ISSUE: February 2020


To ensure receipt of future issues, please add to your address book. Visit



» GaN-Based Wireless Power Enables Efficient, Seamless Multi-Device Charging

» Transmitting Overpower Alert Signals With Low Latency Boosts Reliability Of Bus-Bar Power Lines

» More-Efficient Boost Converter Extends Battery Life For Wearable Medical Patches

» New on
Power Supplies for Industrial Applications
FAE Confidential

» Focus On Magnetics:
Debunking The Gapped Inductor Myth

» Spotlight On Safety & Compliance:
FAE Confidential Power Factor Correction (Part 1): Why We Need It And How It Evolved

» New Power Products

» Other Top Power News

From the Editor's Desk

David G. Morrison
Editor, HOW2POWER TODAY       

For most of its applications, the main goal of wireless charging is simple — make charging easier, if not effortless. That simple objective leads to many challenges and complexities, both technical and market-related. In this issue, an article by Dan Costinett and his colleagues at the University of Tennessee discuss their work in developing a wireless power transfer system that overcomes some key limitations of existing wireless power designs such as limited power levels, low efficiency and lack of spatial freedom. The authors describe in detail the design of a single transmitter, multireceiver wireless charging system for use in a work station. Their prototype system supplies 100 W to five loads over a large charging area, while achieving >90% full load efficiency. Innovative coil design, use of GaN FETs, and a streamlined power architecture are among the techniques these researchers applied to achieve their goals. Others in industry may be pursuing similar paths as they attempt to deliver the benefits of wireless charging to both existing and new applications. No doubt some of these applications will be in industrial settings, and in this issue of the newsletter, we introduce How2Power’s new section on Industrial Power Supplies, which presents information on the companies that make them, where they are used, and the latest new products. This issue also presents a new installment of FAE Confidential, and articles on transmitting overpower alert signals over bus-bar power lines, a boost converter for wearable medical patches, a debunking of the gapped inductor myth, the origins of our power factor correction requirements and much more.


GaN-Based Wireless Power Enables Efficient, Seamless Multi-Device Charging

by Daniel Costinett, Jie Li, Jingjing Sun and Peter Pham, The University of Tennessee, Knoxville, Tenn.

At present, commercial implementations of wireless power transfer (WPT) are largely limited to low power, low efficiency, and a charging paradigm where each device must be well aligned with a dedicated charger. This approach fails to capitalize on the promise of spatial freedom and effortless, pervasive charging which makes WPT attractive. In this article, the authors describe the design of a WPT system for a workstation in which a single transmitter seamlessly charges electronic devices of varying power levels, simultaneously, when placed in arbitrary coplanar positions above a 0.5-m x 0.5-m charging area. This work, in collaboration with Power America, leverages the capabilities of GaN transistors to enable new design paradigms for WPT systems. Read the article…

In the proposed WPT system, a transmit coil design provides
uniform coupling to multiple receiver coils, while use of
high Q coils and a streamlined power architecture increase
the system’s high power conversion efficiency.

In a dc bus-bar power distribution system,
hot swap controllers can isolate a faulty
node that’s experiencing an overcurrent condition.
But additional components will be needed to maintain
regulation under fault and while signaling the system
to throttle back on power consumption.

Transmitting Overpower Alert Signals With Low Latency Boosts Reliability Of Bus-Bar Power Lines

by Viktor Vogman, Power Conversion Consulting, Olympia, Wash.

For server racks with dc bus-bar power distribution, the power supply is usually sized for a full-rack configuration running software that generates the highest power consumption. Such overly conservative power delivery architectures present an opportunity for significant reduction in power supply size and cost. For example, when operating in a failure/nonredundant mode, smaller power supplies can detect an anomalous excessive power condition and then generate a fast interrupt in the form of an overpower alert that signals to the servers to throttle back until the redundancy gets restored and/or power comes back into an acceptable range. This article presents a study of the conditions necessary for reliable transmission of overpower alert signals across a dc bus-bar power delivery network (PDN) in a high-power server rack. It also introduces a simple technique for broadcasting the alert logic signal across such PDNs with a small transmitter/receiver and with minimal latency in node throttling. Read the article…

More-Efficient Boost Converter Extends Battery Life For Wearable Medical Patches

by Eddie Lee and Nazzareno (Reno) Rossetti, Maxim Integrated, San Jose, Calif.

With their ability to continuously record and transmit a patient’s state of health, wearable medical devices are transforming the healthcare industry. But these devices pose some difficulties in power management. This article reviews the challenge of powering a wearable medical patch placed on a patient’s chest while meeting the requirement to operate for five days on a single disposable zinc-air battery. When regulated by a typical boost converter, the battery voltage fails to meet the device operating time requirement. However, when powered by a high-efficiency, low-quiescent boost converter such as the the MAX17224, the same device meets and exceeds the five-day runtime demand. Read the article…

In this medical patch, the sensors
collect data for 4 sec, which is then
transmitted in 100-ms bursts by the
radio to a centralized receiver.


Power Supplies for Industrial Applications

This section presents information and resources to help designers select and evaluate power supplies for industrial applications, which typically feature challenging or unusual electrical, mechanical and/or environmental requirements along with demands for high reliability and long operating life. These power supplies find use in areas such as industrial/factory automation; railway; ships; industrial vehicles and construction equipment; energy generation, power utilities and power distribution; mining; oil & gas; medical equipment and scientific research.

