9314_11 Datasheet, PDF (4/8 Pages) Texas Instruments – Quad Latch

Switching Characteristics V_CC e a5 0V T_A e a25 C (See Section 1 for waveforms and load configurations)
Symbol
Parameter
C_L e 15 pF
Min
Max
Units
t_PLH
t_PHL
t_PLH
t_PHL
t_PLH
t_PHL
Propagation Delay
E to Q_n
Propagation Delay
D_n to Q_n
Propagation Delay
MR to Q_n
Propagation Delay
S_n to Q_n
24
24
ns
12
ns
24
18
ns
24
ns
Functional Description
The ’9314 consists of four latches with a common active
LOW Enable input and active LOW Master Reset input
When the Enable goes HIGH data present in the latches is
stored and the state of the latch is no longer affected by the
S_n and D_n inputs The Master Reset when activated over-
rides all other input conditions forcing all latch outputs LOW
Each of the four latches can be operated in one of two
modes
D-TYPE LATCH For D-type operation the S input of a latch
is held LOW While the common Enable is active the latch
output follows the D input Information present at the latch
output is stored in the latch when the Enable goes HIGH
SET RESET LATCH During set reset operation when the
common Enable is LOW a latch is reset by a LOW on the D
input and can be set by a LOW on the S input if the D input
is HIGH If both S and D inputs are LOW the D input will
dominate and the latch will be reset When the Enable goes
HIGH the latch remains in the last state prior to disable-
ment The two modes of latch operation are shown in the
Truth Table
Truth Table
MR
E
D
S
H
L
L
L
H
L
H
L
H
H
X
X
H
L
L
L
H
L
H
L
H
L
L
H
H
L
H
H
H
H
X
X
L
X
X
X
H e HIGH Voltage Level
L e LOW Voltage Level
X e Immaterial
Q_nb₁ e Previous Output State
Q_n e Present Output State
Q_n
L
H
Q_nb₁
L
H
L
Q_nb₁
Q_nb₁
L
Operation
D Mode
R S Mode
Reset
3