You Need a Power Supply Designed by When?

Editor's note: Scott Deuty will be bringing us a series that will help designers in their selection of online, web-based design solutions for power designers.

You’re in a small company that needs to turn a product quick. Nobody in the company has any power supply design experience yet you need to drive LEDs from a universal (US and European) wall input voltage. What do you do?

I put myself in that scenario and searched Google for “free power supply design software”. A host of responses came up. In fact, there were so many options, I decided to break this blog into parts. Part 1 will be listing the summary of the first two pages from the Google search. Later parts will be a synopsis of the user experience. I feel that this will allow me to give the best information to the reader. It will also enable responses to shape future analysis. Let’s face, it, the Google gods have a way of keeping the best information from us due to their roving algorithm. So if your company’s power supply design software doesn’t appear, please contact me so that I can insert it into the mix. Also, there are some excellent purchasable design software packages out there as well and I’ve used some of them for decades. I’d like to figure a way to look at those too without having to buy the latest version. So if you have suggestions, again please let me know.

Power is a custom market for the most part. Although canned designs do exist, power has never really been standardized. The closest we got were module manufacturers and applications circuits that are curtailed to high volume applications. For the most part these solutions work fine. Still, there exists an element of meeting a spec, footprint, and cost that often drives us to have to create a design or modify an existing application. These blogs target that particular audience. Furthermore, the interest of schedule means that being able to simulate immediately from your computer saves time filtering and choosing hardware or waiting for your applications support to respond.

Because our design is offline, there will be isolation and safety considerations to take into account. A lot of these requirements complicate the design especially for those experiencing it for the first time. I like the challenge associated with the offline source especially since it’s the most common input. Automotive 12V and USB 5V are gaining in popularity as source voltages. While this increases the customized power market further, there will be enough to cover with a universal AC input.

As mentioned in the opening, we are trying to drive LEDs. I wanted to see which packages had an LED solution from the beginning. PowerESim actually had two versions that drove LEDs (Figure 1). I chose the LED driver with PFC figuring that would be a common requirement. Also, the circuit actually solved two problems, power factor correction and driving the LED.

Figure 1

The PowerESim Software has an LED Driver with PFC Readily Available

The PowerESim Software has an LED Driver with PFC Readily Available

As expected from my years in power electronics, a flyback circuit resulted (Figure 2). In addition to that, a number of simulation option links appeared. Many of the software packages have these features so they offer somewhat of a comparison category for us to use when judging the software. These categories include:

  • Loss
  • Thermal
  • Dvt report
  • Life and MTBF
  • Loop and Stability
  • Harmonic
  • Monte Carlo
  • Waveform
  • Magnetic Builder
  • BOM and Vendors
  • Comp Builder
  • Report Builder
Figure 2

The PowerESim Flyback Schematic with the Simulation Option Links Listed on the Left Side

The PowerESim Flyback Schematic with the Simulation Option Links Listed on the Left Side

For some of these packages, I only met with frustration. I won’t mention who however I jumped through a bunch of hoops registering and wasting time only to find out the software didn’t support my browser. I understand the need for registering to gain access however to me, free is free. I don’t want to leave you my information to use your software. If there is business to be had, it will be when your solutions works to a point where I buy your product.

SMPS Power Design’s Raptor tool did offer me separate options to design a PFC and a DC to DC converter however it didn’t let me design the entire system quickly as I needed to.

The Ridley Power 4-5-6 software did allow me to download a demo however it fixed the output voltage and current at a level that was different than I needed.

Schmidt-walter has a design tool that lets you design a flyback circuit. However it doesn’t allow one to create a PFC front end or power LEDs with a constant current like we need to.

LTSPICE was another option however they didn’t have a direct LED driver design tool that popped up in the initial search. I’ll have to dig a little to see if they have a canned circuit to use that designs the circuit to the level of the others.

Fairchild was another option for a canned design to drive LEDs offline with power factor correction incorporated into the solution (Figure 3). Although I had to register for the Fairchild site, it did allow me to continue with evaluating my design while using Google Chrome as a browser.

Figure 3

Fairchild's Power Supply WebDesigner Offers an LED Lighting Design with an Isolated PFC Flyback

Fairchild’s Power Supply WebDesigner Offers an LED Lighting Design with an Isolated PFC Flyback

What I liked about the Fairchild tool was that it gave me the option of determining how many LEDs to run in series on the output (Figure 4)

Figure 4

The Fairchild Software Allows You to Select the Number of LEDs You Desire to Power

The Fairchild Software Allows You to Select the Number of LEDs You Desire to Power

Part 1 of our blog is complete. What started out as wanting to design for a specific application of powering LEDs offline has resulted in two software packages to evaluate. In the next blog, I will take these products for a spin to see what materializes. From there, I’d like to expand this evaluation to more power electronic applications. Again, the world of power design is wide and varied. If your software didn’t apply to this particular application, there may be another opportunity in the future. Stay tuned.


  1. PowerEsim website design
  2. SMPS Power Design
  3. Ridley Engineering Power 4-5-6 design software
  4. schmidt-walter offering for a Fly-back Converter
  5. Fairchild Webdesigner users guide
  6. Fairchild Webdesigner website

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