1

Rev.11/13/00

SP4438 Ultra-Quiet Electroluminescent Lamp Driver

© Copyright 2000 Sipex Corporation

s Patent Pending Output Waveshaping

s Waveshaped Output Optimized For Low

Acoustic Noise And Maximum Efficiency

s Reduced Supply Current And Standby

Current

Lamps (2 to 3 sq. in.)

s Waveshaped Output And Low Frequency

Operation Minimize Stress On EL Lamp To

Extend Its Lifetime

s Uses 820

µH, Sub-2mm Coils

s Gradual Rising And Falling Edges Minimizes

EMI

s +2.7V To +3.3V Battery Operation

s Space-Saving 8-pin MSOP package

APPLICATIONS

s Cellular Radios

s Wireless Communication Products

DESCRIPTION

The SP4438 device is a low noise, high voltage output DC-AC inverter designed to drive

electroluminescent lamps to backlight liquid crystal display and keypads used in cellular

phones, cordless phones, 2-way radios, and other wireless communication products. The

output waveform of the SP4438 device is ideal for cell phone applications requiring low

acoustic noise performance. One external resistor is used to set the internal oscillator

frequency and one inductor is required to generate the high voltage AC output to drive an EL

lamp up to 3 square inches in size. The SP4438 operates from a +3.0V battery source and

has a low power standby mode that draws less than 1

µA, making it ideal for low-power cellular

applications. All input pins are ESD protected with internal diodes to V

is offered in a space-saving 8-pin MSOP package.

EL1

ELEN

COIL

EL2

SP4438

8

7

4

3

2

1

5

6

COIL

SP4438

C1

0.1

µF

L1

820

µH/14Ω

5

1

2

6

4

ELEN

D1

1N4148

47nF

EL2

EL1

EL Lamp

7

8

3

714k

Ω

C2

1nF

Ultra-Quiet Electroluminescent Lamp Driver

For Cellular Phone Applications

SP4438

®