Don Paulus, vice president and GM, Power Management Products at Linear Technology

The semiconductor company offers power solutions for the automotive and networking sectors.

Linear Technology Corp., a key supplier of analog components, continues to update its product offerings in response to trends in various hot industries. It offers power solutions for “green” cars, automotive electronics and wireless sensor networks.

In an interview with Global Sources, Don Paulus, vice president and GM of Power Management Products at Linear Technology, discussed the key developments in these high-growth markets from an analog industry standpoint.

Developments in battery hardware are crucial for many industries such as 4G handsets, wearable devices and electric cars. What role will analog chips play in next-generation batteries and what are they already contributing?

Battery-based systems are proliferating in large-scale energy storage, ranging from hybrid and electric vehicles to grid energy storage systems. ESS devices are used in various applications, including power backup, stabilization and level loading, and renewable sources such as solar and wind power.

Large battery packs are made up of battery cells connected in series to form high-voltage stacks. Batteries lose capacity with time and use, and within a pack do so at varying rates due to differences within the cells and exposure to operating conditions such as thermal gradients. The aging disparities cause mismatches in capacity from cell to cell within a stack, which grow over time. Unfortunately, pack capacity is limited by the weakest unit in the stack.

Traditional passive battery balancing can only protect the stronger cells during charging, creates heat in the process but cannot compensate for the weak ones. Alternatively, the active version adds the capability of transferring charge from stronger to weaker cells, increasing pack capacity and runtime.

Recently, integrated controllers such as Linear Technology’s LTC3300 chip offer high-balance current and enhanced efficiency. This is a bidirectional active controller, which can handle up to six series independently and simultaneously. It manages currents up to 10A at efficiency greater than 90 percent.

Automotive electronics is another hot market. What opportunities are there in this segment for analog components in 2014 and beyond?

The automotive market for analog electronics is rapidly growing, forecast to maintain a rate surpassing that of the overall industry for at least the next several years. It has risen to 20 percent of Linear Technology’s business.

Electronic systems are transforming the transportation experience with growing expectations for connectivity, convenience, safety and fuel efficiency. A typical midsize vehicle now contains more than 100 processors and dozens of motors as electronics replace traditional electromechanical and hydraulic systems. The proliferation of distributed systems and diagnostics in vehicles places greater demand for digital communication, which, in turn, drives higher data rates and increased demand on digital transceivers.

Historically, linear voltage regulators have been used to provide regulated power for digital processors, transceivers and related components. But as power demand increases, its use is increasingly becoming problematic.

Linear regulators are simple, low-cost components with very compact, easy-to-design application circuits. But these have poor efficiency when converting an automotive battery voltage to the low setting needed for digital components. For example, linear conversion from 12 to 5V yields a conversion efficiency of 42 percent, and 12 to 3.3V less than 28 percent. If the power supply load is 280mW at 3.3V, 1W of input power is required, resulting in 720mW lost as heat. Managing system efficiency and the consequent thermal stress is therefore a growing focus for automotive system designers.

One alternative for systems designers is to use a switched-mode DC-DC converter in place of the linear regulator. Switchers are highly efficient but bring their own challenges, including selection and sourcing of inductors, loop compensation, mitigation of radiated EMI and a relatively complex and large solution footprint.

Another option is switched-capacitor charge pump regulators. These components share the compact and simple-to-use advantages of linear variants, but are capable of bridging the efficiency gap between linear and switching regulators.

Linear Technology offers a family of high voltage-capable charge-pump regulators suited for these applications. Its LTC3255 model can service a load of up to 50mA from an input voltage range of 4 to 48V, fault-protected from -52 to 60V. The no-load quiescent current is just 20µA. Efficiency from 12V input to 5V output voltage exceeds 80 percent, and from 12 to 3.3V is 55 percent, resulting in only about 50 percent of the power loss generated by a linear regulator. Unlike linear types, charge pumps are also available for inverting and buck-boost applications.

Sensors and connected wearable devices are seen as a high-growth area as well. How will analog chips fare here?

The introduction of robust and ultralow-power wireless sensor networks such as those enabled by Linear Technology’s Dust Networks SmartMesh product lines is transforming the way sensors are deployed in applications ranging from environmental monitoring to transportation infrastructure to the factory floor. And as sensors are adopted in remote, isolated or dangerous settings, the potential to power them from local ambient energy, free from wires and service, is here today.

Linear Technology introduced the first energy-harvesting ICs specifically designed to condition power from low-level solar, piezoelectric and thermoelectric generator or TEG outputs in 2010. Since then, we have brought to market a family of products, which allows users to supplement a primary cell or rechargeable battery with harvested ambient energy, increasing the system runtime indefinitely or approaching the shelf life of the primary cell. These components handle all aspects of the power system, including DC-DC conversion, power-path control and local energy storage.

The LTC3107 chip, for instance, conditions energy from low-voltage and -impedance sources, including TEGs and thermopiles, converting input as low as 20mV into power for a remote sensor node. It provides seamless transitions between the harvested energy and a primary cell battery, giving priority to the ambient power source and drawing just 80nA from the battery when the harvester is active.

Practical and efficient energy harvesters are a key component to bring the Internet of Things from concept to reality.