Compact High-Efficiency EL Lamp Driver Targets PDAs

Aug. 21, 2000

The SP4403 lamp driver for backlighting electroluminescent (EL) displays suits personal digital assistants. It offers a small form factor, high efficiency, and sufficient drive for a bright output from EL display lamps. Its high coil-switching frequency facilitates the use of 470-µH inductors that are less than 2 mm high. The inductor typically switches at 51.2 kHz with a 90% duty cycle and a maximum peak coil current of 75 mA.

Additionally, the SP4403's resistor-controlled oscillator design delivers narrow lamp frequency distributions, as well as tight performance between -40°C and 85°C. An 8-pin µSOIC package minimizes board-space requirements, and a low-power standby mode draws only 50 nA, typically, and 1 µA maximum in the shutdown mode.

The SP4403 operates from a battery voltage of 2.2 to 4.5 V at a typical, 38-mA supply current. This dc-ac inverter also produces up to 220 V p-p ac (210 V ac typical) when driving an EL display panel operating at a typical frequency of 400 Hz. It's manufactured on a dielectrically isolated biCMOS process.

The SP4405, a pin-compatible version of the SP4403, includes a regulated output voltage that maintains constant brightness over the battery's life.

Currently available, the SP4403 costs $0.87 each in 10,000-unit quantities. Samples are available from stock. Data sheets and additional information can be found at www.sipex.com/newproducts.

Sipex Corp., 22 Linnell Circle, Billerica, MA 01821; (978) 667-8700; fax (978) 670-9001; www.sipex.com.

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.