74ACTQ843 Fairchild Semiconductor, 74ACTQ843 Datasheet - Page 6

• Manufacturer Part Number: 74ACTQ843
• Description: Quiet Seriesa 9-Bit Transparent Latch with 3-STATE Outputs
• Manufacturer: Fairchild Semiconductor

www.fairchildsemi.com
FACT Noise Characteristics
The setup of a noise characteristics measurement is critical
to the accuracy and repeatability of the tests. The following
is a brief description of the setup used to measure the
noise characteristics of FACT.
Equipment:
Procedure:
1. Verify Test Fixture Loading: Standard Load 50 pF,
2. Deskew the HFS generator so that no two channels
3. Terminate all inputs and outputs to ensure proper load-
4. Set the HFS generator to toggle all but one output at a
5. Set the HFS generator input levels at 0V LOW and 3V
Note 10: V
Note 11: Input pulses have the following characteristics: f
t
r
Hewlett Packard Model 8180A Word Generator
PC-163A Test Fixture
Tektronics Model 7854 Oscilloscope
FIGURE 1. Quiet Output Noise Voltage Waveforms
3 ns, t
500 .
have greater than 150 ps skew between them. This
requires that the oscilloscope be deskewed first. It is
important to deskew the HFS generator channels
before testing. This will ensure that the outputs switch
simultaneously.
ing of the outputs and that the input levels are at the
correct voltage.
frequency of 1 MHz. Greater frequencies will increase
DUT heating and effect the results of the measure-
ment.
HIGH for ACT devices and 0V LOW and 5V HIGH for
AC devices. Verify levels with an oscilloscope.
f
OHV
3 ns, skew
and V
OLP
are measured with respect to ground reference.
150 ps.
1 MHz,
6
V
• Determine the quiet output pin that demonstrates the
• Measure V
• Verify that the GND reference recorded on the oscillo-
V
• Monitor one of the switching outputs using a 50 coaxial
• First increase the input LOW voltage level, V
• Next decrease the input HIGH voltage level on the, V
• Verify that the GND reference recorded on the oscillo-
OLP
ILD
greatest noise levels. The worst case pin will usually be
the furthest from the ground pin. Monitor the output volt-
ages using a 50
SMB type connector on the test fixture. Do not use an
active FET probe.
worst case transition for active and enable. Measure
V
case active and enable transition.
scope has not drifted to ensure the accuracy and repeat-
ability of the measurements.
cable plugged into a standard SMB type connector on
the test fixture. Do not use an active FET probe.
output begins to oscillate or steps out a min of 2 ns.
Oscillation is defined as noise on the output LOW level
that exceeds V
exceed V
oscillation occurs is defined as V
until the output begins to oscillate or steps out a min of 2
ns. Oscillation is defined as noise on the output LOW
level that exceeds V
that exceed V
which oscillation occurs is defined as V
scope has not drifted to ensure the accuracy and repeat-
ability of the measurements.
OHP
FIGURE 2. Simultaneous Switching Test Circuit
and V
/V
OLV
and V
IHD
and V
IH
OLP
:
limits. The input LOW voltage level at which
OHV
IH
OHP
and V
IL
limits. The input HIGH voltage level at
on the quiet output during the worst
limits, or on output HIGH levels that
/V
coaxial cable plugged into a standard
IL
OHV
OLV
limits, or on output HIGH levels
:
on the quiet output during the
ILD
.
IHD
.
IL
, until the
IH
,