IMP803
Dual Supply Operation with 1.5V Battery
The IMP803 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 5,
uses the regulated
voltage to operate the IMP803 while the energy for the high-
voltage boost circuit comes from the battery.
The circuit of
Figure 5
thus allows operation with batteries that are
below the 2V minimum specification or above the 6.0V maximum
operating voltage.
Regulated Voltage
(2.0V to 6.5V)
ON = V
DD
R
EL
OFF = 0V
1
V
DD
R
SW
L
R
EL-OSC
V
A
V
B
GND
8
R
CL
2
R
SW-OSC
3
C
S
7
EL lamp
6
5
Battery
Voltage
+
–
V
IN
0.1µF
*
1N4148
4
L
X
C
S
0.1µF
100V
IMP803
* Larger values may be required
depending upon supply impedance
803_13.eps
Figure 5. Dual Supply Operation
Switch Resistance
The IMP803 inductor switch resistance is typically below 3.5Ω, as
shown in
Figure 6.
On Resistance (Ω)
30
25
20
15
10
5
0
1
2
3
4
5
6
7
525_14.eps
V
DD
(V)
Figure 6. Boost Switch On Resistance
© 2000 IMP, Inc.
Electroluminescent Lamp Driver
7
IMP [ IMP, INC ]
