DM74184 DM74185A BCD-to-Binary and Binary-to-BCD Converters
June 1989
DM74184 DM74185A
BCD-to-Binary and Binary-to-BCD Converters
General Description
These monolithic converters are derived from the 256-bit
read only memories DM5488 and DM7488 Emitter con-
nections are made to provide direct read-out of converted
codes at outputs Y8 through Y1 as shown in the function
tables These converters demonstrate the versatility of a
read only memory in that an unlimited number of reference
tables or conversion tables may be built into a system Both
of these converters comprehend that the least significant
bits (LSB) of the binary and BCD codes are logically equal
and in each case the LSB bypasses the converter as illus-
trated in the typical applications This means that a 6-bit
converter is produced in each case Both devices are cas-
cadable to N bits
An overriding enable input is provided on each converter
which when taken high inhibits the function causing all out-
puts to go high For this reason and to minimize power
consumption unused outputs Y7 and Y8 of the 185A and all
‘‘don’t care’’ conditions of the 184 are programmed high
The outputs are of the open-collector type
DM74184 BCD-TO-BINARY CONVERTERS
The 6-bit BCD-to-binary function of the DM74184 is analo-
gous to the algorithm
a Shift BCD number right one bit and examine each dec-
ade Subtract three from each 4-bit decade containing a
binary value greater than seven
b Shift right examine and correct after each shift until the
least significant decade contains a number smaller than
eight and all other converted decades contain zeros
In addition to BCD-to-binary conversion the DM74184 is
programmed to generate BCD 9’s complement or BCD 10’s
complement Again in each case one bit of the comple-
ment code is logically equal to one of the BCD bits there-
fore these complements can be produced on three lines
As outputs Y6 Y7 and Y8 are not required in the BCD-to-bi-
nary conversion they are utilized to provide these comple-
ment codes as specified in the function table when the de-
vices are connected as shown
DM74185A BINARY-TO-BCD CONVERTERS
The function performed by these 6-bit binary-to-BCD con-
verters is analogous to the algorithm
a Examine the three most significant bits If the sum is
greater than four add three and shift left one bit
b Examine each BCD decade If the sum is greater than
four add three and shift left one bit
c Repeat step b until the least-significant binary bit is in the
least-significant BCD location
(Continued)
Connection Diagram
TL F 6561 – 1
Order Number DM74184N or DM74185AN
See NS Package Number N16E
C
1995 National Semiconductor Corporation
TL F 6561
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings
(Note)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
7V
Input Voltage
Output Voltage
Operating Free Air Temperature
Range
Storage Temperature Range
5 5V
7V
0 C to
a
70 C
b
65 C to
a
150 C
Note
The ‘‘Absolute Maximum Ratings’’ are those values
beyond which the safety of the device cannot be guaran-
teed 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
Recommended Operating Conditions
Symbol
V
CC
V
IH
V
IL
V
OH
I
OL
T
A
Parameter
Supply Voltage
High Level Input Voltage
Low Level Input Voltage
High Level Output Voltage
Low Level Output Current
Free Air Operating Temperature
0
Min
4 75
2
08
55
12
70
Nom
5
Max
5 25
Units
V
V
V
V
mA
C
’184 and ’185A Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
V
I
I
CEX
V
OL
I
I
I
IH
I
IL
I
CCH
I
CCL
Parameter
Input Clamp Voltage
High Level Output
Current
Low Level Output
Voltage
Input Current
Input Voltage
Max
Conditions
V
CC
e
Min I
I
e b
12 mA
V
CC
e
Min V
O
e
5 5V
V
IL
e
Max V
IH
e
Min
V
CC
e
Min I
OL
e
Max
V
IH
e
Min V
IL
e
Max
V
CC
e
Max V
I
e
5 5V
V
CC
e
Max V
I
e
2 4V
V
CC
e
Max V
I
e
0 4V
V
CC
e
Max
V
CC
e
Max
65
80
Min
Typ
(Note 1)
Max
b
1 5
Units
V
mA
V
mA
mA
mA
mA
mA
100
04
1
25
b
1
High Level Input Current
Low Level Input Current
Supply Current with
Outputs High
Supply Current with
Outputs Low
95
99
’184 and ’185A Switching Characteristics
at V
CC
e
5V and T
A
e
25 C (See Section 1 for Test Waveforms and Output Load)
