 Every single week Lady Eda does a great search brought to you by digikey. Thank you digikey and Lady Eda uses her Engineering skills for good and she's had to find things on digikey.com Lady Eda. What is this week's great search? Okay? So this was great search. I just talked about how I'm working on Keyboard design so let's go to the overhead real fast because we're gonna Split this off. It's good for me. We show this so this is a keyboard PCB people who make mechanical keyboards Each key has an RGB LED underneath it She looks like that and the RGB LEDs here are everlong RGB LEDs are not digital not smart You know neopixels dot stars. These are plain, you know one anode or one cathode and then RGB That's four pans total and they're driven by this chip here, which is the ISS ISS II S 31 FL 37 41 Which is a 351 39 by 9? LED matrix scanner driver PW driver so that this this will be able to control each of these LEDs And you can have up to 112 or so LEDs Analog LEDs controlled by this matrix driver, so you're probably wondering and here's here's the dev board that I've got for this chip the IS 31 FL IS 31 FL 37 41 That chip again here. This is a STM. Sorry this chip over here. This is a little STM helper driver So this chip, you know is designed to drive a large LED large, you know 120 LEDs With full 8-bit PWM per Channel, okay So folks who know Adafruit are probably like why use analog LEDs when you can just get neopixels You don't need a driver chip. You don't need to route all the lines. You don't need all the night You just send data over one pin and you're done well, let's go to the computer and Let's do some math So the reason why we might want to use here here's just showing you the the matrix driver and how it works Why would you use a chip that costs $2 and then and I'll get LEDs instead of just neopixel LEDs altogether And there's nothing wrong with using neopixels go for it. They're totally cool However, neopixels cost, you know about ten cents apiece and if you do the math, let's say you have you know a hundred Keys on your keyboard and you're doing them with neopixels. So times ten cents apiece That's like the best price if you're getting, you know wheels and wheels of them. You're gonna get as low as 10 cents You're gonna spend $10 just on the LEDs, which isn't bad, right? If you have a very nice keyboard, you want one LED per key. However, once you get to these large quantities The price of analog LEDs, you know, you might be able to make it up, but even though you have an external driver so if you have 100 LEDs and Your analog LEDs cost four cents apiece, which will show some of them are even even less But let's say, you know large quantities four cents. Okay, four dollars, you know That's still a bit because you have to add in the two dollar Driver, but you're still ahead by four bucks. And if you're making a lot of these A lot of this product and you have a lot of LEDs You can see how once you get to like about 64 LEDs ish It starts to turn into, you know, you might be better off getting a driver chip Especially you can get all the LEDs driven by one chip, but you get one chip. It's two bucks. Yes, that's your Your setup cost within each individual LED is only two three four five cents Instead of 10 cents and and yeah for something that only has five LEDs I always go with dot stars and neopixels because they're so cheap and so easy But when I'm thinking about a keyboard design or something with a lot of LEDs on it I'm gonna use a driver like this. So that said we need to find a low-cost Analog RGB SMD LED, which is what this great search is all about. Let's find These little friends here RGB, right? And here's the thing There are basically Three kinds of RGB LEDs. You can have four pin common anode Four pin common cathode or six pin or each LED is individual These days I don't see as many RGB We do stock, you know RGB 50 50 Plain LEDs here, and you'll see that these do have Six pins on them because it's R G and B. There's three individual LEDs However, I don't see these in the smaller sizes. So just be aware Tends to be a common anode common cathode and this is kind of what I see more of these days In this case because of the way this is designed You know common anode is more popular and this is showing a common anode configuration But you could use it with common cathode as well. That said we'll probably look for a common anode design which means that See I think we have a couple common anode. Yeah, we have you know common anode LEDs You know there's a gigantic one, of course, but you'll see there's one positive There's four pads one positive one red minus one green minus one bead minus So you you can usually NPN transistors are a little stronger than you know P channel P NPN or PNP type Transistors, and that's why Common anodes a little bit Better a little bit better Insignificantly really but it is a little better So this is the driver chip again that we're using in case you're interested They are they're gonna have some in stocks shortly So let's look for RGB LED So we're gonna just search for RGB LED and don't forget there is the addressable LEDs These are the neopixels and dot stars and stuff good things. Here's like our favorite the jewel but We don't want that we want Discrete we want individual leds non-addressable analog Okay, so I told you about the configuration you can get Even we can get Common anode common cathode Independence