Supertex inc.

Supertex inc.

1235 Bordeaux Drive, Sunnyvale, CA 94089

Tel: 408-222-8888

www.supertex.com

HV881

Features

terminal

Applications

The HV881 has two internal oscillators and a high voltage

EL lamp driver. An external MOSFET is driven by the switch

oscillator to generate output voltage.

The frequency for the external switching MOSFET is set

by an external resistor connected between the RSW-Osc

pin and the VDD supply pin. The EL lamp driver frequency

can be set by either an external logic signal frequency at

the SEL pin or by an external resistor connected between

the REL-Osc pin and VDD pin. If external frequency is input

at the SEL pin, the REL-Osc pin should be connected to

ground.

An external inductor is connected between the LX and VDD

or VIN pins for split supply applications. Depending upon

the EL lamp sizes, a 1.0 to 10.0nF capacitor is connected

between the CS pin and ground. The C

connected to the internal H-bridge, and the energy stored

in the capacitor is therefore transferred to the EL lamp.

One side of all the sixteen EL lamps is connected to the

respective EL pins (EL1, EL2, etc.), and the other side is

connected to the COM pin.

The external switching MOSFET charges the inductor and

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

will start to increase. Once the voltage at CS reaches the

desired regulation limit, the external switching MOSFET is

turned off to conserve power.

The HV881 allows for controlling the fall time of the EL1

- EL16 outputs by an external resistor from the RSLOPE

pin to the VDD pin. This feature can be used to reduce

the audible noise of the EL lamp or to increase the lamp

brightness.

The brightness of each of the sixteen EL lamps can be

independently controlled to have one of fifteen brightness

levels or can be completely turned off by the serial data

(SDA) input. The serial data input has a 4-bit binary code

for each lamp, to control the brightness level from level 0

to level 15. The brightness is controlled by controlling the

number of EL frequency cycles (from 0 to 15) in a group of

15 cycles.

Dimmable, Low Noise, 16 channel

EL Lamp Driver

General Description

The Supertex HV881 is a 16 channel EL lamp driver with a

single common terminal. It can drive up to a 1nF EL lamp load

(approx. 0.3in2 lamp size) on each of the sixteen channels.

The input supply voltage range is 1.8 to 5.5V. The logic

interface to the device can be as low as 1.7V. The device

has an enable logic input pin to turn the device on or off.

The device is designed to minimize audible noise emitted by

the EL lamp. The HV881 uses an external MOSFET, a single

inductor and minimum number of passive components to

drive all sixteen EL lamps. The device is designed such that

the input voltage to the inductor can be different from the

input voltage to the device (split supply).