 The Great Search brought to you by DigiKey and Ada Fruit. Thank you, DigiKey. Every single week, Lady Ada uses her Power of Engineer to help you guess you find things on digikey.com. Lady Ada, what is the Great Search of this week? Okay, this week, I'm replacing this toy. Let's go to the overhead and I'll show the toy. We designed this PCB to have a different microcontroller. Yeah. And I want- By the way, that's the outside. That's the outside. And so I'm gonna, you know, I know I'm gonna use a microcontroller or something and all the microcontrollers I'm thinking of using, basically none of them have DACs or they don't have DACs with DMA in them. And so instead of fighting an 8-bit DAC on ESP32, I was going to use I2S as an audio output because I wanted to have fairly good quality audio and I wanted to drive the speaker directly. And so, you know, historically, I've used the Max 98357, which is a very, very popular and really wonderful I2S amplifier that it has, you know, only one little weird detail about if you change the clock rate, sometimes it does a little bit of a pop on Raspberry Pi Linux, but otherwise it's a very good I2S amplifier. And I wanted to, I was gonna think of using that, but I thought maybe I would take a look and see if there's any other good options. So let's look at the computer. So this is, again, the chip that I tend to use and it's extremely popular in DigiQ. You can see there's 50,000 in stock almost, you know, 43,000 here and then another 6,500 available at the factory. So, you know, this is a great I2S amplifier chip. And one of the nice things about this in addition is it doesn't have an M clock input. So it's really good if you wanna save one pin. But I also, you know, I've used this chip for, you know, like almost like a decade, it feels like. So I wanted to see if there's any other good options. Not saying that this is an option I'm gonna go with, but it's always good to take a look at some other possibilities. So I'm gonna look in audio amplifiers and I want to look at active surface mount sensors. And I'll tell you one thing that is interesting, which is, you know, you can search for this. The amplifiers that are, I'm gonna say normally stocking and not look at marketplace just for now. One interesting thing is if you look at the amplifiers, for example, this IS-31, the first one, this one is a analog input one, not a digital input one. So in this topic, the audio amplifiers, there's mixed analog input and digital input. And so, you know, the challenge is, is that you want to narrow down as much as you can, but then you will have to search through the data sheets to find some good options. That said, there's a couple of things you can do to simplify things. Like for example, you know, nothing that is eight pins is going to be digital input. Like this is a, like a microphone, capsule input. Nothing with eight pins is going to be digital because if you're gonna do I2S, you need M clock, B clock, LR clock, and data. So that's four. And then you need power and ground. And usually you have more than one power and one ground. And you need the two speaker outputs. And now this is eight, but that's assuming no other inputs. And if you have I2S digital, you almost always have I squared C input, or you have a mute or a shutdown pin. Basically you don't have eight pins. It's very rare to have, I bet you've never seen an eight pin I2S input chip other than like the C, S4434. It's, and that's not a speaker driver. So what I decided to do to kind of simplify this is looking at, first off, I can filter on the power. So I have to drive this quarter watt eight ohm amplifier. So the first thing I did is I just filtered out anything that was less than 300 milliwatts eight ohms. And then no speaker amplifier really is gonna be for the pricing I'm willing to spend, which is, I'm not gonna spend more than a couple of dollars is gonna be more than 10 watts. So I can filter out and just look at that. Second, I don't want either like one channel mono or stereo. I don't want just headphones. I mean, I don't mind if it has also headphone output, I guess, so that's fine. Although, I think two channel stereo is gonna always be more expensive. And then of course you definitely are not gonna fit that into an eight pin chip. Next, I can do power supply, but I think I'm gonna leave that for last. Okay, and then there is package device. So like I said, I think that I'm not gonna look at anything with eight pins. It needs to be nine pins or more. And I also again, do not like BGAs in my process. It's very time consuming to debug them and to place them. And so I'm going to search only and I don't want anything that's 48 pins. I'm gonna go to 32 pins maximum. And then I kind of selected out all the BGAs. There's a lot of BGA amplifiers. I found out while doing this. I also don't think I want 20 SOIC. It's gonna be way too big. Get rid of these BGAs, get rid of this BGA. More BGA removal. 60 SOIC is, you know, maybe that'll fit. That'll be fine. Okay, so let's look at these. Also our internet's much faster today. We're just gonna make sure. Okay, so and then for pricing, let's look at pricing for 500 pieces or more. And so there are features like I2S, I2C and those definitely will be digital. But I'll say that there are some that didn't have I2S in the list that were I2S. So just something to watch out for. Another thing is voltage. I want something that will run off of, I think 3.3 volts. So I'm going to narrow the search here and then sometimes I don't have the power supply. So I'm gonna move anything that needs eight volts because I don't have eight volts available. Okay, so now we've got a couple options. And I'll look at the mono ones later. But like I said, you know, these are mixed together. So this one, for example, is analog inputs and then so are the PAM series, et cetera. Let's look at maybe mono instead of looking at the stereo. Let's look at the only mono. Okay, let's see what we got. So down here, let's see, the max 98 is down here. Yeah, so the max 98 series is down here. Now let me look at multiple, let's show. Oh, by the way, I've never shown this. You can have a display like many more than just 25 at a time. So the max 98, 358 and 57 are down here. So, you know, this is ones that have a lot of stock in them. So I actually went through and like I kind of searched each one to see which ones were analog and digital and that just meant going through the data sheets. But it was worth it because I did find one that had that the pricing was a little bit less. It's about $1.50 in quantity. The TFA 9879. And this is actually a pretty nice amplifier that was available. So let's look at that. It has I2S input. So, you know, I immediately like honed in on like, okay, it's got, you know, an I2S input bus, PCM, you know, 3.3 volt logic. It runs from 2.5 to 5.5 volts. So it's great. You know, I'm gonna have to have a little booster on my design because it runs off two AA's. So I'll have to run it at 3.3 volts anyways. So this will be fine. It also needs a 1.8 volts digital supply, but that's fine. That's not for the amplifier. That's for the internal logic. And another kind of neat thing is that there is a I2C interface, which is a little bit more complicated, but it does mean that it has, let's find it. It's got some cool I2C stuff that you can do. It's got a built in like DSP with digital volume control, which I thought was really nice because oftentimes in your MP3 player, like it might be MP3 playback on your microcontroller, you don't have a volume control setting. Like that is a separate, you know, thing that usually is handled as a post processor. And most MP3 decoders just take whatever digital input and they just like kind of blast it out into the I2S data. And then, you know, sometimes you can do a multiply, but sometimes, you know, you may not have as much time to go through and multiply out every data sample before it gets shipped out. So having the DSP here on the MLog output means that like you could remotely or with a potentiometer that's not in the signal path, use that to tweak the audio volume. And there's also an equalizer and bass and treble control. So I thought that was, you know, like zero crossing volume control, power limiter, basically a very nice, you know, I squared C control interface for this very low-cost amplifier that's also Class D. So you're gonna get good performance, it's good for like, I mean, what's funny is it says like, good for portable gaming and MP3 players. So while, you know, I may still use the, you know, Max 98, 350, 375, I tend to use. And I'm very interested in this part. I think it's a not often used. I've never seen this used in other people's designs, whereas the Max 98 I've seen a lot. But this is definitely my pick of the week for interesting chip. I'm probably gonna make a breakout for this because I like that parametric controller, I squared C, I think that would be really useful when you can't do that on your microcontroller, when you're doing your audio playback. And that's a great search. Where?