ISSUE: April 2019


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» Using A Four-Switch Buck-Boost Bidirectional DC-DC Converter For Battery Backup Applications

» Zero-Drift Precision Op Amps: Measuring And Eliminating Aliasing For More Accurate Current Sensing

» How Ultra-Low IQ Boost Converters Extend IoT Device Runtime

» Configurable IC Simplifies Control Of Animated LED Turn Signals

» Focus On Magnetics:
How To Optimize Turns For Maximum Inductance With Core Saturation

» Spotlight On Safety & Compliance:
Pre-Compliance Testing Is Necessary For All Products

» New Power Products

» Other Top Power News

From the Editor's Desk

David G. Morrison
Editor, HOW2POWER TODAY       

The APEC 2019 conference held last month in Anaheim drew a record 6200+ attendees to discuss a broad array of issues in power electronics. That so many participated is testament to the hard work that has gone into building this event over the years and to the vibrancy of the industry. For several years now, wide-bandgap semiconductors have had a high profile at the conference and each year there are more signs that SiC and GaN power devices are entering the mainstream. The startup era seems to be ending in that now all of the mainline silicon power semiconductor manufacturers either have SiC and/or GaN in their portfolios or have indicated plans to add them. Nevertheless, while the wide-bandgap discussions and developments still grab attention, the tide of power semiconductor innovations may be shifting back to the IC realm where both startups and established companies are developing new power topologies, architectures and circuit solutions. Many of the new devices continue the practice of modifying the familiar flyback and buck converters, and even linear regulators, but do so by combining them with charge pumps and other elements. Innovation in controller design can take some unexpected turns such as one startup’s use of artificial intelligence to enable soft switching of inverters. Among the new devices, some approaches eschew elegant circuit design in favor of extreme but seemingly manageable complexity. Some leverage their abilities to pack more silicon and passives into tiny molded packages, demonstrating the importance of packaging design. You can read about some of these developments in this month’s Power Products news and observe other IC-level innovations in this month’s design articles. This issue also brings further discussion of magnetics design, safety & compliance and more.


Using A Four-Switch Buck-Boost Bidirectional DC-DC Converter For Battery Backup Applications

by Bosheng Sun, Texas Instruments, Dallas, Texas

In this article, the author discusses a dc battery backup system employing a bidirectional dc-dc converter based on the four-switch buck-boost topology. This article begins by reviewing the requirements for a battery-based backup power supply system and explains why the four-switch buck boost converter is well suited to this application. After a quick summary of how the converter’s switches operate under a basic control scheme, a more elaborate six-mode control scheme to achieve high efficiency is described. New challenges caused by the six-mode control scheme such as how to drive the high-side MOSFET with 100% duty, how to transition smoothly between modes and how to optimize loop compensation are also discussed. This is followed by a brief discussion of how this control scheme can be implemented using the UCD3138 digital controller. Read the article…

The multimode control algorithm described
here includes six operating modes.

The chopper-stabilized architecture
periodically measures the input offset
voltage and corrects the offset at
the output.

Zero-Drift Precision Op Amps: Measuring And Eliminating Aliasing For More Accurate Current Sensing

by Farhana Sarder, ON Semiconductor, Phoenix, Ariz.

Zero-drift precision op amps are specialized op amps designed for applications that require high output accuracy due to small differential voltages. Not only do they feature low input offset voltage, but they also have high CMRR, high PSRR, high open-loop gain, and low drift over temperature and time. These features make them ideal for applications such as low-side current sensing and sensor interface. While manufacturers of zero-drift op amps sometimes claim that these devices are free from aliasing effects, in reality, they may in fact be vulnerable to aliasing since these devices use sampling to minimize the input offset voltage. Therefore designers should test their op amp circuits for aliasing. This article presents an effective method for doing so and applies this method to observe differences in aliasing produced by different implementations of zero-drift op amps. Read the article…

How Ultra-Low IQ Boost Converters Extend IoT Device Runtime

by Reno Rossetti and Tom Bui, Maxim Integrated, San Jose, Calif.

Common characteristics in internet of things (IoT) devices include small form factor and the need to operate for long periods of time without consuming too much power. In consumer electronics, boost converters are commonly used to raise and stabilize the sagging voltage of their lithium-ion batteries under load. In this article, we’ll discuss a typical IoT power management solution for small, portable gadgets, as well as its shortcomings. We will then introduce a boost converter, the MAX17222, which addresses these shortcomings while also providing the ability to operate down to minimal amounts of residual battery energy. Read the article…

This boost converter’s True Shutdown
feature disconnects the output from the
input with no forward or reverse current,
resulting in very low leakage current.

The SLG46620 CMIC generates the
digital signals to drive the turn-signal
LEDs through the MOSFETs.

