HV839 Datasheet, PDF (1/9 Pages) Supertex, Inc – High Voltage Dual EL Lamp Driver

HV839
High Voltage Dual EL Lamp Driver
Features
Independent input control for lamp selection
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)
Applications
Mobile cellular phones, dual display
Keypad and LCD backlighting
Portable instrumentation
Dual segment lamps
Hand held wireless communication devices
Typical Application Circuit
General Description
The Supertex HV839 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 ±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 HV839 has an internal oscillator, a switching
MOSFET, and two high voltage EL lamp drivers. An
external resistor connected between the R_SW-OSC pin
and the voltage supply pin V_DD sets the frequency for
the switching MOSFET. The EL lamp driver frequency
is set by dividing the MOSFET switching frequency by
128. An external inductor is connected between the
L_X and the V_DD pins. Depending on the EL lamp size,
a 1.0 to 10.0nF, 100V capacitor is connected between
C_S and Ground. The two EL lamps are connected
between EL₁ to Com and EL₂ to Com. The switching
MOSFET charges the external inductor and
discharges it into the capacitor at C_S. The voltage at
C_S increases. Once the voltage at C_S reaches a
nominal value of 90V, the switching MOSFET is
turned OFF to conserve power. The outputs EL₁ to
Com and EL₂ to Com are configured as H bridges and
switch in opposite states to achieve 180V across the
EL lamp.
A033106