Hi Welcome to the Eev blog an Electronics Engineering Video blog of interest to anyone involved in electronics design. I'm your host Dave Jones Hi A little while ago I surprisingly showed that there wasn't much difference between a traditional linear voltage regulator and a Switch mode voltage regulator. and well, I thought I'd do a follow-up video of that on designing a Switch Mode power supply cuz I've got a lot of feedback everyone wanted to know. Well, how can I design a Switch Mode power supply? Let's go through it step by step.

So how do you design a Switch Mode voltage regulator? Well, you can do it using uh, traditional discrete components. just transistors, inductors, capacitors, resistors, that sort of stuff. but oh, that's that's really pretty ugly way to do it. And unless you have a very specific Niche region to do it, you shouldn't uh, you shouldn't go down that.

Avenue You should use one of the standard offthe Shelf uh. Switch Mode Controller Ic's available today, but which one if you go to Mouser or dig and search for Switch Mode Controller chips? there's thousands of them. The choice is crazy. It's ridiculous.

Where do you start? Well, I'm going to use for this blog I'm going to use one of my favorites and it's probably the closest thing to a Jelly bean. Uh, generic. uh, Switch Mode controller I See, on the market, it's almost certainly probably the world's most popular one. It's the MC 3463 Now, you may not have heard of it before, but I can guarantee it.

It's been around a long time and it's used in practically everything. And one of the great advantages of it is that it's not available. It's not just fixed from one manufacturer now. MC is uh, the old Uh code for Motorola but Motorola don't make chips anymore, it's now on semiconductors, they now on semi make it.

But trust me, if you just putting 34063 into Mouser or Dig Key or any other part search engine, you'll get a whole bunch of different manufacturers who manufacture The Identical functionally and pin compatible chip to the Mc34063 and design in it. The formulas are all exactly the same, so it's a fantastic chip available from anyone. It's um, even available from noname manufacturers. If you really want to go down to, you know, one or two cents per chip, you can get it.

uh, whereas as opposed to a lot of the other uh DC Todc converter switch mode controllers on the market, there they might be you know, only available from National semiconductor or only available from TI or something like that. And really, you don't want to be locked into that, especially for these hobby projects. And the other good thing about the Mc34063 is that um, uh, it's available in a Dip standard Dip8 package and a S So8 package as well so you can plug it straight into your breadboard or your through hole design. Really easy, simple stuff.

Now let's take a look at the data sheet for the Onsi Mc34063a. Here it is. Now here's the internal circuitry for it and as you can see, it's an 8 Pin device. It's very simple.

It's uh, just like in my previous blog, I showed how a a basic this is. Really about as simple as it gets for a Uh switch mode controller. I See and as you can see, it's got a comparator with a built-in 1.2 volt voltage reference. It's got an oscillator which is controlled via an external capacitor.

the timing capacitor on pin 3. There, it's got a Um it's got a Darlington uh transistor. Uh, pair that. Well, it's actually you can configure the output transistor.

It's got a switchin transistor Q1 there. It's got the separate collector and the separate switch emitter. and it's also got a drive collector as well which is important important and we'll go. We might go into that later.

Um. and it's also got a current sense um input pin you put a current sense resistor on there. We'll show you that later and uh, it's It's basically and it's got at Pin five. There is the Um input for the feedback.

So it's very simple and it's very easy. It's It's pretty easy to use, not as easy to use as many of the other ones on the market. In fact, you could probably argue this is one of the more difficult ones to design with. There's lots of formulas as we'll go through, but even because it's um, you know it might be one of the most hardest to use on the market.

I'll show you just how easy it is if you go step by step through the calculations. and the other good thing is take a look at the um, uh, take a look at the specs. It's uh, got a very wide input voltage range from 3 volts to 40 volts input that's huge. Um, it's got uh 1.5 amps, um maximum output uh switching current.

it's reasonably high frequen, it's medium frequency. it goes up to to 100 uh khz, which is pretty good. You can adjust the voltage and it's got a Precision 2vt voltage reference. and the other good thing is that it's configurable to be either a step up or a boost converter.

so 5 Vols in and 12 volts out for example. Or you can configure it the other way. a step down or a buck converter from say 5 Vols down to 3.3 Vols It's very versatile and it's got a third configuration which is the inverting configuration. so you might feed 12 Vols in and you get minus 12 V out.

