 On NPI, this week, brought to you by Digikey at Interfurt, is RichTech. That's right. I don't think we've done RichTech before. I try to make sure that we get every different company because they all have their unique products. So this week is from RichTech. It's the RT3549, if I got that part number right, memorized. So it's a, it is a BGA component and it's very new. I thought this was a very cool design, a product idea, something you would normally expect from one of the bigger, more expensive companies. But RichTech, I do really love their power supplies, their boost converters, I use them all the time. So I thought this was a very neat design. So especially it's intended for laptops, but I think in tablets, but I think it could be useful for people doing other lighting projects as well. So like I said, this is the RT4539. So this is a like, for me, it's like a four in one product. It's an NPI that does four things in, you know, as one chip. And that tight integration, you know, is going to make it first off very small, but also very efficient, power wise. So this is a 36 volt, high efficiency boost converter with I squared C controlled, six channel LED driver. So you know, there's all the specs on the right. So let's go through the basically the four things that it does. So the first thing is, it's a boost converter. So the input supply voltage is, you know, three to 24 volts. It can give you up to 36 volt output. Let's go the next image. So what's nice about this design is, you know, this chip, actually, you look at it, it has, I like how little you need to get it running. The switch is built in. You just need an inductor and a forward diode. You program in the boost converter specifications over I squared C. But basically you can drive this from, you know, because it goes from three to 24 volts, pretty much any battery that you're driving your system from, you can give the V in and the logic level for the MCU is different than the V in. It's actually like you can use, you know, 1.8 volts or higher for that signaling. So your V in can come from the battery and your MCU can still use pullups on the enable PWM, SCL, SDA, I squared C pins to do the control. So for example, just as one of many registers that are available, you want to change the boost switching frequency. This can be handy to avoid, you know, beat frequencies between the PWM, to avoid interference with the RF. Also changing the frequency will change your efficiency versus your power output and, you know, your inductor usage. So you can tweak that in software. Of course, there's a lot more settings that you can adjust in software. But the first thing is that this is a boost converter. So that's that's first up goes up to 36 volts. Second thing is it's a six channel, constant current mirrored sync driver for LED strands. So actually let's go back to here. So when you have LED backlight, again, this is designed for a tablet, although, you know, you could probably use it for other lighting projects. You want to have all your LEDs at the same color temperature and the same current so that you have consistent, even color throughout the entire LED panel. And one way to do that is to have all the LEDs in a strand. You know, they're all serious characters. Why do you need that 36 volt boost converter? Because you can have 10 LEDs in a row and now they need like 30 volts to drive them. But at least it forces you to make sure that they all have the exact same current between them. So you might end up with a panel, especially a really big panel. Once you get to like, you know, over five inch diagram or 3.5 diagonal, you'll have multiple strands of five to 10 LEDs. But you want them also to be balanced between them as well. Like not just obviously every LED in the strand has the same amount of current, but you also want each strand to individually have the same amount of current. And so if you look inside, there's actually a little current mirror on the bottom left there. There's a box that provides the constant current control. Again, the constant current is control is all done by I squared C. And it's mirrored to each one. Each one has a matching transistor, you know, emitter, whatever, source, resistor, comparator. So they all get equivalent current through them. And then there's also like a feedback loop that will let you know if the LEDs strand is open or closed. That's good for debugging as well. So you don't have shorts or if your LED panel is damaged, you can feed that back to the microcontroller that's running it. So part one, boost converter, part two, constant current driver. Part three, PWM driver. So obviously you do have constant current to set all the LEDs to the same brightness. But then constant current can do like very rough brightness control. But PWM is where you'll get a lot more precision. And what I thought was really neat is one of the things we have a guide on is why you don't want to use linear control of PWM for LEDs because our eyes are logarithmic. And that's why if you do linear control, you'll notice that as you get to dimmer effects, you start to see more flicker and you have a lot less granularity. Whereas what our eyes really look like, that's especially true if you're using night mode, right? At night mode, it's like there is like off and then just a little bit light and then really light and then much much wider like it goes very quickly. Unless you have existential controls, you see here the PWM duty cycle is is done exponentially for you so that you get the smooth curve where there's a lot more control at the dimmer lights and then as it gets brighter, it goes up very quickly. And this is what our brains like more than linear. And that's handled for you. So it's kind of nice. It's all built in again over this I-squared C connection. And then number four is there's all this other extra stuff that they added in over I-squared C control to make the lighting easier to handle. So for example, slope management, like you want to go from one brightness PWM curve to another, you can actually tell it, hey, do a ramp for me or a slope. And here's how gradually I want you to do it to control. So you're not sitting there like manually tweaking the PWM rate over and over again to get your linear slope. You just say, hey, go from this range to that range, do it in, you know, 512 milliseconds. And then you can check when it's done. So it's kind of like a four-in-one LED driver, kind of neat. I thought it was like a really nice design. And again, it's designed for tablets and laptops because they get the best stuff. But I think this would be very useful also for there's user projects or if you're doing like LED lighting, not backlight lighting, but just like, you know, you're controlling LEDs. All of this extra capability would be so great. I mean, just even the exponential PWM control is miles better than most LED drivers that I've seen for like automotive or commercial use. OK. And available on Digi-Key. Check it out on Digi-Key's site. It's non-stock. It's very new. It's super new. It's super new. So it's not even a sign-up page yet. However, if you're interested in this, do contact Digi-Key sales and they will get you samples. I've found that's a very effective way to say, hey, I'm only interested in this chip. Can you get me samples? This is cutting edge ion. This is the NPIs of NPIs. I prefer to go with the ones that are in stock, but this one I thought was too good to pass up.