Supertex inc.
HV859
Initial Release
High Voltage EL Lamp Driver for Low Noise Applications
Features
Patented audible noise reduction
Patented lamp aging compensation
210 V
PP
output voltage for higher brightness
Patented output timing for high efficiency
Single cell lithium ion compatible
150nA shutdown current
Wide input voltage range 1.8V to 5.0V
Separately adjustable lamp and converter
frequencies
Output voltage regulation
Split supply capability
General Description
The Supertex HV859 is a high voltage driver designed for
driving Electroluminescent (EL) lamps of up to 5 square
inches. The input supply voltage range is from 1.8V to 5.0V.
The device uses a single inductor and a minimum number of
passive components. The nominal regulated output voltage
that is applied to the EL lamp is ±105V. The chip can be
enabled/disabled by connecting the resistor on R
SW-OSC
to V
DD
/
ground.
The HV859 has two internal oscillators, a switching MOSFET,
and a high voltage EL lamp driver. 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 the V
DD
pin. An external inductor is
connected between the L
X
and V
DD
pins or V
IN
for split supply
applications. A 0.003-0.1µF 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 105V, 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 ±105V across
the EL lamp.
Applications
LCD backlighting
Mobile Cellular Phone keypads
PDAs
Handheld wireless communication products
Global Positioning Systems (GPS)
Typical Application Circuit
ON = V
DD
OFF = 0V
R
SW
C
DD
R
EL
1
2
3
Enable
R
SER
V
DD
R
SW-osc
R
EL-osc
GND
V
A
V
B
C
S
L
X
8
7
6
+
V
DD
EL Lamp
D
-
4
5
+
V
IN
C
IN
HV859MG/
HV859K7
L
X
C
S
-
NR040306
Supertex inc.
·
1235 Bordeaux Drive, Sunnyvale, CA 94089
·
Tel: (408) 222-8888
·
FAX: (408) 222-4895
·
www.supertex.com
1
SUPERTEX [ Supertex, Inc ]