Very versatile chip. that's why I Love it! It's one of the cheapest on the market. it's like 50s and it's available from everyone. Magic! And just to prove that it's really is a generic Jelly Bean uh switch mode controller used in cheap products I've got one of these Nokia You know, one of these just noname one hung low brand? um Nokia car chargers.

You've seen them right? They plug in the car cigarette lighter, let's crack it open and see what's in there. and I've opened quite a few of these and check it out. You can see there's the input fuse and there's a there's a um eight pin wh here we go. There's an 8 Pin um uh standard uh dip package chip and bingo.

Lo and behold, What do you see the MC 34063? It's from Uh UTC where so it's not an on semi uh one. But as I said, it's available from a bunch of Manufacturers And check it out. there's the inductor. There's the probably output filter cap.

There's an input filter cap. There's the sense resistor there and very simple. So if it's used in these things which you can buy on eBay for like $2 then you know that this chip is a beauty to use. It's an industry standard device.

No problems at all. Now let's take a look at the three different configurations this ship can be used in. on the data sheet. here it is.

The first one is the Step Up converter which is the example I'm going to use today. We're going to go through this step by step, calculate it and build it and then measure it. Now here it is. As you can see, there's on the left hand side there there's 12 Vols input.

This is just an example. this is Um, this is. the example. provided in the Motorola data sheet.

there's 12 volts in, there's 100 microfarad input filter cap. there's a a 22 ohm sense resistance between pins 6 and seven there and then that goes through the inductor L up the top there that's 170 microen and we'll go through the calculations how to get all these values and then that goes around into Q1 which is the switch in uh, transistor down to ground there and then there's a 1n 5819 shock key diode. Now that's important. It's got to be a shot key uh type because they're fast and they're designed for high switching frequencies and they got low voltage drop as well.

Very important to choose a shocky one there for most applications. And as you can see the example here, there's an output filter cap um C0 there C out 330 microfarads and in this example it's 28 Vols 175 milliamps maximum output and you can see R1 and R2 There are the feedback resistors which set the output voltage into pin five there in into the comparator. So it's very simple to do and let's take a look. the second configuration which is the step down converter here.

Now as you can see it's it's not too different except that the inductor has been the inductor and diode have basically uh moved around a bit. There's still in this example there's 25 volts going in the same filter cap as before, the same sense resistor as before, but now look, pins 1 and 8 are now tied together whereas before the inductor was between pins 1 and 8. That's how vers atile this chip is. You just configure it in a different Uh pin configuration and you get a totally different functionality out of the chip.

So it's going to take 25 volts in and it's going to give us 5 volts out at 500 milliamps maximum. Now as you can see, it goes into Q1: the switch in uh, the switch in transistor there and then there's a then there's a reverse biased uh Diode to ground and I explained this uh, last time how it all works. so I won't go through it again. but then there's a series output inductor 220 micro Henry's micro Henries this time which goes to the output Fielder cap and then the sense resistors as before.

so very simple. Once again, you just rearrange a few of the components. Totally different functionality I Love it. And here's the third configuration, the voltage inverting uh configuration.

Now as you can see, it's got 4.5 Vol to 6 Vol input and it gives us- 12 Vol at 100 milliamps output. So not only has it boosted uh, it's it's actually boosted the voltage as well as inverted it. And this is very handy. If you'll say only got a single battery supply and you want to power a dual Supply op amp or something like that, you might use something like this, but this is generally for higher power.

You might use a switch capacitor converter for that, but we won't go into it. Um, but let's take a look. once again. the configuration on the input on Pin six there is exactly the same.

