TLF5845

March 1988

DS7880DS8880 High Voltage 7-Segment DecoderDriver

General Description

The DS7880DS8880 is custom designed to decode four

lines of BCD and drive a gas-filled seven-segment display

tube

Each output constitutes a switchable adjustable current

sink which provides constant current to the tube segment

even with high tube anode supply tolerance or fluctuation

These current sinks have a voltage compliance from 3V to

at least 80V typically the output current varies 1% for out-

put voltage changes of 3 to 50V Each bit line of the decod-

er switches a current sink on or off as prescribed by the

input code Each current sink is ratioed to the b-output cur-

rent as required for even illumination of all segments

Output currents may be varied over the 02 to 15 mA range

for driving various tube types or multiplex operation The

output current is adjusted by connecting an external pro-

ance with the programming curve The circuit design pro-

vides a one-to-one correlation between program input cur-

rent and b-segment output current

The Blanking Input provides unconditional blanking of any

output display while the Ripple Blanking pins allow simple

leading- or trailing-zero blanking

Features

Y

Current sink outputs

Y

Adjustable output current02 to 15 mA

Y

High output breakdown voltage110V typ

Y

Suitable for multiplex operation

Y

Blanking and Ripple Blanking provisions

Y

Low fan-in and low power

Logic Diagram

TLF5845 – 1

C1995 National Semiconductor Corporation

RRD-B30M105Printed in U S A