IMP52 7
P
OWER
M
ANAGEMENT
Single Cell Battery Powered
Electroluminescent Lamp
Driver/Inverter
The IMP527 is an Electroluminescent (EL) lamp driver designed for
systems that must operate down to 1 volt and below. The input supply
voltage range is 0.9V to 2.5V. Typical output lamp drive voltage is 180V.
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 driven 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 1µA typical with a V
DD
of 1.5V. The chip
can be disabled by connecting R
SW
, the oscillator frequency setting resis-
tor, to ground. A disable pad (active low), 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 180V peak-to-peak. This conserves power and
extends battery life.
The IMP527 is available in MicroSO and SO-8 packages and in die form.
Key Features
N
Wide operating voltage range - from 0.9V to 2.5V
N
Simple design requires few passive components
N
180V peak-to-peak typical AC output voltage
N
Adjustable output frequency controls lamp
color and power consumption
N
Adjustable converter frequency minimizes
circuit power consumption
N
Disable mode extends battery life
N
Disable current 1µA typical
N
Compact MicroSO package option
Applications
N
N
N
N
N
N
N
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
–
IMP527
R
EL-OSC
8
Lamp Drive
Oscillator
Q
527_01.eps
© 2000 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP [ IMP, INC ]
