DS7880 Datasheet, PDF (1/6 Pages) National Semiconductor (TI) – High Voltage 7-Segment Decoder/Driver

March 1988
DS7880 DS8880 High Voltage 7-Segment Decoder Driver
General Description
The DS7880 DS8880 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 0 2 to 1 5 mA range
for driving various tube types or multiplex operation The
output current is adjusted by connecting an external pro-
gram resistor (R_P) from V_CC to the Program input in accord-
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 current 0 2 to 1 5 mA}
Y _{High output breakdown voltage 110V typ}
Y _{Suitable for multiplex operation}
Y _{Blanking and Ripple Blanking provisions}
Y _{Low fan-in and low power}
Logic Diagram
C1995 National Semiconductor Corporation TL F 5845
TL F 5845 – 1
RRD-B30M105 Printed in U S A