Philips Semiconductors
Product specification
CMOS single-chip 8-bit microcontrollers
80C31/80C51/87C51
ALE
t
WHLH
PSEN
t
t
WLWH
LLWL
WR
t
LLAX
t
t
WHQX
t
AVLL
QVWX
A0–A7
FROM RI OR DPL
PORT 0
PORT 2
DATA OUT
A0–A7 FROM PCL
INSTR IN
t
AVWL
P2.0–P2.7 OR A8–A15 FROM DPH
A0–A15 FROM PCH
SU00008
Figure 3. External Data Memory Write Cycle
INSTRUCTION
ALE
0
1
2
3
4
5
6
7
8
t
XLXL
CLOCK
t
XHQX
t
QVXH
OUTPUT DATA
0
1
2
3
4
5
6
7
WRITE TO SBUF
t
XHDX
t
SET TI
VALID
XHDV
INPUT DATA
CLEAR RI
VALID
VALID
VALID
VALID
VALID
VALID
VALID
SET RI
SU00027
Figure 4. Shift Register Mode Timing
V
–0.5
CC
0.7V
CC
CC
0.45V
0.2V
–0.1
t
CHCX
t
t
t
CHCL
CLCX
CLCH
t
CLCL
SU00009
Figure 5. External Clock Drive
18
1996 Aug 16
NXP [ NXP ]
