SN74LS85M データシートの表示（PDF） - ON Semiconductor
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SN74LS85M Datasheet PDF : 7 Pages
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SN74LS85
A0 A1 A2 A3 B0 B1 B2 B3
A0 A1 A2 A3 B0 B1 B2 B3
L
IA > B
OA > B
L
IA < B
SN74LS85
OA < B
H
IA = B
OA = B
A0 A1 A2 A3 B0 B1 B2 B3
IA > B
OA > B
IA < B
SN74LS85 OA < B
IA = B
OA = B
A>B
A<B
A=B
L = LOW LEVEL
H = HIGH LEVEL
Figure 1. Comparing Two n-Bit Words
APPLICATIONS
Figure 2 shows a high speed method of comparing two
24-bit words with only two levels of device delay. With the
technique shown in Figure 1, six levels of device delay result
Table 1
WORD LENGTH NUMBER OF PKGS.
1 −4 Bits
5 −24 Bits
25 −120 Bits
1
2−6
8 −31
when comparing two 24-bit words. The parallel technique
can be expanded to any number of bits, see Table 1.
NOTE:
The SN74LS85 can be used as a 5-bit comparator only
when the outputs are used to drive the A0−A3 and B0−B3
inputs of another SN74LS85 as shown in Figure 2 in posi-
tions #1, 2, 3, and 4.
(LSB)
A0 A1 A2 A3 B0 B1 B2 B3
A0 A1 A2 A3 B0 B1 B2 B3
L
IA > B
OA > B
L
IA < B
#5
OA < B
H
IA = B
OA = B
INPUTS
A19
B19
L
(MSB)
A20 A21 A22 A23 B20 B21 B22 B23
A0 A1 A2 A3 B0 B1 B2 B3
IA > B
OA > B
IA < B
#1
OA < B
IA = B
OA = B NC
A5 A6 A7 A8 B5 B6 B7 B8
A0 A1 A2 A3 B0 B1 B2 B3
A4
IA > B
OA > B
B4
IA < B
#4
OA < B
L
IA = B
OA = B NC
INPUTS
A10 A11 A12 A13 B10 B11 B12 B13
A0 A1 A2 A3 B0 B1 B2 B3
A9
IA > B
B9
IA < B
OA > B
#3
OA < B
L
IA = B
OA = B NC
A15 A16 A17 A18 B15 B16 B17 B18
A0 A1 A2 A3 B0 B1 B2 B3
A14
IA > B
B14
IA < B
OA > B
#2
OA < B
L
IA = B
OA = B NC
MSB = MOST SIGNIFICANT BIT
LSB = LEAST SIGNIFICANT BIT
L = LOW LEVEL
H = HIGH LEVEL
NC = NO CONNECTION
A0 A1 A2
IA > B
IA < B
IA = B
A3 B0 B1 B2 B3
OA > B
#6
OA < B
OA = B
Figure 2. Comparison of Two 24-Bit Words
http://onsemi.com
4
OUTPUTS
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