 Welcome to Desk of Lady Aida, a special storm edition. You surprised me, I was looking so deeply in the eyes of my circuit board. Yeah, hello, we're doing a Saturday, Desk of Lady Aida. It's a little bit earlier than our usual Sunday show, but that's because, well, partially we're not sure it's gonna happen tomorrow, there's this big storm coming in, we thought we would get this show on the road on the day we know we can do it. Yeah, we're the type of people, if we could take care of something now and get to show out more, we'll do it. Yeah, and you know, in the tomorrow, whatever happens, look, we'll still be online, we won't do a show of course, but the next week we'll probably back to Sunday. All right, so what are you working on this week? All right, well this week, as I was gazing deeply, I was just wrapping up a design for a new STEM at QT board. I had a bunch of people recently email ask for an MCP 23017, that's a 16 channel IO expander over I squared C. We actually stocked the DIP version of this chip and so like I've always kind of been like, I do we need a breakout? I mean like the DIP chip you can use in a breadboard. But you know, there's people who probably want to use STEM at QT and have like a plug and play experience with this chip and make it easy. And it's a little cost enough, it's not a big deal. Like, and you know, we already stocked this component because we use it in one of our, a couple of our boards. You know, we like the MCP 23017, I thought it showed on the computer when I was. Yeah. Yeah. So this is the QFN chip here. And then, you know, it's kind of a weird design because there's so many pins broken out. What I did is I made the right side. This is the B channel, eight pins and the A channel, eight pins, so it's 16 total. And then a row of ground pins there. They're covered with solder mask here. So it'll have like a white stripe behind them, but it'll be a copper three, of course. And then on the left side, I have the control pins, you know, I squared C and power. And then, you know, the interrupts and address pins. And then it's a STEMI QT, it's just really long. You can still chain them. So, you know, I'll order the PCBs for this shortly. So that's the STEMI QT design. But what I worked on is, let's see, LED driver and, so this board that I've been working on for a bit, we finally got the PCBs in. It's the 13 by nine RGB matrix. And so the PCBs came in and we fabbed them. We shot a little one minute video that you folks can watch on YouTube or Twitter, whatever. But I thought I'd also show the board on the overhead. So let me show it off. Just start. And, okay, so we've got that IS 31 FL 30 and 41 over here. It's kind of a weird design. The reason I did it this way is because, I'm not like most STEMI QT boards, I wanted to have these be tidal vaults. So, you know, the LEDs are at the edge so you can, you know, chain them side by side. You can have four of them on one I squared C bus. If you wanted to make, you know, a longer shape or like a, you know, a rectangular shape or something, you could do it. The prototype didn't have this bottom area. It was actually like you could tile it also on the bottom way, but I was actually really worried that the LEDs would get cracked off. I didn't like having three exposed sides. And I thought like, well, I think people will, you know if you really want a large matrix you should use an RGB, you know, LED matrix like the 32 by 64 we have, you shouldn't, this is that kind of designed for small layouts. And so even though it's like, you know, why not do a thing? It's like, well, I thought mounting holes would be more useful. So I made a design decision. These are actually made with two different LEDs. You can actually sort of see on the overhead this one is slightly wider cover to the LED than this one. I got two sources of LEDs. Of course, I love to dual source components. The LEDs themselves are dual sourced. They're about a penny a piece and long RGB, two millimeter LEDs. And basically what we did is we split the job in half. We made 48 boards total. So 24 were with one LED and 24 were the other. And that's four panels each. And the reason we did that is to check the yield, right? If the copper plating or the tin coating on one LED wasn't, because if one LED doesn't work, the whole thing doesn't work, right? So this is a very, to me, like emotionally stressful board to put together because whenever, you know, if you have a board with only six things, it's like, okay, you only have six things to worry about. You have a board with 130 things. Now you have many more to worry about. And if one doesn't work, the whole thing has to be thrown out because you're not gonna be able to rework this. This is very hard to rework without damaging all the LEDs. So, you know, having the yield be perfect is essential to making this board possible. But actually both came out quite nice. So I thought I can show, I have two basic demos. One