54LS279 Datasheet, PDF (1/6 Pages) National Semiconductor (TI) – Quad S-R Latches

May 1989
54LS279 DM54LS279 DM74LS279
Quad S-R Latches
General Description
The ’LS279 consists of four individual and independent Set-
Reset Latches with active low inputs Two of the four latch-
es have an additonal S input ANDed with the primary S
input A low on any S input while the R input is high will be
stored in the latch and appear on the corresponding Q out-
put as a high A low on the R input while the S input is high
will clear the Q output to a low Simultaneous transistion of
the R and S inputs from low to high will cause the Q output
to be indeterminate Both inputs are voltage level triggered
and are not affected by transition time of the input data
Features
Y _{Alternate military aerospace device (54LS279) is avail-}
able Contact a National Semiconductor Sales Office
Distributor for specifications
Connection Diagram
Dual-In-Line Package
TL F 6420 – 1
Order Number 54LS279DMQB 54LS279FMQB 54LS279LMQB
DM54LS279J DM74LS279M or DM74LS279N
See NS Package Number E20A J16A M16A N16E or W16A
Function Table
Inputs
Output
S(1)
R
Q
L
L
H
L
H
H
H
L
L
H
H
Q₀
H e High Level
L e Low Level
Q₀ e The Level of Q before the indicated input conditions were established
This output level is pseudo stable that is it may not persist when the S and R
inputs return to their inactive (high) level
Note 1 For latches with double S inputs
H e both S inputs high
L e one or both S inputs low
C1995 National Semiconductor Corporation TL F 6420
RRD-B30M105 Printed in U S A