From (Input)
To (Output)
Enable G
to Output
Enable G
to Output
Binary Select
to Output
Binary Select
to Output
R
L1
e
400X R
L2
e
600X
C
L
e
15 pF (See Test Circuit)
Min
t
PLH
t
PHL
t
PLH
t
PHL
Propagation Delay Time
Low to High Level Output
Propagation Delay Time
High to Low Level Output
Propagation Delay Time
Low to High Level Output
Propagation Delay Time
High to Low Level Output
Max
35
35
35
35
ns
ns
ns
ns
Symbol
Parameter
Units
Note 1
All typicals are at V
CC
e
5V T
A
e
25 C
2
General Description
(Continued)
DM74184 BCD-to-Binary
TABLE I Package Count and Delay Times
for BCD-to-Binary Conversion
Input
(Decades)
2
3
4
5
6
6-Bit Converter
Packages
Required
2
6
12
19
28
Total Delay Times (ns)
Typ
56
140
196
280
364
BCD 9’s
Complement Converter
Max
80
200
280
400
520
BCD’s 10’s
Complement Converter
TL F 6561 –2
TL F 6561 – 3
TL F 6561 – 4
DM74185A Binary-to-BCD
TABLE II Package Count and Delay Times
for Binary-to-BCD Conversion
Input
(Bits)
4 to 6
7 or 8
9
10
11
12
13
14
15
16
17
18
19
20
Packages
Required
1
3
4
6
7
8
10
12
14
16
19
21
24
27
Total Delay Times (ns)
Typ
25
50
75
100
125
125
150
175
175
200
225
225
250
275
Max
40
80
120
160
200
200
240
280
280
320
360
360
400
440
6-Bit Converter
TL F 6561 – 5
3
Function Tables
Binary
Words
E
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
All
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
53
55
57
59
61
63
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
X
Inputs
Binary Select
D
C
B
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
X
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
X
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
X
A
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
X
Enable
G
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
Y8
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Y7
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Y6
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
H
H
H
H
H
Outputs
Y5
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
L
L
H
H
H
Y4
L
L
L
L
L
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
L
L
H
Y3
L
L
L
L
H
L
L
L
L
H
L
L
L
L
H
L
L
L
L
H
L
L
L
L
H
L
L
L
L
H
L
L
H
Y2
L
L
H
H
L
L
L
H
H
L
L
L
H
H
L
L
L
H
H
L
L
L
H
H
L
L
L
H
H
L
L
L
H
Y1
L
H
L
H
L
L
H
L
H
L
L
H
L
H
L
L
H
L
H
L
L
H
L
H
L
L
H
L
H
L
L
H
H
4
Function Tables
(Continued)
BCD-to-Binary Converter
BCD
Words
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
Any
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
H
H
Inputs
(See Note A)
Outputs
(See Note B)
BCD 9’s or BCD 10’s Complement Converter
BCD
Word
E
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Any
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
H
H
X
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
H
Inputs
(See Note C)
D
L
L
L
L
L
L
L
L
H
H
L
L
L
L
L
L
L
L
H
H
X
C
L
L
L
L
H
H
H
H
L
L
L
L
L
L
H
H
H
H
L
L
X
B
L
L
H
H
L
L
H
H
L
L
L
L
H
H
L
L
H
H
L
L
X
A
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
L
H
X
G
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
Outputs
(See Note D)
Y8
H
H
L
L
L
L
L
L
L
L
L
H
H
L
L
L
L
L
L
L
H
Y7
L
L
H
H
H
H
L
L
L
L
L
L
L
H
H
H
H
L
L
L
H
Y6
H
L
H
L
H
L
H
L
H
L
L
L
L
H
H
L
L
H
H
L
H
E D C B A G Y5 Y4 Y3 Y2 Y1
L
L
L
L
L
H
H
H
H
H
L
L
L
L
L
H
H
H
H
H
L
L
L
L
H
L
L
L
L
H
L
L
L
L
H
L
L
L
L
H
L
L
H
H
L
L
L
H
H
L
L
L
H
H
L
L
L
H
H
L
L
H
L
H
L
L
H
L
H
L
L
H
L
H
L
L
H
L
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
L
L
L
L
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
H
L
L
L
L
H
H
H
H
L
L
L
L
H
H
H
H
L
L
L
L
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
H
H
H
X X X X X H
H
e
High Level L
e
Low Level X
e
Don’t Care
Note A
Input Conditions other than those shown produce highs at outputs Y1 through Y5
Note B
Output Y6 Y7 and Y8 are not used for BCD-to-Binary conversion
Note C
Input conditions other than those shown produce highs at outputs Y6 Y7 and Y8
Note D
Outputs Y1 through Y5 are not used for BCD 9’s or BCD 10’s complement conversion
When these devices are used as complement converters input E is used as a mode control With this input low the BCD 9’s complement is generated when it is