You got the voltage in filter cap, the current sense resistor once again. Uh, Pins 8 and one are tied together just like our Um step down configuration. But as you can see, the difference between the step down and the inverting is that the inductor and the diode have switched places. Now instead of the diode going to ground on Pin 2, there you've got the inductor going to ground and then you've got the Uh 1n 5819 Shocky Diode there.

Um, once again reversed uh uh bias going into the the output and there there's an output filter cap and the feedback resistors R1 and R2 Again, as you can see, very versatile chip. why wouldn't you have this as a standard component in your junk box? Okay, enough of the talk. Let's do a real design. Now on to the real scary stuff.

Hold on to your hat, take a look at this from the data sheet. This is the Uh table of formulas that you have to use to calculate um all the different Uh Val the different Uh configurations. Now as you can see the columns, there's one for Um Step Up There's one in the middle for step down and there's one for voltage inverting So Today we're going to look up uh, we're going to look at this Step Up configuration which is in this second column there and there are all the formulas that we're going to have to use Um and the various calculations are on the side. Now it looks complicated, but really, it's not that bad.

and I'll show you there. You know there's no complex math here. you just have to basically fill in the blanks, go through step by step. And the good thing about this table is that the actual values each row there.

they are actually the steps you need to take. They're they're not numbered. They should be like there should be another column there that says um, step, step, number, and then 1, 2, 3, 4. Because these you'll go through these formulas step by step.

and really, if you just looked at this data sheet before, it might scare you off. but it's not that bad. so let's give it a go. Okay, let's go through a real example.

Basically you got to start with what spec you want. Now let's write these down. Okay, so we know we got a good Baseline to know what we're working with. We're going to use.

Let's say we want a step up converter. That's today's example. Okay, we have. We have an input voltage of five.

let's say 5 Vols Okay, we're taking a standard 5V power supply. Let's say it's plus - 10% You need to know the variation in there as you'll see later. Um, now at the go. Today is to get a voltage output of 15 Vols Okay, so we want 5 volts in and we want our little circuit to give us 15 Vols out at 100 milliamps maximum current.

Now this isn't. Don't confuse this with a constant current. Uh, generator. it doesn't generate 100 milliamps.

it just will generate 15. It's a voltage Supply So it will generate 15 volts and allow you to draw up to 100 100 milliamps. Now you also need to know what sort of Ripple you want on the output because DC to DC converters don't Just if this is uh, if this is volts up here and this is timed down here, it doesn't just generate a flat voltage like that. You won't see if you hook your oscilloscope up to the output of this DC to DC converter that we're going to build.

you won't just see a flatline. a nice steady voltage at 15. Vol You will actually see Ripple like that. It will actually go go up and down and you want to know the peak to Peak value between there and there Now I'm just going to taken, you know, a reasonably low figure for a 15 volt.

Supply I'm going to be pretty happy if we get say 100 molts Ripple That's quite reasonable. So they're the specs that we're going to work with. We're going to plug them into our formulas and we're going to design our circuit. We're going to build it and see what happens.

Okay, here we go all the calculations step by step as per that table. I Just showed you in the data sheet and here it is. Don't blame me, but check it out. It looks complicated.

Okay, it looks really complicated I Admit, but it's not. Stick with me I Know this looks like a mess. so instead of just uh, holding it side by side like I normally do I'm going to put it here and go through it because it's important. Let's check it out now.

I'll try and do this in one take. Okay, now these are the equations. These are the um, these are the parameters of the Sur circuit down here, which we saw in our table before. Okay, here's our here's our table.

Here's the table we had okay and these values down here. Um, the these parameters match these and the rows are the same and we've just we're just going through the calculations and our numbers will pop out the other end. Magic. Watch this.

Now the first thing we need to calculate is T on Uh, T off t on on T on / T off. Now this is the formula for it from the data sheet. Now let's punch in the numbers now. our voltage output.

Okay, that is 15 volts. That's the voltage we want out of our circuit. Now the forward voltage drop. Okay, you've got to choose a diode now.

