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Continious output voltage regulation control
(from 50V to 200V)
General Description
The Supertex HV829A/B are high voltage EL lamp driver inte-
grated circuits designed for driving EL lamps of up to 70nF at
1000Hz. The input supply voltage range is from 2.7V to 5.5V.
These devices use a single inductor, a high voltage switching
FET and a minimum number of passive components. The
HV829A/B will supply the EL lamp with an AC square wave with
a peak-to-peak voltage of two times the set regulated DC
voltage.
The HV829A/B has one internal oscillator and a high voltage EL
lamp driver. The frequency for the external switching MOSFET
is set by an external resistor connected between the R
SW-osc
pin
and GND. The EL frequency for the HV829A is equal to the
switching frequency divided by 64 where the EL frequency for the
HV829B is equal to the switching frequency divided by 128. Gate
of the external MOSFET is connected to the Gate pin. An
external inductor is connected between the Drain of external
MOSFET and V
DD
pin. A 0.01-2.5碌F capacitor is connected
between Cs and ground. The EL lamp is connected between V
A
and V
B
. The output voltage regulation level is controlled via the
V
REG
pin for dimming and/or conservation of power. The output
voltage regulation can be controlled continuously between 50V
and 200V depending on the voltage applied to V
REG
pin (0.75V
to 3V).
The switching MOSFET charges the external inductor and
discharges it into the capacitor at C
S
. The voltage at C
S
will start
to increase. Once the voltage at C
S
reaches a nominal value
chosen by the user, the switching MOSFET is turned OFF to
conserve power. The outputs V
A
and V
B
are configured as an H
bridge and are switching in opposite states to achieve the AC
voltage of +/- VREG voltage across the EL lamp.
Application
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Electronic Organizers
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Handheld Portable Computers
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Display Signs
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Portable Instrumentation Equipment
Typical Application Circuit
Off=V
DD
On=GND
V
DD
1
V
DD
V
A
8
EL Lamp
V
B
7
Gate
6
C
S
5
BAV21
Lx
Vreg
2
R
SW-osc
3
V
REG
4
GND
+
V
IN
-
C
IN
HV829ASG
C
S
250V
VN2224N3 or
TN2425N8
09/05/02
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
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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