HV833X データシートの表示（PDF） - Supertex Inc
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HV833X Datasheet PDF : 9 Pages
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HV833
External Component Description
External Component
Selection Guide Line
Diode
Fast reverse recovery diode, 100V 1N4148 or equivalent.
Cs Capacitor
0.003µF to 0.1µF, 100V capacitor to GND is used to store the energy transferred from the inductor.
REL-osc
The EL lamp frequency is controlled via an external REL resistor connected between REL-osc and VDD of the
device. The lamp frequency increases as REL decreases. As the EL lamp frequency increases, the amount
of current drawn from the battery will increase and the output voltage VCS will decrease. The color of the EL
lamp is dependent upon its frequency.
RSW-osc
The switching frequency of the converter is controlled via an external resistor, RSW between RSW-osc and VDD
of the device. The switching frequency increases as RSW decreases. With a given inductor, as the switching
frequency increases, the amount of current drawn from the battery will decrease and the output voltage, VCS,
will also decrease.
Lx Inductor
The inductor L is used to boost the low input voltage by inductive flyback. When the internal switch is on,
x
the inductor is being charged. When the internal switch is off, the charge stored in the inductor will be
transferred to the high voltage capacitor CS. The energy stored in the capacitor is connected to the internal
H-bridge and therefore to the EL lamp. In general, smaller value inductors, which can handle more current,
are more suitable to drive larger size lamps. As the inductor value decreases, the switching frequency of the
inductor (controlled by RSW) should be increased to avoid saturation.
220µH Murata (LQH43MN221) inductors with 5.4Ω series DC resistance is typically recommended. For
inductors with thesame inductance value but with lower series DC resistance, lower RSW value is needed to
prevent high current draw and inductor saturation.
Lamp
As the EL lamp size increases, more current will be drawn from the battery to maintain high voltage across
the EL lamp. The input power, (VIN x IIN), will also increase. If the input power is greater than the power
dissipation of the package (300mW), an external resistor in series with one side of the lamp is recommended
to help reduce the package power dissipation.
Enable/Disable Configuration
The HV833 can be easily enabled and disabled via a logic control
signal on the RSW and REL resistors as shown in the Typical
Application Circuit on the front page. The control signal can be
from a microprocessor. RSW and REL are typically very high
values. Therefore, only 10’s of microamperes will be drawn from
the logic signal when it is at a logic high (enable) state. When
the microprocessor signal is high the device is enabled and when
the signal is low, it is disabled.
Split Supply Configuration for Battery
Voltages of Higher than 6.5V
The Typical Application Circuit on the first page can also be used
with high battery voltages such as 12V as long as the input
voltage, VDD, to the HV833 device is within its specifications of
1.8V to 6.5V.
©2002 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.
9
05/02/02rev.8
1235 Bordeaux Drive, Sunnyvale, CA 94089
TEL: (408) 744-0100 • FAX: (408) 222-4895
www.supertex.com
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