I've just chosen at one you know I've used before. It's the B 220a from Diod Inc And you need to look at the Uh VI curve. Okay for this particular diode. Now as you can see on the Y axis, here is is the forward current for that diode and on the X-axis is the instantaneous forward voltage drop.

So the So the current versus the voltage drop. Now, Um, we don't know the actual Peak current through the diode at the moment. Okay, so let's just take um, the example of say 1 amp. Let's just say it's going to be 1 amp for our 100 mols output.

Okay, you go across on that curve there and you drop down and that's 0.4 volts. That's the voltage drop of the Diod we're going to use. It's not going to be too critical because it's a small function of the 15 volts we've got here. But let's plug in4.

Vol Okay, and then we have to subtract the Uh input voltage minimum. You know how I said it was 5 Vols Uh. input Voltage: plus - 10% Well, 5 Vol - 10% is 4 1/2 Vols There it is. Now there's the same value.

Again, plug in 4 and 1/2 minus the saturation voltage of the trans transistor. Now the saturation voltage. You've got to go back to the data sheet. Now here it is: I'll put it up.

Now here it is now the saturation Uh voltage. the output switch. Now there's two saturation voltages. One is for the Darlington configuration, which is only applicable to the step down.

We're using a step up, so we have to look at the second one. here. The saturation voltage over here vat is uh, let's take the typical value of 0.45 Let's round that up to 0.5 Okay, so we come back here. You plug it in Saturation voltage: 0.5 You punch that into your calculator and you get a value of 2.7 Now let's go on to the second parameter.

t on plus T off has the simple formula of one on F F is the switching frequency. Now as I said, the switching frequency of this device has a maximum value of 100 khz and I'm going to choose that maximum value. Why? Because a switch in DC to DC converter the higher frequency you go, the smaller the indu dor you have to use. And inductors are big devices.

You know, if you've got a large value of inductance, it requires a large a physically large inductor. I don't want that. Okay, so the higher the switching frequency, the, the more losses you will get at a higher switching frequency. But it's a bit of a trade-off but we won't worry about that.

I'm going to choose 100 khz. That gives us 10 micros seconds for t on plus T off. Now let's go on to the next one. T off T off is a bit more complicated formula.

It's t on plus T off, right? It's not they're not separate values, it's that that parameter there. t on plus T off. Okay, 10 microseconds there it is. Uh, divided by T on on T off.

which is that one there 2.7 + 1. Plug that into your calculator. See, it's not as complicated as it looks. 2.7 microsc.

Now let's go on to T on. Okay, T on is a as simple. it's just t on plus T off which is that value up there 10 micros minus the T off value. We just calculated 2.7 microc and it gives you a value of 7.3 microc because you'll have a waveform which has an on time like that and an off time like that.

Okay, that's your switching. That'll be your on time for example, and that'll be your off time. Now the next thing we need to calculate is our type in capacitor called CT. This is the external capacitor that sets our switching frequency for us.

Now the formula is Uh, 4 * 10- 5 * T on. So uh, we know t on. We just calculated that 7.3 microc. So you multiply that by 4 * 10- 5 and you get 292 picofarads and that's the value we will plug into our circuit for CT as we'll see later.

Now the next parameter is I Peak which is the peak current through your switching devices I.E your inductor and your diode. Okay, so the formula is 2 * IO Max time ton on T off which we got up here t on on T off + 1 uh equals um and you plug the values in. Okay, so our our output maximum current as I said 100 milliamps or .1 amps. everything's in amps.

Okay, so it's 2 * .1 * 2.7 which we got up there + 1 Plug it in 0.74 amps and that is the peak current through our diode. You know how I said I chose a 2 Amp B220 diode. Well, that would be a good ballpark. You'd need at least a 1 amp diode in there with a low enough Uh voltage drop a a low enough VF um to get an efficient circuit.

So a two amp diode in this Uh circuit would work nicely cuz that's our Peak current. Our output current as I said is only 100 milliamps. Okay, 100 milliamps output current. but our Peak is 0.74 That's the thing with switching converters you've got to watch out for.

