Milestone-Proposal:First Integrated PWM Controller for Switching Power Supplies

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Docket #:2008-21

This Proposal has been approved, and is now a Milestone Nomination

This is a draft proposal, that has not yet been submitted. To submit this proposal, click on "Edit with form", check the "Submit this proposal for review" box at the bottom, and save the page.

Is the achievement you are proposing more than 25 years old?

Is the achievement you are proposing within IEEE’s fields of interest? (e.g. “the theory and practice of electrical, electronics, communications and computer engineering, as well as computer science, the allied branches of engineering and the related arts and sciences” – from the IEEE Constitution)

Did the achievement provide a meaningful benefit for humanity?

Was it of at least regional importance?

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)?

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony?

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated?

Has the owner of the site agreed to have it designated as an Electrical Engineering Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

First Integrated PWM Controller for Switching Power Supplies

Plaque citation summarizing the achievement and its significance:

In what IEEE section(s) does it reside?


IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

IEEE Organizational Unit(s) arranging the dedication ceremony:

IEEE section(s) monitoring the plaque(s):

Milestone proposer(s):

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates of the intended milestone plaque site(s):

Texas Instruments, North Campus, 13532 North Central Expressway, Dallas, TX 75243

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need.

The milestone plaque would be installed outside the SC Building that has other TI landmarks installed. The outside location is chosen so that anyone at the building can easily see the milestone and its significance.

Are the original buildings extant?


Details of the plaque mounting:

How is the site protected/secured, and in what ways is it accessible to the public?

The building is one of many at TI’s North Campus in Dallas, Texas, which is guarded electronically and by booths staffed with security personnel. The public can enter the campus after showing personal identification.

Who is the present owner of the site(s)?

Texas Instruments Incorporated

A letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property:

A letter or email from the appropriate Section Chair supporting the Milestone application:

What is the historical significance of the work (its technological, scientific, or social importance)?

This invention is of significant technological importance as it revolutionized the technology of power supply design, ushering the industry into a conversion from large, heavy, and very inefficient linearly controled designs, to high-frequency switching solutions, a technology known before the advent of the SG1524, but ignored by all but the most sophisticated designers due to the perceived high cost, extreme complexity, and poor reliability – all of which disappeared with the introduction of the SG1524. </p> </p> </p>

With this product, switching power supplies became ubiquitous and pervasive throughout all forms of electronic systems, doing for electronic power supplies what Jack Kilby’s invention of the integrated circuit did for computing systems. What obstacles (technical, political, geographic) needed to be overcome? Switching power supplies, also known as switchers or switched-mode power supplies [SMPSs], were being built using discrete components at least as far back as the 1950s. And by the early 1970s, some of the individual analog and digital functions needed to perform PWM—the control technique commonly used to regulate the output of the switching power supply—were becoming available as separate individual ICs. But as stated above, the challenge of incorporating these functions onto a single chip led to the need for circuit innovation and invention for almost each functional block. New circuit designs that had to be invented included: 1. An accurate timing clock that could be free running or externally synchronized 2. An anti-saturation circuit that allowed faster switching in a non-digital process 3. An under voltage lockout circuit to allow analog control of digital thresholds 4. A latching comparator for stable PWM insensitive to switching noise 5. A new temperature compensated voltage reference device 6. And the combining of these functions into a single circuit requiring only 16 package pins. There was also the internal political obstacle of obtaining the needed company product development resources for a product for which there was no demonstratable market potential. But with this product, switching power supplies became ubiquitous and pervasive throughout all forms of electronic systems. The SG1524 led to a plethora of follow-on product designs, many of them also pioneered by Mammano and the design team that he headed. In addition, the SG1524 was also duplicated by many other semiconductor companies, becoming one of the most widely copied designs in semiconductor history. The current power management industry has reached $20 billion annually and has been growing at a pace of 20-30% a year. The use of PWM controllers are intertwined with the modern electronics industry, and have enabled a wide range of products, including applications in: • All types of power supplies for electronic equipment • Digital computing and data processing hardware • Radio, television, and other consumer entertainment products • Electronic controls for military and aerospace applications • Modern-day automotive systems and accessories • Telecommunications equipment • Medical electronics


• High efficiency controls for alternate energy sources What features set this work apart from similar achievements? The SG1524 PWM controller IC was unique in its time as the semiconductor industry was then heavily involved in the advancement of digital computing circuits and what analog efforts there were, were largely relegated to operational amplifiers and linear voltage regulators. At that point, the semiconductor industry was committed to two separate processes – a gold-doped, high-speed digital process and a slower, more difficult to control analog process that had to be carefully separated from the digital manufacturing line. Because the control of switching power supplies required both analog and digital functions, the biggest challenge of the time was the combining both functions into one chip to be built with a single process, and the introduction of the SG1524 was one of the first practical examples to prove that this was possible.

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Robert Mammano’s seminal IC design of the SG1524, and the many variations it inspired, tamed the complexity of SMPSs, shrinking their size and making them cost-effective and more reliable in countless applications. References to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or citations to pages in scholarly books. At least one of the references must be from a scholarly book or journal article. Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.