參數(shù)資料
型號: MC74HC646
廠商: Motorola, Inc.
英文描述: Octal 3-State Bus Transceivers and D Flip-Flops
中文描述: 八路三態(tài)總線收發(fā)器和D觸發(fā)器
文件頁數(shù): 5/14頁
文件大小: 328K
代理商: MC74HC646
MC54/74HC646
High–Speed CMOS Logic Data
DL129 — Rev 6
3–5
MOTOROLA
FUNCTION TABLE — HC646
Control Inputs
Data Port Status
Storage Flip–
Flop States
Description of Operation
Output
Enable
Direc–
tion
A–to–B
Clock
B–to–A
Clock
A–to–B
Source
B–to–A
Source
A
B
QA
QB
H
X
H, L,
H, L,
X
X
Input:
X
Input:
X
no change
no change
The output functions of the A and B
ports are disabled
X
X
L
H
X
X
X
X
L
H
L
H
X
X
X
X
L
H
The ports may be used as inputs to
the storage flip–flops. Data at the in-
puts are clocked into the flip–flops
with the rising edge of the Clocks.
L
H
Input:
Output:
The output mode of the B data port is
enabled and behaves according to
the following logic equation:
B = [A
(A–to–B Source)]
+ [Q
A
(A–to–B Source)]
1.) When A–to–B Source is low, the
data at the A data port are dis-
played at the B data port. The
states of the storage flip–flops are
not affected.
H, L,
X*
L
X
L
H
L
H
no change
no change
no change
no change
H
X
X
QA
no change
no change
2.) When A–to–B Source is high, the
states of the A storage flip–flops are
displayed at the B data port.
X*
L
X
L
H
L
H
L
H
no change
no change
3.) When A–to–B Source is low, the
data at the A data port are clocked
into the A storage flip–flops by a ris-
ing–edge signal on the A–to–B
Clock.
H
X
L
H
QA
QA
L
H
no change
no change
4.) When A–to–B Source is high, the
data at the A data port are clocked
into the A storage flip–flops by a ris-
ing–edge signal on the A–to–B
Clock. The states, QA, of the stor-
age flip–flops propagate directly to
the B data port.
L
L
Output:
Input:
The output mode of the A data port is
enabled and behaves according to
the following logic equation:
A = [B
(B–to–A Source)]
+ [Q
B
(B–to–A Source)]
1.) When B–to–A Source is low, the
data at the B data port are dis-
played at the A data port. The
states of the storage flip–flops are
not affected.
X*
H, L,
X
L
L
H
L
H
no change
no change
no change
no change
X
H
QB
X
no change
no change
2.) When B–to–A Source is high, the
states of the B storage flip–flops are
displayed at the A data port.
X*
X
L
L
H
L
H
no change
no change
L
H
3.) When B–to–A Source is low, the
data at the B data port are clocked
into the B storage flip–flops by a ris-
ing–edge signal on the B–to–A
Clock.
X
H
QB
QB
L
H
no change
no change
L
H
4.) When B–to–A Source is high, the
data at the B data port are clocked
into the B storage flip–flops by a ris-
ing–edge signal on the B–to–A
Clock. The states, QB, of the stor-
age flip–flops propagate directly to
the A data port.
* The clocks are not internally gated with either the Output Enables or the Source inputs. Therefore, data at the A and B ports may be clocked into
the storage flip–flops at any time.
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