Let There Be (Better!) Light

SOI is a central pillar of NXP’s energy-efficient lighting strategy. In this exclusive ASN interview, Jacques Le Berre, the company’s director of marketing and business development for Lighting Solutions, explains why.

Advanced Substrate News (ASN): Looking at overall trends and the “big picture” in the lighting market, what do consumers want / what are governments requiring?

Jacques LeBerre (JLB): Each country around the world has set deadlines for banning the sales of incandescent lamps, thereby requiring the adoption of alternative technologies. For the next five years, fluorescent lighting is the only technology capable of replacing incandescents. The market for CFLs [Compact Fluorescent Lamps], which are essentially for residential use, is growing fast: by 2015, it is expected that around 6 billion CFL lamps will be sold.

The second alternative is LED [Light-Emitting Diode] lighting. While this technology is well known in many applications ranging from consumer electronics, mobile phone and more recently LCD displays, in the general lighting space its performance is reaching a threshold in terms of light output (for both lumens/Watt and lumens/package) and cost. While LEDs continues to gain traction in  areas such as street lighting and signage, wherein cost-of-ownership plays a major role in the purchasing criteria, we need to see a strong cost erosion for LEDs to be able to compete with fluorescents across the full range of applications.

However, the consumer experience of CFLs has been pretty disappointing so far. While long lifetimes could be a major benefit, consumers complain of  low quality (reliability), low performance lamps (poor color rendering, short life) with slow ignition (0.5 to 1 second) and long ramp to full light output (30 sec to 2 minutes). Public authorities in Europe and industry initiatives in the US are pushing the CFL lamp manufacturers to take major qualitative steps addressing: product lifetime, switching cycles, ignition time, ramp-up time, dimming, color, flicker, end-of-life considerations and more.

These features are hardly achievable using discrete components.

ASN: What is the role of SOI in NXP’s solutions? Which markets are you targeting?

JLB: NXP uses SOI wafers for the its power devices for both CFL and LED lighting. Whenever, the controller function (the “digital” part) can be cost effectively combined with the pure power circuitry (the “switch”), then NXP proposes monolithic integration of the two parts: the controller and the power. This is the case in NXP’s non-dimmable CFL driver range for current and future products. When “digital content” increases, currently the best cost/performance ratio is achieved using two silicon processes, with the analog power part (mainly the switches) based on SOI wafers. This the case in the NXP dimmable driver range and AC/DC LED driver range.

ASN: What advantages does SOI offer – both to you and to design engineers for lighting products?

JLB: Our power ICs leverage NXP’s proven and highly robust EZ-HV (high-voltage) SOI technology, which provides a number of unbeatable advantages. First, there’s the high level of power density (Watts/mm²), so the footprint is much reduced.

It also confers stable performance in high temperature environments, which in lighting can range from 100 to 150°C. This is because there is less drift in Resistance for the transistor in the on-state (Rds(on)) in SOI compared to standard MOS processes.  The MHz switching capability is also enhanced thanks to reduced parasitic capacitance.

ASN: What does the future hold for SOI-based lighting solutions?

JLB: Power management solutions – including lighting – were one of the things that first pushed us to develop our EZ-HV SOI a decade ago, and we’ve built an important business around it: our new products are based wholly or partly on SOI. The challenges we’re working on are the cost roadmap of SOI wafers, and the volume ramp up to match the planned growth of the IC lighting markets in fluorescent and LED lighting. That said, we’re an extremely strong player in lighting drivers. SOI enables us to offer the highest levels of integration available on the market today. Clearly, the SOI future continues bright for NXP lighting.

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