HV835 Datasheet, PDF (1/6 Pages) Supertex, Inc – Low Noise Dual EL Lamp Driver

Supertex inc.
Low Noise Dual EL Lamp Driver
HV835
Initial Release
Features
► Low audible noise
► Independent input control for lamp selection
► 160V_PP output voltage
► 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 MLP/DFN-10 package
Applications
► Dual display cellular phones
► Keypad and LCD backlighting
► Portable instrumentation
► Dual segment lamps
► Handheld wireless communication devices
General Description
The Supertex HV835 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 a minimum num-
ber of passive components to drive two EL lamps. The nominal
regulated output voltage of ±80V 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 HV835 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 R_SW-OSC pin and
the voltage supply pin, V , sets the frequency for the switching
DD
MOSFET. The EL lamp driver frequency is set by dividing the
MOSFET switching frequency by 512. 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 switching MOSFET charges the external
inductor and discharges it into the capacitor at C . The voltage
S
at C_S increases. Once the voltage at C_S reaches a nominal value
of 80V, the switching MOSFET is turned OFF to conserve power.
Typical Application Circuit
1.5V
0
+
V_DD
-
1.5V
0
C_DD
0.1µF
+
V_IN
-
C_IN
4.7µF
845kΩ
1 _C1
2 _VDD
3
R_SW-OSC
4
C₂
5 _GND
EL₁ ¹⁰
9
EL₂
Com ⁸
C_S ⁷
L_X ⁶
HV835K7-G
1.0µF
1.0µF
D
L_X
330µH
3.3MΩ
EL Lamp 1
3.3MΩ
EL Lamp 2
C_S
3.3nF, 100V
· · · · ^{Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: [phone] FAX: [phone] www.supertex.com}
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