5-59
FAST AND LS TTL DATA
BCD TO 7-SEGMENT
DECODER
The SN54 / 74LS48 is a BCD to 7-Segment Decoder consisting of NAND
gates, input buffers and seven AND-OR-INVERT gates. 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 input for the LS48.
The circuit accepts 4-bit binary-coded-decimal (BCD) and, depending on
the state of the auxiliary inputs, decodes this data to drive other components.
The relative positive logic output levels, as well as conditions required at the
auxiliary inputs, are shown in the truth tables.
The LS48 circuit incorporates automatic leading and / or trailing edge
zero-blanking control (RBI and RBO). Lamp Test (LT) may be activated any
time when the BI / RBO node is HIGH. Both devices contain 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)
Internal Pull-Ups Eliminate Need for External Resistors
Input Clamp Diodes Eliminate High-Speed Termination Effects
14
13
12
11
10
9
1
2
3
4
5
6
VCC
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)
LOGIC DIAGRAM
INPUT
BLANKING INPUT OR
RIPPLE-BLANKING
OUTPUT
RIPPLE-BLANKING
INPUT
LAMP-TEST
INPUT
A
B
C
D
a
b
c
d
e
f
g
OUTPUT
SN54/74LS48
BCD TO 7-SEGMENT
DECODER
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
SN54 / 74LS48
14
15
NUMERICAL DESIGNATIONS -- RESULTANT DISPLAYS
0
1
2
3
4
5
6
7
8
9
10
11 12
13
NOTES:
(1) BI/RBO is wired-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.
(2) 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.
(3) 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).
(4) 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.
TRUTH TABLE
SN54 / 74LS48
INPUTS
OUTPUTS
5-60
FAST AND LS TTL DATA
SN54/74LS48
PIN NAMES
LOADING (Note a)
HIGH
LOW
A, B, C, D
RBI
LT
BI / RBO
BI
BCD Inputs
Ripple-Blanking (Active Low) Input
Lamp-Test (Active Low) Input
Blanking Input or Ripple-
Blanking Output (Active Low)
Blanking (Active Low) Input
0.5 U.L.
0.5 U.L.
0.5 U.L.
0.5 U.L.
1.2 U.L.
0.5 U.L.
Open-Collector
0.25 U.L.
0.25 U.L.
0.25 U.L.
0.75 U.L.
2(1) U.L.
0.25 U.L.
3.75 (1.25) U.L. (48)
NOTES:
a) Unit Load (U.L.) = 40
A HIGH / 1.6 mA LOW
b) Outut current measured at VOUT = 0.5 V
Output LOW drive factor is SN54LS / 74LS48: 1.25 U.L. for Military (54), 3.75 U.L. for Commercial (74).
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
H
H
H
H
H
H
L
1
1
H
X
L
L
L
H
H
L
H
H
L
L
L
L
1
2
H
X
L
L
H
L
H
H
H
L
H
H
L
H
3
H
X
L
L
H
H
H
H
H
H
H
L
L
H
4
H
X
L
H
L
L
H
L
H
H
L
L
H
H
5
H
X
L
H
L
H
H
H
L
H
H
L
H
H
6
H
X
L
H
H
L
H
L
L
H
H
H
H
H
7
H
X
L
H
H
H
H
H
H
H
L
L
L
L
8
H
X
H
L
L
L
H
H
H
H
H
H
H
H
9
H
X
H
L
L
H
H
H
H
H
L
L
H
H
10
H
X
H
L
H
L
H
L
L
L
H
H
L
H
11
H
X
H
L
H
H
H
L
L
H
H
L
L
H
12
H
X
H
H
L
L
H
L
H
L
L
L
H
H
13
H
X
H
H
L
H
H
H
L
L
H
L
H
H
14
H
X
H
H
H
L
H
L
L
L
H
H
H
H
15
H
X
H
H
H
H
H
L
L
L
L
L
L
L
BI
X
X
X
X
X
X
L
L
L
L
L
L
L
L
2
RBI
H
L
L
L
L
L
L
L
L
L
L
L
L
L
3
LT
L
X
X
X
X
X
H
H
H
H
H
H
H
H
4
5-61
FAST AND LS TTL DATA
SN54/74LS48
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
TA
Operating Ambient Temperature Range
54
74
55
0
25
25
125
70
C
IOH
Output Current -- High
a to g
54, 74
100
A
IOH
Output Current -- High
BI / RBO
54, 74
50
A
IOL
Output Current -- Low
a to g
54
74
2.0
6.0
mA
IOL
Output Current -- Low
BI / RBO
BI / RBO
54
74
1.6
3.2
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 Voltage for
All Inputs
VIL
Input LOW Voltage
54
0.7
V
Guaranteed Input LOW Voltage for
All Inputs
VIL
Input LOW Voltage
74
0.8
V
Guaranteed Input LOW Voltage for
All Inputs
VIK
Input Clamp Diode Voltage
1.5
V
VCC = MIN, IIN = 18 mA
VOH
Output HIGH Voltage
2.4
4.2
A
VCC = MIN, IOH = 50
A,
VIN = VIH or U.L. per Truth Table
VOH
Output HIGH Voltage
2.4
4.2
A
VCC = MIN, IOH = 50
A,
VIN = VIH or U.L. per Truth Table
IO
Output Current a to g
1.3
2.0
mA
VCC = MIN, VO = 0.85 V
Input Conditioner as for VOH
VOL
Output LOW Voltage a to g
54, 74
0.4
V
IOL = 2.0 mA
VCC = MIN, VIH = 2.0 V
VIL = VIL MAX
VOL
Output LOW Voltage a to g
74
0.5
V
IOL = 6.0 mA
VCC = MIN, VIH = 2.0 V
VIL = VIL MAX
VOL
Output LOW Voltage
BI / RBO
54, 74
0.4
V
IOL = 1.6 mA
VCC = MAX, VIH = 2.0 V
VIL = VIL MAX
VOL
Output LOW Voltage
BI / RBO
74
0.5
V
IOL = 3.2 mA
VCC = MAX, VIH = 2.0 V
VIL = VIL MAX
IIH
Input HIGH Current
(Except BI / RBO)
20
A
VCC = MAX, VIN = 2.7 V
IIH
Input HIGH Current
(Except BI / RBO)
0.1
mA
VCC = MAX, VIN = 7.0 V
IIL
Input LOW Current
(Except BI / RBO)
0.4
mA
VCC = MAX, VIN = 0.4 V
IIL
Input LOW Current BI / RBO
1.2
mA
VCC = MAX, VIN = 0.4 V
ICC
Power Supply Current
25
38
mA
VCC = MAX
IOS
Short Circuit Current BI / RBO (Note 1)
0.3
2.0
mA
VCC = MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(VCC = 5.0 V, TA = 25
C)
Symbol
Parameter
Limits
Unit
Test Conditions
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
tPHL
Propagation Delay Time, HIGH-to-LOW
Level Output from A Input
100
ns
CL = 15 pF, RL = 4.0 k
tPLH
Propagation Delay Time, LOW-to-HIGH
Level Output from A Input
100
ns
CL = 15 pF, RL = 4.0 k
tPHL
Propagation Delay Time, HIGH-to-LOW
Level Output from RBI Input
100
ns
CL = 15 pF, RL = 6.0 k
tPLH
Propagation Delay Time, LOW-to-HIGH
Level Output from RBI Input
100
ns
CL = 15 pF, RL = 6.0 k
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