Interview with Jim Marinos

Featured Engineer

Jim Marinos

Jim Marinos - Executive VP of Engineering and Marketing at Payton America

How did you get into electronics/engineering and when did you start?

I started in electronics when I was about 10 years old. I always liked electronics and mechanical parts, and since I was a child I always enjoyed taking things apart.

When I started in college, I took all of the general math and science classes and realized I would like to specialize in electrical engineering. I have a bachelor’s in electrical engineering from Pratt Institute in Brooklyn, NY. After graduating with an electrical engineering degree, I really had no idea what I was going to do until I got my first job.

My first job after graduating was at Bell Labs in New Jersey working with switch mode power supplies. I worked there for a couple of years, and then moved on to a couple of similar companies, until ultimately landing a job at Payton American, Inc. For 22 years or so, before joining Payton, I designed or managed a group of engineers, working with power supplies up to 10kWatts.

Can you tell us more about your work history?

I have been involved in the design and development of switch mode power systems for military applications and magnetic designs since 1982.

I started to work for Payton American, Inc. in 1998 as Director of Marketing. Since then the business has transformed. In my present position, I manage all aspects of business activities including sales, marketing and engineering, hiring and training of technical representatives in North and South America, as well as developing new major accounts and negotiating sales contracts.

Prior to this job, I was the Director of Engineering for Lambda Novatronics (now GE Aerospace) and held design positions with Ceag, Bell Labs, and Superior Manufacturing.

What other activities have you been involved in outside of work?

I am serving on the Board of Directors of the Power Sources Manufactures Association (PSMA) as the Vice President. I am also a Senior Member of IEEE and have been an IEEE member for 31 years, serving on a panel to review Senior Member Applications in 2011, as well as serving as Session Chair for the last five years at APEC lectures.

I have written numerous technical papers on switch mode power supplies and planar magnetics.

What is the hardest/trickiest bug you have ever fixed?

Designing a power supply with extreme requirements for radiation tolerance. This power supply was designed to withstand high levels of radiation in space. All the testing was performed at the White Sands Nuclear Range in New Mexico. I spend 2 weeks at the lab performing all kind of radiation testing on the power supply until it met all the requirements. The challenge was to make something work without knowing a lot of the details due to the secret level.

What is on your bookshelf?

Electronics and magnetics textbooks and a lot of reference materials

What are your technical expertises?

Technical design expertise in the design of switch mode power supplies up to 1 MHz switching frequency.
Military designs of modular switching power systems for EMP and nuclear environments.
Magnetics design, from 47 Hz to 1 MHz and 1 VA to 10,000 VA.

What do you like most about what you do?

I enjoy solving problems, talking to other engineers, and getting to learn new material and processes.

Can you tell us a little about Planar Transformers?

They have no wires. We use PC boards and copper stampings to make the turns. For example, if you need 10 turns, instead of having 10 turns of wire, you can make turns on the PC board. For the high current, we use copper stampings, so we can do 1,000 amps in strictly copper and it is flat. The benefit of being flat is the simplicity of electromechanical connections and thermal transfer. Planar magnetics is what I call solid-state magnetics. We typically have 2 to 18 PCB layers in the planar transformers, depending on the number of turns and windings. The PCB’s and the copper stampings are combined in order to create an optimum efficient design. We have our own PCB board house so we can engineer and produce small runs, but for the high volumes, we produce them in the Far East. They are not your normal PCB because they are using heavy copper, so it has to be a special house to handle the heavy copper. The amount of thickness of the copper is chosen based on the switching frequency and is crucial to minimize the skin effect and the losses of the transformer.

Efficiency of all of our planar magnetics depends on the output power level, switching frequency and thermal cooling; the higher the power, the higher the efficiency of the planar. We can go up to 99.8 percent and as low as 95 percent. So for about 100 watts, the efficiency will be 95 to 97 percent, and for the high power, it can go up to 99.7 percent. The efficiency compared to conventional magnetics is much higher. Efficiency plays a major role on the MTBF, mean time between failures, of a power supply. The cooler the internal area the higher the life of a power supply.

In many cases, the cost of a planar transformer can be lower than the cost of a conventional transformer. The most important point when it comes to cost is the overall cost of a transformer. A planar transformer is typically a drop in part with minimum manufacturing involvement.

In what applications do you find these transformers?

You can find them in pretty much everything that has a switch-mode power supply and does not utilize any air flow. A good example is all the automotive applications. The environment is extreme, with little cooling and high vibration levels. You can find them in space on many satellites and spacecrafts. You can find them in welding machines and portable charges. You can even find them in power supplies that supply power to flat screen TV’s.

Do you do custom designs?

98 percent of our business is custom work. We produce very few off-the-shelf transformers. The power supply business is so unique; everyone designs differently, which is why our designs have to be custom.

Typically we will get a design request, and will respond within 24 hours of the initial request. There is no charge for doing the design and the proposal. Samples can be available in few weeks.

Our library has more than 100,000 parts, so if someone calls for a custom design, we use materials we have. It is like a kit that we put together using the materials in our inventory, so customers end up with a custom design using standard parts.

A lot of times people look for planar transformers when they have height restrictions. Our transformers are also about four to five times lighter than a conventional transformer. The main reason for that is because heat is removed by conduction, not by air flow, which automatically makes the part much smaller.

Are your transformers used for more than just power supply designs?

We primarily design power supply transformers. Our transformers go up to about 1 MHz in frequency for power supplies.

What direction do you see your business heading in the next few years?

Everybody is looking for a green design, which means more efficient, smaller, and lighter designs that push the engineers to use planars to achieve those goals. It is not a solution to everything, but it can be a big step toward achieving the “green” goals.

What challenges do you foresee in our industry?

I feel that cost of materials and availability is going to become a very big issue in the future.

The business is expanding; planar transformers are becoming the key to a lot of different applications. Particularly in the last few years, they have had a large effect on automotive technology. Our military design background significantly helps with impacting the automotive industry—there are a lot of regulations in both the automotive industry and the military. They do have similar designs, the induction cool with no air flow. The cost of the magnetics is a fraction of the military cost systems because of the volumes, but the design principles are the same.

Where can we read more about Planar Transformers?

You can get more information here.

Visit Jim's EEWeb Profile

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