IMP528
P
OWER
M
ANAGEMENT
Key Features
High-Voltage EL Lamp Driver
ꢀ 220V peak-to-peak typical AC output voltage
ꢀ Low Power: 420µA typical VDD 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
– 220 VPP 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.
with EL lamp
ꢀ Adjustable output lamp frequency for control of
lamp color, lamp life, and power consumption
ꢀ Adjustable converter frequency to minimize
Unlike other EL lamp drivers, the IMP528 does not require an external
protection resistor in series with the EL lamp.
power consumption
ꢀ High-Voltage CMOS Process
ꢀ MicroSO package option
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.
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.
ꢀ GPS units/Pagers/Cellular phones
ꢀ PDAs/Handheld computers
ꢀ Safety illumination
ꢀ Portable instrumentation
ꢀ Battery-operated displays
ꢀ LCD modules
The IMP528 is available in MicroSO and SO-8 packages and in die or
wafer form.
Block Diagram
ꢀ Toys
4
1
VDD
LX
3
2
5
Switch
Oscillator
RSW-OSC
CS
GND
Q
+
–
7
V
C
A
Regulation
Control
VREF
Q
Bridge
Output
Driver
IMP528
Q
Q
6
VB
8
Lamp Drive
Oscillator
REL-OSC
528_01.eps
© 2001 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP [ IMP, INC ]
