IMP803
P
OWER
M
ANAGEMENT
High-Voltage EL Lamp Driver
The IMP803 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 IMP803 drives EL lamps of up to
30nF capacitance to high brightness; EL lamps with capacitances greater
than 30nF can be driven, but will be lower in light output. The typical
regulated output voltage that is applied to the EL lamp is 180V peak-to-
peak. The circuit requires few external components, a single inductor,
single diode, two capacitors and three resistors. Two of these resistors
set the frequency for two internal oscillators.
The IMP803 operates over a 2.0V to 6.5V supply voltage range. A
regulated, low-power source can supply the low quiescent current of the
IMP803. 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 180V peak-to-peak. This conserves power and
extends battery life.
The IMP803 is available in MicroSO and SO-8 packages and in die or
wafer form.
Key Features
N
Low Power: 420µA typical V
DD
current
N
Wide operating voltage range - from 2.0V to 6.5V
N
180V peak-to-peak typical AC output voltage
N
Large output load capability - drive lamps
with more than 30nF capacitance
N
Adjustable output lamp frequency for control of
lamp color, lamp life, and power consumption
N
Adjustable converter frequency to minimize
power consumption
N
Device can be Enabled/Disabled
N
Low quiescent current – 20nA (disabled)
N
High-Voltage CMOS Process
N
MicroSO package option
Applications
N
N
N
N
N
N
N
GPS units/Pagers/Cellular phones
PDAs/Handheld computers
Safety illumination
Portable instrumentation
Battery-operated displays
LCD modules
Toys
4
L
X
C
S
Block Diagram
V
DD
1
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
–
IMP803
R
EL-OSC
8
Lamp Drive
Oscillator
Q
803_01.eps
© 2000 IMP, Inc.
408-432-9100/www.impweb.com
1
IMP803
Pin Configuration
SO/ MicroSO
V
DD
R
SW-OSC
C
S
L
X
1
2
3
4
IMP803
8
7
6
5
R
EL-OSC
V
A
V
B
GND
803_02.eps
Pin Compatible With HV803 and IMP560
Ordering Information
Part Number
IMP
803
LG
IMP
803
IMA
IMP
803
SX*
IMP
803/
D1**
Input Voltage
2.0V to 6.5V
2.0V to 6.5V
2.0V to 6.5V
2.0V to 6.5V
Regulated Output Voltage
Yes
Yes
Yes
Yes
Temperature Range
– 40°C to +85°C
– 40°C to +85°C
25°C
25°C
Pins-Package
8-SO
8-MicroSO
Dice
Dice
* Disable pad not active
** Disable pad active
Add /T to ordering part number for Tape and Reel.
Absolute Maximum Ratings
V
DD
, V
RSW-OSC
and V
REL-OSC
. . . . . . . . . . . . . . . –0.5V to +7.0V
V
CS
, L
X
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5V to +120V
Operating Temperature Range . . . . . . . . . . . . –40°C to +85°C
Storage Temperature Range . . . . . . . . . . . . . . –65°C to +150°C
Power Dissipation (SO) . . . . . . . . . . . . . . . . . . 400mW
Power Dissipation (MicroSO) . . . . . . . . . . . . . 300mW
V
A
, V
B
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5V to V
CS
(pin 3)
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.
Electrical Characteristics
Unless otherwise noted, V
DD
= 3.0V, R
SW
= 750kΩ, R
EL
= 2.0MΩ, and T
A
= 25°C.
Parameter
ON-resistance of MOS Switch
Output Voltage Regulation
Output Voltage Peak-to-peak (in regulation)
Quiescent V
DD
Supply Current, Disabled
Input Current at V
DD
Pin
Input Current at V
DD
Pin
Input Current: I
DD
Plus Inductor Current
Output Voltage at V
CS
V
A-B
Output Drive Frequency
Switching Frequency
Switching Duty Cycle
Symbol
R
DS(ON)
V
CS
V
A
-V
B
I
DDQ
I
DD
I
DD
I
IN
V
CS
f
EL
f
SW
D
SW
Conditions
I = 100mA
V
DD
= 2.0 to 6.5V
V
DD
= 2.0 to 6.5V
V
RSW-OSC
< 100mV
V
DD
= 3.0V, See Figure 1
V
DD
= 5.0V, See Figure 2
V
DD
= 3.0V, See Figure 1
V
DD
= 3.0V, See Figure 1
V
DD
= 3.0V, See Figure 1
V
DD
= 3.0V, See Figure 1
V
DD
= 3.0V, See Figure 1
Min
80
160
Typ
3.5
90
180
20
420
500
20
74
370
70
88
Max
8
100
200
200
700
750
31
100
430
90
Units
Ω
V
V
nA
µA
µA
mA
V
Hz
kHz
%
© 2000 IMP, Inc.
