Auto Electronics

Power ICs are Making the Automotive Grade

Not long ago, it seemed that many semiconductor vendors paid little or no attention to automotive applications. The reasons (or excuses) for this inattention were many. Electrical requirements — particularly for under-the-hood applications — were too rigorous and the qualification process imposed by carmakers and their system suppliers was difficult and lengthy. And despite the high cost of entry into the market, semiconductor manufacturers would be forced to reduce the cost of their wares to the bare minimum.

Moreover, the growth in the automotive electronics marketplace seemed rather modest when compared with the more meteoric rises seen in telecom, computing, and consumer electronics. But when many of those markets slowed, the modest but steady growth in the automotive applications began to look very enticing to some chipmakers.

Another lure was the emergence of new automotive applications. As my colleague Ashok Bindra described in his previous editorial “Automotive Electronics Spurs Semiconductor Growth,” (Wards Auto Electronics, March 2005, page 6), a variety of new automotive functions would generate demands for many automotive-specific ICs: “Because there is pressure to implement emerging advanced automotive safety, engine, infotainment, chassis control, and wireless technologies, analysts predict this decade will witness an unprecedented growth in automobile electronics content.”

The market downturns in other areas of electronics and the emergence of new automotive electronic systems have been much discussed in recent years. Such discussions explain why many semiconductor vendors have become interested in automotive applications, while also suggesting that a great deal of automotive-oriented IC development must be going on behind the scenes.

Today, I believe we're starting to see the fruits of that development work, particularly in the power management area. In recent months, as I have sorted through the steady stream of power component announcements, I have been coming across more devices designed with automotive applications in mind.

One example is National Semiconductor's just announced LM5005, an integrated buck regulator that steps down a 7 V to 75 V input to a voltage as low as 1.225 V at up to 2.5 A of output current. Another is Linear Technology's “H-Grade” version of the LTC1772, a current-mode step-down dc-dc controller that operates up to a 140 °C junction temperature instead of the usual 125 °C limit. Similarly, the company has released an “H-Grade” version of the LT1976, a 60-V, 1.4 A buck converter with very low (100 µA) quiescent current. The latter two chips were introduced last month. Earlier in the year, Vishay Siliconix introduced a series of 40 V and 60 V n-channel MOSFETs with low on-resistance, high (3.4 V) threshold voltage, and junction temperature ratings up to 175 °C.

Although this sampling of parts may be just a trickle, it may not be long before this trickle becomes a torrent. One reason is the ability of the automotive power components to address high-temperature requirements in industrial applications. The industrial equipment market is attractive to component developers for some of the same reasons as automotive. It tends to experience modest but steady growth, plus product life cycles tend to be very long.

Some of the power controllers being developed for automotive feature wide input voltage ranges, which also makes them suitable for telecom applications. In recent years, many chipmakers extended the high-voltage capabilities of their semiconductor processes, so they could build power controllers that operate off of high-voltage dc supplies like the 48 V telecom bus. As more high-voltage components are developed for telecom, it will be natural for vendors to introduce automotive-grade versions.

However, there will always be factors that prevent some power components from crossing over into automotive applications. Consider for example, that some automotive companies won't accept the more advanced power packages such as DFNs and QFNs, which proliferate in telecom and elsewhere. But as these advanced packages become dominant (and well tested) in other fields, even automotive designers may be tempted to adopt them.

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