Interview with Dave Divins

Featured Engineer

Dave Divins

Dave Divins - Senior Field Applications Engineer, International Rectifier

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

I started out with an interest in computer science. When I was 13, I took a test and got into Thomas Edison Technical and Vocational High School, with the intent of studying computer science. I was first required to take courses in basic electrical circuits, and I excelled. Then I took the computer science courses. However when I got into computer science, I felt like the classes were too hard and realized my interest lied in engineering. That’s when I decided that I would become an engineer.

From there I went to the City University of New York. At City College I found that analog was one of my favorite subject areas, so I focused on electromagnetics and analog in school. I got my BEEE at City. Then I got a job at GE Aerospace as a hardware engineer and went for my master’s in the Electrical Engineering at Binghamton University.

What kind of work did you do at GE?

I was doing power supply design, IC design, and system architecture definitions for flight and engine control systems on aircraft. The flight control systems that I worked on went into F-18, A-10, and F14. The engine control system that I worked on included the T-700 engines use on Apache helicopters and the CFM56 family of aircraft engines.

Where did you go after GE?

I went to Ford Electronics, which is now Visteon, and I was working with suppliers defining and qualifying analog ICs used in Ford vehicles. Visteon designs and manufactures automotive systems and components. Its divisions include interiors, driver information, in-car entertainment, and climate control. I worked there for two years and then went to work in software at Analogy, which is now Synopses, supporting the Saber Simulator. I was the application engineer for them creating demos, teaching classes and providing tech support for Saber. I was working on anything to do with DC motors, valves, or anything electromechanical—in order words, anything that could be simulated with Ordinary Differential Equations. I continued to work there for about six years. Then I started to work for International Rectifier in June 2000, and I have been here ever since.

Are there any particular product lines that you cover?

I cover everything in IR’s commercial product offering, MOSFETs, IGBTs, general purpose high voltage gate driver, inverter modules, special purpose high voltage gate drivers for lighting, motor drives, and Class D audio amplifiers. Also cover Intelligent Power Switches targeted for automotive applications and micro-electronic relays. In recent years I’ve been working with a portfolio of point of load solutions for powering Digital Cores, FPGAs, graphics IC’s and the like.

Can you tell us more about the product lines at IR?

Our big claim to fame is the two-sided cooled MOSFET called DirectFET®. This is a MOSFET that is packaged in copper can. The two sided cooling allows you put the heat sink on the top and bottom of the MOSFET. This can’t be done with traditional encapsulated MOSFETs. The die of the DirectFET® is exposed, sort of like chip scale packaging and the top is a copper housing that the die is attached to. This is something that is pretty unique to IR. We have the patent on it . The market for this product is everywhere.

Does IR have dev kits and boards?

If you go to our website, there is a whole section dedicated to referenced designs and demo boards. It includes boards for motor drives, Class D Audio Amps, LED lighting, Point of Load converters, Isolated Power Supplies. IR is known for its prowess in high voltage power solutions.

Also, we were the first ones with the inverter modules that are now in all of the major washing machines in the world.

What are your favorite hardware tools that you use?

Tektronix TDS3014 Oscilloscope. It’s simple and gets the job done.

What are your favorite software tools that you use?

SPICE and Excel. I like to use the 800-pound gorilla, LT Spice for quick simulation. IR has permission from Linear Technology to use it, and it is a great and really easy tool to do a quick simulations.

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

IGBT failures in a SR motor drive. The boot strap caps voltage dropped to just above the under voltage lockout of the gate driver during a pause period, and low transconductance IGBTs blew. The solution was to add a boot strap capacitance refresh pulse in the software just before the PWM sequence resumed. This took a while to diagnosis and was found using simulation.

What is on your bookshelf?

Over the past few years the Internet has become my bookshelf.

Do you have any tricks up your sleeve?

Always analyze and/or simulate before you commit to hardware.

What has been your favorite project?

Defining an LED IC that my company put into production. At one point there was a lack of a high voltage, efficient, non-isolated LED driver solution on the market. Thus I wrote a preliminary spec for a hysteretic high voltage sync buck MOSFET driver. This spec was used to develop the IRS25401 gate driver.

Do you have any note-worthy engineering experiences?

Designing an Active Clamp Forward power supply using a high voltage sync buck controller IC. I designed the power supply using simulation. First I had to model the high voltage Sync-Buck driver (IR3651) in Spice. Then use it along with models of other analog power components (discrete and IC’s) simulation the entire supply. I had the board laid out and, with only a few modifications; we had the power supply working. It was a 48V->12V@100W supply.

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

Because of the world energy situation, growth in energy efficient products should continue for the foreseeable future, thus leading to continued growth in our market segment.

What challenges do you foresee in our industry?

Component suppliers are required to provide a larger part of the customer’s solution than before. This requires a significant amount front end support on our part before the customer actually puts their end product into production. We get involved in the design including schematic and layout reviews. We sometimes have to develop software for our motion products. We have to maintain product specific application design tools. Provide reference designs including bill of materials and layout files. We sometimes have to get involved with EMI and UL certifications. In general there is more burden put on the component supplier than ever before.

Visit David's EEWeb Profile

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