NSC DM74185A

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 connections 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 illustrated in the typical applications. This means that a 6-bit
converter is produced in each case. Both devices are cascadable to N bits.
An overriding enable input is provided on each converter
which when taken high inhibits the function, causing all outputs 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 analogous to the algorithm:
a. Shift BCD number right one bit and examine each decade. 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 complement code is logically equal to one of the BCD bits; therefore, these complements can be produced on three lines.
As outputs Y6, Y7 and Y8 are not required in the BCD-to-binary conversion, they are utilized to provide these complement codes as specified in the function table when the devices are connected as shown.
DM74185A BINARY-TO-BCD CONVERTERS
The function performed by these 6-bit binary-to-BCD converters 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
C1995 National Semiconductor Corporation
TL/F/6561
RRD-B30M105/Printed in U. S. A.
DM74184/DM74185A BCD-to-Binary and Binary-to-BCD Converters
June 1989
Absolute Maximum Ratings (Note)
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.
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage
Input Voltage
Output Voltage
Operating Free Air Temperature
Range
7V
5.5V
7V
0§ C to a 70§ C
b 65§ C to a 150§ C
Storage Temperature Range
Recommended Operating Conditions
Symbol
Parameter
Min
Nom
Max
Units
4.75
5
5.25
V
Low Level Input Voltage
0.8
V
VOH
High Level Output Voltage
5.5
V
IOL
Low Level Output Current
12
mA
TA
Free Air Operating Temperature
70
§C
VCC
Supply Voltage
VIH
High Level Input Voltage
VIL
2
V
0
’184 and ’185A Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol
Parameter
Conditions
Min
Typ
(Note 1)
Max
Units
VI
Input Clamp Voltage
VCC e Min, II e b12 mA
b 1.5
V
ICEX
High Level Output
Current
VCC e Min, VO e 5.5V
VIL e Max, VIH e Min
100
mA
VOL
Low Level Output
Voltage
VCC e Min, IOL e Max
VIH e Min, VIL e Max
0.4
V
II
Input Current @ Max
Input Voltage
VCC e Max, VI e 5.5V
1
mA
IIH
High Level Input Current
mA
Low Level Input Current
VCC e Max, VI e 2.4V
VCC e Max, VI e 0.4V
25
IIL
b1
mA
ICCH
Supply Current with
Outputs High
VCC e Max
65
95
mA
ICCL
Supply Current with
Outputs Low
VCC e Max
80
99
mA
’184 and ’185A Switching Characteristics
at VCC e 5V and TA e 25§ C (See Section 1 for Test Waveforms and Output Load)
Symbol
Parameter
RL1 e 400X, RL2 e 600X
CL e 15 pF (See Test Circuit)
From (Input)
To (Output)
Min
Units
Max
tPLH
Propagation Delay Time
Low to High Level Output
Enable G
to Output
35
ns
tPHL
Propagation Delay Time
High to Low Level Output
Enable G
to Output
35
ns
tPLH
Propagation Delay Time
Low to High Level Output
Binary Select
to Output
35
ns
tPHL
Propagation Delay Time
High to Low Level Output
Binary Select
to Output
35
ns
Note 1: All typicals are at VCC e 5V, TA 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)
Packages
Required
Typ
Max
2
3
4
5
6
2
6
12
19
28
56
140
196
280
364
80
200
280
400
520
6-Bit Converter
Total Delay Times (ns)
BCD 9’s
Complement Converter
BCD’s 10’s
Complement Converter
TL/F/6561–2
TL/F/6561 – 4
TL/F/6561 – 3
DM74185A Binary-to-BCD
TABLE II. Package Count and Delay Times
for Binary-to-BCD Conversion
Input
(Bits)
Packages
Required
4 to 6
7 or 8
9
10
11
12
13
14
15
16
17
18
19
20
1
3
4
6
7
8
10
12
14
16
19
21
24
27
Total Delay Times (ns)
Typ
Max
25
50
75
100
125
125
150
175
175
200
225
225
250
275
40
80
120
160
200
200
240
280
280
320
360
360
400
440
3
6-Bit Converter
TL/F/6561 – 5
Function Tables
Inputs
Binary
Words
Outputs
E
Binary Select
D
C
B
A
Enable
G
Y8
Y7
Y6
Y5
Y4
Y3
Y2
Y1
0
2
4
6
1
3
5
7
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
L
H
L
H
8
10
12
14
9
11
13
15
L
L
L
L
L
L
L
L
H
H
H
H
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
H
H
H
H
L
L
L
L
L
L
H
L
L
H
L
16
18
20
22
17
19
21
23
L
L
L
L
H
H
H
H
L
L
L
L
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