is the GFX demo, which is, you know, a little text, colorful text demo. This is I squared C, so I just plugged in over here into my metro board, my breadboard, okay, uploading and it's going to be very bright. So I'll put the cover on it, okay, uploading. Go, go, so there you go. So you've gotta, let's see if I can get this too. It doesn't like it, but you can see it's got a colorful, you know, the colors are changing and the text is scrolling through on the LED matrix. So a great little demo, really fast and easy to do. And of course I'll probably show a demo also with two boards. So it's actually ready to go. So the tests, you know, the testers are made. We'll put these in the shop this coming week. This'll be the new product for the week. And then the other project, which I was working on is the deconstruction version of this, right? Which is you take this LED matrix and you split it apart into LED glasses. So this layout is, it took me like a week to do this layout because it was a total pain. And so now we've got, it's kind of weird because it's got like five by 12 LEDs here, right? There's a little like scrolling texty square area. You can, there's a lot of resistors. We can still see that there's a grid of LEDs. And then overlaid on that grid are two 24 LED circles. Because one thing I really always liked about our Neopixel goggle project is I like the look of round glasses. You know, you might want to have like texture designs but you also want the round element as well. So it's kind of got a mix of both which I think it's kind of a unique design that Philby came up with, we kind of collaborated on. So the next part that I gotta do because we, you know, actually what's interesting is I did not put this together by hand because this is a, these boards, the first proto I put together by hand and it's a total nightmare to hand place these. So what we did is we actually programmed a pick-and-place to do one PCB at a time. At my pick-and-place, I could do it. You cannot do this with a board house. They will normally not put together. They will not program a pick-and-place for two PCBs. They only made, only made two of these, this one and this one. Because I'm a boss lady and I don't have a pick-and-place. I was like, and I told her, I'm not doing this. I make every prototype by hand except for this is not worth it. So, but they were happy to do it because it's gonna be the same design for the final. So we loaded it in and then we did a little laser cut piece to hold it down flat because there's nothing to grip onto here. It's, because it's rounded and we put it through the pick-and-place. And actually this board, it's a little hard to see because I'm running that Adafruit text demo but of course it doesn't map because all the LEDs are in different directions. It's not split. You can kind of- It's cool looking, yeah. You can sort of see like the RUIT. You can sort of see the text but it's like split apart and weird because the RGB mapping is a pain. That's the part I have to do next which is map. Do you wanna do a couple of questions on this? Well, let me just wrap up and then we'll do it. So we gotta do the mapping for it which is gonna be annoying because I'm gonna have to figure out how are you gonna do that in software? I don't know how yet. To indicate that there's both a flat area and two round areas. So it might actually end up being, you get three objects, the left ring, the right ring and then the text overlay and you'll kind of address them as three different objects. But underlying it will be one chip which is like weird but why not? And I'll probably do that in Python first because it's faster to do the iteration because again, the math is a little, to be honest, it's a kind of psychotic because I'm one line, half of them are here and one are here and then like these, even though these are lines, they actually, because they're not, because the numbers, it doesn't divide evenly. It kind of curls up and then this one curls around and like basically, I made it all work but there's, it's not, it's totally not linear. So we're gonna have to fix that all. We'll fix that in post as they say. So this is a, this is the beginning of the design, but I think it'll look cool. All right, so what's the question? All right, some of the questions that came up. Yeah. How do you factor yield into your price on that? And then are those neopixels or dot stars? These are neither neopixels nor dot stars. That's what makes it actually possible to do this. They're analog RGB LEDs. So check out the previous desk of Lady A's where we talk about why not dot stars or neopixels. The yield is multiplied by the cost, the inverse of the cost. And if you have bad yield, then you have to increase the cost by whatever multiplier gives you that yield. Usually yield improves. I'm not worried about it. The yield about this too much because even though it is a nightmare to have 133 components on a board, the LED matrices