Dialog Semiconductor's New iW3640 Simple 2-Channel Colour Mixing Eliminates Cost of MCU and Power Supply

iW3640 Key Features:
•    2-channel, sunset dimming SSL LED driver: 25W output power
•    Low BOM cost – no external MCU or power supply; PrimAccurate™ control eliminates secondary-side regulator or optical feedback isolator
•    NTC-based LED over-temperature protection derating
•    High power factor (PF) > 0.95, low total harmonic distortion (THD) < 15%
•    Phase-cut dimming with wide dimmer compatibility, automatic detection of dimmer type
•    Wide dimming range: 1% to 100%
•    Meets global energy standards, including European Union IEC61000-3-2
•    NEMA SSL 6 compliant
•    Zhaga hot-plug compliant

While typical LED bulbs retain the same harsh white colour as they dim, the dual driver output of the iW3640 lets designers use amber LEDs in parallel with the main white LEDs allowing LED bulbs to gain warmth as they dim. Dialog’s patented, built-in digital dimming technology detects the dimmer type and phase - automatically adjusting LED colour mixing in step with light intensity to provide smooth dimming that closely matches the warmth and ambiance of a traditional dimmable incandescent bulb. The result is a much more intimate LED lighting experience in residential and commercial settings, where lighting plays an important role in setting the mood.

By integrating the driver for a second string of LEDs and using the digital engine to control transitions, the iW3640 eliminates the cost of the external MCU and dedicated power supply required by conventional warm dimming techniques.

“Lighting ambiance is important and users are disappointed when their LED bulbs do not dim with the same warmth they are accustomed to with incandescent bulbs,” said Mark Tyndall, Senior VP Corporate Development and Strategy, General Manager of the Power Conversion Business Group at Dialog. “Producing LED bulbs that dim in a similar way to incandescent bulbs usually requires a more complex and expensive design. The iW3640 offers the simplest two-colour mixing topology to easily solve the problem of harsh white LED dimming with a much lower overall BOM cost.”

Dialog’s digital dimming technology allows the iW3640 to work with virtually all phase-cut wall dimmers, including leading-edge dimmers (R-type or R-L type) and trailing-edge dimmers (R-C type), as well as digital dimmers. The iW3640 adjusts light temperature from bright white down to warm amber, with flicker-free dimming down to 1% of initial brightness. As the driver detects increased dimming angles, the duty cycle of the secondary LED string is also increased, creating more warmth as the design goes deeper into dimming. Additionally, cycle-by-cycle waveform analysis technology facilitates fast dimmer setting response.

The iW3640 addresses bulb overheating issues by including an over-temperature protection (OTP) derating function that monitors the temperature inside the sealed SSL bulb. The OTP feature is configured via an NTC resistor and when thermal conditions in the bulb reach the temperature pre-set by the designer, the iW3640 automatically reduces the current drive to the LEDs in small, imperceptible increments, then seamlessly restores brightness as temperature falls, with no need for a full shutdown. This allows the electrolytic capacitors in the LED circuit to operate within the maximum lifetime of the SSL bulb, resulting in a predictable bulb operating life, and helping to ensure the long-term reliability and safety consumers expect from LED replacement bulbs. Additional iW3640 safety features include LED open/short circuit, over-current, current sense resistor short-circuit, and input over-voltage protection.

The iW3640 two-stage AC/DC SSL LED driver meets global regulations for power quality and efficiency, including the European Union IEC61000-3-2 standard, with a high power factor of >0.95, low total harmonic distortion <15%, and low ripple voltage <20%. It is compatible with the Zhaga(1) hot-plug LED module for LED light interchangeability and the configurable dimming curves are compliant with the NEMA SSL 6(2) dimming standard.

Packaging, Pricing, Availability:
The iW3640 is available now in production quantities. It comes in a standard, 14-lead SOIC package and is priced at US $0.94 each in 1000-piece quantities. Product brief is available:  iW3640 Product Brief

About Dialog Semiconductor:
Dialog Semiconductor creates highly integrated, mixed-signal integrated circuits (ICs) optimised for personal portable, low energy short-range wireless, lighting, display and automotive applications. The company provides flexible and dynamic support, world-class innovation and the assurance of dealing with an established business partner.
With its focus and expertise in energy efficient system power management, and with a technology portfolio including audio, short range wireless and VoIP technology, Dialog brings decades of experience to the rapid development of ICs for personal portable applications including Smartphones, Tablet PCs, digital cordless and gaming applications.
Dialog’s power management processor companion chips are essential for enhancing both the performance in terms of extended battery lifetime and the consumers’ multimedia experience. With world-class manufacturing partners, Dialog operates a fabless business model.
Dialog Semiconductor Plc is headquartered near Stuttgart with a global sales, R&D and marketing organisation. In 2012, it had $774 million in revenue and was one of the fastest growing European public semiconductor companies. At the end of 2012 it had approximately 850 employees. The company is listed on the Frankfurt (FWB: DLG) stock exchange (Regulated Market, Prime Standard, ISIN GB0059822006 and is a member of the German TecDax index. It also has convertible bonds listed on the Euro MTF Market on the Luxemburg Stock Exchange (ISIN XS0757015606).