Functional Description
The ABT16373 contains sixteen D-type latches with
TRI-STATE standard outputs. The device is byte controlled
with each byte functioning identically, but independent of the
other. Control pins can be shorted together to obtain full
16-bit operation. The following description applies to each
byte. When the Latch Enable (LEn) input is HIGH, data on
the Dn enters the latches. In this condition the latches are
transparent, i.e., a latch output will change states each time
its D input changes. When LEn is LOW, the latches store in-
formation that was present on the D inputs a setup time pre-
ceding the HIGH-to-LOW transition of LEn. The TRI-STATE
standard outputs are controlled by the Output Enable (OEn)
input. When OEn is LOW, the standard outputs are in the
2-state mode. When OEn is HIGH, the standard outputs are
in the high impedance mode but this does not interfere with
entering new data into the latches.
Logic Diagrams
Truth Tables
Inputs
LE1
OE1
D0– D7
XH
X
HL
L
HL
H
LL
X
Outputs
O0– O7
Z
L
H
(Previous)
Inputs
Outputs
LE2
X
OE2
H
D8– D15
X
O8– O15
Z
HL
L
L
HL
H
H
LL
X (Previous)
H = High Voltage Level
L = Low Voltage Level
X = Immaterial
Z = High Impedance
Previous = previous output prior to HIGH to LOW transition of LE
DS100201-3
www.national.com
DS100201-4
2
