MC74HC244A
http://onsemi.com
4
SWITCHING WAVEFORMS
Figure 1. Figure 2.
V
CC
GND
t
f
t
r
DATA INPUT
A OR B
OUTPUT
YA OR YB
10%
50%
90%
10%
50%
90%
t
TLH
t
PLH
t
PHL
t
THL
ENABLE
A OR B
OUTPUT Y
OUTPUT Y
50%
50%
50%
90%
10%
t
PZL
t
PLZ
t
PZH
t
PHZ
V
CC
GND
HIGH
IMPEDANCE
V
OL
V
OH
HIGH
IMPEDANCE
TEST CIRCUITS
*Includes all probe and jig capacitance
C
L
*
TEST POINT
DEVICE
UNDER
TEST
OUTPUT
Figure 3. Test Circuit
*Includes all probe and jig capacitance
C
L
*
TEST POINT
DEVICE
UNDER
TEST
OUTPUT
Figure 4. Test Circuit
CONNECT TO V
CC
WHEN
TESTING t
PLZ
AND t
PZL
.
CONNECT TO GND WHEN
TESTING t
PHZ
AND t
PZH
.
1 kW
PIN DESCRIPTIONS
INPUTS
A1, A2, A3, A4, B1, B2, B3, B4
(Pins 2, 4, 6, 8, 11, 13, 15, 17)
Data input pins. Data on these pins appear in noninverted
form on the corresponding Y outputs, when the outputs are
enabled.
CONTROLS
Enable A, Enable B (Pins 1, 19)
Output enables (active−low). When a low level is applied
to these pins, the outputs are enabled and the devices
function as noninverting buffers. When a high level is
applied, the outputs assume the high impedance state.
OUTPUTS
YA1, YA2, YA3, YA4, YB1, YB2, YB3, YB4
(Pins 18, 16, 14, 12, 9, 7, 5, 3)
Device outputs. Depending upon the state of the
output−enable pins, these outputs are either noninverting
outputs or high−impedance outputs.