60
300
50
2
408-432-9100/www.impweb.com
IMP803
Typical Characteristics
V
CS
, I
IN
vs. Inductor Value
100
800
I
DD
vs. V
DD
L = 560µH
700
V
IN
= 3.0V
80
V
CS
V
CS
(V), I
IN
(mA)
I
DD
(µA)
I
IN
60
600
40
500
20
400
0
0
200
400
600
800
1000
803_03.eps
300
2.0
3.0
4.0
5.0
6.0
803_6.eps
Inductor (µH)
V
DD
(V)
V
CS
,
I
IN
vs. V
IN
100
L = 470µH
80
V
CS
80
100
L = 330µH
V
CS
,
I
IN
vs. V
IN
V
CS
V
CS
(V), I
IN
(mA)
V
CS
(V), I
IN
(mA)
60
60
40
40
20
I
IN
0
2.0
3.0
4.0
5.0
6.0
803_04.eps
20
I
IN
0
2.0
3.0
4.0
5.0
6.0
803_07.eps
V
IN
(V)
V
IN
(V)
V
CS
,
I
IN
vs. V
IN
100
L = 1mH
80
V
CS
80
100
L = 560µH
V
CS
,
I
IN
vs. V
IN
V
CS
V
CS
(V), I
IN
(mA)
60
V
CS
(V), I
IN
(mA)
60
In Regulation
40
40
20
I
IN
0
2.0
3.0
4.0
5.0
6.0
803_05.eps
20
I
IN
0
2.0
3.0
4.0
5.0
6.0
803_08.eps
V
IN
(V)
V
IN
(V)
© 2000 IMP, Inc.
Electroluminescent Lamp Driver
3
IMP803
Pin Descriptions
Pin Number
1
2
3
4
5
6
Name
V
DD
R
SW-OSC
C
S
L
X
GND
V
B
Function
Positive voltage supply for the IMP803. Inductor L may be connected here or to a
separate unregulated supply.
Switch-mode resistor pin. Switching frequency is determined by an external resistor, R
SW
.
Boost converter storage capacitor. The voltage across the EL lamp is equal to twice the
voltage at C
S
.
Connection to flyback inductance, L.
Ground pin.
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
.
EL lamp drive. (See above)
The EL lamp oscillator frequency setting pin. The oscillator frequency is controlled
by external resistor R
EL
.
7
8
V
A
R
EL-OSC
External Components
External Component
Diode
Capacitor C
S
Resistor R
EL
Description and Selection Guide
Catch diode. A fast reverse recovery diode, with BV > 100, such as a 1N4148.
This is the high voltage capacitor that stores the inductive energy transferred through the
catch diode. A 100 volt capacitor between 10nF and 100nF is recommended.
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 2MΩ resistor between the R
EL-OSC
pin and the
V
DD
supply results in a lamp frequency around 350Hz: a 1MΩ resistor will give
≈700Hz.
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.
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.
Resistor R
SW
Inductor L
Lamp, R
CL
An external resistor (R
CL
) in series with the lamp will protect the output drivers from high transient
currents during lamp commutation.
High Voltages Present
The IMP803 generates high voltages and caution should
be exercised.
4
408-432-9100/www.impweb.com
© 2000 IMP, Inc.
IMP803
Application Information
Test and Application Circuit, 3.0V
Figure 1
shows the IMP803 configured to drive a 3-square-inch
EL lamp, represented as a 10nF capacitor. With a 3.0V input, the
EL lamp will be driven to moderate brightness.
ON = V
DD
2MΩ
OFF = 0V
R
EL
1
V
DD
560µH
1
750kΩ
L
R
SW
1N4148
R
EL-OSC
V
A
V
B
GND
8
2kΩ
2
R
SW-OSC
3
C
S
7
R
CL
6
5
10nF
Equivalent to
3 in
2
lamp
+
V
IN
= 3.0V
4
L
X
0.1µF
100V
–
0.1µF
2
IMP803
C
S
Note:
1. Murata part # LQH4N561K04 (DC resistance <14.5
Ω
)
2. Larger values may be required depending upon supply impedance.
803_09.eps
Figure 1. 3.0V Application
Test and Application Circuit, 5.0V
Figure 2
shows a 5.0V input application driving a 6-square-inch
EL lamp.
ON = V
DD
2MΩ
OFF = 0V
R
EL
1
V
DD
560µH
1
750kΩ
L
R
SW
1N4148
R
EL-OSC
V
A
V
B
GND
8
2kΩ
2
R
SW-OSC
3
C
S
7
R
CL
6 in
2
lamp
6
5
+
V
IN
= 5.0V
4
L
X
0.1µF
100V
–
0.1µF
2
IMP803
C
S
Note:
1. Murata part # LQH4N561K04 (DC resistance <14.5
Ω
)
2. Larger values may be required depending upon supply impedance.
803_10.eps
Figure 2. 5.0V Application
© 2000 IMP, Inc.
Electroluminescent Lamp Driver
5
京公网安备 11010802033920号
EEWORLD
