 The Great Search brought to you by Digikey and Adafruit. Thank you, Digikey. Every single week, Lady Adafruit shows you how to find stuff on digikey.com. And one of the most useful skills you can have on planet Earth right now is being able to find parts. Lady Adafruit, what is the Great Search this week? Okay, for this week, so I was working on this iSquared C adapter board that can connect to LED arcade buttons. I love these, these are durable, they're pressy, and of course they're glowy. So I've got a PWM output and a digital input that's being read. And some of these LED arcade buttons really need 5 volt power. Even if the board itself is 3 volt logic, I need to give the LEDs 5 volts for them to light up. And that's not unusual. A lot of arcade stuff is very, is still very kind of 5 volt land. Because a lot of controller boards are meant to plug into USB and so they have, you know, 5 volts available. But since these STEMIQ keyboards can plug into 3.3 volt logic and power, I want to make sure that we had a way to give them to generate that 5 volts. So normally you're like, oh, I've got 3 volts and I need 5 volts. No problem, I get a boost converter. And, and I love boost converters. There's nothing, there's nothing wrong with DC-DC boost converters. But they're always like, you know, you're like, how hard can it be? Before you know you need a chip and they need a diode and they need an inductor. And then like, you sometimes even need, you know, a compensation cap or you need a resistor divider. And, you know, when I don't need a lot of current, if I need only like 50, maybe 100 milliamps of current, I actually prefer to go with a charge pump. They're great for when you just need a reference voltage, if you need a small amount of current. They're not very power efficient because they always double the input voltage and then regulate it down. They can't, they're not like a boost converter where it can change the PWM rate into the inductor to change the boost voltage. They'll always double, they're doublers. The way they take the capacitor and they switch the connections back and forth, they basically double the amount of voltage. So if you give it 3.3 volts, it'll double it to 6.6 and then linearly regulate down to 5. So again, they're not power efficient, but they're really cheap and something like this, which isn't going to be battery powered. Personally, I think it's just fine. Okay, so let's go to the computer and I'll show you. So this is, this is a schematic I have for every LED switch. So I've got the switch here, one pin connected to ground, one pin is connected to the digital input. And then over here, the other one, I've got the 5 volt power and then because I have, I might have 3 volt logic, I have to use an end channel, a FET to, you know, or you can use an NPN in this case, I'm using the end channel FET to quickly turn on and off or you basically connect the other side of the LED to ground. I can't do high level, not easily because, again, the logic level might be 3 volts, so I have to reference it to ground. I can't reference it from 5 volts below. Just a PWM controller and then this is the switch cap. So again, I like switch cap converters because they're so simple. You know, you've got your VCC input and then you've got your switch cap, which is one microfarad, and then you've got the output, which is 5. And another nice thing is these are always, they kind of come in a standard 6 pin TESOP SOP 23 package. There's a shutdown pin if you want it, but pretty much it's like voltage in, voltage out, one small capacitor, no inductor, no resistor, no compensation, no diode. So I'm a big fan of these. I really like them. And again, they're good up to usually about 50 to 100 milliamps. So you can draw, you know, you can draw a couple of LEDs from them. So let's go to Digikey. And so finding these is a little bit interesting because they can actually be in two different spots. So, you know, I usually just type in DC-DC charge pump to try to filter out all the inductor based boost converters. So normally you'd think, okay, let me go to, you know, PMIC voltage regulators and that's not a bad place to start. Let's go with active, positive, single output, and the output is 5 volts fixed. So that'll at least get us, you know. And there's, once I do other voltages, by the way, for example, if you're doing UART to TTL, UART TTL to like RS232 logic, you'll want to boost up to plus or minus 10 volts. So you actually usually get two charge pumps, one that takes your 5 volts and gives you 10, and another one that inverts the 10 back to negative 10. So let's filter and then let's see what we've got available. So there's, you know, there's a couple of things. They do come in other packages and I will say a lot of them, you know, are in the 5-pin or 6-pin category. So if I'm looking for one that's equivalent to, you know, the package that I'm using, it's going to look something like this, you know, this 6-sot. So let's also only look for in stock, looks like a foot 56 options. But here's the thing, they're cheap. I mean, like, you know, for quantity one, they're 95 cents. This is probably the closest, you know, again, that package, you know, originally used the AP3602. AP3602 has just continued, but, you know, luckily there's a lot of, you know, crossable, pin compatible charge pumps, but here's, you know, there's a bunch. So the thing is, is that, you know, there are some here, but you can also find them in, oh, I know one more thing, I just wanted to, before I leave, show you the current output. So a lot of them, you know, they'll give you, as long as you give them, again, it can't be less than one half the voltage because it's a doubler. So you have to give it at least like 2.7 volts. But yeah, a lot of them will give you, you know, 150, 120 milliamps, 60. They say it's a small but a fair amount of current. And another nice thing is they're not noisy. You'll never get inductor noise from them. The other place to look though, and this is the thing, you got to be careful because, you know, I went here and I was like, ah, you know, I found a couple options. But also look under LED drivers. They're also, you know, they're often considered for like LED drivers. And so even though, and I see this for a lot of DCDCs, check both locations because, you know, for example, my OLED boost converters, whenever I look for those, the chip I use, which is a constant current, sorry, a constant voltage, like the fan 533, 13 volt boost converter. It's actually sorted under LED drivers, not under voltage regulators. It's one of those things. Okay, so again, active, one output, voltage, 5 volts. Wait, no, sorry, voltage output, 5 volts. And let's also only look in stock. So there's also a couple here. And so actually the one that I'm using nowadays is this RT61AGE. Now there's not a lot in stock right now. There's only 130 because I recently bought a wheel of 4000. But this is what I use. And it's, you know, it's dropping replaceable with the AP3602. And it works lovely. You know, just gives you a nice clean 5 volts with just an extra capacitor. And, you know, in quantity there, they can be as little as 30 or 40 cents for chip, which again, by the time you add the inductor and the diode and the chip is going to be, you know, maybe half the price of a boost converter with only like one or two placements. You'll need that one capacitor in the chip. So if you're doing manufacturing, you're paying for placement and you're paying five to 10 cents of placement, you know, it's also going to be cheaper to go with a charge pump. So this is my great search. Charge pump.