 Great search brought to you by did you key and a fruit every single week lady ad uses her powers of engineering to help you find Things on did you keep site this week? We're flip-flopping. We're flipping and flopping So what is the flip? What's a flip and flop it? So I don't know the technical word for this technique But I've seen it and it tends to happen around park shortage times like I've seen this is one of those like beasts that Evolves when there's park shortages like the McRib like the McRib so this is this is designed for a Can bus Adapter for the feather wings. So this here is the MCP 25 1 5 in SOIC and Here is the transceiver, which is I think Part number I think it's the MCP 24 25 42 so A tradition originally I wanted to use this the MCP 25 625 however This part is completely dawn off the face of the earth. I'm never gonna find it for like another year or two And so I thought let's let's go back to a design that includes the standalone can controller to SPI interface very common and still available plus a Can FD transceiver and between the two of these like you've got your your can design The only issue is is that now I'm a little I'm a little burnt right because it's like I waited too long to order parts for my Other design which I kind of preferred. I thought it was a little superior But I didn't want to wait till 2023 to get the board out and I don't know when I'm gonna get chips So I don't want to wait. I want to release it But I'm a little concerned that I'm not going to be able to get You know the most common package for this chip is SOIC But I may not be able to get SOIC now since this board is large enough I decided to do a flip-flop design what that means is I have the SOIC package out here And then inside the SOIC package I put the QFN package and then Over here likewise if you look you can see the SOIC package Large here and then inside I have a TDFN package So there's two packages and I can flip flop between the two I can I can click in place whichever one I want There is a risk to this you're gonna have solder, you know if you unless you decide to have separate stencils If you have one stencil that stencils gonna be cut you're gonna have solder underneath the the chips However, SOICs they're not like super flush against the PCB and so like I don't mind doing it with SOICs I wouldn't necessarily do it with a T-SOP maybe But SOICs are kind of big and they can float a little bit higher. There's there's a little bit more space So is this you know the best engineering practice? Yeah, probably not. However Desperate times bring desperate measures. So let's go Did you key and find which packages are available for the transceiver and the Can controller and so we can pick What we're going to you know, how did I pick what we would I ended up using? Sounds cool. So oh by the way, if anyone's wondering where I took the name flip-flop from it's from flip-flop hub Not flip-flops like you know latches and stuff There's I was building like a first time I used this I was like in the middle of building a single speed No, it's like oh you can use one or the other. It's like a flip-flop hub. Okay. I don't know made sense of the time Did you handbook is here by the way you can pick that up? So let's start with the MCP 2515. This is the can controller and So traditionally again The SOIC is what you would normally pick up and you can see here This is available in four packages, which is good, right? It's like It's a little counter-intuitive, but sometimes there's multiple packages again If you're using the flip-flop design, you're maybe more likely to be able to get something that'll fit So let's look let's skip the dip and Go to SOIC T stop and QFN now we're desperate So we don't care what the packaging is normally I would say get cut tape or tape in real But I'll take tube because I just I need chips So what it looks like is the QFN is in stock now So it means I could probably launch with the QFN, but you'll know it's more expensive than the SOIC like you get the SOIC for 191 or 209 and the MCP 2515 in QFN is you know, 224 So it's sorry. It's a little bit more expensive than the SOIC version but again, what's really expensive not having any parts so What I did do just got a curiosity is I added some to my cart to see the lead time again It's not promise But it gives you a sense. So I basically said like okay. I'm gonna if I bought 1000 of these You know, they think they're gonna get them You know in in August maybe September So what I could do is launch this product now using the QFN and then when the SOIC comes into stock You know, I can order those now And then when they ship, you know, I can decide, okay Then I'll switch over to the SOIC and just we program the pick-and-place and that's not a big deal It takes only like 10-20 minutes So the other question is why did I yeah, so that's why I picked The SOIC and the QFN. There's also a TSOP version, but Honestly because it was out of stock and it was as expensive as the QFN and I Kind of figured it would be like it was like if I was gonna pick two things I was like well I think I'm gonna pick the QFN and the SOIC like it was a little bit of a gut thing But it's also like the QFN is currently in stock and the SOIC is the most popular package So like that's the that's the the two I picked so the next part was the mcp mcp 2 4 2 5 4d and also by the way check the data sheets because it'll also have the packages So you can see here there's actually two versions of this there's the 2 5 4 2 and 2 5 4 4 I want the 2 5 4 2 which allows 3 volt logic and 5 volt trans transceiver volt. Yeah, it's a convert 3.3 volt logic from the Can transceiver sorry for the can converter The transceiver will let you take 3 volts in and send 3 volts out But convert it to plus or minus 5 volts on the outside, which is more people like that because it can go a little