Datasheet

Philips Semiconductors Product specification
80C51/87C51/80C52/87C52
80C51 8-bit microcontroller family
4 K/8 K OTP/ROM low voltage (2.7 V–5.5 V),
low power, high speed (33 MHz), 128/256 B RAM
2000 Aug 07
27
t
LLAX
ALE
PSEN
PORT 0
PORT 2
WR
A0–A7
FROM RI OR DPL
DATA OUT A0–A7 FROM PCL INSTR IN
P2.0–P2.7 OR A8–A15 FROM DPF A0–A15 FROM PCH
t
WHLH
t
LLWL
t
WLWH
t
AVLL
t
AVWL
t
QVWX
t
WHQX
t
QVWH
SU00026
Figure 16. External Data Memory Write Cycle
012345678
INSTRUCTION
ALE
CLOCK
OUTPUT DATA
WRITE TO SBUF
INPUT DATA
CLEAR RI
VALID VALID VALID VALID VALID VALID VALID VALID
SET TI
SET RI
t
XLXL
t
QVXH
t
XHQX
t
XHDX
t
XHDV
SU00027
1230 4567
Figure 17. Shift Register Mode Timing
V
CC
–0.5
0.45V
0.7V
CC
0.2V
CC
–0.1
t
CHCL
t
CLCL
t
CLCH
t
CLCX
t
CHCX
SU00009
Figure 18. External Clock Drive