HV823LG-G Datasheet, PDF (1/8 Pages) Supertex, Inc – High Voltage EL Lamp Driver IC

Supertex inc.
HV823
High Voltage EL Lamp Driver IC
Features
► Processed with HVCMOS^® technology
► 2.0 to 9.5V operating supply voltage
► DC to AC conversion
► 180V peak-to-peak typical output voltage
► Large output load capability typically 50nF
► Permits the use of high-resistance elastomeric
lamp components
► Adjustable output lamp frequency to control lamp
color, lamp life, and power consumption
► Adjustable converter frequency to eliminate
harmonics and optimize power consumption
► Enable/disable function
► Low current draw under no load condition
Applications
► Handheld personal computers
► Electronic personal organizers
► GPS units
► Pagers
► Cellular phones
► Portable instrumentation
General Description
The Supertex HV823 is a high-voltage driver designed for driving EL
lamps of up to 50nF. EL lamps greater than 50nF can be driven for
applications not requiring high brightness. The input supply voltage
range is from 2.0V to 9.5V. The device uses a single inductor and
a minimum number of passive components. The nominal regulated
output voltage that is applied to the EL lamp is ±90V. The chip can
be enabled by connecting the resistors on the RSW-Osc pin and
the REL-Osc pin to the VDD pin, and disabled when connected to
GND.
The HV823 has two internal oscillators, a switching MOSFET and a
high-voltage EL lamp driver. The frequency of the switching converter
MOSFET 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 the REL-Osc pin and
the VDD pin. An external inductor is connected between the LX pin
and the VDD pin. A 0.01µF to 0.1µF capacitor is connected between
the CS pin and the GND. The EL lamp is connected between the
VA and VB pins.
The switching MOSFET charges the external inductor and discharg-
es it into the C_S capacitor. The voltage at C_S will start to increase.
Once the voltage at C_S reaches a nominal value of 90V, the switch-
ing MOSFET is turned OFF to conserve power. The output pins VA
and VB are configured as an H-bridge and are switched in opposite
states to achieve 180V peak-to-peak across the EL lamp.
For additional information, see Application Notes AN-H33 and
AN-H34.
Block Diagram
VDD
RSW-Osc
Enable *
GND
Switch
Osc
+
Disable
C_{_}
V_REF
LX
CS
Q
VA
Q
Output
Osc
Q
VB
REL-Osc
* Enable is available in die form only.
Q
Supertex inc. ● 1235 Bordeaux Drive, Sunnyvale, CA 94089 ● Tel: [phone] ● www.supertex.com