NSC DM74LS249 Bcd to 7-segment decoder with open-collector output Datasheet

DM74LS249
BCD to 7-Segment Decoder with Open-Collector Outputs
General Description
The ’LS249 has active HIGH open-collector outputs and incorporates the Lamp Test and BI/RBO inputs. Additionally,
the ’LS249 will light the top bar (segment a) for numeral 6
and the bottom bar (segment d) for numeral 9.
Connection Diagram
Logic Symbol
Dual-In-Line Package
TL/F/10213 – 2
TL/F/10213 – 1
VCC e Pin 16
GND e Pin 8
Order Number DM74LS249N
See NS Package Number N16E
Pin Names
A0 – A3
BI
LT
BI/RBO
a–g
C1995 National Semiconductor Corporation
TL/F/10213
Description
BCD Inputs
Blanking Input (Active LOW)
Lamp Test Input (Active LOW)
Blanking Input (Active LOW) or
Ripple Blanking Output (Active LOW)
Segment Outputs (Active HIGH)
RRD-B30M105/Printed in U. S. A.
DM74LS249 BCD to 7-Segment Decoder with Open-Collector Outputs
February 1992
Absolute Maximum Ratings
(Note)
Supply Voltage
Note: 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.
7V
Input Voltage
Operating Free Air Temperature Range
Storage Temperature Range
7V
0§ C to a 70§ C
b 65§ C to a 150§ C
Recommended Operating Conditions
Symbol
Parameter
VCC
Supply Voltage
VIH
High Level Input Voltage
VIL
Low Level Input Voltage
IOH
High Level Output Current (BI/RBO)
IOL
Low Level Output Current
TA
Free Air Operating Temperature
Min
Nom
Max
4.75
5
5.25
Units
V
2
V
0
0.8
V
b 0.25
mA
8
mA
70
§C
Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
Typ
(Note 1)
Max
Units
b 1.5
V
VI
Input Clamp Voltage
VCC e Min, II e b18 mA
VOH
High Level Output Voltage
(BI/RBO)
VCC e Min, IOH e Max
VIL e Max
ICEX
High Level Output Current
(a thru g)
VCC e Min, VO e 5.5V
VOL
Low Level Output Voltage
VCC e Min, IOL e Max,
VIH e Min
0.35
0.5
IOL e 4 mA, VCC e Min
0.25
0.4
II
Input Current @ Max
Input Voltage
VCC e Max, VI e 7V
IIH
High Level Input Current
VCC e Max, VI e 2.7V
IIL
Low Level Input Current
VCC e Max, VI e 0.4V
IOS
ICC
Short Circuit Output Current
VCC e Max (Note 2)
Supply Current
VCC e Max, VIN e 4.5V
2.7
V
250
mA
V
0.1
mA
20
mA
Inputs
b 0.4
BI/RBO
b 1.2
b 0.3
Note 1: All typicals are at VCC e 5V, TA e 25§ C.
Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.
2
3.4
mA
b 2.0
mA
15
mA
Switching Characteristics
VCC e a 5.0V, TA e a 25§ C
RL e 2 kX
Symbol
Parameter
CL e 15 pF
Min
Units
Max
tPLH
tPHL
Propagation Delay Time
An to a–g (54LS RL e 2 kX)
100
100
ns
tPLH
tPHL
Propagation Delay Time
BI to a–g (54LS RL e 6 kX)
100
100
ns
Numerical DesignationsÐResultant Displays
TL/F/10213 – 3
Truth Table
Decimal
or
Function
Inputs
Outputs
LT
A3
A2
A1
A0
BI/RBO
a
b
c
d
e
f
g
0
1
2
3
H
H
H
H
L
L
L
L
L
L
L
L
L
L
H
H
L
H
L
H
H
H
H
H
H
L
H
H
H
H
H
H
H
H
L
H
H
L
H
H
H
L
H
L
H
L
L
L
L
L
H
H
4
5
6
7
8
H
H
H
H
H
L
L
L
L
H
H
H
H
H
L
L
L
H
H
L
L
H
L
H
L
H
H
H
H
H
L
H
L
H
H
H
L
L
H
H
H
H
H
H
H
L
H
H
L
H
L
L
H
L
H
H
H
H
L
H
H
H
H
L
H
9
10
11
12
13
H
H
H
H
H
H
H
H
H
H
L
L
L
H
H
L
H
H
L
L
H
L
H
L
H
H
H
H
H
H
H
L
L
L
H
H
L
L
H
L
H
L
H
L
L
L
H
H
L
H
L
H
L
L
L
H
L
L
H
H
H
H
H
H
H
14
15
BI
LT
H
H
X
L
H
H
X
X
H
H
X
X
H
H
X
X
L
H
X
X
H
H
L
H
L
L
L
H
L
L
L
H
L
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
Note
1
1
2
3
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 e input may be HIGH or LOW.
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.
3
Logic Diagram
TL/F/10213 – 4
4
5
DM74LS249 BCD to 7-Segment Decoder with Open-Collector Outputs
Physical Dimensions inches (millimeters)
16-Lead Molded Dual-In-Line Package (N)
Order Number DM74LS249N
NS Package Number N16E
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