74F524 Datasheet, PDF (4/14 Pages) NXP Semiconductors – 8-bit register comparator open-collector 3-State

Philips Semiconductors
8-bit register comparator (open collector + 3-State)
Product specification
74F524
CS/O output of the most significant device will be forced Low,
disabling the subsequent devices but enabling its own status
outputs. The corrected status condition is thus indicated. The same
applies if the register byte is less than the data byte, only in this
case the EQ and GT outputs go Low, whereas the LT output floats
High.
If an equality condition is detected in the most significant device, its
C/SO output is forced High. This enables the next less significant
device and disables its own status outputs. In this way, the status
output proximity is handed down to the next less significant device
which now effectively becomes the most significant byte. The worst
case propagation delay for a compare operation involving ‘n’
cascaded 74F524s will be when an equality condition is detected in
all but the least significant byte. In this case, the status priority has
to ripple all the way down the chain before the correct status output
is established. Typically, this will take 35+6(n–2) ns.
APPLICATION
GREATER THAN
H = TWO’s COMPLEMENT
L = MAGNITUDE
EQUAL TO
LESS THAN
M GT EQ LT
H
C/SI
SE
C/SO
S0 S1 I/O
L
M GT EQ LT
SE
C/SI
C/SO
S0 S1 I/O
V_CC
L
M GT EQ LT
SE
C/SI
C/SO
L
S0 S1 I/O
RD
WR
MSB 8
8
Figure 1. Cascading 74F524s for Comparing Longer Words
LSB 8
SF01012
FUNCTION TABLE
INPUTS
SE C/SI S0
S1
Data comparison
H
H
L
L
X
H
L
L
L
X
H
X
H
L
X
H
H
L
H
X
H
L
L
H
X
H
H
H
H
X
H
L
H
H
X
L
L H or L² H or L²
OA–OH > I/O0–I/O7
L
L H or L² H or L²
OA–OH = I/O0–I/O7
L
L H or L² H or L²
OA–OH < I/O0–I/O7
L
H H or L² H or L²
OA–OH > I/O0–I/O7
L
H H or L² H or L²
OA–OH = I/O0–I/O7
L
H H or L² H or L²
OA–OH < I/O0–I/O7
(1) = High if I/On=Dn, otherwise Low
2 = Must meet setup and hold time requirements
H = High voltage level
L = Low voltage level
X = Don’t care
OUTPUTS
EQ GT LT C/SO
H
H
H
(1)
H
H
H
L
H
H
H
Q0
H
H
H
(1)
H
H
H
L
H
H
H
(1)
H
H
H
L
L
H
H
L
H
H
H
L
L
H
H
L
L
H
L
L
H
L
L
H
L
L
H
L
1990 Aug 07
4
OPERATING MODE
Hold
Shift
Read
Load
Compare
(GT=CT=off)
Compare
(GT=CT=on)