W78LE54C/W78L054C
9. AC CHARACTERISTICS
The AC specifications are a function of the particular process used to manufacture the part, the
ratings of the I/O buffers, the capacitive load, and the internal routing capacitance. Most of the
specifications can be expressed in terms of multiple input clock periods (T
CP
), and actual parts will
usually experience less than a
±20
nS variation. The numbers below represent the performance
expected from a 0.6micron CMOS process when using 2 and 4 mA output buffers.
Clock Input Waveform
XTAL1
T
CH
F
OP,
T
CP
T
CL
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNIT
NOTES
Operating Speed
Clock Period
Clock High
Clock Low
F
OP
T
CP
T
CH
T
CL
0
50
25
25
-
-
-
-
20
-
-
-
MHz
nS
nS
nS
1
2
3
3
Notes:
1. The clock may be stopped indefinitely in either state.
2. The T
CP
specification is used as a reference in other specifications.
3. There are no duty cycle requirements on the XTAL1 input.
Program Fetch Cycle
PARAMETER
SYMBOL
MIN.
TYP.
MAX.
UNIT
NOTES
Address Valid to ALE Low
Address Hold from ALE Low
ALE Low to
PSEN
Low
T
AAS
T
AAH
T
APL
T
PDA
T
PDH
T
PDZ
T
ALW
T
PSW
1 T
CP
-Δ
1 T
CP
-Δ
1 T
CP
-Δ
-
0
0
2 T
CP
-Δ
3 T
CP
-Δ
-
-
-
-
-
-
2 T
CP
3 T
CP
-
-
-
2 T
CP
1 T
CP
1 T
CP
-
-
nS
nS
nS
nS
nS
nS
nS
nS
4
1, 4
4
2
3
4
4
PSEN
Low to Data Valid
Data Hold after
PSEN
High
Data Float after
PSEN
High
ALE Pulse Width
PSEN
Pulse Width
Notes:
1. P0.0
−
P0.7, P2.0
−
P2.7 remain stable throughout entire memory cycle.
2. Memory access time is 3 T
CP
.
3. Data have been latched internally prior to PSEN going high.
4. "
Δ
" (due to buffer driving delay and wire loading) is 20 nS.
- 14 -
TRIQUINT [ TRIQUINT SEMICONDUCTOR ]
