Copyright © 2006 Penton Media, Inc., All rights reserved.
Printing of this document is for personal use only.
Reprints

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.