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Timing parameter abbreviations. |
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|  MIL-M-38510/245B
6.5.1 Timing parameter abbreviations. All timing abbreviations use lower case characters with upper case
character subscripts. The initial character is always t and is followed by four descriptors. These characters specify
two signal points arranged in a "from-to" sequence that define a timing interval. The two descriptors for each signal
point specify the signal name and the signal transitions. Thus the format is:
t
X
X
X
X
Signal name from which interval is defined
Transition direction for first signal
Signal name to which interval is defined
Transition direction for second signal
a.
Signal definitions:
A = Address
D = Data in
Q = Data out
W = Write enable
E = Chip enable
S = Chip select
G = Output enable
b.
Transition definitions:
H = Transition to high
L = Transition to low
V = Transition to valid
X = Transition to invalid or don't care
Z = Transition to off (high impedance)
EXAMPLE:
The example shows write pulse setup time defined as tWLEH time from write enable low to chip enable high.
c.
Timing limits. The table of timing values shows either a minimum or a maximum limit for each parameter.
Input requirements are specified from the external system point of view. Thus, address set-up time is shown as a
minimum since the system must supply at least that much time (even though most devices do not require it). On the
other hand, responses from the memory are specified from the device point of view. Thus, the access time is shown
as a maximum since the device never provides data later than that time.
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