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iWatt SSL LED drivers cut BOM cost by 40%

Posted: 04 Jun 2013     Print Version  Bookmark and Share

Keywords:iWatt  SSL LED driver  solid state lighting  iW3606  iW3608 

iWatt Inc. has announced its latest single-stage, solid state lighting (SSL) LED drivers. The company's iW3606 (8W output power) and iW3608 (15W output power) offers LED bulb manufacturers an alternative approach to significantly lower cost and tackle the lifetime and performance issues in dimmable applications, stated the firm.

Both LED drivers allow SSL designers to reduce their BOM cost by 20-40 percent compared to competitive solutionsd iWatt note. The devices incorporate iWatt’s patented, configurable over-temperature protection (OTP) and derating functionality to provide predictability and reliability of bulb operating life and offer what the company believes is the industry’s lowest pop-on current, < 5 percent of light output, the company added.

Geared for all retrofit bulbs, including candle and GU10 lamp replacements used in existing phase-cut dimmer installations, the iW3606 and iW3608 manage the key issues that could impact consumer adoption of SSL lighting, including poor dimming performance (pop-on, popcorning, dead travel, drop-out, flicker), short bulb lifetime or failure and high cost. Both drivers meet or exceed global regulations for power quality and efficiency with a high power factor (PF) of > 0.92, low total harmonic distortion (THD) of < 20 percent and 82 percent efficiency.

The on-chip OTP and derating feature of the drivers address the thermal issues caused by the high and unpredictable operating temperatures in dimmable SSL applications. The lifetime of many of the components in the LED driver circuit, especially electrolytic capacitors, degrades as temperatures increase, potentially reducing overall bulb lifetime to less than 2,000 hours, well under the 30,000 to 50,000 hours expected for SSL bulbs. iWatt’s OTP derating monitors the temperature inside the sealed SSL bulb and when thermal conditions reach a point set by the system designer, the LED drivers automatically reduce the current drive to the LEDs, lowering the power dissipation and resulting in cooler overall operation. This helps prevent exceeding the temperature rating of the electrolytic capacitors in the system, helping to ensure a predictable and safer bulb operating life.

The iW3606 and iW3608 feature a wide, flicker-free dimming range from 100 percent all the way down to one percent of measured light, to closely match the dimming performance of incandescent bulbs, boasted the firm. This enables the smooth, “natural” dimming consumers expect, with no light drop-out at the low end of the dimming range and virtually no dead travel where the light turns off before the dimmer control reaches the bottom of its travel. The very low internal power consumption of the iW3606 and iW3608 allows them to start at a very low dimming level of < 5 percent of light output, noted the company. This virtually eliminates pop-on, a phenomenon where the light does not turn on at low dimmer levels and as the dimmer level is raised, the light suddenly turns on. This also helps eliminate popcorning effects, in which various bulbs in multiple-light installations on the same dimmer circuit can turn on at different dimmer setting thresholds.

Both devices use iWatt’s patented digital dimming technology with its embedded intelligence that detects dimmer characteristics to provide wide dimmer compatibility, including TRIAC, trailing edge and non-traditional R, R-C and R-L types, with automatic dimmer detection.

The iW3606 and iW3608 claim to enable nearly 40 percent and 20 percent lower BOM costs respectively compared to competitive single-stage solutions, which can require as many as nine additional external components, indicated iWatt. The lower BOM costs are achieved via high levels of integration, including on-board OTP and derating, along with replacing field effect transistors (FETs) with lower-cost bipolar junction transistors (BJTs). A combination of BJTs and valley mode switching lowers electromagnetic interference and reduces the need for external EMI filtering components. Also, iWatt’s patented PrimAccurate primary-side control eliminates the need for a secondary-side regulator and optical feedback isolator. Additional savings come from the standard, low-cost 8-lead SOIC package that can be used in single-layer PC boards for additional cost savings and a smaller design footprint.

The iW3606 and iW3608 are available in production. Pricing for the iW3606 is Rs.25.00 ($0.46) and Rs.27.72($0.51) for the iW3608, both in 1000-piece quantities.

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