External Data Memory Write Cycle
tLHLL
ALE
tWHLH
PSEN
tLLWL
tWLWH
WR
tLLAX
tQVWX
tWHQX
tAVLL
tQVWH
A0 - A7 FROM RI OR DPL
DATA OUT
A0 - A7 FROM PCL
INSTR IN
PORT 0
PORT 2
tAVWL
P2.0 - P2.7 OR A8 - A15 FROM DPH
A8 - A15 FROM PCH
External Clock Drive Waveforms
tCHCX
tCHCX
tCLCH
tCHCL
VCC - 0.5V
0.7 VCC
0.2 VCC - 0.1V
0.45V
tCLCX
tCLCL
External Clock Drive
Symbol
1/tCLCL
tCLCL
Parameter
Oscillator Frequency
Clock Period
High Time
Min
0
Max
Units
33
MHz
ns
30
12
12
tCHCX
tCLCX
ns
Low Time
ns
tCLCH
Rise Time
5
5
ns
tCHCL
Fall Time
ns
AT89S52
26