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| HV843 Datasheet, PDF (1/6 Pages) Supertex, Inc – Low Noise Dual EL Lamp Driver | |||
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HV843
Low Noise Dual EL Lamp Driver
Initial Release
Features
⺠Low audible noise
⺠Independent input control for lamp selection
⺠180Vpp output voltage
⺠Split supply capability
⺠Patented output timing
⺠One miniature inductor to power both lamps
⺠Low shutdown current
⺠Wide input voltage range 2.0V to 5.8V
⺠Output voltage regulation
⺠No SCR output
⺠Available in DFN/MLP - 10 package
Applications
⺠Dual display cellular phones
⺠Keypad and LCD backlighting
⺠Portable instrumentation
⺠Dual segment lamps
⺠Hand held wireless communication devices
General Description
The Supertex HV843 is a low noise, 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 a
minimum number of passive components to drive two EL lamps.
The nominal regulated output voltage of ±90V is applied to the
EL lamps. The two EL lamps can be turned ON and OFF by the
two logic input control pins, C1 and C2. The device is disabled
when both C1 and C2 (pins 1 and 4) are at logic low.
The HV843 has an internal oscillator, a switching MOSFET, and
two high voltage EL lamp drivers. Each driver has its own half
bridge common output (COM1 and COM2) connected to a single
pin called COM which minimizes the DC offset seen by the EL
lamp. An external resistor connected between the RSW-OSC pin and
the voltage supply pin, VDD, sets the frequency for the switching
MOSFET. The EL lamp driver frequency is set by dividing the
MOSFET switching frequency by 512. An external inductor is
connected between the LX and the VDD pins. Depending on the EL
lamp size, a 1.0 to 10.0nF, 100V capacitor is connected between
CS and Ground. The switching MOSFET charges 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 90V, the switching MOSFET is turned OFF to conserve power.
Typical Application Circuit
1.5V
0
+
VDD
-
1.5V
0
CDD
0.1µF
+
VIN
-
CIN
4.7µF
845kΩ
1
C1
2 VDD
3 RSW-OSC
4 C2
5 GND
EL1 10
EL2 9
Com 8
CS 7
LX 6
HV843K7-G
1.0µF
1.0µF
D
LX
330µH
3.3MΩ
EL Lamp 1
3.3MΩ
EL Lamp 2
CS
3.3nF, 100V
1
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