Okay, you don't go and use a an an inductor and a diode rated at 100 milliamps cuz that's your output current. No, you need to. uh, choose the inductor and the diode based on your Peak current here. It's a very important vital thing and a trap for young players.

Now our next value. Our next parameter down here is RSC which is our sense current resistor. That's what SC stands for uh, current sense resistor And the formula is simple. It's 0.3 on the peak current we just calculated.

plug that in 0.4 ohms and that's the value we'll plug into our circuit for RSC as we'll see later. Now here's where we get down to our other Uh value vales for our components: Our Inductor L the minimum value of our inductor for this particular circuit. This is the formula: VN minimum as we've seen we've seen that before is 4.5 Okay, there's the value minus vat now. I've seen Vsap before is 0.5 There, it is divided by the peak current we calculated here 74 times the on time which we calculated up here.

You see how all these previous calculations we've done allow us to fill in these equations later. So you plug that into your calculator and you get 39 Micr Henries. That's the value of our inductor we need to use for our circuit. Pretty simple.

Now our C C out our output capacitor, our filter capacitor. Here's the formula for it. It's 9 times I I the output current um, which is 100 milliamps which is our which is our spec for our circuit times ton which we've calculated before 7.3 micros on the output Ripple Now as we said at the start, as per our spec, I said I'd be happy with say 100 m volts Ripple on this circuit. So 0.1 volts there it is.

100 milliamps. Plug it in and you get 66 microfarads and that's the output capacitance we need on our switchin regulator. Tada wasn't that easy piece of cake. It looks complicated, but it's not.

You just need some basic math and go through step by step easy. And there's one more thing we have to calculate. We have to calculate the feedback resistor values for our circuit. Now once again, on the data sheet down here here it is the desired output voltage V out equals Here's the formula.

It's a pretty standard formula used for a lot of DC to DC converters 1.25 which is the internal reference voltage uh, Time 1 + R2 on R1 Now if you rearrange that formula, let's um, let's say you want to pick, you can pick any value of R1 Just rearrange it. It's um, R2 = V out on 1.25 -1 * R1 and that gives you your values. Now we can go back to the data sheet and we can plug in all of the values into our example. Step up.

uh, converter circuit here straight out of the data sheet. Now we got 5 Vols in. Okay, we didn't need to calculate the value of the input cap. that can be um, any.

really. it depends on your Source but we won't go into that now. RSC We calculated on the Whiteboard before that was 0.4 Ohms. Okay, now our inductor up.

Oh sorry this um, this series resistor here to drive um for for this transistor over here. we'll leave that at the example value of 180 ohms cuz we didn't need to calculate that so we'll just leave it. now. Our inductor we calculated on the Whiteboard was approximately 39 micro Henries.

There it is Now now our timing capacity here. We also CT we calculated on the Whiteboard before was 292 Paa Farads doesn't have to be that exact. Um, and our output filter cap. We calculated that as well.

And there it is. 66 microfarads and that those V oh sorry. we've got one more thing here. R1 and R2 I showed you that formula just before.

Now if we choose R1 as 10K then um 110k for R2 will give us 15 vol Vol out 15 Vols at our 100 milliamps uh, maximum. And so if we plug these values, if we build this circuit and plug these values in, it should work exactly as we predict. Now, some of these values won't be spot on to the E12 or E24 preferred values. 39 micro Henri's um is in the E12 range, but you might find that a 33 microhenry is easier to get, so you might want to use, say a 33.

Um, a once again, a 04 ohm sense resistor. You're not going to get one of them, so you might choose a 39 Ohm sense resistor. It's not hugely critical the timing capacity. You you won't be able to buy a a 292 Paaka farer capacitor and it doesn't matter.

So you might use a a 270 Paa Farad or even a 330 Paa Farad capacitor in there. Um, these values you can get 10K 110k. No problems. 66 Microfarads isn't a preferred value.

