Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I
2
C, PWM,
capture/compare, high I/O, low voltage (2.7V鈥?.5V), low power
P87C552
ALE
t
WHLH
PSEN
t
LLWL
WR
t
WLWH
t
AVLL
PORT 0
t
LLAX
A0鈥揂7
FROM RI OR DPL
t
QVWX
t
DW
DATA OUT
t
WHQX
A0鈥揂7 FROM PCL
INSTR IN
t
AVWL
PORT 2
P2.0鈥揚2.7 OR A8鈥揂15 FROM DPH
A8鈥揂15 FROM PCH
SU00213
Figure 50. External Data Memory Write Cycle
V
CC
鈥?.5
0.45V
0.7V
CC
0.2V
CC
鈥?.1
t
CHCL
t
CLCX
t
CLCL
t
CHCX
t
CLCH
SU00009
Figure 51. External Clock Drive XTAL1
INSTRUCTION
ALE
0
1
2
3
4
5
6
7
8
t
XLXL
CLOCK
t
QVXH
OUTPUT DATA
0
WRITE TO SBUF
t
XHQX
1
2
3
4
5
6
7
t
XHDV
INPUT DATA
VALID
CLEAR RI
VALID
t
XHDX
SET TI
VALID
VALID
VALID
VALID
VALID
VALID
SET RI
SU00027
Figure 52. Shift Register Mode Timing
1999 Mar 30
68