W78E51B_05 Datasheet, PDF (16/25 Pages) Winbond – 8-BIT MICROCONTROLLER

W78E51B
8.3.1 Clock Input Waveform
XTAL1
T_CH
TCL
F OP, TCP
PARAMETER
Operating Speed
SYMBOL
FOP
MIN.
0
TYP.
-
Clock Period
Clock High
TCP
25
-
TCH
10
-
Clock Low
TCL
10
-
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.
40
-
-
-
8.3.2 Program Fetch Cycle
PARAMETER
SYMBOL
MIN.
TYP.
Address Valid to ALE Low
TAAS
1 TCP -Δ
-
Address Hold from ALE Low
TAAH
1 TCP -Δ
-
ALE Low to PSEN Low
TAPL
1 TCP -Δ
-
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 -Δ 2 TCP
PSEN Pulse Width
TPSW
3 TCP -Δ 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. "Δ" (due to buffer driving delay and wire loading) is 20 nS.
MAX.
-
-
-
2 TCP
1 TCP
1 TCP
-
-
8.3.3 Data Read Cycle
PARAMETER
SYMBOL
MIN.
ALE Low to RD Low
TDAR
3 TCP -Δ
RD Low to Data Valid
TDDA
-
Data Hold from RD High
TDDH
0
Data Float from RD High
TDDZ
0
RD Pulse Width
TDRD
6 TCP -Δ
Notes:
1. Data memory access time is 8 TCP.
2. "Δ" (due to buffer driving delay and wire loading) is 20 nS.
TYP.
-
-
-
-
6 TCP
MAX.
3 TCP +Δ
4 TCP
2 TCP
2 TCP
-
UNIT
MHz
nS
nS
nS
UNIT
nS
nS
nS
nS
nS
nS
nS
nS
UNIT
nS
nS
nS
nS
nS
NOTES
1
2
3
3
NOTES
4
1, 4
4
2
3
4
4
NOTES
1, 2
1
2
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