 And welcome to the great search. So every single week Lady Eda uses her powers of engineering to help you find the things you need on Planet Earth on digikey.com. Lady Eda, what is the great search of the week this week? Okay, this week, I'm just gonna be a big shock to you, but it's a part that's impossible to get and you need to find a drop-in replacement. Isn't that that new plant-based burger impossible part? Impossible part. Well, you know, there's this part shortage and we're in it. And it's probably gonna last a couple more years and so, you know, we're doing, we're being a lot more proactive in our purchasing department to make sure that we can get parts knowing that it could be like over a year or two until we get replacements. And so, I was going to the computer and I'll show the part that I was tasked by the purchasing department to find a replacement for. Find this. So the AP3429, this is a buck converter to really lovely buck converter chip and we make a little breakout for it. The breakout has the chip in the middle and the inductor and some passives. The inductor and the passives are really easy to get but that chip, you know, it's a very specific chip. So the good news is that we do have some in stock. We have some that'll last us, you know, maybe like three or four months. But we no longer like, you know, we used to purchase like 12 weeks before we needed a part because 12 weeks is like forever. But now we're purchasing like a year in advance basically. So, you know, when you go to Digikey and this is the part I would get the AP3429, standard lead time is 52 weeks. And if I type in like, okay, when is the next estimated ship date? It's in 2024. It's two years from now. So it's 104 weeks lead time. That's long enough that, you know, yes, we'll book some, but I don't expect to be able to get some. So let's find a suitable replacement. Now, because the lead time is so long, sometimes if the lead time is like, you know, four or five months, it's like, well, I think to find something today to kind of like keep production going, but this is so far ahead that I'm actually gonna look for some parts that are similar in functionality, even if they might not be pin compatible because it's worth it to do a board re-spin. I'm like, basically I'm waiting more than like two or three months. I'll just spin the board over, get a new stencil. It's not a big deal, but I wanna keep the overall functionality the same. So as usual, the first place I go when I look for replacements I go to the product attributes and manufacturer, I don't care who it comes from, package, I don't really care. I do want an active step down and I want it to be a positive buck. Now I actually don't need it to be adjustable. Though this one happens to be adjustable and I have two resistors that set it to 3.3 volts out, but I'm actually totally cool if I get something that's not adjustable, it's fixed output 3.3 volts. So I'm not gonna check this box. I'm not gonna check the number of outputs and I'll tell you why later. I'm not gonna check the voltage in out or the current or the frequency switching. I'm going to check off for a synchronous rectifier and I am going to check off for surface mount. Normally I would check off the package and device as well because it's like, okay, I want like a, you know, a SOT 23 only. And there were a bunch of SOT 235 parts that I could get but somewhere not immediately in stock. And like, you know, it's a bit of a gambling game because it's like, well, what if I can get a similar part in three months or I can get a part right now, but it's got a different package. So it's like, you gotta balance what you think you can get and whether it's worth your time to do redesigns. So let's view similar. And the reason I didn't pick one on the output is because there's actually a couple that have one or two outputs and there's also that dash. And I wanted to make sure that I did end up, you know, when I ended up looking because I was doing the search earlier this week, I did find a good part under like the dash number of outputs. So let's go down. Okay, so the most important thing for this board is that it has a two peak, sorry, two amp switch inside. It's nice. You don't need an external MOSFET. It's got the switch inside of it. It's also got, you know, the diode, you know, the two, basically the two switching switches, FETs inside. And it's got a two amp limit, which is really nice. So let's make sure that we get something that's close to two amps. So let's look at the current output. This isn't necessarily the switch current, but it's a really good approximation of it. The part that I was referencing before had two amps. For a book converter, pretty much the current output is the same as the switch current. That's not true for boost converters, by the way. But it is true for buck converters because they're reducing the voltage. And so like the current is reduced, not increased. But when you increase the voltage, you have to increase the incoming current. When you're reducing the voltage, you're reducing the incoming current. So current output. So we definitely want it to be, let's go for at least 1.5 amps up to like four amps. I think that's reasonable. That cuts it down a lot to 2,000 remaining options. Now we kind of see like, there's a couple of different packages here. I do want something that's about the same size, even if it's not the exact same package. Like there's, I could get it, there could be a DSBGA package, there could be a QFN, but I want it to be small and about the same size. So I don't want a lot of pins. I wanna keep it simple. So I'm gonna go with like, you know, here's all the different variations, but I'm gonna go with like, you know, anything that's like a SOT 25, whatever, the, you know, basically a, you know, very similar to package to this, but I'm okay with six or eight pins. And then I'm okay with, well, let me start with that, you know, and I can always get maybe, you know, I can add a DFNs or something here. Okay, I don't want, so I see way too big. So let's look at those. Okay, cool. So let's see what we got down here. So we do start to see some parts that are kind of similar. The AP, you know, this is very similar, you know, when you have AP 3429 from Diode's Inc, they make a lot of other similar but converters. This one has actually quite nice as a three amp switch built in synchronous, you know, close to one megahertz. And it's, this is a T-SOT 26. This is a six pin, not a five pin. So it's not pin compatible. So let's first quickly look for