Visit this section

FAE Confidential

In this latest installment of FAE Confidential, the authors continue to discuss how the role of semiconductor FAEs has changed over the years. How and why did the role change so radically? Here in part 2 of their series the authors attempt to answer that question by examining the period when companies began to question the value of their FAEs.

Read The War On FAEs (Part 2): New Management Brings Benign Neglect

Sponsored by Payton Planar Magnetics
A monthly column presenting information on power magnetics design, products, or related technology

Debunking The Gapped Inductor Myth

by Gregory Mirsky, Vitesco Technologies, A Spinoff Of Continental Automotive Systems, Deer Park, Ill.

While browsing the Internet, the author recently discovered that many engineers do not treat gapped magnetics correctly: some state that an air gap increases the saturation flux density, others say that inductors based on an air gap in the magnetic core store energy in the gap only. Neither statement is true because the gap in the core just lowers the core’s effective permeability, leaving the core material saturation flux density intact. And the energy is stored in the whole gapped magnetic, with the energies stored in the gap and the rest of the core in reverse proportion to the permeabilities of air and the magnetic material. Sometimes, the energy stored in the core may be substantial. Anyway, we have to deal with all possible cases of magnetic energy storage distribution over the gapped core as will be explained and illustrated in this article. A new approach to designing gapped-core inductors is also presented. Read the full article…

Sponsored by Power Integrations
A monthly column discussing standards and regulatory requirements affecting power electronics

Power Factor Correction (Part 1): Why We Need It And How It Evolved

by Kevin Parmenter, Chair, and James Spangler, Co-chair, PSMA Safety and Compliance Committee

The application of power factor correction (PFC) in switched-mode power supplies is well established and the circuits used to implement active PFC are widely known. Along with knowledge of PFC circuits and components, many engineers likely have an awareness of the PFC standards that govern product compliance. But when it comes to why these PFC requirements are in place and what were the industry or market conditions that drove their adoption, the record is not so clear. Here in part 1 we review the history of how PFC evolved and the technical requirements it produced. This discussion includes a review of the IEC 61000-3-2 power factor standard and the limits it imposes on harmonics generated by non-resistive loads, and where PFC is currently required. Read the full article…


Power Integrations’ SID1181KQ
SCALE-iDriver gate driver.

Highly Robust Gate Drivers Achieve AEC-Q100 Automotive Qualification

 Photo: This single-channel IGBT and MOSFET driver has reinforced galvanic isolation provided by the company’s FluxLink technology. The device’s 8-A peak output enables it to drive IGBTs and MOSFETs up to 600 A (typ.) without any additional active components. The driver targets EV power trains and on-board chargers as well as charger stations and other high reliability drivers and inverters.

See the full story…

Renesas Electronics’ ISL78083
automotive camera PMIC.

PMIC For Automotive Surround View Camera Systems

 Diagram: The highly integrated automotive camera power management IC accepts direct-from-battery (36-V to 42-V) or power-over-coax (15-V to 18-V) supply sources and generates multiple supply rails with up to 750 mA per output. This power level offers ample headroom for existing image sensors up to 7-megapixel and future sensors with even higher resolution.

See the full story…

Infineon’s CoolMOS PFD7 series
superjunction MOSFETs.

600-V Superjunction MOSFETs Enable High Power Density

 Photo: According to the company, its CoolMOS PFD7 product family of superjunction MOSFETs offers up to 1.17% efficiency increase compared to its CoolMOS P7 product family, which leads to a power density increase of 1.8 W/in3. CoolMOS PFD7 pushes the SJ MOSFET technology to lower conduction and charge/discharge losses as well as reduced turn-off and gate-driving losses.

See the full story…

More Power Products. . .

Rad Hard Regulator Integrates Synchronous Buck And LDO For Satellites

Battery Charger Is Explosion Proof

600-V Input DC-DC Converters Deliver 5 kW

Robust Gate Drivers For Fast Switching SiC Power Modules


The PSMA Energy Management Committee will host an APEC 2020 industry session titled “Not Knowing the Rules Can Ruin Your Power Converter Design”, which hits on stumbling blocks to product success. Time-saving databases covering global energy efficiency and safety & compliance standards and regulations will also be introduced. Meet How2Power columnists, Jim Spangler and Kevin Parmenter in this session.

Renesas Electronics’ ISL91301B power management IC has been adopted in Google Coral AI products including the Mini PCIe Accelerator, M.2 Accelerator A+E Key, M.2 Accelerator B+M Key, and System-on-Module.

On April 21, the Components for Military & Space Electronics Conference & Exhibition (CMSE) will present tutorials on: “Thermal Materials Developments, Thermal Materials Testing, and Thermal Systems Key Solutions for Mil/Aerospace Electronics Systems,” “Capacitor Reliability Seminar” and “Volatiles Control in Hermetic Electronic Components”.

Silanna Semiconductor has announced that its SZ1101 and SZ1105 active clamp flyback controllers for high-power-density ac-dc adapters are now fully qualified and in production.

ARPA-E has announced funding opportunity announcements for four new programs funding new technology development for electric aviation, feedstock monitoring, and carbon storage technology, as well as an opportunity to scale energy technology.