HV850

________________________________________________________________________________

Supertex, Inc.

1/21/04

1

Initial Release

High Voltage Low Noise Inductorless EL Lamp Driver

Features

No external components required when using an

external EL clock frequency

EL frequency can be set by an external resistor

Low Noise

DC to AC converter

Drives up to 4.5nF load (approx. 2.0

Output voltage regulation

Enable function

Applications

Cell phone keypads and displays

Transceivers

MP3 Players

Watches

Pagers

Measuring instruments/gauges

Typical Application Circuits

General Description

Supertex HV850 is a high voltage electroluminescent

(EL) Lamp Driver IC. It is designed to drive EL lamps

HV850 converts a low voltage DC input to a high

voltage AC output across an EL lamp. It uses a

charge pump scheme to boost the input voltage

eliminating the need for an external inductor, diode,

and high voltage capacitor commonly found in

conventional topologies.

The charge pump circuit discharges its energy into

an EL lamp through a high voltage H-bridge. Once

the voltage reaches its regulated limit, it is turned off

to conserve power. The EL lamp is then discharged

to ground and the H-bridge changes state to allow

the charge pump to charge the EL lamp in the

opposite direction.

The EL lamp frequency can be set either by an

where the clock frequency is divided by 128 to set

the EL lamp frequency.

EL lamp frequency set by an external clock

EL

Lamp

V

DD

V

B

R

EL

GND

V

A

HV850MG

EN

Clk-in

Clk-en

V

GND=OFF

V

DD

GND

C

DD

V

DD

+

-

V

DD

EL

Lamp

V

DD

V

B

R

EL

GND

V

A

HV850MG

EN

Clk-in

Clk-en

V

GND=OFF

C

DD

V

DD

+

-

R

EL