You might get 68. Uh, Microfarads you'll be able get, but you might want to round that up. To say a nice easier value to get like 100 Microfarad. So we might use those values in our actual built up circuit.

And here we are: I've built up the actual circuit I Just so happen to have a board which matches the MC uh 30 4063 device and uh, we I've wired it up and as you can see, there's the output voltage I'm putting 5 volts into it. Uh, from my power supply up here, we're getting 15 Vols out No problems. And here is the the Um output. This is AC coupled 100 Ms per division.

um I'll try and get a better look at that, but um, let's take a look at the output uh uh configuration on uh the output Ripple under load. now that's at zero load I've got my uh, dummy load from uh last time from a previous blog so I can dial in any load I want that was that's with zero load. Now as you can see the Uh Ripple 100 MTS per division we we wanted about 100 MTS Ripple We're getting about 200 MTS um Peak As you can see there, Um, but that isn't I Guess that's not too bad at all really. Um, but as you can increase the load, let's check it out.

see watch it change. That's now 10 milliamps load and let's take it up to 20 milliamps load. And as you can see it, the Ripple starts to get um, it it changes. That's the Uh operation mode of the DC to DC converter.

uh changing based on the load. but we can actually freeze that and take a look at some of those Peaks As you can see, they're about almost 200 molts peak-to Peak uh Ripple which is probably a bit higher than what we um actually wanted and what we uh calculated but you know it's still within the ballpark. and as you can see the uh, the Peaks are actually uh, different. You can see the different change in mode of operation of the actual device based on that particular load and we can go past 100 milliamps.

There's nothing stopping us there. That's 13. That's 150 milliamps, That's 170, That's 200 milliamps. so that's double our calculated uh value.

And there you go. that's the output Ripple Um, and as you can see, it's dropped down to the output vol voltage has dropped down to 13 volts now at 200 milliamps. So it's um, starting to uh starting to drop out. Okay now let's say we weren't happy with that output.

Ripple and I'm not. Let's add in an an optional uh LC output filter here because I'm using 33 micro Henri's up here. I'm going to use another one here and I'm going to use the same 100 microfarad output cap as well. and I've built that up and let's take a look at it.

Here it is here. I've added as can see I've added in the extra uh, uh, I've added in the extra output cap and the inductor there and this is the ripple at No Load. This is no. this is same scale as before 100 Ms but as you can see, it's much much cleaner.

If we turn that up to 20 m per division, there you go. it's actually quite clean. that's at no load. Now let's turn this load up.

That's now 30 milliamps, 40, 50 60. Let's go up to our maximum of what we wanted: 100 milliamps. That's 100 milliamps. That's 20 molts per division.

Ripple As you can see, it's not. It's not too bad at all. It's quite low and you can add some extra filtering if you want if you weren't uh, happy with that. but that's what an extra LC output filter can do for you.

And also, let's see where the DC the DC converter drops out. Now this is my current here. It's basically reading 2 milliamps at the moment. this is my output voltage: 15 volts.

If we wind the current up, let's see where it drops out. It easily meets our spec of 100 milliamps. That's what that's what we designed it for and it goes a bit but a bit but a bit above that and 170. it's starting to drop.

There we go at about 170 milliamps. Um, it's the output voltage is starting to drop. It enters drop out because our values aren't optimized for that higher current. But if you obviously wanted to go up to 220 milliamps say you would have, uh, done those calculations again and you would have got different values for the components which would have allowed you to goone up to that current.

Okay, now let's see if we can actually characterize the performance of this DC Todc converter circuit over its entire current range. Now Ladies and gentlemen, boys and girls, I've mentioned this before, but say it again. This is a classic example of why any good lab needs four multimeters. Because to measure the performance of a power supply like this, you need to measure the input voltage and current which I'm do with these two meters and the output voltage and current with these two meters.

So I need four meters at the same time Now Voltage times, current is input power and that's what we want. We want to know the input power. So this is measuring the input current. This is measuring the input voltage and this.

These two here are measuring the output power. This is measuring the output current and measuring the output. Put voltage. and let's um, take say, um, our power supplies from 0 to 100 milliamps.

