January 1995 13
Philips Semiconductors
Family Specifications
AC switching parameters
fiInput frequency; for combinatorial logic devices
the maximum number of inputs and outputs
switching in accordance with the device truth
table. For sequential logic devices the clock
frequency using alternate HIGH and LOW for
data input or using the toggle mode, whichever is
applicable.
foOutput frequency; each output.
fmax Clock frequency; clock input waveform should
have a 50% duty cycle and be such as to cause
the outputs to be switching from 10%VDD to
90%VDD in accordance with the device truth
table.
tr, tfClock input rise and fall times; 10% and 90%
value.
tPLH Propagation delay time; the time between the
specified reference points, normally the 50%
points on the input and output waveforms, with
the output changing from the defined LOW level
to the defined HIGH level.
tPHL Propagation delay time; the time between the
specified reference points, normally the 50%
points on the input and output waveforms, with
the output changing from the defined HIGH level
to the defined LOW level.
tTLH Transition time, LOW-to-HIGH; the time between
two specified reference points on a waveform,
normally 10% and 90% points, that is changing
from LOW to HIGH.
tTHL Transition time, HIGH-to-LOW; the time between
two specified reference points on a waveform,
normally 90% and 10% points, that is changing
from HIGH to LOW.
tWPulse width; the time between the 50% amplitude
points on the leading and trailing edges of a
pulse.
thold Hold time; the interval immediately following the
active transition of the timing pulse (usually the
clock pulse) or following the transition of the
control input to its latching level, during which
interval the data to be recognized must be
maintained at the input to ensure their continued
recognition. A negative hold time indicates that
the correct logic level may be released prior to
the timing pulse and still be recognized.
tsu Set-up time; the interval immediately preceding
the active transition of the timing pulse (usually
the clock pulse) or preceding the transition of the
control input to its latching level, during which
interval the data to be recognized must be
maintained at the input to ensure their
recognition. A negative set-up time indicates that
the correct logic level may be initiated sometime
after the active transition of the timing pulse and
still be recognized.
tPHZ 3-state output disable time, HIGH to Z; the time
between the specified reference points, normally
the 50% point on the output enable input voltage
waveform and a point representing a 0.1 VOH
drop on the output voltage waveform of a 3-state
device, with the output changing from the output
HIGH level (VOH) to a high impedance OFF-state.
tPLZ 3-state output disable time, LOW to Z; the time
between the specified reference points, normally
the 50% point on the output enable input voltage
waveform and a point representing a
0.1 (VDD −VOL) rise on the output voltage
waveform of a 3-state device, with the output
changing from the output LOW level (VOL) to a
high impedance OFF-state.
tPZH 3-state output enable time, Z to HIGH; the time
between the specified reference points, normally
the 50% point on the output enable input voltage
waveform and a point representing a 0.1 VOH rise
on the output voltage waveform of a 3-state
device, with the output changing from a high
impedance OFF-state to the output HIGH level
(VOH).
tPZL 3-state output enable time, Z to LOW; the time
between the specified reference points, normally
the 50% point on the output enable input voltage
waveform and a point representing a
0.1 (VDD −VOL) voltage drop on the output
voltage waveform of a 3-state device, with the
output changing from a high impedance
OFF-state to the output LOW level (VOL).
tRRecovery time; the time between the end of an
overriding asynchronous input, typically a clear or
reset input, and the earliest permissible
beginning of a synchronous control input,
typically a clock input, normally measured at 50%
points on both input voltage waveforms.