The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these
limits. The parametric values defined in the “Electrical Characteristics” table are not guaranteed at the absolute maximum ratings. The “Recommended Operating
Conditions” table will define the conditions for actual device operation.
Note 3:
OFF state at a–g.
Electrical Characteristics
Over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
V
OH
I
OFF
V
OL
Parameter
Input Clamp Voltage
High Level
Output Voltage
Output High Current
Segment Outputs
Low Level
Output Voltage
V
CC
= Min, I
OL
= Max,
V
IH
= Min, a − g
I
OL
= 3.2 mA, BI /RBO
I
OL
= 12 mA, a –g
I
OL
= 1.6 mA, BI /RBO
I
I
I
IH
I
IL
I
OS
I
CC
Input Current
@
Max
Input Voltage
High Level Input Current
Low Level Input Current
Short Circuit
Output Current
Supply Current
V
CC
V
CC
V
CC
V
CC
= Max, V
I
= 7V
= Max, V
I
= 10V
= Max, V
I
= 2.7V
= Max, V
I
= 0.4V
DM54
DM74
DM74
DM74
DM74
DM74
DM54
20
−0.4
DM54
DM74
−0.3
−0.3
−2.0
−2.0
13
mA
µA
mA
mA
0.25
0.35
0.4
0.5
0.5
0.4
0.4
100
µA
V
Conditions
V
CC
= Min, I
I
= −18 mA
V
CC
= Min, I
OH
= Max,
V
IL
= Max, BI /RBO
V
CC
= 5.5V, V
O
= 15V a − g
Min
Typ
(Note 4)
−1.5
DM54
DM74
2.4
2.7
3.4
250
µA
V
V
Max
Units
V
CC
= Max
(Note 5) , I
OS
at BI/RBO
V
CC
= Max
Note 4:
All typicals are at V
CC
= 5V, T
A
= 25˚C.
Note 5:
Not more than one output should be shorted at a time, and the duration should not exceed one second.
www.fairchildsemi.com
2
Switching Characteristics
at V
CC
= +5.0V, T
A
= +25˚C
Symbol
t
PLH
t
PHL
t
PLH
t
PHL
Parameter
Propagation Delay
An to a –g
Propagation Delay
RBI to a –g (Note 6)
Conditions
Min
R
L
= 665Ω
C
L
= 15 pF
Max
100
100
100
100
ns
ns
Units
Note 6:
LT = HIGH, A0–A3 = LOW
Functional Description
The ’LS47 decodes the input data in the pattern indicated in
the Truth Table and the segment identification illustration. If
the input data is decimal zero, a LOW signal applied to the
RBI blanks the display and causes a multidigit display. For
example, by grounding the RBI of the highest order decoder
and connecting its BI/RBO to RBI of the next lowest order
decoder, etc., leading zeros will be suppressed. Similarly, by
grounding RBI of the lowest order decoder and connecting
its BI/RBO to RBI of the next highest order decoder, etc.,
trailing zeros will be suppressed. Leading and trailing zeros
can be suppressed simultaneously by using external gates,
i.e.: by driving RBI of a intermediate decoder from an OR
gate whose inputs are BI/RBO of the next highest and lowest
order decoders. BI/RBO also serves as an unconditional
blanking input. The internal NAND gate that generates the
RBO signal has a resistive pull-up, as opposed to a totem
pole, and thus BI/RBO can be forced LOW by external
means, using wired-collector logic. A LOW signal thus ap-
plied to BI/RBO turns off all segment outputs. This blanking
feature can be used to control display intensity by varying
the duty cycle of the blanking signal. A LOW signal applied to
LT turns on all segment outputs, provided that BI/RBO is not
forced LOW.
3
www.fairchildsemi.com
Logic Diagram
DS009817-3
Numerical Designations—Resultant Displays
DS009817-4
www.fairchildsemi.com
4
Logic Symbol
DS009817-2
V
CC
= Pin 16
GND = Pin 8
Truth Table
Decimal
or
Function
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
BI
RBI
LT
LT
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
X
H
L
RBI
H
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L
X
A3
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
X
L
X
A2
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
X
L
X
A1
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
X
L
X
A0
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
X
L
X
BI/RBO
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
H
a
L
H
L
L
H
L
H
L
L
L
H
H
H
L
H
H
H
H
L
b
L
L
L
L
L
H
H
L
L
L
H
H
L
H
H
H
H
H
L
c
L
L
H
L
L
L
L
L
L
L
H
L
H
H
H
H
H
H
L
d
L
H
L
L
H
L
L
H
L
H
L
L
H
L
L
H
H
H
L
e
L
H
L
H
H
H
L
H
L
H
L
H
H
H
L
H
H
H
L
f
L
H
H
H
L
L
L
H
L
L
H
H
L
L
L
H
H
H
L
g
H
H
L
L
L
L
L
H
L
L
L
L
L
L
L
H
H
H
L
(Note 8)
(Note 9)
(Note 10)
(Note 7)
(Note 7)
Inputs
Outputs
Note
Note 7:
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 or a decimal 0 is not desired. X = input
may be HIGH or LOW.
Note 8:
When a LOW level is applied to the blanking input (forced condition) all segment outputs go to a HIGH level regardless of the state of any other input con-
dition.
Note 9:
When ripple-blanking input (RBI) and inputs A0, A1, A2 and A3 are 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).
Note 10:
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
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