IMP525
P
OWER
M
ANAGEMENT
Single Cell Batter y Powered
Electroluminescent Lamp
Dr iver/Inver ter
The IMP525 is an Electroluminescent (EL) lamp driver designed for sys-
tems that must operate down to 1 volt and below. The input supply volt-
age 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 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 1碌A(chǔ) typical with a V
DD
of 1.5V. The chip
can be disabled by connecting R
SW
, the oscillator frequency setting
resistor, 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 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
N
Wide operating voltage range - from 0.9V to 2.5V
N
Simple design requires few passive components
N
112V 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 1碌A(chǔ) 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
4
Block Diagram
V
DD
1
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
鈥?/div>
IMP525
R
EL-OSC
8
Lamp Drive
Oscillator
Q
525_01.eps
漏 2000 IMP, Inc.
408-432-9100/www.impweb.com
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