like, let's find one that's definitely like, you know, pin compatible. So that would be a SOT 23.5 or maybe an SC 74. I think that's the same thing. I can never remember. And when we do that, if we're like, okay, it needs to be pin compatible, we do get a couple options. This one was one good one and 1.5 amp current. I think this package will fit. I think this is very similar to the SOT 23.5. You know, high frequency 1.5 megahertz. So that was a good one. And then of course, this one, let's sort by stock. Let's see what's available now. Not a lot. Let's instead look at ones that have two amp current. Cause like, you know, we reduced that requirement but let's go back and see if there's anything. So the, I mean, there's not a lot of good options. So it turns out that this one, the TLV 62569, I did look at this one. I'm trying to remember one of these that actually had the ship date. Or maybe not. This was the closest alternative. Okay, so this one had a ship date of like only a year from now. So, you know, that's one alternative. You might be able to get this faster if I really do need something that's pin compatible. But like I said, I'm actually kind of willing. So the part that was I was willing to get is a TLV 62569. So that's pin compatible from TI coming pretty quickly. But if I don't care about the mounting type, like if it doesn't need to be pin compatible, what I'll do is I will X out, like cause these are all the things that I, you know, I searched by, that's why I'm not mounting type package case. You know, I made this as a requirement. If I remove that as a search element, I get back to like all my options. And then I go back to maybe only the 60FNs and the SOT 23s. Let me see if I can find the part. So in the end, what I thought was, you know, if I'm willing to go with a slightly different package, hold on, I still have my current limitation, right? Did I, yeah. And I went with what was available. I think it was, oh, I don't remember what it was. I wanted something that was a SOT 236 because that would be the easiest for me to adapt and I could not come up. But it was in this family, hold on. It was package case output configuration. I know it was this part, but I'm trying to remember how I found this part. Oh, cause it was two, it was two and a half amps. Sorry about that. Oh, it's too picky. When I removed the pickiness, and I said it doesn't have to be just two amps, it can be two amps or above. So this is the thing, this is why the search is actually really hard. You wanna be specific, but there are a lot of times where it's okay if it's over and there's some times when it's better when it's under and you just have to kind of like be careful. Like one, as you've seen, don't be too picky. I was like, oh, I only want exactly two amps, but then that search constrained and I didn't actually find something that was a really good option. When we have parts of plenty, we'll rename the show Lady Eight as picky parts pick, but for now it's the great search. So don't be so picky. That would have been a really good one, picky parts pick. So this is what, sorry, this is the one I found. You can't be picky right now because there's not enough parts. There's not enough parts, but this part has almost 50,000 pieces in stock. So the only thing that's, and it's a very good price too. It's like 20 cents in quantity, adjustable outputs. What's nice is actually, this has a really wide input range, 4.2 volts to 18 volts and a wide output range of 0.8 to seven volts, two and a half amps output, even faster frequencies. In essence, this is actually a better chip than the AP. 3429, the only thing is it's got an extra pin because it has a little, I think it has a little booster inside and you have to add a capacitor. So, hold on, there's no data sheet here, but let me search for your data sheet. Okay, so instead of five pins, you've got six pins and the extra pin, you've got the ground and input, the switch and the feedback, the enable and then BST, which is your boost pin. And yeah, this is used to boost the internal, there's a little mini switch cap I think that is used to power the internal FET switch. So, you can turn it on and off very quickly. So you have to add another capacitor, which is a very small capacitor. It can be like a 603 or 402. It's not current, certainly there's not current because it's capacitively coupled. So the rest of the components are the same. So basically, if it really is two years until I can get the AP3429, what I'll probably do is I'll redesign this board and I'll scooch this part over a little bit to add the capacitor and they'll swap this to be a six pin part. I'll have to revise the stencil, but the functionality is gonna be the same because it's only a better component and then I'll just update the description to say, hey, we can't get this part because it's like 2024. Who knows what's gonna happen on this planet in two years? It certainly couldn't have guessed what would happen back in 2018, what would happen in 2020. Yeah, it's not a good idea to try to guess what's gonna go on. I'm not even getting there. And so that's what I would do. So, I came up with a couple of options here. One I could probably get within one year and then one that's kind of a better option. Considering I can get 50,000 of these, I'm probably gonna start the revision now. I know it's really early, but in six months I'm gonna run out of that part. I wanna have something ready ahead of time, which is another thing I would recommend because I think when this part started, I think we were all like, oh, well, you know, they'll come back eventually, right? Like it's gonna end. I don't know that that's true anymore. And so what I would recommend is, look now what parts you won't be able to get for a year. Like get all your parts for a year and if you can't, do the redesign now. Don't wait till later because I just got like swept up. You know, I basically got blindsided by a part that I'll be honest, I was promising, oh, no, you're gonna get it. You're gonna get 10,000 pieces, you're gonna get it, you're gonna get it. And then they just like basically told us last week, like you're never gonna get it. And it's not like that song from like the 90s, never gonna get it, never gonna get it. And there was, I think that was right. Yeah. Okay, so it's like that, but with STMP-811's and CP-2104's. Anyway, my great search part, the AP62250, it's actually a pretty sweet buck converter. If you need like a 20-cent buck converter, this one is quite nice, it'll do the job. And that's a great search.