2001 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP528
IMP528
P
OWER
M
ANAGEMENT
Block Diagram
High-
High-
V
V
olt
olt
ag
ag
e EL Lam
e EL Lam
p Dr
p Dr
iv
iv
er
er
220 V
220 V
PP
PP
Dr
Dr
iv
iv
e
e
N GPS units/Pagers/Cellular phones
N PDAs/Handheld computers
N Safety illumination
N Portable instrumentation
N Battery-operated displays
N LCD modules
N Toys
N 220V peak-to-peak typical AC output voltage
N Low Power: 420A typical V
DD
current
N Wide operating voltage range-from 2.0V to 6.5V
N Large output load capability - drives lamps
with more than 50nF capacitance
N Eliminates external protection resistor in series
with EL lamp
N Adjustable output lamp frequency for control of
lamp color, lamp life, and power consumption
N Adjustable converter frequency to minimize
power consumption
N High-Voltage CMOS Process
N MicroSO package option
Key Features
Applications
+
528_01.eps
V
DD
1
L
X
4
C
S
3
V
A
7
V
B
6
R
SW-OSC
2
Switch
Oscillator
Regulation
Control
IMP528
Bridge
Output
Driver
Q
Q
Q
V
REF
Lamp Drive
Oscillator
C
GND
5
R
EL-OSC
8
Q
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.
I M P 5 2 8
I M P 5 2 8
2
408-432-9100/www.impweb.com
2001 IMP, Inc.
Electrical Characteristics
Absolute Maximum Ratings
Ordering Information
Pin Configuration
Parameter
Symbol
Conditions
Min
Typ
Max
Units
ON-resistance of MOS Switch
R
DS(ON)
I = 100mA
3.0
8
Output Voltage Regulation
V
CS
V
DD
= 2.0 to 6.5V
110
V
Output Voltage Peak-to-peak (in regulation)
V
A
-V
B
V
DD
= 2.0 to 6.5V
220
V
Input Current at V
DD
Pin
I
DD
V
DD
= 3.0V, See Figure 1
420
700
A
Input Current at V
DD
Pin
I
DD
V
DD
= 5.0V
500
750
A
Quiescent V
DD
Supply Current, Disabled
I
DDQ
V
RSW-OSC
< 100mV
20
200
nA
Input Current: I
DD
Plus Inductor Current
I
IN
V
DD
= 3.0V, See Figure 1
21
31
mA
V
A-B
Output Drive Frequency
f
EL
V
DD
= 3.0V, See Figure 1
250
Hz
Switching Frequency
f
SW
V
DD
= 3.0V, See Figure 1
61
kHz
Switching Duty Cycle
D
SW
V
DD
= 3.0V, See Figure 1
88
%
4
L
X
3
C
S
2
R
SW-OSC
1
V
DD
5
GND
6
V
B
7
V
A
8
R
EL-OSC
528_02.eps
IMP528
SO/ MicroSO
Part Number
Input Voltage
Regulated Output Voltage
Temperature Range
Pins-Package
IMP528ESA
2.0V to 6.5V
Yes
40C to +85C
8-SO
IMP528EMA
2.0V to 6.5V
Yes
40C to +85C
8-MicroSO
IMP528/D*
2.0V to 6.5V
Yes
25C
Dice
IMP528/D1**
2.0V to 6.5V
Yes
25C
Dice
V
DD
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5V to +7.0V
V
RSW-OSC
and V
REL-OSC
. . . . . . . . . . . . . . . . . . . 0.5V to V
DD
+0.3V
V
CS
, L
X
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5V to +120V
Operating Temperature Range . . . . . . . . . . . . 40C to +85C
Storage Temperature Range . . . . . . . . . . . . . . 65C to +150C
Power Dissipation (SO) . . . . . . . . . . . . . . . . . . 400mW
Power Dissipation (MicroSO) . . . . . . . . . . . . . 300mW
V
A
, V
B
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5V to V
CS
(pin 3)
Unless otherwise noted, V
DD
= 3.0V, R
SW
= 910k
, R
EL
= 2.7M
, and T
A
= 25C.
Note: All voltages are referenced to GND.
These are stress ratings only and functional operation is not
implied. Exposure to absolute maximum ratings for prolonged
time periods may affect device reliability.
Pin Compatible With IMP803 and IMP560
* Disable pad not active
** Disable pad active
Add /T to ordering part number for Tape and Reel.
I M P 5 2 8
I M P 5 2 8
2001 IMP, Inc.
Electroluminescent Lamp Driver
3
Pin Descriptions
External Components
Pin Number
Name
Function
1
V
DD
Positive voltage supply for the IMP528. Inductor L may be connected here or to a
separate unregulated supply.
