65V Synchronous Buck Converters with Ultralow IQ

July 10, 2014 // By Jeff Gruetter, Linear Technology
Power ICs are increasingly playing a pivotal role in the car. Besides high efficiency and low EMI emission, they have to supply complex circuitry - and multiple voltage levels. This article discusses approaches to meet all these requirements.

Introduction

“Globally, legislation continues to drive the development of next generation vehicle technology, offering further enhancements to emissions control and safety. Industry competition and consumer expectations are leading to higher levels of vehicle connectivity to the cloud and personal portable devices. As a result demand for enabling semiconductor devices is expected to grow at a CAAGR (compound average annual growth rate) of five percent over the next seven years, with the total market worth over $41 billion by 2021 compared to $27.5 billion in 2013. The Strategy Analytics analysis also identifies that demand for microcontroller and power semiconductors will drive over 40 percent of revenues.” [Source: Strategy Analytics May 2014]

Strategy Analytics provides a very quantitative description of forecasting the growth of electronics content in automobiles and commercial vehicles, but more importantly the prevalent role that power ICs play in this growth. These new power IC designs must offer:

  1. The highest efficiency possible to minimize thermal issues and optimize battery run-time.
  2. Operation from a wide range of battery input voltages; both single-cell (automotive) and dual-cell (commercial vehicle) lead acid applications that can accommodate wide transient voltage swings.
  3. Ultralow quiescent current to enable always-on systems such as security, environmental control and infotainment systems to stay engaged without draining the vehicles battery when its engine (alternator) is not running.
  4. Switching frequencies of 2MHz or greater to keep the switching noise out of the AM Radio band and to keep solution footprints very small.
  5. Lowest EMI/EMC emission possible to reduce noise interference concerns within electronic systems.

The goal of the increased performance levels of power ICs is to design increasingly complex and numerous electronic systems found in automobiles to maximize comfort, safety and performance while simultaneously minimizing harmful emissions. Specific applications fueling the growth for electronic content in cars are found in every aspect of the vehicle. For example, new safety systems, including lane monitoring, adaptive safety control and automatic turning, dimming headlights

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