PDU54
APPLICATION NOTES
ADDRESS UPDATE
The PDU54 is a memory device. As such,
special precautions must be taken when
changing the delay address in order to prevent
spurious output signals. The timing restrictions
are shown in Figure 1.
After the last signal edge to be delayed has
appeared on the OUT pin, a minimum time, T
OAX
,
is required before the address lines can change.
This time is given by the following relation:
T
OAX
= max { (A
i
- A
i-1
) * T
INC
, 0 }
where A
i-1
and A
i
are the old and new address
codes, respectively. Violation of this constraint
may, depending on the history of the input signal,
cause spurious signals to appear on the OUT
pin. The possibility of spurious signals persists
until the required T
OAX
has elapsed.
conditions are those for which the delay
tolerance specifications and monotonicity are
guaranteed. The
suggested
conditions are
those for which signals will propagate through the
unit without significant distortion. The
absolute
conditions are those for which the unit will
produce some type of output for a given input.
When operating the unit between the
recommended and absolute conditions, the
delays may deviate from their values at low
frequency. However, these deviations will
remain constant from pulse to pulse if the input
pulse width and period remain fixed. In other
words, the delay of the unit exhibits frequency
and pulse width dependence when operated
beyond the recommended conditions. Please
consult the technical staff at Data Delay Devices
if your application has specific high-frequency
requirements.
Please note that the increment tolerances listed
represent a design goal. Although most delay
increments will fall within tolerance, they are not
guaranteed throughout the address range of the
unit. Monotonicity is, however, guaranteed over
all addresses.
INPUT RESTRICTIONS
There are three types of restrictions on input
pulse width and period listed in the
AC
Characteristics
table. The
recommended
PACKAGE DIMENSIONS
24 23 22 21 20 19 18 17 16 15 14 13
.580
MAX.
.010
±
.002
1
2
3
4
5
6
7
8
9 10 11 12
.600
±
.005
1.270
±
.010
Lead Material:
Nickel-Iron alloy 42
TIN PLATE
.380
MAX.
.015 TYP.
.018 TYP.
.070 MAX.
1.100
±
.010
11 Equal spaces
each .100
±
.010
Non-Accumulative
PDU54-xx (Commercial DIP)
PDU54-xxM (Military DIP)
Doc #98004
3/18/98
DATA DELAY DEVICES, INC.
Tel: 973-773-2299
Fax: 973-773-9672
http://www.datadelay.com
2
DATADELAY [ DATA DELAY DEVICES, INC. ]
