Motorola SN54LS47J, SN74LS47D Datasheet

5-56

FAST AND LS TTL DATA

BCD TO 7-SEGMENT
DECODER/DRIVER

The SN54 /74LS47 are Low Power Schottky BCD to 7-Segment Decod­er/Drivers consisting of NAND gates, input buffers and seven AND-OR-IN­VERT gates. They offer active LOW, high sink current outputs for driving
indicators directly. Seven NAND gates and one driver are connected in pairs
to make BCD data and its complement available to the seven decoding
AND-OR-INVERT gates. The remaining NAND gate and three input buffers
provide lamp test, blanking input/ripple-blanking output and ripple-blanking
input.

The circuits accept 4-bit binary-coded-decimal (BCD) and, depending on
the state of the auxiliary inputs, decodes this data to drive a 7-segment display
indicator. The relative positive-logic output levels, as well as conditions
required at the auxiliary inputs, are shown in the truth tables. Output
configurations of the SN54/74LS47 are designed to withstand the relatively
high voltages required for 7-segment indicators.

These outputs will withstand 15 V with a maximum reverse current of
250 µA. Indicator segments requiring up to 24 mA of current may be driven
directly from the SN74LS47 high performance output transistors. Display
patterns for BCD input counts above nine are unique symbols to authenticate
input conditions.

The SN54 /74LS47 incorporates automatic leading and/or trailing-edge
zero-blanking control (RBI and RBO). Lamp test (L T) may be performed at any
time which the BI/RBO node is a HIGH level. This device also contains an
overriding blanking input (BI) which can be used to control the lamp intensity
by varying the frequency and duty cycle of the BI input signal or to inhibit the
outputs.

• Lamp Intensity Modulation Capability (BI/RBO)

• Open Collector Outputs

• Lamp Test Provision

• Leading/Trailing Zero Suppression

• Input Clamp Diodes Limit High-Speed Termination Effects

14 13 12 11 10 9

1 2 3 4 5 6

V

CC

7

16 15

8

f

g a b c d e

B C LT BI/RBO RBI D A GND

CONNECTION DIAGRAM DIP (TOP VIEW)

PIN NAMES LOADING (Note a)

HIGH

LOW

A, B, C, D
RBI
LT
BI/RBO

a, to g

BCD Inputs
Ripple-Blanking Input
Lamp-Test Input
Blanking Input or
Ripple-Blanking Output
Outputs

0.5 U.L.

0.5 U.L.

0.5 U.L.

0.5 U.L.

1.2 U.L.

Open-Collector

0.25 U.L.

0.25 U.L.

0.25 U.L.

0.75 U.L.

2.0 U.L.

15 (7.5) U.L.

NOTES:
a) 1 Unit Load (U.L.) = 40 µA HIGH, 1.6 mA LOW.
b) Output current measured at V

OUT

= 0.5 V

The Output LOW drive factor is 7.5 U.L. for Military (54) and 15 U.L. for Commercial (74) Temperature Ranges.

SN54/74LS47

BCD TO 7-SEGMENT

DECODER/DRIVER

LOW POWER SCHOTTKY

J SUFFIX

CERAMIC

CASE 620-09

N SUFFIX

PLASTIC

CASE 648-08

16

1

16

1

ORDERING INFORMATION

SN54LSXXJ Ceramic
SN74LSXXN Plastic
SN74LSXXD SOIC

16

1

D SUFFIX

SOIC

CASE 751B-03

LOGIC SYMBOL

VCC = PIN 16
GND = PIN 8

7 1 2 6 3 5

13 12 11 10 9 15 14 4

A B C D LT RBI

a b c d e f g

BI/
RBO

INPUTS OUTPUTS

TRUTH TABLE

5-57

FAST AND LS TTL DATA

SN54/74LS47

14 15

LOGIC DIAGRAM

NUMERICAL DESIGNATIONS — RESULTANT DISPLAYS

0 1 2 3 4 5 6 7 8 9 10 11 12 13

INPUT

BLANKING INPUT OR
RIPPLE-BLANKING
OUTPUT

RIPPLE-BLANKING
INPUT

LAMP-TEST
INPUT

A

B

C
D

a a

b b

c c

d d

e e

f f

g g

OUTPUT

DECIMAL

OR

FUNCTION

LT RBI D C B A BI/RBO a b c d e f g NOTE

0 H H L L L L H L L L L L L H A
1 H X L L L H H H L L H H H H A
2 H X L L H L H L L H L L H L
3 H X L L H H H L L L L H H L
4 H X L H L L H H L L H H L L
5 H X L H L H H L H L L H L L
6 H X L H H L H H H L L L L L
7 H X L H H H H L L L H H H H
8 H X H L L L H L L L L L L L

9 H X H L L H H L L L H H L L
10 H X H L H L H H H H L L H L
11 H X H L H H H H H L L H H L
12 H X H H L L H H L H H H L L
13 H X H H L H H L H H L H L L
14 H X H H H L H H H H L L L L
15 H X H H H H H H H H H H H H
BI X X X X X X L H H H H H H H B

RBI H L L L L L L H H H H H H H C

LT L X X X X X H L L L L L L L D

H = HIGH Voltage Level
L = LOW Voltage Level

X = Immaterial
NOTES:
(A) BI/RBO

is wire-AND logic serving as blanking Input (BI) and/or ripple-blanking output (RBO). The blanking out (BI) must be open or held

at a HIGH level when output functions 0 through 15 are desired, and ripple-blanking input (RBI

) must be open or at a HIGH level if blanking

of a decimal 0 is not desired. X = input may be HIGH or LOW.

(B) When a LOW level is applied to the blanking input (forced condition) all segment outputs go to a LOW level regardless of the state of

any other input condition.

(C) When ripple-blanking input (RBI

) and inputs A, B, C, and D are at LOW level, with the lamp test input at HIGH level, all segment outputs

go to a HIGH level and the ripple-blanking output (RBO) goes to a LOW level (response condition).

(D) When the blanking input/ripple-blanking output (BI/RBO

) is open or held at a HIGH level, and a LOW level is applied to lamp test input,

all segment outputs go to a LOW level.