W78IRD2 Datasheet, PDF (62/76 Pages) Winbond – 8-BIT MICROCONTROLLER

W78IRD2
18.3 A.C. 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 (TCP), and actual parts will usually
experience less than a ±20 ns variation.
Clock Input Waveform
XTAL1
T_CH
T_CL
FOP, TCP
PARAMETER
Operating Speed
Clock Period
Clock High
Clock Low
SYMBOL
Fop
TCP
TCH
TCL
MIN.
0
25
10
10
TYP.
-
-
-
-
Notes:
1. The clock may be stopped indefinitely in either state.
2. The TCP specification is used as a reference in other specifications.
3. There are no duty cycle requirements on the XTAL1 input.
MAX.
20
-
-
-
UNIT
MHz
ns
ns
ns
NOTES
1
2
3
3
Program Fetch Cycle
PARAMETER
SYMBOL
MIN.
TYP.
Address Valid to ALE Low
TAAS
1 TCP-∆
-
Address Hold from ALE Low
TAAH
1 TCP-∆
-
ALE Low to PSEN Low
TAPL
1 TCP-∆
-
PSEN Low to Data Valid
TPDA
-
-
Data Hold after PSEN High
TPDH
0
-
Data Float after PSEN High
TPDZ
0
-
ALE Pulse Width
TALW
2 TCP-∆ 2 TCP
PSEN Pulse Width
TPSW
3 TCP-∆ 3 TCP
Notes:
1. P0.0 − P0.7, P2.0 − P2.7 remain stable throughout entire memory cycle.
2. Memory access time is 3 TCP.
3. Data have been latched internally prior to PSEN going high.
4. "∆" (due to buffer driving delay and wire loading) is 20 ns.
MAX.
-
-
-
2 TCP
1 TCP
1 TCP
-
-
UNIT
ns
ns
ns
ns
ns
ns
ns
ns
NOTES
4
1, 4
4
2
3
4
4
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