© 2001 IMP, Inc.

408-432-9100/www.impweb.com

1

IMP528

IMP528

Block Diagram

High-

er

– 220 V

PP

Dr

N GPS units/Pagers/Cellular phones

N PDAs/Handheld computers

N Safety illumination

N Portable instrumentation

N Battery-operated displays

N LCD modules

N Toys

N 220V peak-to-peak typical AC output voltage

N Wide operating voltage range-from 2.0V to 6.5V

N Large output load capability - drives lamps

with more than 50nF capacitance

N Eliminates external protection resistor in series

with EL lamp

N Adjustable output lamp frequency for control of

lamp color, lamp life, and power consumption

N Adjustable converter frequency to minimize

power consumption

N High-Voltage CMOS Process

N MicroSO package option

Key Features

Applications

–

+

528_01.eps

1

4

3

7

6

2

Switch

Oscillator

Regulation

Control

IMP528

Bridge

Output

Driver

Q

Q

Q

Lamp Drive

Oscillator

C

GND

5

8

Q

The IMP528 is an Electroluminescent (EL) lamp driver with the four EL

lamp driving functions on-chip. These are the switch-mode power sup-

ply, its high-frequency oscillator, the high-voltage H-bridge lamp driver

and its low-frequency oscillator. The IMP528 drives EL lamps of up to

50nF capacitance to high brightness; EL lamps with capacitances greater

than 50nF can be driven, but will be lower in light output. The typical

regulated output voltage that is applied to the EL lamp is 220V peak-to-

peak. The circuit requires few external components; a single inductor,

single diode, two capacitors and two resistors. Two of these resistors

set the frequency for two internal oscillators.

Unlike other EL lamp drivers, the IMP528 does not require an external

protection resistor in series with the EL lamp.

The IMP528 operates over a 2.0V to 6.5V supply voltage range. A

regulated, low-power source can supply the low quiescent current of the

IMP528. The inductor may be driven from an independent, unregulated

supply voltage in dual supply applications.

An internal circuit shuts down the switching regulator when the lamp

drive voltage reaches 220V peak-to-peak. This conserves power and

extends battery life.

The IMP528 is available in MicroSO and SO-8 packages and in die or

wafer form.