we get are low cost and they have thousands of LEDs per board and they make it work. So I think we can make this work as well. Okay, all right, what else you got? Okay, so that's the PCV. So I thought then after some more questions we could kind of roll into... Oh, can you lift up the diffuser from touching it all the way to a little bit further out? Like this? Yeah, then go closer, closer, closer. This is up against it. That's up against it. Good, like an inch out. That's nice. Like the New York City concert which cancels it. This is like our simulation of this concert. Do, do, do, do, do, do. This means something. Okay, all right, you wanna do the great search? Yeah, let's do the great search. All right. Where in the world is that part I need? The great search with DigiKey. The great search brought you by DigiKey and Adafruit. Lady Adie uses her powers of engineering to find the things that you're looking for every single week. Okay. All right, this week we have a special request. I don't think you got the grab your window computer and I have the graphic up here. Yeah, let's see here. You're doing really big. Yeah, you wanna... Yeah, we'll pop really fast. Yeah, we saw this on YouTube so you're gonna know. Okay, so we had a YouTube comment from CypherLoco. Hi there, I would like to suggest request a great search segment. Please do a booster DC-DC switching regulator, one with low quiescent current that is great for battery-powered IoT device. I'm obsessed with battery, sorry, with low power devices. Okay, yes, that's a good idea. It's actually quite hard to search. What's funny is that's the thing that everybody wants but it's actually quite hard to search for. And the reason it's hard to search for is there's, unlike linear regulators where the pass-through current is, sorry, linear regulators have, there's two components of the current you're drawing and the quiescent current. And the quiescent current does increase with more pass-through current, but not at low currents, it's very steady. It's like, you know that if you're drawing a milliamp or less, the quiescent current is going to be five microamps, 10 microamps, whatever. And then you just add to that whatever the current going through it is because it's a linear regulator, the current is the current out. It's almost completely identical other than quiescent. Whereas for boost converters, for DC-DC converters, particularly boost converters, of course, more current goes in than goes out because there's more voltage on the output than the input. And so by definition, if you're drawing one milliamp, if you're in your microcontroller system, your IoT thing is drawing, say, one milliamp of current, it could be so inefficient is drawing 10 milliamps from the source battery. And so while what normally we would call quiescent current is something you're looking for, you're actually also looking for the efficiency at low currents. And I'll give you, you know, there are, again, dozens and dozens of DC regulators and I'm not, it's actually quite hard to find the exact, you know, it's like you don't have any specifications for the input voltage or output voltage or current requirements or whatever. So I'm not going to find the specific chip, but I'll give you some hints at how to use the search to find something close to what you want. So that's kind of the best I can do, given the broad specification required. So first up, you know, if you go to DigiKey, so let's go to my computer and you search for, you know, DC-DC control converters. Note that there's DC-DC converters and DC-DC controllers. Controllers usually require having external transistors. I can say control transistors are good for high current or high voltage or like other very weird setups. 99% of the time these days, people don't use controllers or use converters where they regulate everything's kind of built in. Usually you toss an inductor, maybe a diode, a couple of capacitors and you're done. So just note that there's two versions, converters and controllers here and we're going to go with the converter. There's 10 times as many, so that's surprising. That's another thing. There's over a quarter million different converters, so that's going to be a beast to find something. But, you know, a couple of things that I'm going to quickly do to just pair this down is I'm going to look for in stock only, and which is going to basically take away 90% because a lot of chips are in stock. And exclude marketplace. We're only looking at stuff that's in stock at Digi-Key. I'm also going to look for ones that only have a single output voltage and they're active. So, you'll be able to get them. I'm assuming it's just for somebody manufacturing. So you want it in stock now and also you want it to be available. Also, you didn't mention any voltage requirements, but I'm going to say you want a boost converter that gives you, you know, from a couple of alkaline batteries, maybe a lithium-ion