Supertex inc.
HV841
Initial Release
High Voltage Dual EL Lamp Driver
Features
General Description
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Independent input control for lamp selection
The Supertex HV841 is a high voltage driver designed for driving
two EL lamps with a combined area of 3.5 square inches. The input
supply voltage range is from 2.0V to 5.8V. The device is designed to
reduce the amount of audible noise emitted by the lamp. This device
uses a single inductor and minimum number of passive components
to drive two EL lamps. The nominal regulated output voltage of
100V is applied to the EL lamps. The chip can be enabled/ disabled
by connecting C1 and C2 (pins 1 and 4) to VEN/ Ground.
Split supply capability
Patented output timing
One miniature inductor to power both lamps
Low shutdown current
Wide input voltage range 2.0V to 5.8V
Output voltage regulation
No SCR output
Available in small packages (10-lead MSOP and
10-lead DFN/MLP)
The HV841 has an internal oscillator, a switching MOSFET, and two
high voltage ELlamp drivers. An external resistor connected between
the RSW-OSC and the voltage supply pin V sets the frequency for the
switching MOSFET. The EL lamp driverDfDrequency is set by dividing
the MOSFET switching frequency by 128. An external inductor is
connected between the LX and the VDD pins. Depending on the EL
lamp size, a 1.0 to 10.0nF, 200V capacitor is connected between CS
and Ground. The two EL lamps are connected between EL1 to Com
and EL2 to Com.
Applications
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Mobile cellular phones, dual display
Keypad and LCD backlighting
Portable instrumentation
Dual segment lamps
The switching MOSFETcharges the external inductor and discharges
it into the capacitor at CS. The voltage at CS increases. Once the
voltage at CS reaches a nominal value of 100V, the switching
MOSFET is turned off to conserve power. The outputs EL to Com
and EL to Com are configured as H bridges and switch in1opposite
states t2o achieve 200V across the EL lamp.
Hand held wireless communication devices
Typical Application Circuit
VEN = ON
0 = OFF
EL Lamp 11
VEN = ON
0 = OFF
1
2
10
C1
EL1
9
EL2
VDD
RSW-OSC
+
EL Lamp 21
8
RSW-OSC
Com
3
4
5
VDD
CDD
7
C
2
CS
D
-
6
LX
GND
HV841MG-G/
HV841K6-G
LX
+
-
CS
VIN
~
CIN
1
The bigger sized lamp should be tied to EL1 and the smaller
sized lamp to EL2 terminals (pins 10 and 9 respectively)
NR033106
Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: (408) 222-8888 FAX: (408) 222-4895 www.supertex.com
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