1
HV857DB1
11/27/01
Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability
indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to
workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the
Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
HV857DB1
EL Lamp Driver
Introduction
The Supertex HV857DB1 demo board contains all necessary
circuitry to demonstrate the features of the HV857 EL lamp
driver.
Simply connect it to a power supply and a lamp. For additional
assistance in designing EL driver circuits, please refer to appli-
cation notes AN-H33 (effect of external components on perfor-
mance of Supertex EL drivers) and AN-H43 (EL lamp driver
circuits to reduce audible lamp noise).
Specifications
Input Voltage
1.8V to 5.0V
Supply Current
25mA
Lamp Size Range
up to 2.6in
2
Lamp Frequency
250Hz
Converter Frequency
80KHz
Demo Board Connections:
EN
Enable Input
Enables/Disables the lamp driver. A logic high (connect to V
DD
)
enables the driver and a logic low (connect to GND) disables the
driver. This input can be connected to a mechanical switch, or
to a logic circuit output with a source impedance of less than
20K
.
V
DD
IC Supply
Supplies the HV857 EL driver IC. The supplied circuit is opti-
mized for 3.0V operation. The operating range can be from 1.8V
to 5.0V. Connect to positive terminal of a power supply.
V
IN
Inductor Supply
Supplies the high voltage power converter. Connect to positive
terminal of a power supply.
GND
Circuit Ground
Connect to V
DD
and V
IN
negative terminals. Supply bypass
capacitors for both V
DD
and V
IN
are provided on the demo board.
External supply bypass capacitors are not required.
V
A
and V
B
Lamp Connections
Connect to an EL lamp. Polarity is irrelevant.
* Note: Make sure all the above connections are made before powering up the supply voltages.
Board Layout and Connections
HV857
Cdd
Rel
Rsw
Cin
+
L
X
D
Cs
V
IN
EN
V
DD
GND
V
B
V
A
2
HV857DB1
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 FAX: (408) 222-4895
www.supertex.com
11/27/01rev.4
2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
1
2
3
4
8
7
6
5
V
DD
R
SW-osc
V
B
R
EL-osc
GND
V
A
L
X
C
S
HV857MG
EL Lamp
ON=V
DD
OFF=0V
Enable
4.7
F
L
X
=
220
H
SB01-15
C
S
=
3.3nF
100V
560K
2.0M
Inductor: Murata LQH32CN221K21
0.1
F
+
-
V
DD
+
-
V
IN
HV857DB1 Schematic
Cdd
Cin
Typical Performance
The specific external components used in the above circuit are L
X
=220
H Murata (LQH32CN221K21), Cs= 3.3nF 100V NPO.
The following was observed when driving a 2.6in
2
Green lamp.
The following was observed when driving a 1.7in
2
Green lamp.
The above circuit may need to be optimized further based on specification of the lamp used.
V
D
D
=
V
N
I
)
V
(
I
N
I
)
A
m
(
V
S
C
)
V
(
f
L
E
)
z
H
(
s
s
e
n
t
h
g
i
r
B
m
l
-
t
f
m
/
d
c
2
8
.
1
3
.
4
2
6
.
9
6
0
5
2
6
2
.
4
6
.
4
1
0
.
2
9
.
4
2
3
.
2
7
0
5
2
7
0
.
5
3
.
7
1
0
.
3
6
.
4
2
0
.
5
8
0
5
2
9
0
.
8
7
.
7
2
0
.
4
3
.
0
2
0
.
0
9
0
5
2
4
6
.
8
6
.
9
2
0
.
5
7
.
7
1
7
.
2
9
0
5
2
1
8
.
8
2
.
0
3
V
D
D
=
V
N
I
)
V
(
I
N
I
)
A
m
(
V
S
C
)
V
(
f
L
E
)
z
H
(
s
s
e
n
t
h
g
i
r
B
m
l
-
t
f
m
/
d
c
2
8
.
1
1
.
2
2
3
.
6
7
0
5
2
1
9
.
4
8
.
6
1
0
.
2
5
.
0
2
8
.
9
7
0
5
2
6
7
.
5
7
.
9
1
0
.
3
3
.
7
1
0
.
9
8
0
5
2
5
2
.
7
8
.
4
2
0
.
4
7
.
3
1
0
.
2
9
0
5
2
9
4
.
7
6
.
5
2
0
.
5
7
.
1
1
5
.
3
9
0
5
2
4
5
.
7
8
.
5
2
SB01-15=150V Sanyo Diode
* Note: Tie V
DD
and V
IN
together if split supplies are not used.
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