 Great search brought to you by digikey and a to fruit every single week. Lady It uses her power of engineering to help you find things on digikey.com lady What is a great search of the week this week? Okay, so this week? It's actually a lesson I learned about finding alternative parts for obsolete components. We just always read the PCN Even though you might think like oh you take the suggestion of what the alternative component is It's always good to read the PCN. Sometimes there's like it will hints inside of it So this week one of the parts that I had to find alternative for is This SPI F-RAM chip, so let's go to the computer and I will Shut off. Okay, so SPI F-RAM is like I think one of the underrated chip technologies out there because we every week we have somebody who's like You know leaving like last week somebody's like I really need a you know to overclock my RP2040 or my you know sami 51 because I'm trying to stream data from an accelerometer to an SD card and I'm running into it. I'm not able to stream the data. I need to be faster and What they don't realize is that it's there's it's not frequency-based. It's not how fast the processor is What you're dealing with is? You're writing date to to Nor flash Like SPI flash or on a micro SD card and when you do that you have to erase blocks and you have to write blocks And that can take hundreds of milliseconds And so, you know, you can stream data to SD cards by like Being really careful with like internal memory management and then you buffer the data and you write the data In fact a lot of times when you look at how digital cameras work They'll have a big chunk of SRAM when you take a photo It has to stream the data to the SRAM and then it writes that data to the SD card because again the SD card can take hundreds of milliseconds to erase and write Flash blocks now you can like pre erase the blocks and there's like stuff you can do but basically if you're trying to stream data to Non-volatile storage e-pram and flash memory have this issue of like, you know block erase block writing taking a long time Whereas F-RAM does not have this issue F-RAM is instantaneous. It basically is the speed of SRAM With the non-volatility of flash memory, but it's a little bit more expensive. So like this is, you know 256 kilobytes But you know, it has the price cost of get multiple times what it would be if it was Nor flash, but that's the trade-off, right? You know, you you want to have very fast data use this so You know, I do recommend people who especially when they're doing like data logging in like model rockets or UAVs anywhere where there's a really high chance of damage like you're you want to write the data and you want to store it But there's also a chance that thing could explode and like you want to be able to recover the data or like power gets cut very quickly or for extreme low power usage because again, you don't have to you don't have to have that power spike to erase blocks or write blocks and Unlike SRAM, you don't have to provide power constantly you can cut the power after you've written the data So it definitely has a really cool use case, but anyways this chip that we use is No longer available. It's obsolete so You know, this is the part that we were purchasing 4 megabit SPI 40 megahertz and 8 SOP Unavailable, you know, again, this is chip shortage a lot of things are going obsolete Older lines are getting dropped and so you know, you go down to substitutes and There is a substitute and it is in stock and I you know, I may still use this part but what's interesting is well first off is a little bit more expensive and also have to Get a couple samples and make sure that not only is it pin compatible but also that The commands used to like read and write data like there is a standard Calgenic for SPI data, but there's often extensions to it. Not every company uses the same extensions You know, we've dealt with this in circuit Python. Basically, you should always look at the date You know get the chip after looking at the data sheet But then I was like, you know what, you know before I book this order Let's look at the PCN the Product change notification from Fujitsu and you can see this was the last time by you know We we bought some at the end, but we're gonna run out soon so the chip that we're using is this one is is affected and Basically, you have to read what's going on and basically it sounds like There's a company that was doing the packaging that they would actually take the die and they would put it into an SOIC chip and then bomb the wires and Like they're basically shutting down the SOP production And So they're gonna change That perhaps that you know, they're gonna change from that Specific packaging manufacturing to a different one and what's interesting is that I've seen this before in other companies and they usually don't change the part number They just change the packaging and they're like, hey, you know, whatever. Sorry like you It's like a little bit thinner a little bit wider like give the deal But in this case, they actually did change the part number. So what was this one is now? this instead of JNE it's BCE and Just for kicks. I was like, well, you know, like is that available and it turns out that it is available to order No, it's not immediately available You know, it's going to basically be in stock in five months So I'm going to probably like get samples of that Cypress chip But what's interesting is this wasn't recommended as an alternative for the chip that went obsolete so just like be aware like Sometimes what's obsolete is the packaging not the chip itself the silicon itself is available But it's under a different package But you wouldn't know that unless you read the PCN and I know these PCNs are a little bit drier sometimes But I really do recommend going to them because sometimes they have Useful information like I at first I was like is this is only available in like USAN or TDFN No, it's actually still SOIC. It's just from a different packaging company. So Given that I feel pretty confident that this will be a drop-in replacement. What I can do is, you know order You know 500 or 1000 pieces of this They'll show up in March hopefully and then meanwhile I can also go back to that Cypress chip That was recommended Try this because it's available in stock and I might like have it as an alternative Just make sure that the firmware works with both Use this it's a little bit more expensive, but it'll like get me to March and then in March I can get that new old You know packaging style and swap back and forth. So, you know, it's a chip shortage We're kind of coming out of it, but they're still like a little bit of rockiness on the way out So staying flexible with different components swapping back and forth is going to What basically gets you through the next six months. I think of just dealing with Minimal shortages. I mean the lead time Five months is is a lot, but look, it's not two years. You know, I'm not seeing 99-week lead times anymore. So I'm gonna pick up some of these and try this out. This is my great search pick