MC74AC194 Datasheet, PDF (1/7 Pages) Motorola, Inc – 4-Bit Bidirectional Universal Shift Register

4ĆBit Bidirectional
Universal Shift Register
The MC74AC194/74ACT194 is a high-speed 4-bit bidirectional universal shift
register. As a high-speed multifunctional, sequential building block, it is useful in
a wide variety of applications. It may be used in serial-serial, shift left, shift right,
serial-parallel, parallel-serial, and parallel-parallel data register transfers. The
′AC/ACT194 is similar in operation to the ′AS195 universal shift register, with
added features of shift left without external connections and hold (do nothing)
modes of operation.
• Typical Shift Frequency of 150 MHz
• Asynchronous Master Reset
• Hold (Do Nothing) Mode
• Fully Synchronous Serial or Parallel Data Transfers
FUNCTIONAL DESCRIPTION
The MC74AC/74ACT194 contains four edge-triggered D flip-flops and the
necessary interstage logic to synchronously perform shift right, shift left, parallel
load and hold operations. Signals applied to the Select (S0, S1) inputs
determine the type of operation, as shown in the Mode Select Table. Signals
on the Select, Parallel data (P0–P3) and Serial data (DSR, DSL) inputs can
change when the clock is in either state, provided only that the recommended
setup and hold times, with respect to the clock rising edge, are observed. A
LOW signal on Master Reset (MR) overrides all other inputs and forces the
outputs LOW.
MODE SELECT TABLE
Operating
Mode
Reset
MR S1
LX
Inputs
S0 DSR
X
X
DSL Pn
XX
Outputs
Q0 Q1 Q2 Q3
LLLL
Hold
Hl
l
X
X X q0 q1 q2 q3
Shift Left
Hh
l
Hh
l
X
l
X q1 q2 q3 L
X
h X q1 q2 q3 H
Shift Right
H
l
h
H
l
h
l
X X L q0 q1 q2
h
X X H q0 q1 q2
Parallel Load H h h
X
X pn p0 p1 p2 p3
l = LOW voltage level one setup time prior to the LOW-to-HIGH clock transition.
h = HIGH voltage level one setup time prior to the LOW-to-HIGH clock transition.
Pn (qn) = Lower case letters indicate the state of the referenced input (or output) one setup
time prior to the LOW-to-HIGH clock transition.
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
FACT DATA
5-1
MC74AC194
MC74ACT194
4-BIT BIDIRECTIONAL
UNIVERSAL SHIFT
REGISTER
N SUFFIX
CASE 648-08
PLASTIC
D SUFFIX
CASE 751B-05
PLASTIC
MR ¹
16 VCC
DSR 2
15 Q0
P0 3
P1 4
14 Q1
13 _Q2
P2 5
12 Q3
P3 ⁶
11 _CP
7
DSL
8
GND
10 S1
9 S0
2 34 56 7
9
S0DSR ^{P0 P1 P2 P3 DSL}
10 S1
11
CP _{MR Q0 Q1 Q2 Q3}
1 15 14 13 12