farther Anyway, so let's check out the 2 5 4 2 And see what packages are available. So Again, we'll go to transceivers And there are three packages available now unlike the um a little bit like the mcp 2 5 1 5 You can put an so I see you can kind of put anything underneath but Two of these packages are incompatible with each other like you can't mix them Which is a little sad. So let's look at the bottom and I'll show you So the so I see is a standard large so I see which is, you know classic So there's the 8 td f n which is 2 by 3 millimeters and this has a Uh ground pad underneath it and that means of course you can't put anything Underneath it because that ground pad would short to whatever and you do really need that placement pad When you do your td f ns so I have to choose the so I see And either the 2 by 3 td f n or the 3 by 3 d f n which are Almost the same thing. I'm kind of like a little confused why they have two Nearly identical smt packages like Yeah, like an s o i c t sop and d f n I can understand but t d f n and d f n I don't know maybe some customer really wanted it Um, so s o i c so let's see if any of these are in stock I don't know they're in stock Um, they're not in stock here uh But you can Uh, that's weird. Okay. I thought they were in stock, but they're not so the s o i c is um This one the dash e s n And let's see when You might have this in stock So right so these are going to be in stock maybe in about a month So that's a good choice to pick for um the package and then the other package I ended up with the uh t d f n and let's try this again at car and this one also Some of them are going to come in in 2021 The rest in 2022. I don't know we'll find out if if the the dates get pulled in a little bit Um another thing is when you're doing the flip flop design um If you're doing like often the pins line up quite nicely So like a t-stop or a q f n you can see how like all the lines kind of go out spidery very easily However, um, the only packages I could really could fit under the s o i c without having um See the v is on The only package I could really fit under this s o i c and have it uh Route out to get to the remaining pads without having v as everywhere was the 2 by 3 t d f n if you have Some like really small If you have some really small chips Sometimes over the really wide s o i c you can sometimes put it Between the pads and like have it snake out um, however in this case It really won't fit so the only way to do it is sort of to do it like right angle in this way And then try to get like all the signals out through the side, which is it's all right okay, so This is my guess. I think it's gonna work out. I think I'm able to get the s o i c version of this I think for this chip i'm going to end up mixing and matching between the two But it's free to add a flip flop package onto your pcb design So you might as well do it right like it doesn't cost anything the pcb Once you finish and tape out the pcb, you're done So I'm going to be doing this for like the next year probably Um, like until I can get chips again because I don't know when that's going to be So you're going to see a lot of designs that I do that have like s o i c and then a q f n or like A t-sop and like a t d f n underneath it Whenever there's more than one package I used to just go with like the smallest package or the cheapest package was the most convenient one But that time's kind of not happening right now So, um, you're going to see a bunch of these including one of the designs that I finished Last week for an e-prom breakout e-proms are available in uh t-sop or s o i c and so When I did the layout for the design I added both And that's the great search. All right. Good luck everybody. Someone has some good, uh comments here Yeah, not a question or anything. They just said so much fun here early 90s gpo ram shortages at ati boards laid out for s ran dram and vram and through whole pl cc s o i c if it arrived it got soldered. Absolutely. I mean this is Welcome back. This is not the first time it's happened And I was actually wondering like when there was the shortage in 2009 right after a recession There's always like this like terrible shortage and I remember that the arduino smd came out because you couldn't get Yeah, you couldn't get dip chips So there was a special version Of the arduino uno that came out that had an smd chip because and now they actually I think reverted back to having the dip chip But at the time You couldn't and you can kind of tell that they sort of just deleted the dip And and plugged in the qfn I remember people thought like this is the end of arduino because they just want like a permanently soldered chip in Yeah, um No, there's other stuff that you should worry about arduino. I have an article coming out this week But that here it is. This is the one I was thinking of that wasn't it that ain't it This was clever and I'm glad they did it. So this hold on. Let me show the image Because I thought this this is interesting Can I view an image? Can I view an image? Okay, so this image You can see here. It's a flip flop design. Yeah, they have a qfp And a qfn, but you see it routes very nicely so they they probably started with um Yeah, the dip was gone. So like, okay, we know like I didn't design this. I'm just guessing start with the dip they pulled the dip out put the um qfn in because Dips you actually can they're so thin you actually can't really put any chips in between And then they quickly were like, uh, oh, we can't even get qfn so we can get qfps Okay, big package qfp now if anyone ever learns what the official name for this technique is I'd like to know because I call it flip flopping, but I don't know Sounds like dual sockets It's not it's not dual sourceable Well, it can be even one than two All right, and that and that's a great search. Thank you everybody