IMP525
P
OWER
M
ANAGEMENT
Single Cell Battery Powered
Electroluminescent Lamp
Driver/Inverter
The IMP525 is an Electroluminescent (EL) lamp driver designed for sys-
tems that must operate below 1 volt. The input supply voltage range is
0.9V to 2.5V. Typical output lamp drive voltage is 112V. All four EL lamp-
driving functions are on-chip. These are the switch-mode power supply,
its high-frequency oscillator, the high-voltage H-bridge lamp driver and
its low-frequency oscillator. EL lamps of up to 6nF capacitance can be dri-
ven to high brightness.
The circuit requires few external components; one inductor, one diode,
one capacitor and two resistors. The resistors set the frequency for the
two oscillators.
A disable mode puts the chip into a low current-drain state. When dis-
abled, quiescent current drops to 2µA maximum with a V
DD
of 1.5V. The
chip can be disabled by connecting R
SW
, the oscillator frequency setting
resistors, to ground. A disable pad, accessible only on the die, can also be
used to disable the driver.
An internal circuit shuts down the switching regulator when the lamp
drive voltage exceeds 112V peak-to-peak. This conserves power and
extends battery life.
The IMP525 is available in MicroSO and SO-8 packages and in die form.
Key Features
x
Wide operating voltage range - from 0.9V to 2.5V
x
Simple design requires few passive components
x
112V peak-to-peak typical AC output voltage
x
Adjustable output frequency controls lamp
color and power consumption
x
Adjustable converter frequency minimizes
circuit power consumption
x
Disable mode extends battery life
x
Disable current under 2µA
x
Compact MicroSO package option
Applications
x
x
x
x
x
x
x
Audio/TV remote control units
Pagers/Cellular phones
PDAs
Clocks and radios
Portable GPS receivers
LCD modules
Toys
Block Diagram
V
DD
1
4
L
X
C
S
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
–
IMP525
R
EL-OSC
8
Lamp Drive
Oscillator
Q
525_01.eps
IMP, Inc.
San Jose, CA
408-432-9100/www.impweb.com
IMP [ IMP, INC ]
