HV833 Ver la hoja de datos (PDF) - Supertex Inc

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componentes Descripción

Fabricante

HV833

High Voltage EL Lamp Driver

Supertex Inc 

HV833

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 sig-

nal 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 (en-

able) state. When the microprocessor signal is high the de-

vice is enabled and when the signal is low, it is disabled.

Enable/Disable Table

Enable Signal

VDD

0V

HV833

Enable

Disable

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 specifi-

cations of 1.8V to 6.5V. Split supply configuration is shown

on Fig. 2.

External Component Description

External Component

Diode

CS Capacitor

Selection Guide Line

Fast reverse recovery diode, 100V 1N4148 or equivalent.

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 pins 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

LX Inductor

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

RSW-Osc and VDD pins 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.

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.

Lamp

A 220µH Murata (LQH43MN221) inductor with 5.4Ω series DC resistance is typically

recommended. For inductors with the same inductance value but with lower series DC resistance,

a 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 (300mW), an external resistor in series with

one side of the lamp is recommended to help reduce the package power dissipation.

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