So now that we've selected parts for the various rails of our system and we've selected multiple devices to compare for each output so that we can get a comparison of using different types of devices for the requirements that we've defined, we would hit the "Continue" button. And what will happen is we'll build a system view with system efficiencies for the whole system.
By default the system will pick the first device in our list. However, we can change that. So we have options to change for each one. It comes up in a non-expanded view. If you go to an expanded view, you can see a little bit more detail. So in the case of the ISL8200, we don't have efficiency data for that. But on the ISL8225, once we pick up the device, we actually have efficiency data for it, we'll see the actual curve for that device, and we can adjust the requirements of the light load, typical load, and max load for that particular supply. And we'll see in our summary, where those efficiency points are, and then those will be summarized over the whole system in the top graphs up here.
Each one of these, you can expand the section and you'll see...so in this case, we had a lot of different devices that we had options selecting. And if it has a parentheses, "S" behind it, that means it's a single device solution. If it's a dual output, then you would have a "D." If it's in a current share configuration where it's multiple devices doing current share to make that output, then it would have a "CS" behind it. And that's just so you can identify what type of solution it is.
So in this case, we had four devices, and we can look at the curves and we can pick out which best matches our requirements and gives us the best overall efficiency based on our requirements. So in this case, the orange line looks pretty nice; it's an ISL85033 and it's got very good efficiency across most of the range of what we defined better than some of the other parts.
One little feature you can do here; if you want to turn off stuff so it's not as cluttered, you can click on the names of the different ones you want to turn off. And you'll be left with just the one device on the screen. Conversely, you can turn these back on if you want to.
Basically, you would go through and define all of the ones you want to pick for your system. Let's pick...actually, this would be a good candidate to do the dual device. ISL85033 is a dual. So if you're doing the dual here, then the secondary rail has to also be the same part. Otherwise, you would get an error. And the LDO supply, we had a couple options for that part as well. ISL8102, ISL8103, and ISL8111 too. Just leave it with that one.
So once you're done, you basically have an overall of your system. You can look at your overall system efficiency and power dissipation of the total system. You can make adjustments to each rail. So if your light load was more four amps and your typical load was more like 12 amps, you can make those adjustments and you can see how that affects the overall system efficiency at those key design points.
So once you have all that done, the next thing would be to generate a reference design. I'll do that here next.