Configurable IC Simplifies Control Of Animated LED Turn Signals

by Muhammad Saqib and Aamir Hussain Chughtai, Dialog Semiconductor, Lahore, Pakistan

Many automotive manufacturers now provide indicator lights (turn signals) with animated LED patterns to enhance the aesthetics of these lights and to create a “trademark” look that distinguishes their vehicles. The animations can be implemented without an MCU but typically require several discrete ICs. These control components are used in combination with an LDO regulator and one or more automotive LED drivers. An alternative approach to generating the LED control signals based on the SLG46620 configurable mixed signal IC (CMIC) is presented here. The configurability of the CMIC provides a high level of flexibility, which allows a supplier to cater to the varying requirements of several manufacturers without any change in hardware design. Moreover, this approach achieves significant reductions in the PCB footprint and the bill-of-materials cost. Read the article…

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

How To Optimize Turns For Maximum Inductance With Core Saturation

by Dennis Feucht, Innovatia Laboratories, Cayo, Belize

Some inductor applications require a minimum inductance over the full current range of inductor operation. As current increases, saturation increases and the saturation factor, ksat, decreases from 1 at zero current. The typical inductor operating range of ksat in power applications is 0.8 to 0.5. As turns, N, are increased, inductance, L, increases by N2, but so does saturation, causing ksat to decrease. N has an optimal value, Nopt, at maximum L because increasing saturation progressively decreases L with increasing turns (as Ni increases) while the turns themselves increase L. If the saturation curves decrease faster than N2, then adding more turns decreases inductance. So in essence, finding the optimum number of turns (and achieving max inductance) means finding the maximum number of turns that can be wound on a core before inductance starts to decrease due to saturation. Therefore to solve for the optimal operating-point, we need an equation that models core saturation. Read the full story…

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

Pre-Compliance Testing Is Necessary For All Products

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

For some companies, pre-compliance testing may seem like a source of unnecessary expense or extra steps in an already time-constrained product development schedule. Or it may be something they’ve given no thought to at all. But when the risks associated with not performing pre-compliance testing are considered, it becomes clear that pre-compliance testing is a means of avoiding unwanted increases in product development cost. Pre-compliance testing alerts the design, engineering management and marketing teams that an issue may be lurking in the weeds and informs them of the potential problem before the product ships. By applying pre-compliance testing prior to production, excessive redesign costs, and production delays can be avoided. Read the full article…


Murata Manufacturing’s
MYMGA1R86RELC2RA dc-dc converter.

6-A Buck Converter Achieves Tiny Size, High Efficiency Using Novel Architecture

 Photo: This point-of-load converter produces a programmable output of 0.7 V to 1.8 V at up to 6 A in a package measuring 12 mm x 9 mm x 2 mm. This footprint is said to be 25% less than that of the nearest competitor.

 Diagram: The converter uses a two-stage architecture that combines a “pipeline” stage switched-capacitor network (charge pump) with a buck stage.

 Photo: Using a charge pump to stepdown the 12-V input to 4 V, allows use of low-voltage MOSFETs in the buck, which improves efficiency while also supporting the use of higher switching frequencies.

See the full story…

Pre-Switch’s 3-phase gate-drive solution.

Gate Driver Uses AI To Bring Soft Switching Benefits To Inverters

 Photo: Pre-Switch uses artificial intelligence to adjust switch timing and achieve ZVS/ZCS operation in an inverter across variations in input voltage, input and output current, device and temperature variations, and topology or switch type.

 Diagram: Adaptive soft-switching topology is implemented using a controller IC in combination with resonant power and gate drive circuitry. In the case of Pre-Drive3, the company packages this technology as a three-phase controller board in which the resonant power and gate driver circuitry is optimized for the particular power switch being used in the application.

See the full story…

Power Integrations’ InnoMux chipset.

Chipset Makes Flybacks More Efficient In Powering Displays

 Diagram: InnoSwitch3-MX and InnoMux ICs power supply architecture. This 91%-efficient single-stage architecture provides independently regulated multiple CV and CC outputs, eliminating the post regulators used in conventional two-stage designs.

 Diagram: The InnoMux chipset monitors all outputs and steers energy only to the output requiring energy.

See the full story…

Rohm Semiconductor’s
SCT3xxxxxHR series SiC MOSFETs.

Large Portfolio Of Automotive-Grade SiC MOSFETs For EV Applications

 Table: The addition of 10 new automotive-grade SiC MOSFETs in the SCT3xxxxxHR series enables the company to offer what’s described as the industry's largest lineup of AEC-Q101 qualified SiC MOSFETs that provide the high reliability necessary for automotive on-board chargers and dc-dc converters.

 Diagram: These automotive-grade SiC MOSFETs are manufactured in a vertically integrated production system, which enables high levels of quality control and device reliability.

See the full story…

More Power Products. . .

Regulator Uses Less Power, Fewer Parts Than Conventional Cap-Drop Designs

PMBus Power Modules Deliver High Power Density For FPGAs, DSPs, ASICs And Memory

1000-A Voltage Regulator Solution For Next-Gen AI And 5G Networking

1-kVA Frequency Converters Feature Universal Input And Split-Phase Output

Regulated LED Driver For Automotive Applications

Isolated ICs Ensure Precise Current And Voltage Measurements


Richardson RFPD has announced the launch of the GaN & SiC for Power Electronics Tech Hub, a microsite featuring the latest news on gallium nitride and silicon carbide innovations and product releases.

The Power Sources Manufacturers Association (PSMA) has announced the 2019 edition of the Power Technology Roadmap. The report, which forecasts the power technology and power delivery trends through 2023, adds a new section surveying global academic research activities.

For those looking to exhibit at the upcoming IEEE Energy Conversion Congress & Expo in Baltimore, the prospectus for ECCE 2019 is now ready for viewing and download. Here it is.

UnitedSiC, a manufacturer of SiC power semiconductors, has announced a strategic investment and long-term supply agreement from Analog Devices.

At the upcoming PCIM Europe conference, Yole will host a market briefing on the “Impact of EV/HEV on the Power Electronics industry”.

Dialog Semiconductor has announced the completion of its transaction for the license of certain power management ICs and the transfer of certain assets to Apple.