Versatile Smart-Building LED Dimmer IC Family Provides Design Flexibility

April 9, 2013

Marvell's 88EM8801 LED-control ICs are part of a scalable reference design for dimmable LED lighting in industrial/architectural construction.

Don Tuite

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With Marvell’s 88EM8801 family of LED-control ICs, LED lighting fixture manufacturers can create new, more sophisticated products for smart office buildings and factories. The devices provide 10-bit precision pulse-width modulation (PWM) dimming control for two LED strings. The light output level can be precisely varied from full brightness down to 0.1% deep dimming.

A one-time programmable (OTP) memory block lets lighting manufacturers calibrate each string to its respective target LED current during manufacturing. As a result, manufacturers don’t need to hand-select LEDs by bins for consistent brightness from fixture to fixture.

Red LEDs can be mixed in the string with cool white LEDs or bluish green LEDs to create light with desirable “warm” correlated color temperature (CCT) characteristics or a high color rendering index (CRI) for matching lighting effects to natural sunlight. An I²C-compatible two-wire serial interface (TWSI) that can connect with many different communication units, such as ZigBee, power-line communications (PLC), or Wi-Fi, provides lighting control.

A two-stage, four-channel smart external LED driver reference design kit supports designs up to 40 W. The basic kit comprises one 88EM8042 baseboard and two 88EM8801controllers. It also can be enhanced with optional plug-in modules that support ZigBee RF or wired 0-10V or Digital Addressable Lighting Interface (DALI) wired control, enabling lighting manufacturers to provide more precise dimming, occupancy sensors, and precise color management (see the figure).

Marvell’s 88EM8042 starts with a basic board (upper left) that constitutes the ac-dc stage for multiple 88EM8801 drivers and an I2C interface that operates with the company’s ZigBee RF and DALI wired controllers or a simple microcontroller programmed to handle the traditional 0-10V interface that’s the industry’s long-standing standard for old-fashioned dimmable lighting.

Marvell

About the Author

Don Tuite

Don Tuite writes about Analog and Power issues for Electronic Design’s magazine and website. He has a BSEE and an M.S in Technical Communication, and has worked for companies in aerospace, broadcasting, test equipment, semiconductors, publishing, and media relations, focusing on developing insights that link technology, business, and communications. Don is also a ham radio operator (NR7X), private pilot, and motorcycle rider, and he’s not half bad on the 5-string banjo.