or standard what standard I don't know but we're gonna actually ignore that for now. Let's just start with we just want active and Let's go with normally stocking because right now there's a lot of stuff that's not in stock so You know a lot of times I'm like I only want to get stuff in stock if I'm getting a replacement part or a one-off but because stocks are of Components are just so volatile right now. I'd rather see everything and then check what the lead times are it could be reasonable Usually LEDs are not I don't think it either are strongly affected by the silicon shortage because they're not complicated Transistor based Silicon made by TSMC. They're they're you know made more locally. They're made by smaller fabs. Okay So next question is do we want surface mount bottom entry right angle through hole? Well, I definitely don't want through hole In the future in case I don't want right angle or bottom entry although I might eventually look for a bottom entry one just because I want it to You know poke through the PCB underneath the each switch, so I'm gonna go with your surface mount So already only have like, you know 200 options available So the next thing is is that like everything else is kind of I don't really care again coming out of common cathode doesn't matter You know cut tape or tape and real I mean it's good I'm gonna eventually person keep tape and real because I'm gonna be using so many of these I do want to see the prices at a very large quantity. So about 50,000 is what I'm gonna put in for the prices and Then so what I did for fun, which was which is you know, sometimes my trick is I I sort downward by quantity So for example this LED it's a very small LED, but you can see it's got four pads This is a believe a common anode and there's two million in stock, which is which is pretty cool. This Happens to be a one by one Sized one millimeter by one millimeter LED, which is a little bit small. I want something a tiny bit bigger So I will show what the one millimeters are used for so if we go to the overhead real fast. So this is a Ultra I mean it looks like it looks like it's a texture, but it's actually your individual LEDs. These are One millimeter by one millimeter. I think LED is here. So they're used in LED panels Also, sometimes I see them on deaf boards as like micro indicators. They're super cute But this is a little bit too small for me. I want something a little bit bigger and a little bit brighter So let's go back to the Computer so for dimensions You know, I think I'm gonna go at least 1.4 squared 8 by 8 it's kind of big, but let's just do that. Okay, so we got rid of the ultra tiny ones and So this one is kind of need this actually a reverse amount one which I thought was kind of interesting but I actually I think I'm going to start with You know this size which you can see there's a couple options that are very similar in size I think this is one point This is three sorry this is One point six by one point six, which is you know a little you know, it's it's a bit bigger But it looks like there's a couple different standard sizes for this and in fact if you look at the Go here if we look at the Overhead so this grid this matrix grid these are this is that size and I can even tell by looking at it It's the same package. So this LED is similar to What was used on the eval board? This doesn't zoom in right Okay, so yeah, you can see these are these are a little rectangular. Okay, so let's go back to the computer So I ended up Decided to go with this and there's a couple things that I liked about this LED One it's nice and big looks like I can even hand solder at the other one Obviously it's picking place only this one I like how you can you I could I could debug, you know solder this pretty easily with a fine tip it has common anode connectivity and The LED milcandela is a really high so 630 Milcandela for each one is I zoom too much 630 milcandela each is is nice and bright. It means that even when I PWMing like it'll look really good You can do global current control so I can have a lot less current and still get a very bright light also sounds like it, you know, it says Mixed white. I wonder if this is Balanced so that when all the LEDs are on it kind of looks It kind of looks white and looks like these are bend as well. So This is a pretty nice LED and again. It's like five cents in quantity. So a good If I'm looking at making something with 60 LEDs like a 60% keyboard Adding these up and then including the driver chip could end up being a really Good option another nice thing about these LED drivers is you don't write the entire Number of LEDs at once and also happens over I squirts your SPI so you can use DNA and You can change individual LEDs You don't have to write the whole thing out which can speed up the system quite a bit because you're just you're just writing out Like set LED to X, you know or set this other LED to Y You don't have to write out the entire LED strip like you do with neopixels and dot stars So pretty cool. I like that. There's a couple options in this size as well, and there's 12,000 stocks So I'm digging it. This is the B38 G3 RGB from Harvard Tech. There's a lot of LED makers So it looks like a jelly bean part and I'm going to pick some of these up And then we'll probably see these in a couple weeks when I design them into my keyboard controller for exciting All right, that's a great church