Supertex inc.
Low Noise Dimmable EL Lamp Driver
Features
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Adjustable output regulation for dimming
220V
PP
output voltage for higher brightness
Single cell lithium ion compatible
150nA shutdown current
Separately adjustable lamp and converter frequencies
3x3 QFN-12 package
Split supply capability
HV860
Initial Release
The HV860 has two internal oscillators, a switching
MOSFET, and a high voltage EL lamp driver H-bridge. The
frequency for the switching MOSFET is set by an external
resistor connected between the R
SW-OSC
pin and the supply
pin V
DD
. The EL lamp driver frequency is set by an external
resistor connected between R
EL-OSC
pin and V
DD
pin. An
external inductor is connected between the L
X
and V
DD
pins or V
IN
for split supply applications. A 3.0nF capacitor
is connected between C
S
and ground. The EL lamp is
connected between V
A
and V
B
.
The switching MOSFET charges the external inductor and
discharges it into the capacitor at C
S
. The voltage at C
S
will
start to increase. Once the voltage at C
S
reaches a nominal
value of 110V, the switching MOSFET is turned OFF to
conserve power. The outputs V
A
and V
B
are configured as
an H bridge and are switching in opposite states to achieve
±110V across the EL lamp.
EL lamp dimming can be accomplished by changing the
input voltage to the V
REG
pin. The V
REG
pin allows an external
voltage source to control the V
CS
amplitude. The V
CS
voltage
is approximately 87 times the voltage seen on V
REG
.
Applications
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Mobile cellular phone keypads
PDAs
Handheld wireless communication products
Global Positioning Systems (GPS)
General Description
The Supertex HV860 is a high voltage driver designed for
driving Electroluminescent, (EL), lamps of up to 5 square
inches. The input supply voltage range is from 2.5V to 4.5V.
The device uses a single inductor and a minimum number of
passive components. Using the internal reference voltage,
the regulated output voltage is at a nominal voltage of 110V.
The EL lamp will therefore see ±110V. An enable pin, (EN),
is available to turn the device on and off via a logic signal.
Typical Application Circuit
V
IN
C
IN
L
X
R
REG
2
3
5
D
C
S
7
9
8
V
DD
C
DD
1.5V = On
0V = Off
10
V
REG
V
DD
R
SW-OSC
R
EL-OSC
EN
V
REF
R
SW
L
X
C
S
V
A
V
B
12
1
R
EL
11
EL
Lamp
GND
4
HV860K7
NR040306
Supertex inc.
·
1235 Bordeaux Drive, Sunnyvale, CA 94089
·
Tel: (408) 222-8888
·
FAX: (408) 222-4895
·
www.supertex.com
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SUPERTEX [ Supertex, Inc ]
