HV825MG Ver la hoja de datos (PDF) - Supertex Inc

Número de pieza

componentes Descripción

Fabricante

HV825MG

High Voltage EL Lamp Driver

Supertex Inc 

HV825

External Component Description

External Component

Selection Guide Line

Diode

Fast reverse recovery, 1N4148 or equivalent.

CS Capacitor

REL-osc Resistor

0.01 to 0.1µF, 100V capacitor to GND is used to store the energy transferred from the inductor.

The lamp frequency is controlled via the REL-osc. The lamp frequency increases as the REL-osc decreases.

As the lamp frequency increases, the amount of current drawn from the battery will increase and the output

voltage VCS will decrease. This is because the lamp will draw more current from VCS when driven at higher

frequencies.

In general, as the lamp size increases, larger REL-osc is recommended to provide higher VCS. However, the

color of the lamp is dependent upon its frequency and the shade of the color will change slightly with different

frequencies.

RSW-osc Resistor

LX Inductor

CSW Capacitor

The switching frequency of the inductor is controlled via the RSW-osc. The switching frequency increases as

the RSW-osc decreases. As the switching frequency increases, the amount of current drawn from the battery

will decrease and the output voltage VCS will also decrease.

The inductor LX is used to boost up the low input voltage. When the internal switch is on, the inductor is being

charged. When the internal switch is off, the charge 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

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-osc)

should be increased to avoid saturation.

The test circuit uses a Murata (LQH4N561) 560µH inductor. Using different inductor values or inductors from

different manufacturers will affect the performance.

As the inductor value decreases, smaller RSW-osc value shall be used. This will prevent inductor saturation.

Inductor with the same inductance value (560µH) but lower series resistance will charge faster. The

RSW-osc resistor value needs to be decreased to prevent inductor saturation and high current consumption.

A 1nF capacitor is recommended from RSW-OSC to GND. This capacitor is used to shunt any switching noise

that may couple into the RSW-OSC pin.

©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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