Driver ICs for HB LEDs: a large and growing market

The total market for HB LED driver ICs is forecast to grow to more than $1.9 billion in 2011, according to Vrinda Bhandarkar and Bob Steele of Strategies Unlimited.

Mar 13th, 2008
Content Dam Leds En Articles Print Volume 5 Issue 3 Features Driver Ics For Hb Leds A Large And Growing Market Leftcolumn Article Thumbnailimage File
The performance of HB LEDs has dramatically improved over the last few years. The question commonly raised regarding LEDs in lighting has changed from “Can LEDs be efficient enough to compete with other lighting technologies?” to “How can we maximize the extraction of light from the LED system?”

Figure 1 - Driver market
The best commercially available white LEDs are now fast approaching 100 lm/W, demonstrating a potential to compete with other efficient lighting technologies. The electrical, thermal, and optical systems that are instrumental in optimizing light output from a LED system have come under increasing scrutiny.

LED manufacturers test and bin their products for luminous flux and color based on a 25 millisecond power pulse, at a fixed junction temperature of 25°C (77°F). However, the actual light output from an LED in a system application depends on the electrical system to deliver the right current, the thermal management system to maintain the junction temperature at an acceptable level, and the optical system to extract the light out of the package.

Managing power

Power can be managed at the device, or system level. At the system level if the power supply is AC, it needs to be converted to from AC-DC and then DC-DC to the appropriate voltage and current for driving the LED package. The LED driver circuit manages power to the LED and is designed to deliver constant current. Since LEDs are P-N junction devices with a steep I-V curve, the driver circuit needs to minimize fluctuations in voltage which result in large swings in current. Beyond a threshold voltage (rated differently for each LED) the higher the current, the higher is the junction temperature, and faster is the degradation of LED.

The objective of the design of an LED driver is to maximize the efficiency of conversion to the desired constant current at the lowest possible cost under electrical and physical conditions of a particular power source. The best topology of a power circuit design for a given application depends on the specific requirement of the power supply (which include cost and time factors) and the personal experience of the designer.

Figure 2
The configuration of the driver can be a combination of integrated circuits (ICs) and discrete devices (see Figure 2). The use of dissipative resistors for current regulation for HB LEDs is ubiquitous; however, these are the least efficient solutions. Linear regulators, which are transistorized resistors, offer better efficiencies –more than 50%. As the sophistication of drivers progresses from linear regulators to switch mode drivers with pulse width modulation (PWM) for dimming and color changing LEDs, the drivers incorporate ICs in the circuitry. ICs have the potential to improve the efficiency of the driver s to more than 90%.

Driver IC markets

In 2007, the total market for HB LED driver ICs was $979 million, dominated by the maturing Mobile Appliances segment (see Figure 1). Mobile appliances have always been the largest market for LED driver ICs, and the semiconductor industry has addressed this market by offering efficient and low cost driver ICs. It is a high volume market striving to reduce the size of the LED driver circuit, reduce the bill of materials, and improve the efficiency of the driver so that the battery power can be further shared with ever increasing applications on the mobile phones, smart phones, MP3 players, handheld games, video and still cameras, auto navigation units, and laptops.

Although mobile phone applications dominate the market for LED driver ICs, the opportunities to grow revenues are shrinking, while the other burgeoning applications for HB LEDs offer a higher growth potential for driver ICs. Among mobile appliances, LED driver ICs for laptop display backlight applications will see dramatic increases in revenue.

The second largest segment of the market for driver ICs is Signs and Displays. Driver ICs for HB LED signs can be further sub-segmented as single color and full color applications. The driver ICs in single color signs have to be configured to control each individual pixel. If there are multiple LEDs in the pixel, each pixel is a string that needs a dedicated channel to drive and control the LEDs. In the case of RGB full color displays, each LED has to be addressable to enable color-changing applications. The driver ICs will see a faster growth in the full color display segment than in single color.

Backlighting and automotive

The excitement around using LEDs as backlights for large LCD displays (monitors and TVs) continues. However, until the cost differential with standard CCFL backlights declines, LED usage is likely to be limited to high-end models. In 2007, except for Samsung, no other manufacturer offered TVs with LED backlights. Samsung uses standard blue LEDs with green and red phosphors. These RGB backlights are offered only for 40-70 inch models.

Drivers will have a significant role to play in TVs with RGB backlights with local dimming. The constant feedback loop needed to maintain the white point and control over individual LEDs for local dimming will add significantly to the cost of driving LEDs. For 2007-2011, the largest contributor to revenue growth in the display segment is forecast to come from the growth in the revenues in the HB LED applications for LCD TV backlights.

In automotive applications the use of LEDs is not necessarily accompanied by driver ICs, especially for signaling. But the increasing penetration of LED headlamps, as well as the increasing use of high power white LEDs in interior lighting, will increase the sales of driver IC s to the automotive segment in the next five years.

Lighting

The fastest growing segment for driver ICs is in general illumination applications. The market for general illumination is fragmented, and large volume shipments to luminaire manufacturers are just beginning in 2008. The power management IC industry has identified the need for high efficiency (more than 80%) drivers for drive currents of more than 350 mA, and is introducing ICs specifically designed for lighting applications. In the meanwhile, many LED fixture vendors are resorting to customized IC designs, while others are using off-the-shelf ICs that are not optimized for high current LEDs.

In the past, the market was dominated by architectural applications emphasizing saturated color and color-changing ability of LEDs rather than energy efficiency. With improved efficacy of white LEDs, their use is growing even within architectural applications. In 2008, LEDs are being touted as energy efficient technology for general illumination. Given the high lumen output capability of LEDs, the efficiency of LED drivers is becoming vital to claiming the competitive advantage of energy efficiency. The driver IC manufacturers have identified this as a key market opportunity.

Market forecast

In the period 2007-2011, market growth for driver ICs will be mostly driven by growth in the general illumination, signs and displays, and automotive applications, at a combined CAGR of 38%. The total market for HB LED driver ICs is forecast to grow to more than $1.9 billion in 2011.

A report just published by Strategies Unlimited, entitled HB LED Driver IC Market Review and Forecast – 2007, provides analysis of the market for LED driver ICs by application and geographic region, as well as a detailed market forecast.

More information on the report is available by contacting Tim Carli, Sales Manager, at +1 650-941-3438 ext. 23, or by e-mail at tcarli@strategies-u.com.

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