Therefore, let's measure it in say 10 milliamp steps. Let's record all these values in 10 milliamp steps from 0 to 100 milliamps and that will give us a reasonable rough graph of the performance efficiency of this circuit. Let's do it now. I'll just go through the first reading as you can see, this is our output current and it's roughly 10 mli and our output voltage 15.06 Vols And as you can see, our input voltage is 4.95 volts and the input current is Uh 59.4 milliamps.

So let's uh, write these down in a table format and increment it to 100 milliamps. and Bingo! we have our figures from 10 to 100 milliamps. Let's go graph them and after plotting the data, here's what we get. We've got efficiency on the Y axis here from 50 to 60% and we've got current on the X-axis from 10 milliamps up to 120 milliamps.

I Just went over the 100 and as you can see it, uh, it's It's a fairly typical response for an efficiency curve for a DC to DC converter such as this, and it Peaks at about 100 odd milliamps there. Um, as our design uh example should have shown, but um, yeah, 59. almost 60% efficiency isn't that terrific, but it's okay, There's there's nothing inherently wrong with that if you optimize the Uh values of your inductor, if you optimize the type of the inductor, if you've got a certain inductor um, type here, that's going to affect your efficiency, your diode, your type of diode is going to affect your efficiency and so on. But uh, you can modify those to increase your efficiency as required.

Okay, I've changed the inductor on here. It's a different brand, different type. It's a 47 Micr Henri's instead of a 33 micr Henries. Let's get the efficiency graph again with that inductor and see how it goes.

And one thing with this new inductor. As you can see at 120 milliamps output current, it's actually dropping out. the voltage is dropping out whereas at 110, it was just about 100. it's just in there at 15, so it drops out right on 100.

And here's the efficiency graph again with the 47 Micro Henry inductor As you can see it: Peaks Uh, sooner, it's a higher efficiency. it goes up to almost. It goes over 65% which isn't too bad, but it actually Peaks at A At At at a lower current and then drops back down drastically. So as you can see, changing the Uh, changing the parametric values in the circuit changes its characteristic, efficiency, response, and all sorts of things.

so you can play around with this to your heart's content, choosing optimizing the type of inductor you've got. uh based on the equivalent uh, the series resistance of the inductor, the uh, the shocky diode you're using your output. filtering. All sorts of stuff will affect the efficiency performance graph.

So there you go. There's an example of using the MC 3463 DC Todc converter chip for a basic Step Up configuration. Now you can do step down or invert in and you can play around with the efficiency and just change. Just use the For the different configurations, you just use the different Uh formulas.

They're only slightly different, slightly different circuit configurations. But as you can see, I mean you know it looks quite complex right? but it's not really. Um, they're very basic Uh calculations. You just need to go through the motions and do it, build up your circuit, measure it.

Component selections a big thing. Uh, you might you know you have to look at the peak current is one of the major things you need to choose an inductor which is suitably rated for your Peak current which has the lowest Um series resistance possible. So the physically the bigger inductor should in theory have a lower series resistance um which will help with your efficiency. So you know in this case, point7 Uh amps Peak current calculated well.

You might choose a 2 Amp uh in inductor in a 2 Amp diode or something like that, but you can play around to your heart's content. so there you go: DC to DC converters. Pretty easy to design and this is one of the more complex examples. There are simpler to use devices than the Mc34063.

this is you know, these formulas are quite complex. Usually they're a lot simpler because the chip uh takes care of a lot of the stuff and you might only have a very simple oneline formula for one of the other National instruments chips or something like that, but generally they're more expensive. They more obscure single Source I Love the Mc34063. It's just a basic chip.

It's not by far the highest performance device out there. If you want the utmost in you know, efficiency and low power and all sorts of stuff, go for one of the more uh, obscure uh devices out there. But for a jelly bean part that does almost everything, it's beautiful. Keep some in your junk box and think about using it next time you want a simple DC to DC converter, it ain't that hard.

See you.