HV825
High Voltage EL Lamp Driver IC
Features
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Processed with HVCMOS
®
technology
1.0V to 1.6V operating supply voltage
DC to AC conversion
Output load of typically up to 6nF
Adjustable output lamp frequency
Adjustable converter frequency
Enable function
General Description
The Supertex HV825 is a high voltage driver designed for driving
EL lamps typically up to 6nF. The input supply voltage range
is from 1.0V to 1.6V. The device uses a single inductor and a
minimum number of passive components. The typical output
voltage that can be applied to the EL lamp is ±56V.
The HV825 can be enabled/disabled by connecting the R
SW-Osc
resistor to V
DD
/GND.
The HV825 has two internal oscillators, a switching bipolar
junction transistor (BJT), and a high voltage EL lamp driver.
The frequency for the switching BJT is set by an external
resistor connected between the RSW-Osc pin and the VDD
supply pin. The EL lamp driver frequency is set by an external
resistor connected between REL-Osc pin and the VDD pin. An
external inductor is connected between the LX and VDD pins.
A 0.01 to 0.1µF, 100V capacitor is connected between the CS
pin and the GND pin. The EL lamp is connected between the
VA pin and the VB pin.
The switching BJT charges the external inductor and discharges
it into the 0.01 to 0.1µF, 100V capacitor at the CS pin. The volt-
age at the CS pin will start to increase. The outputs VA and VB
are configured as an H-bridge and are switching in opposite
states to achieve a peak-to-peak voltage of two times the V
CS
voltage across the EL lamp.
Applications
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Pagers
Portable Transceiver
Cellular phones
Remote control units
Calculators
HV825 Block Diagram
LX
VDD
CS
RSW-Osc
Switch
Osc
Q
VA
GND
Q
Output
Osc
Q
VB
REL-Osc
Q
SUPERTEX [ Supertex, Inc ]
