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componentes Descripción

Fabricante

HV830X

High Voltage EL Lamp Driver

Supertex Inc 

HV830

External Component Description

External Component

Diode

Cs Capacitor

REL-osc

RSW-osc

CSW Capacitor

Lx Inductor

Lamp

Selection Guide Line

Fast reverse recovery diode, BAS21LT1 or equivalent.

0.01µF to 0.1µF, 200V capacitor to GND is used to store the energy transferred from the inductor.

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.

A 3.3MΩ resistor would provide lamp frequency of 220 to 280Hz. Decreasing the REL-osc by a factor of 2 will

increase the lamp frequency by a factor of 2.

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.

A 1nF capacitor is recommended on RSW-osc to GND when a 0.01µF CS capacitor is used. This capacitor

is used to shunt any switching noise that may couple into the RSW-osc pin. The CSW capacitor may also be

needed when driving large EL lamp due to an increase in switching noise.

The inductor Lx is used to boost the low input voltage by inductive flyback. 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 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 inductors with 5.4Ω series DC resistance is typically recommended. For inductors with the

same inductance value but with lower series DC resistance, lower RSW value is needed to prevent high current

draw and inductor saturation.

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 (400mW), an external resistor in series with one side of the lamp is recommended

to help reduce the package power dissipation.

Figure 3: Split Supply Configuration

ON = VDD

OFF = 0V

VDD = Regulated

Voltage

+

VIN = Battery

Voltage –

Remote

Enable

REL

RSW

Lx

BAS21LT1

0.1µF*

CS

200V

1 VDD REL-osc 8

2 RSW-osc

VA 7

3 Cs

VB 6

4 Lx

GND 5

HV830LG

1nF

EL Lamp

*Larger values may be required depending upon supply impedance.

For additional information, see Application Notes AN-H33 and AN-H34.

©2001 Supertex Inc. All rights reserved. Unauthorized use or reproduction prohibited.

4

11/12/01

1235 Bordeaux Drive, Sunnyvale, CA 94089

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

www.supertex.com

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