9

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.

R

EL-osc

The EL lamp frequency is controlled via an external R

device. The lamp frequency increases as R

of current drawn from the battery will increase and the output voltage V

lamp is dependent upon its frequency.

R

SW-osc

The switching frequency of the converter is controlled via an external resistor, R

of the device. The switching frequency increases as R

frequency increases, the amount of current drawn from the battery will decrease and the output voltage, V

will also decrease.

Lx Inductor

The inductor L

When the internal switch is on,

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 C

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 R

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 R

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, (V

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 R

Application Circuit on the front page. The control signal can be

from a microprocessor. R

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, V

1.8V to 6.5V.

1235 Bordeaux Drive, Sunnyvale, CA 94089

TEL: (408) 744-0100 • FAX: (408) 222-4895

www.supertex.com

05/02/02rev.8

©2002 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.