SN54LS95B Datasheet, PDF (2/6 Pages) Motorola, Inc – 4-BIT SHIFT REGISTER

SN54 / 74LS95B
6
S
1
DS
LOGIC DIAGRAM
P0
P1
P2
P3
2
3
4
5
9
CP1
8
CP2
R
R
R
R
VCC = PIN 14
GND = PIN 7
= PIN NUMBERS
SQ
13
Q0
FUNCTIONAL DESCRIPTION
The LS95B is a 4-Bit Shift Register with serial and parallel
synchronous operating modes. It has a Serial (DS) and four
Parallel (P0 – P3) Data inputs and four Parallel Data outputs
(Q0 – Q3). The serial or parallel mode of operation is controlled
by a Mode Control input (S) and two Clock Inputs (CP1) and
(CP2). The serial (right-shift) or parallel data transfers occur
synchronous with the HIGH to LOW transition of the selected
clock input.
When the Mode Control input (S) is HIGH, CP2 is enabled. A
HIGH to LOW transition on enabled CP2 transfers parallel
data from the P0 – P3 inputs to the Q0 – Q3 outputs.
When the Mode Control input (S) is LOW, CP1 is enabled. A
SQ
12
Q1
SQ
11
Q2
SQ
10
Q3
HIGH to LOW transition on enabled CP1 transfers the data
from Serial input (DS) to Q0 and shifts the data in Q0 to Q1, Q1
to Q2, and Q2 to Q3 respectively (right-shift). A left-shift is ac-
complished by externally connecting Q3 to P2, Q2 to P1, and
Q1 to P0, and operating the LS95B in the parallel mode (S =
HIGH).
For normal operation, S should only change states when
both Clock inputs are LOW. However, changing S from LOW
to HIGH while CP2 is HIGH, or changing S from HIGH to LOW
while CP1 is HIGH and CP2 is LOW will not cause any changes
on the register outputs.
MODE SELECT — TRUTH TABLE
OPERATING MODE
INPUTS
OUTPUTS
S CP1 CP2 DS Pn Q0 Q1 Q2 Q3
Shift
Parallel Load
L
X
I
X
L q0 q1 q2
L
X
h X H q0 q1 q2
HX
X Pn P0 P1 P2 P3
Mode Change
L
L
XX
L
L
XX
H
L
XX
H
L
XX
L
H
XX
L
H
XX
H
H
XX
H
H
XX
No Change
No Change
No Change
Undetermined
Undetermined
No Change
Undetermined
No Change
L = LOW Voltage Level
H = HIGH Voltage Level
X = Don’t Care
I = LOW Voltage Level one set-up time prior to the HIGH to LOW clock transition.
h = HIGH Voltage Level one set-up time prior to the HIGH to LOW clock transition.
Pn = Lower case letters indicate the state of the referenced input (or output) one set-up time prior to the Pn
= HIGH to LOW clock transition.
FAST AND LS TTL DATA
5-172