5-56
FAST AND LS TTL DATA
BCD TO 7-SEGMENT
DECODER/DRIVER
The SN54/74LS47 are Low Power Schottky BCD to 7-Segment Decod-
er/Drivers consisting of NAND gates, input buffers and seven AND-OR-IN-
VERT 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 (LT) 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
VCC
7
16 15
8
fg 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 VOUT = 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.
5-58
FAST AND LS TTL DATA
SN54/74LS47
GUARANTEED OPERATING RANGES
Symbol Parameter Min Typ Max Unit
VCC Supply Voltage 54
74 4.5
4.75 5.0
5.0 5.5
5.25 V
TAOperating Ambient Temperature Range 54
74 –55
025
25 125
70 °C
IOH Output Current — High BI/RBO 54, 74 –50 µA
IOL Output Current — Low BI/RBO
BI/RBO 54
74 1.6
3.2 mA
VO (off) Off-State Output Voltage a to g 54, 74 15 V
IO (on) On-State Output Current a to g
On-State Output Current a to g 54
74 12
24 mA
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min Typ Max
Unit
Test Conditions
VIH Input HIGH Voltage 2.0 V Guaranteed Input HIGH Theshold Voltage
for All Inputs
VIL
Input LOW Voltage
54 0.7
V
Guaranteed Input LOW Threshold Voltage
for All Inputs
VIL
Input LOW Voltage
74 0.8
V
Guaranteed Input LOW Threshold Voltage
for All Inputs
VIK Input Clamp Diode Voltage –0.65 –1.5 V VCC = MIN, IIN = –18 mA
VOH
Output HIGH Voltage, BI/RBO
2.4
4.2
V
V
CC = MIN, IOH = –50 µA,
VIN = VIN or VIL per Truth Table
VOH
Output HIGH Voltage, BI/RBO
2.4
4.2
V
VCC = MIN, IOH = –50 µA,
VIN = VIN or VIL per Truth Table
VOL
Output LOW Voltage
BI/RBO
54, 74 0.25 0.4 V IOL = 1.6 mA
V
CC = MIN, VIN = VIN or
VIL per Truth Table
VOL
Output LOW Voltage
BI/RBO
74 0.35 0.5 V IOL = 3.2 mA
VCC = MIN, VIN = VIN or
VIL per Truth Table
IO (off) Off-State Output Current
a thru g 250 µAVCC = MAX, VIN = VIN or VIL per Truth
Table, VO (off) = 15 V
VO (on)
On-State Output Voltage
a thru g
54, 74 0.25 0.4 V IO (on) = 12 mA
VCC = MAX, VIN = VIH
or VIL per Truth Table
VO (on)
On-State Output Voltage
a thru g
74 0.35 0.5 V IO (on) = 24 mA
CC = MAX, VIN = VIH
or VIL per Truth Table
IIH
Input HIGH Current
20 µA VCC = MAX, VIN = 2.7 V
IIH
Input HIGH Current
0.1 mA VCC = MAX, VIN = 7.0 V
IIL Input LOW Current BI/RBO
Any Input except BI/RBO –1.2
–0.4 mA VCC = MAX, VIN = 0.4 V
IOS BI/RBO Output Short Circuit Current (Note 1) –0.3 –2.0 mA VCC = MAX, VOUT = 0 V
ICC Power Supply Current 7.0 13 mA VCC = MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (TA = 25°C)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min Typ Max
Unit
Test Conditions
tPHL
tPLH Propagation Delay, Address
Input to Segment Output 100
100 ns
ns
V
CC = 5.0 V
CL = 15 pF
tPHL
tPLH Propagation Delay, RBI Input
To Segment Output 100
100 ns
ns
VCC = 5.0 V
CL = 15 pF
AC WAVEFORMS
VIN
VOUT
1.3 V 1.3 V
1.3 V 1.3 V
tPHL tPLH
Figure 1 Figure 2
1.3 V 1.3 V
1.3 V1.3 V
tPLH
tPHL
VIN
VOUT
