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
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 2.0 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
鹵90V.
The chip can be enabled by connecting the resistors on
R
SW-osc
and R
EL-osc
to V
DD
and disabled when connected to GND.
The HV823 has two internal oscillators, a switching MOSFET,
and a high-voltage EL lamp driver. The frequency for the switch-
ing converter MOSFET is set by an external resistor connected
between the R
SW-osc
pin and the supply pin V
DD
. The EL lamp
driver frequency is set by an external resistor connected be-
tween R
EL-osc
pin and the V
DD
pin. An external inductor is
connected between the L
x
and V
DD
pins. A 0.01碌F to 0.1碌F
capacitor is connected between C
S
and GND. The EL lamp is
connected between V
A
and V
B
.
The switching MOSFET charges the external inductor and
discharges 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 switching MOSFET is turned OFF to conserve power. The
outputs V
A
and V
B
are configured as an H-bridge and are
switched in opposite states to achieve 180V peak-to-peak across
the EL lamp.
Applications
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Handheld personal computers
Electronic personal organizers
GPS units
Pagers
Cellular phones
Portable instrumentation
Pin Configuration
蟼螒
V
DD
R
SW-osc
C
s
L
x
1
2
3
4
8
7
6
5
Absolute Maximum Ratings*
Supply Voltage, V
DD
Output Voltage, V
Cs
Operating Temperature Range
Storage Temperature Range
Power Dissipation
Note:
*All voltages are referenced to GND.
11/12/01
R
EL-osc
V
A
V
B
GND
-0.5V to +10V
-0.5V to +120V
-25擄C to +85擄C
-65擄C to +150擄C
400mW
SO-8
Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability
indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to
workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the
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Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current databook or to the Legal/Disclaimer page on the Supertex website.
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