2
R
SW-OSC
Switch-mode resistor pin. Switching frequency is determined by an external resistor, R
SW
.
3
C
S
Boost converter storage capacitor. The voltage across the EL lamp is equal to twice the
voltage at C
S
.
4
L
X
Connection to flyback inductance, L.
5
GND
Ground pin.
6
V
B
EL lamp drive. The lamp is connected in a high-voltage bridge circuit with V
B
providing
the complementary connection to V
A
. The peak-to-peak AC voltage across the EL lamp is
thus two times V
CS
.
7
V
A
EL lamp drive. (See above)
8
R
EL-OSC
The EL lamp oscillator frequency setting pin. The oscillator frequency is controlled
by external resistor R
EL
.
External Component
Description and Selection Guide
Diode
Catch diode. A fast reverse recovery diode, with BV > 150V, such as an FDLL400 (150V).
Capacitor C
S
This is the high voltage capacitor that stores the inductive energy transferred through the
catch diode. A capacitor with WV > 120V between 10nF and 100nF is recommended.
Resistor R
EL
The EL lamp oscillator frequency setting resistor. This resistor, connected between the
R
EL-OSC
pin and V
DD
, provides an oscillator frequency inversely proportional to R
EL
;
as R
EL
increases, the EL lamp frequency decreases along with the current drawn by the lamp.
Lamp color is also determined by this frequency. A 2.7M
resistor between the R
EL-OSC
pin and
the V
DD
supply results in a lamp frequency around 250Hz.
Resistor R
SW
Switching Oscillator frequency setting resistor. The switching oscillator resistor is connected
between the R
SW-OSC
pin and the V
DD
supply. The switching frequency is inversely proportional
to the resistor value, dropping as the resistance increases.
Inductor L
The inductor provides the voltage boost needed by means of inductive "flyback". The internal
MOSFET switch alternately opens and closes the ground connection for the inductor at the
L
X
pin. When this internal switch opens, the inductor potential will forward-bias the catch
diode and the current will pass through the storage capacitor C
S
, charging it to a high voltage.
Smaller inductors are preferred to prevent saturation. As the value of the inductor
increases (and the series DC resistance of the inductor decreases), the switching frequency
set by R
SW
should be increased to prevent saturation. In general, smaller value inductors that
can handle more current are more desirable when larger area EL lamps must be driven.
I M P 5 2 8
I M P 5 2 8
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408-432-9100/www.impweb.com
2001 IMP, Inc.
+
V
DD
R
SW-OSC
C
S
L
X
R
EL-OSC
V
A
V
B
GND
8
7
6
5
1
2
3
4
IMP528
2.7M
R
EL
910k
220
H
1
V
IN
= 3.0V
0.1
F
2
FDLL400
L
L
EN
3
EL lamp
10nF
(3 in
2
lamp)
Note:
1. Murata part # LQH4N221K04 (DC resistance <5
)
2. Larger values may be required depending upon supply impedance.
3. EN is connected to V
DD
to enable and to GND to disable.
528_03.eps
10nF
200V
R
SW
C
S
Figure 1. 3.0V Application
Test and Application Circuit, 3.0V
Figure 1 shows the IMP528 configured to drive an EL lamp with a
3.0V input.
Dual Supply Operation with 1.5V Battery
The IMP528 can also be operate from a single battery cell when a
regulated voltage higher than 2.0V is also available. This dual
supply configuration, shown in Figure 2, uses the regulated
voltage to operate the IMP528 while the energy for the high-
voltage boost circuit comes from the battery.
+
EN
2
V
DD
R
SW-OSC
C
S
L
X
R
EL-OSC
V
A
V
B
GND
8
7
6
5
1
2
3
4
IMP528
R
EL
Regulated Voltage
(2.0V to 6.5V)
R
SW
V
IN
L
Battery
Voltage
0.1
F
1
FDLL400
EL lamp
528_04.eps
1. Larger values may be required depending upon supply impedance.
2. EN is connected to V
DD
to enable and to GND to disable.
10nF
200V
C
S
Figure 2. Dual Supply Operation
Application Information
I M P 5 2 8
I M P 5 2 8
2001 IMP, Inc.
Electroluminescent Lamp Driver
5
HighVoltages Present
Switch Resistance
The IMP528 inductor switch resistance is typically below 3.5
, as
shown in Figure 3.
On Resistance (
)
V
DD
(V)
528_05.eps
1
2
3
4
5
6
7
0
5
10
15
20
25
30
Figure 3. Boost Switch ON-Resistance
The IMP528 generates high voltages and caution should
be exercised.
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