IMP528
P
OWER
M
ANAGEMENT
High-Voltage EL Lamp Driver
– 220 V
PP
Drive
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.
Key Features
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220V peak-to-peak typical AC output voltage
Low Power: 420µA typical V
DD
current
Wide operating voltage range - from 2.0V to 6.5V
Large output load capability - drives lamps
with more than 50nF capacitance
Eliminates external protection resistor in series
with EL lamp
Adjustable output lamp frequency for control of
lamp color, lamp life, and power consumption
Adjustable converter frequency to minimize
power consumption
High-Voltage CMOS Process
MicroSO package option
Applications
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GPS units/Pagers/Cellular phones
PDAs/Handheld computers
Safety illumination
Portable instrumentation
Battery-operated displays
LCD modules
Toys
4
L
X
C
S
Block Diagram
V
DD
1
R
SW-OSC
GND
2
Switch
Oscillator
3
5
+
C
Regulation
Control
Q
7
V
REF
Bridge
Output
Driver
Q
6
V
B
Q
V
A
–
IMP528
R
EL-OSC
8
Lamp Drive
Oscillator
Q
528_01.eps
© 2001 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP [ IMP, INC ]
