Supertex inc.

Supertex inc.

www.supertex.com

Doc.# DSFP-HV859

C073013

HV859

Features

frequencies

Applications

General Description

The Supertex HV859 is a high voltage driver designed for driving

Electroluminescent (EL) lamps of up to 5.0 square inches. The

input supply voltage range is from 1.8 to 5.0V. The device uses a

single inductor and a minimum number of passive components.

The nominal regulated output voltage that is applied to the EL

lamp is ±105V. The chip can be enabled/disabled by connecting

the resistor on RSW-Osc to VDD/ground.

The HV859 has two internal oscillators, a switching MOSFET,

and a high voltage EL lamp driver. The frequency for the

switching MOSFET is set by an external resistor connected

between the RSW-Osc pin and the supply pin VDD. The EL

lamp driver frequency is set by an external resistor connected

between REL-Osc pin and the VDD pin. An external inductor is

connected between the LX and VDD pins or VIN for split supply

applications. A 0.003-0.1µF capacitor is connected between CS

and ground. The EL lamp is connected between VA and VB.

The switching MOSFET charges the external inductor and

discharges it into the capacitor at CS. The voltage at CS will

start to increase. Once the voltage at CS reaches a nominal

value of 105V, the switching MOSFET is turned OFF to conserve

power. The outputs VA and VB are configured as an H bridge

and are switching in opposite states to achieve ±105V across

the EL lamp.

Typical Application Circuit

High Voltage EL Lamp Driver

for Low Noise Applications

D

+

-

+

-

V

DD

V

IN

C

DD

C

IN

R

SW

R

EL

C

S

R

SER

L

X

EL Lamp

Enable

ON = V

DD

OFF = 0V

1

2

3

4

8

7

6

5

HV859

VDD

RSW-Osc

REL-Osc

GND

VA

VB

CS

LX