L
L
H
H
H
H
L
L
L
H
L
L
H
L
L
L
H
L
L
H
24
26
28
30
25
27
29
31
L
L
L
L
H
H
H
H
H
H
H
H
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
H
H
H
H
L
L
L
H
L
L
H
L
H
H
L
L
L
H
L
L
32
34
36
38
33
35
37
39
H
H
H
H
L
L
L
L
L
L
L
L
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
L
H
H
H
H
H
H
H
H
L
L
L
H
L
H
H
L
H
L
H
L
40
42
44
46
41
43
45
47
H
H
H
H
L
L
L
L
H
H
H
H
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
L
H
L
H
48
50
52
54
49
51
53
55
H
H
H
H
H
H
H
H
L
L
L
L
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
H
H
H
H
L
L
L
L
L
L
H
L
L
H
L
56
58
60
62
57
59
61
63
H
H
H
H
H
H
H
H
H
H
H
H
L
L
H
H
L
H
L
H
L
L
L
L
H
H
H
H
H
H
H
H
H
H
H
H
L
L
H
H
H
H
L
L
L
H
L
L
H
L
L
L
H
L
L
H
X
X
X
X
X
H
H
H
H
H
H
H
H
H
All
4
Function Tables (Continued)
BCD-to-Binary Converter
Inputs
(See Note A)
BCD
Words
BCD 9’s or BCD 10’s Complement Converter
Outputs
(See Note B)
Inputs
(See Note C)
BCD
Word
Outputs
(See Note D)
E²
D
C
B
A
G
Y8
Y7
Y6
0
2
4
6
8
1
3
5
7
9
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
L
L
H
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
H
L
L
H
H
L
L
H
L
H
L
0
1
2
3
4
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
L
L
H
H
L
L
H
L
H
L
L
L
L
L
L
H
H
L
L
L
L
L
H
H
H
H
L
H
L
H
10
12
14
16
18
11
13
15
17
19
L
L
L
L
L
H
H
H
H
H
L
L
L
L
H
L
L
H
H
L
L
H
L
H
L
L
L
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
L
L
L
H
H
L
L
H
L
H
L
H
5
6
7
8
9
L
L
L
L
L
L
L
L
H
H
H
H
H
L
L
L
H
H
L
L
H
L
H
L
H
L
L
L
L
L
L
L
L
L
L
H
L
L
L
L
L
H
L
H
L
20
22
24
26
28
21
23
25
27
29
H
H
H
H
H
L
L
L
L
L
L
L
L
L
H
L
L
H
H
L
L
H
L
H
L
L
L
L
L
L
L
L
L
L
L
H
H
H
H
H
L
L
H
H
H
H
H
L
L
H
L
H
L
H
L
0
1
2
3
4
H
H
H
H
H
L
L
L
L
L
L
L
L
L
H
L
L
H
H
L
L
H
L
H
L
L
L
L
L
L
L
H
H
L
L
L
L
L
H
H
L
L
L
H
H
30
32
34
36
38
31
33
35
37
39
H
H
H
H
H
H
H
H
H
H
L
L
L
L
H
L
L
H
H
L
L
H
L
H
L
L
L
L
L
L
L
H
H
H
H
H
L
L
L
L
H
L
L
L
L
H
L
L
H
H
H
L
H
L
H
5
6
7
8
9
H
H
H
H
H
L
L
L
H
H
H
H
H
L
L
L
H
H
L
L
H
L
H
L
H
L
L
L
L
L
L
L
L
L
L
H
H
L
L
L
L
L
H
H
L
X X X X X H
H
H
H
H
H
Any
X
X
X
X
X
H
H
H
H
E D C B A G Y5 Y4 Y3 Y2 Y1
Any
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.
² 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
high, the BCD 10’s complement is generated.
Test Circuit
Typical Applications
TL/F/6561 – 6
CL includes probe and jig capacitance
TL/F/6561 – 7
FIGURE 1. BCD-to-Binary Converter
for Two BCD Decades
MSDÐMost significant decade
LSDÐLeast significant decade
Each rectangle represents a DM74184
5
Typical Applications (Continued)
TL/F/6561 – 9
FIGURE 2. BCD-to-Binary Converter for Six BCD Decades
MSDÐMost significant decade
LSDÐLeast significant decade
Each rectangle represents a DM74184
6
Typical Applications (Continued)
TL/F/6561 – 10
FIGURE 4. 6-Bit Binary-to-BCD Converter
MSDÐMost significant decade
LSDÐLeast significant decade
Note A: Each rectangle represents a DM74185A.
Note B: All unused E inputs are grounded.
TL/F/6561 – 8
FIGURE 3. BCD-to-Binary Converter
for Three BCD Decades
MSDÐMost significant decade
LSDÐLeast significant decade
Each rectangle represents a DM74184
TL/F/6561 – 11
TL/F/6561 – 12
FIGURE 5. 8-Bit Binary-to-BCD Converter
FIGURE 6. 9-Bit Binary-to-BCD Converter
MSDÐMost significant decade
LSDÐLeast significant decade
MSDÐMost significant decade
LSDÐLeast significant decade
Note A: Each rectangle represents a DM74185A.
Note A: Each rectangle represents a DM74185A.
Note B: All unused E inputs are grounded.
Note B: All unused E inputs are grounded.
7
Typical Applications (Continued)
TL/F/6561–13
FIGURE 7. 12-Bit Binary-to-BCD
Converter (See Note B)
TL/F/6561 – 14
FIGURE 8. 16-Bit Binary-to-BCD Converter (See Note B)
MSDÐMost significant decade
LSDÐLeast significant decade
Note A: Each rectangle represents a DM74185A.
Note B: All unused E inputs are grounded.
8
9
DM74184/DM74185A BCD-to-Binary and Binary-to-BCD Converters
Physical Dimensions inches (millimeters)
16-Lead Molded Dual-In-Line Package (N)
Order Number DM74184N or DM74185AN
NS Package Number N16E
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