battery up to five volts. Just, that may not be what it is, but hey, you know, do the best I can. And also, you know, it'll probably be a surface mount part. Actually, did I pick the right? Yeah, I think I picked the right chip. Okay, so I want... Oh, you know what? I picked modules by accident. Whoops. I didn't mean to do that. Sorry. Oh, yeah. Sorry, I picked power supplies, board them out. That's not what I wanted. See, made a mistake. DC-DC converter. I wanted the, sorry, I wanted the voltage regulators, DC-DC-DC. I like how you show how you can get down a path, but then how you can back out of it. Yeah, sorry, the DC-DC converters is actually like plug-in outlet things. Cause I was like, why is this all like very physically large? I wanted the chips themselves. If I'd looked at the images, I wouldn't notice, but let's look at the chips. Okay, so I'm looking at voltage regulators, DC-DC switching regulators. This makes more sense. So I still want in stock and I'm going to exclude marketplace. Okay, and I want active parts and I want ones with a single output. I'm gonna make it simple. One output. I'm going to look at only, you know, there's ratio metric, step up, whatever, whatever, whatever. I just want basics. You know, there's ones that can be step up, step down. I'm just going to do step up only and not ratio metric just every day. So let's do that. I also want to have adjustable fixed figure. I don't really matter. I don't want charge pump. I kind of want boost, but there's a lot of options. I'm gonna leave this for now and I want it to be positive only. I'm gonna use positive output. Okay, so there's one thing that you'll notice of all these searches that, oh, and I think I do want it to be synchronous. Synchronous means you don't need a diode on the output. Usually it makes it a little bit more efficient. So you'll note that because I required it to be in stock, there's not a lot of options. A lot of DC regulators are out, but one thing you'll notice is that you can select input means and output means and current outputs and switching and synchronous and whatever in packages. One thing you can't search for is quiescent current. Another thing you can't search for is the boost converter mode. So for when you're dealing with low currents, there's two modes. There's PFM and PWM and there's probably others I'm not thinking of, but there's the kind of two popular ones. And Digikey even has a article. It's like, oh, if you want to look in more detail, they have an article using PFM to improve switching DC-DC regulator efficiency at low loads. We've also covered, whenever we covered boost converters, they're often a pin that allows you to change which mode. If you look here and here on the left, this is PWM mode, which is efficient at high current, 100 milliamps, 10 to 1,000 milliamps, you'll get fairly good efficiency, 90, 95. However, when you get to low efficiencies, it plummets to 20%, 30% efficient, which like totally sucks because if you're gonna spend a lot of your time at that low current and you want to be asleep for very long time, you want good efficiency at low current. So the trade-off is PFM mode, which is on the right, which PFM stands for, let's see. Pulse frequency modulation, which is actually a little bit like PDM. It changes the frequency to adapt to the load. You get much, much better efficiency at low current. So you'll want to find something with PFM mode. But of course, like you saw, that's not a searchable thing on Digi-Key. And that's okay. I mean, like with regulators, there are so many specific weirdnesses that you're not gonna be, this is why it's hard to search for them. This is where I would actually say to go to something like TI and, because TI make boost regulators, a lot of companies make boost regulators and use their search to find parts and then go to Digi-Key to see if they have them in stock. So for example, if you look for the step-up boost regulator section on ti.com, you'll see they're like, you want a controller, you want a converter and I want a converter. And here you can actually search, let's say I want from about 2.5 volts to maybe four volts max and I want five volts out and then maybe a quarter of an amp, 250 milliamps, you know, so it's a Wi-Fi or a Lora or something. And then I want to search by quiescent current, which they do have here, the typical quiescent current. You can find some good options. So the only problem is these, you know, I'll search for this one, which I don't, let me make a new Digi-Key thing. If you search for this part, I didn't search for this particular one, but I'm like 99% sure. Oh no, actually this one isn't stock. This one isn't stock, but the one I was searching for, this one, the 61, 322, which are great circuit chips. It pretty much has like almost, that it doesn't really have any in stock. This is a different chip I think, but for the regulator, there's like 900 in stock of this one and the other versions