At the beginning you say "this very small chip", and it would be cool to include the actual dimensions. This will make it possible to get a sense for the size of the features from the magnified die picture.
p.s. You write some of the best articles, I love the way you break things down and present them in an approachable way. Thank you, Ken!
PS awesome blog!
I'd imagine that their better response latency is eaten up by downstream capacitors anyway. Maybe they'd have better dynamic range to allow them to converge on a clean signal better than a stream of digitized samples that are always probably little off converged one way or the other by some quantum?
I'll be the first to admin that power control isn't my forte though, and most arguments I can come up absolutely sound like the specious stuff you hear out of 'audiophiles'.
Which is perhaps for the good, if you look for example on the boost topology, where saturation of the inductor leads to the shorting of the input through a switching transistor to the ground... :)
Here, Microchip markets this particular line of PIC MCUs as a "field-programmable switch-mode power controller". But weirdly I haven't seen that language on their main site.
As far as the chips themselves, I haven't looked at a modern power supply controller chip, but I've looked at other power chips . The biggest difference is they are CMOS instead of bipolar. They are also much more complex and dense, so I can't reverse engineer them with my microscope.
What would be the path forward if you chose to try an do that? A different light frequency microscope? Or something way more complex and expensive?
(Or would having the imaging capability not matter because the complexity is too high even if you could see it properly?)
Your posts are fantastic, not only do we get a peek inside, but we learn about how electronics work, and why designers make choices.
* How do you know if the base silicon is N-doped or P-doped? (does it matter?)
* Why are the layouts of NPN and PNP so different? I’ve seen many die photos and you can (usually) easily tell which transistor is which.
* Lastly, are there any guides on learning how to decipher a die shot into a “schematic”? How do I know which colors mean what? (they vary between IC)
(if it’s not obvious, I’m still learning about this stuff)
I'm kind of guessing that the substrate silicon is P-type since that seems to be more common. As for the colors, each IC is different. There are charts relating colors to thickness, but that doesn't really help me.
do you think recent GaN power adapters have very different power ICs ?
But because of differences between GaN and Si, the selection of reasonably compatible controllers and gate drivers is smaller. For example, many ICs made for Si are underperformers for GaN, or they might need some "translation" circuitry because of different gate voltage requirements.
There are certainly many gains to be made with GaN-specific supporting ICs, but that hasn't really happened yet. My personal threshold for acknowledging a fundamentally different technology would be replacing all the Si in the gate drive loop with GaN. The idea is to not hold back the GaN switch from realizing its full potential with slower and less efficient Si.
The GaN switch itself is, of course, quite different from a Si power switch.
Ones designed with power electronics use in mind are made intentionally close to silicon FETs on specs.
For schematics of power supplies using this UC3842 chip, see this site, near the bottom of the page.
Before looking at the URL I guessed it would be that site. The author is also on YouTube under the name DiodeGoneWild, and not surprisingly posts videos about SMPS electronics too.
It surprises me that this role hasn't been replaced with a tiny ARM core running some firmware to do the same. The benefit is the core can be self-tuning. It can detect components going out of spec and warn and/or compensate. It can have digital comms with the rest of the system to set all kinds of parameters, allowing a more flexible design and allowing bug fixes in the field. It can have lookup tables to tune efficiency for input/output voltage, load, etc, in a way an analogue design never could.
Considering a tiny microcontroller has a BOM cost of just 4 cents, in the same region as dedicated power supply chips, I don't see why software-controller-switched-mode-supplies aren't common.
Electronics is mostly KISS, not only motivated by the financial factor but also reliability, manufacturing, etc.
So far micro controllers are too expensive, too sensitive to unstable power supply, too complex in general (requiring some support components in some cases, have an additional prefabrication step for flashing firmware by the chip vendor, and cost a lot more.
There is no clear advantage to the approach you mentioned.
I ended up repairing it by hard-resetting the NVRAM and forcing the power control computer back to its initial "reset" state.
This was a common enough problem that the manufacturer had a step-by-step guide showing how to fix it on their website.
The moral of the story is that adding complexity, even when that complexity is designed to increase robustness, usually just means that there are more systems that can fail.
The problem is that you can't make every controller with an MCU, and you can't always make a competitive controller with an MCU.
There are already controller ICs that are configurable. In fact, modern controllers are a mix of analog and digital hardware. They do everything an MCU would do in that situation, but faster, less invasively, and with less power. Often, they do more than an MCU because they're not slowed down by an instruction cycle.
See my comment before last for an example of a software-configurable hardware controller.
Condition monitoring is a thing, and it's done with MCUs, DSPs, and FPGAs. But controllers sit on the non-isolated side of the gate driver, where they have basically no physical access to any useful signals. That's why condition monitoring is separate.
The lookup table idea is used for motor control. It's called a firing angle table. But that's a slower application.
Not self-tuning, though, they have to be tuned and all that software written.
Dedicated PMIC chips will be mixed signal, with digital control and analog failsafes.
Supposedly it can also detect shoot-through and modify timing to compensate.