MIC4833

With Output Voltage Slew Rate Control

MLF and MicroLead Frame are registered trademark of Amkor Technologies

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (

General Description

The MIC4833 is a low noise dual Electroluminescent (EL)

Panel driver used in backlighting applications. The

MIC4833 converts a low DC voltage to a high DC voltage

using a boost converter and then alternates the high DC

voltage across the EL panels using an H-bridge. The

MIC4833 incorporates internal wave-shaping circuitry

specifically designed to reduce audible noise emitted by

EL panels. The two EL panels may be dimmed by applying

a PWM signal to the device. The MIC4833 drives two

outputs from a single inductor and requires a minimum

number of passive components. It features an operating

input voltage range of 2.3V to 5.8V, making it suitable for

1-cell Li-ion and 2- or 3-cell alkaline/NiCad/NiMH battery

applications.

An external resistor may be used to adjust the output

voltage slew rate to reduce audible noise. The MIC4833

features separate oscillators for the boost and H-bridge

stages to allow independent control. External resistors set

the operating frequencies of each stage allowing the EL

circuit to optimize efficiency and brightness.

The MIC4833 is available in a 12 pin 3mmx3mm MLF

®

package, and has an operating junction temperature range

of –40

°C to +125°C.

Features

•

Drives two EL panels, up to 4 in

brightness

•

Independent input control for each of the two panels

and allows PWM dimming.

•

220Vpp regulated AC output waveform

•

2.3V to 5.8V DC input voltage

•

Wave-shaping circuit to reduce audible noise

•

Adjustable slew rate for audible noise reduction

•

Independently adjustable boost converter and EL

panel frequency

•

Single inductor to power both panels

•

0.1uA typical shutdown current

•

12 pin 3mmx3mm MLF

•

–40

Applications

•

Mobile Phones

•

MP3s/Portable Media Players (PMP)

•

Clocks/ Watches

•

Remote Controls

•

Cordless Phones

•

GPS Devices

•

PDAs

_________________________________________________________________________________________________

Typical Application

ENA

VDD

RSW

REL

ENB

1.78M

220µH

MIC4833

332k

GND

SLEW

VIN

Li Ion

3V to 4.2V

0.01µF

ELA

ELB

COM

CS

SW

50k

2.2nF

250V

10µF

VIN

Li Ion

3V to 4.2V

High

Low

High

Low

High

Low

EL Lamp A

EL Lamp B

October 2008

M9999-100308

(408) 955-1690

Low Noise Dual EL Driver