dm74ls249 National Semiconductor Corporation, dm74ls249 Datasheet - Page 3

• Manufacturer Part Number: dm74ls249
• Description: Bcd To 7-segment Decoder With Open-collector Outputs
• Manufacturer: National Semiconductor Corporation

Function
Switching Characteristics
V
Truth Table
Note 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 X
Note 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
Note 3 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 HIGH level
Decimal
CC
LT
or
10
11
12
13
14
15
BI
0
1
2
3
4
5
6
7
8
9
e a
Symbol
t
t
t
t
PLH
PHL
PLH
PHL
5 0V T
LT
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
X
L
A
e a
A
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
X
X
25 C
3
Propagation Delay Time
A
Propagation Delay Time
BI to a – g (54LS R
n
A
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
X
X
to a – g (54LS R
2
Inputs
Parameter
Numerical Designations Resultant Displays
A
H
H
H
H
H
H
H
H
e
L
L
L
L
L
L
L
X
X
L
1
input may be HIGH or LOW
L
L
A
H
H
H
H
H
H
H
H
X
X
L
L
L
L
L
L
L
L
e
e
0
6 kX)
2 kX)
BI RBO
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
3
H
H
H
H
H
H
H
H
H
a
L
L
L
L
L
L
L
L
L
Min
H
H
H
H
H
H
H
H
H
H
b
L
L
L
L
L
L
L
L
C
R
L
L
e
e
H
H
H
H
H
H
H
H
H
H
H
c
L
L
L
L
L
L
L
15 pF
2 kX
Outputs
d
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
Max
100
100
100
100
H
H
H
H
H
H
H
e
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
f
g
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
TL F 10213 – 3
Units
ns
ns
Note
1
1
2
3