Components: I/O Expanders Dim LEDs In Microprocessor Buses

Nov. 15, 2004
The PCA9530/31/32/33 2-, 4-, 8-, and 16-bit I/O expanders with a reset function can dim LEDs in I2C and SMBus applications. Each LED may be dimmed in one of 256 brightness levels. Also, they may switch on and off or flash at one of two...

The PCA9530/31/32/33 2-, 4-, 8-, and 16-bit I/O expanders with a reset function can dim LEDs in I2C and SMBus applications. Each LED may be dimmed in one of 256 brightness levels. Also, they may switch on and off or flash at one of two programmable rates without tying up the bus master or overloading the bus. Blink rates vary between 0.625 and 1.6 seconds. The duty cycle is programmable in 256 steps. LEDs are dimmed by varying the duty cycle, which changes the average current as the LEDs blink at 160 Hz. The ICs contain a ±10% accurate oscillator and need no external parts. Open-drain outputs directly drive LEDs to a maximum of 25 mA/bit. Free samples are available.

Philips Semiconductorswww.semiconductors.philips.com; (800) 435-1966
About the Author

Roger Allan

Roger Allan is an electronics journalism veteran, and served as Electronic Design's Executive Editor for 15 of those years. He has covered just about every technology beat from semiconductors, components, packaging and power devices, to communications, test and measurement, automotive electronics, robotics, medical electronics, military electronics, robotics, and industrial electronics. His specialties include MEMS and nanoelectronics technologies. He is a contributor to the McGraw Hill Annual Encyclopedia of Science and Technology. He is also a Life Senior Member of the IEEE and holds a BSEE from New York University's School of Engineering and Science. Roger has worked for major electronics magazines besides Electronic Design, including the IEEE Spectrum, Electronics, EDN, Electronic Products, and the British New Scientist. He also has working experience in the electronics industry as a design engineer in filters, power supplies and control systems.

After his retirement from Electronic Design Magazine, He has been extensively contributing articles for Penton’s Electronic Design, Power Electronics Technology, Energy Efficiency and Technology (EE&T) and Microwaves RF Magazine, covering all of the aforementioned electronics segments as well as energy efficiency, harvesting and related technologies. He has also contributed articles to other electronics technology magazines worldwide.

He is a “jack of all trades and a master in leading-edge technologies” like MEMS, nanolectronics, autonomous vehicles, artificial intelligence, military electronics, biometrics, implantable medical devices, and energy harvesting and related technologies.

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