than the dangerous acids, making it more approachable.

It's all in German, but Google Translate does a good enough job that it's easy to follow.

He's got a very interesting comparison of STM32 originals and clones, as well as various voltage references, 555 timers etc.

A personal favorite is the LTZ1000[3]. The die is a piece of art.

[1]: https://www.richis-lab.de/index.htm

[2]: https://www.richis-lab.de/decap-ofen.htm

[3]: https://www.richis-lab.de/REF03.htm

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#12

Post by CamperBob2 »

kens wrote: post #3

Any other suggestions for common yet generally unknown chips?

8051 ( https://en.wikipedia.org/wiki/Intel_MCS-51 ).

Still probably the most common microcontroller in existence, just because it's embedded in so many other ICs. 40 years old this year.

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#13

Post by segfaultbuserr »

jakehop wrote: post #10
kens wrote: post #3

Any other suggestions for common yet generally unknown chips?

The NE555-timer is quite a cool little thing. More common operational amplifiers are also worth looking into (TL072 is one of my favorites). Lastly, the 7400-series logic chips are SO interesting. If you need the programmer's version of a jigsaw puzzle, try to build somewhat advanced designs using those. It's very fun and a good learning experience (although hard!). This guy is building a computer on a breadboard – v…

NE555 is not "unknown" (most popular chip in the entire history of electronic engineering), 74xx and TL072 are not unknown either, anyone who knows a little bit of hardware knows the chip.

TL431 is popular yet unknown to most people outside the world of switched-mode power supply. I think the OP wants some popular yet relatively less-known chip to those who is outside of the field.

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#14

Post by yftsui »

kens wrote: post #3

Any other suggestions for common yet generally unknown chips?

UC2842/3842 (Primary side of a Flyback SMPS), versus TL431 which is on the secondary side.

Power supplies shipped in the past 10 years are most likely using an Onsemi variant of TI UC2842/3842.

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#16

Post by dfox »

ggm wrote: post #4

there is something reassuringly "analogue" about how these artifacts get over the technology limits of diffusion/mask/layer systems, to make building blocks: "I need a resistor? fine: lay out a huge amount of stuff" "No, I need it more accurate! fine: lay out tracks, now burn fuses to select from unit-scale tracks the 'right' number, and if you want better use a laser to do it"

The general rule for precision electronics is that you want to avoid anything that needs high absolute accuracy (because such things get expensive fast even as discrete components) and instead rely on accurate ratios between parameters, matched pairs of components and inaccurate, but long term stable parameters that can be calibrated out.

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#17

Post by JadeNB »

dfox wrote: post #16
ggm wrote: post #4

there is something reassuringly "analogue" about how these artifacts get over the technology limits of diffusion/mask/layer systems, to make building blocks: "I need a resistor? fine: lay out a huge amount of stuff" "No, I need it more accurate! fine: lay out tracks, now burn fuses to select from unit-scale tracks the 'right' number, and if you want better use a laser to do it"

The general rule for precision electronics is that you want to avoid anything that needs high absolute accuracy (because such things get expensive fast even as discrete components) and instead rely on accurate ratios between parameters, matched pairs of components and inaccurate, but long term stable parameters that can be calibrated out.

> The general rule for precision electronics is that you want to avoid anything that needs high absolute accuracy (because such things get expensive fast even as discrete components) and instead rely on accurate ratios between parameters, matched pairs of components and inaccurate, but long term stable parameters that can be calibrated out.

The omitted serial comma made that really hard to parse for me. In case it did for anyone else, I think that it's:

> (accurate ratios between parameters) and (matched pairs of components) and (inaccurate, but long-term stable, parameters that can be calibrated out).

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#18

Post by mrunkel »

magicalhippo wrote: post #11

Richi's Lab[1] also contains a large number of pictures and analysis of decapped ICs. He's also documented his decapping process[2] which uses an oven rather than the dangerous acids, making it more approachable. It's all in German, but Google Translate does a good enough job that it's easy to follow. He's got a very interesting comparison of STM32 originals and clones, as well as various voltage references, 555 time…

Particularly for German, I highly recommend https://deepl.com it does a much better job than google translate.

Re: Reverse-engineering the TL431: the most common chip you’ve never heard of (2014)

#19

Post by 2sk21 »

ggm wrote: post #4

there is something reassuringly "analogue" about how these artifacts get over the technology limits of diffusion/mask/layer systems, to make building blocks: "I need a resistor? fine: lay out a huge amount of stuff" "No, I need it more accurate! fine: lay out tracks, now burn fuses to select from unit-scale tracks the 'right' number, and if you want better use a laser to do it"

Even more fundamentally, feels amazing to me now that this was all manually laid out!

Each generation of ICs made it easier to create more sophisticated computers which in turn enabled the creation of yet more sophisticated ICs.

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