that they don't. So, you know, this is the challenge is like the, you're not going to be able to, when you go to the company site, like TI or Maxim or Analog, you'll get all the part options, but then when you actually search for the part on Digi-Key, they may not be in stock and TI is never going to tell you, like you can't search by what is actually available. You can only like search by prices and stuff. One of the chips that did make it in this list is the TPS 61023, which we actually have a breakout for. And this one is a fairly high current output. Another thing that you might want to look for is, they do have like other things you can search for on TI. So like light load efficiency is one thing. So if you go to, if this would be under features, you can set things that you want. Like if you're like, oh, I really want bypass mode or light load efficiency, you can see these parts. And then, you know, you can search for, like this is, you know, a six micro amp quiescent current part, that's the part I was searching for before. Yeah, so you can see, you know, what, sorry, you can see the, sorry, the quiescent current here, the switching frequency max and min, because again, usually there's multiple frequencies you can switch at and also put into PFM mode. And then you can go back to DigiKey to actually buy it and see if it's in stock. The other thing that I did is, if you do want to not go through every factory and search for like the different parts within like the TI or Maxon brands, is I did do a search where I just sorted by price and then I looked like what was in stock and what was available. And I did notice that there were a lot of these, this part which I actually kind of liked was named low power boost converter. And it was available in a fairly easy to solder package and there's a lot of them in stock which was pretty surprising. And there's even a featured product list of this. I don't know if I covered this on INFPI but the reason I thought this was interesting is it has a input to output bypass feature. So basically you can turn off the DC converter and have the input current input voltage go to the output so you don't have that, you don't have that boost converter inefficiency. You basically turn it into a linear regulator. If you have a chip that, and this is something we did cover this on INFPI, there's this idea of like, okay, if you have something with a radio because you're using IoT, but your radio you can turn off your radio and run the whole system at a lower voltage like two volts and then turn on the boost converter to put it to high voltage mode so then you can use the radio at a higher voltage and get more current output. That's a good trick to get the low power savings of having a lower voltage, lower quiescent current because it's in a pass through linear mode. And then when you ready to actually use Wi-Fi or lower Bluetooth, you kick this up to five volts or three volts or whatever you need to get that extra voltage lift, turn on your radio, do your transmission at a high voltage, high power output. And then when you're done, again, go back into a low power mode. So I thought that this was kind of neat. This also has a, let's take a little small, but it has a automatic PFMPWM operation. So that's another good sign if you want to use something with low quiescent current and also has 4.5 microamps, typical quiescent. So even though this wasn't, I was kind of looking around and seeing what chips were available. I was thinking if you're a beginner especially and it's available in an MSOP package, which it looks like it is. This would be easier to solder than a lot of the BGA packages. And it looks like it's designed for IoT. So this might be a good chip to check out, especially since they had a lot of these in stock. You can pick up the MCP16, 418 and family. There's a bunch of these. There's fixed and adjustable and I think various voltages. So yeah, check these out. I think these are pretty cool. At least can be a good option for a fairly inexpensive, it's about a dollar a piece, IoT ready, low quiescent current, auto PFMP, but PWMO DC-DC converter. So I'll try them out. If they work out for you, let me know. All right, that's great church. Yay. Where? All right, so that's the desk of Lady Aida for this week, everybody. Thank you so much for joining us. We'll have our shows during the week. Tomorrow we'll probably post some stuff up on social media more, but we got the show out and the great search. And so probably gonna be a little bit flooded and we got a little text message that says there's gonna be power outage in your area. Yeah, that's a nice thing. We got a power outage warning. Swords of fun. But we've got, well, we don't have candles, we do have neopixels and we have a solar charger. That's right. We're gonna keep it going. Not our first rodeo. Thanks everybody. And thanks for tuning in on the special Saturday edition desk of Lady Aida. Bye. Stay dry.