MC74AC646 Datasheet, PDF (2/9 Pages) Motorola, Inc – OCTAL TRANSCEIVER/REGISTER WITH 3-STATE OUTPUTS (NON-INVERTING)

MC74AC646 MC74ACT646
FUNCTION TABLE
Inputs
G
DIR
CAB
CBA
SAB
SBA
H
X
H or L H or L
X
X
H
X
X
X
Data I/O*
A0–A7
B0–B7
Input
Input
Operation or Function
Isolation
Store A and B Data
L
L
L
L
X
X
X
L
X
X
X
H
Output
Input
Real Time B Data to A Bus
Stored B Data to A Bus
L
H
X
X
L
X
L
H
H or L
X
H
X
Input
Output
Real Time A Data to B Bus
Stored A Data to B Bus
* The data output functions may be enabled or disabled by various signals at the G and DIR inputs. Data input functions are always enabled; i.e., data at the bus
pins will be stored on every LOW-to-HIGH transition of the appropriate clock inputs.
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
= LOW-to-HIGH Transition
LOGIC DIAGRAM
G
CAB 1
SAB 2
DIR ₃
A0 ₄
24 VCC
DIR
23 CBA
CBA
SBA
22 ^SBA
CAB
21 ^G
SAB
A1 5
A2 6
A3 ₇
20 B0
19 B1
18 ^B2
1 OF 8 CHANNELS
D0
C0
A4 ₈
17 ^B3
A5 ₉
16 ^B4
A0
B0
A6 ₁₀
15 ^B5
D0
C0
A7 ₁₁
14 ^B6
GND ₁₂
13 ^B7
PIN NAMES
A0–A7
B0–B7
CAB, CBA
SAB, SBA
DIR, G
Data Register Inputs
Data Register A Outputs
Data Register B Inputs
Data Register B Outputs
Clock Pulse Inputs
Transmit/Receive Inputs
Output Enable Inputs
TO 7 OTHER CHANNELS
Please note that this diagram is provided only for the understanding of logic
operations and should not be used to estimate propagation delays.
FACT DATA
5-2