Datasheet

117
AT89C51RB2/RC2
4180E–8051–10/06
Shift Register Timing
Waveforms
External Clock Drive
Waveforms
AC Testing Input/Output
Waveforms
AC inputs during testing are driven at V
CC
- 0.5 for a logic “1” and 0.45V for a logic “0”.
Timing measurement are made at V
IH
min for a logic “1” and V
IL
max for a logic “0”.
Float Waveforms
For timing purposes as port pin is no longer floating when a 100 mV change from load
voltage occurs and begins to float when a 100 mV change from the loaded V
OH
/V
OL
level
occurs. I
OL
/I
OH
≥ ± 20mA.
Clock Waveforms Valid in normal clock mode. In X2 mode XTAL2 must be changed to XTAL2/2.
INPUT DATA
VALIDVALID VALID VALID
0123456 87
ALE
CLOCK
OUTPUT DATA
WRITE to SBUF
CLEAR RI
T
XLXL
T
QVXH
T
XHQX
T
XHDV
T
XHDX
SET TI
SET RI
INSTRUCTION
01234567
VALID VALID VALID VALID
V
CC
-0.5V
0.45V
0.7V
CC
0.2V
CC
-0.1
T
CHCL
T
CLCX
T
CLCL
T
CLCH
T
CHCX
INPUT/OUTPUT
0.2 V
CC
+ 0.9
0.2 V
CC
- 0.1
V
CC
-0.5V
0.45 V
FLOAT
V
OH
- 0.1 V
V
OL
+ 0.1 V
V
LOAD
V
LOAD
+ 0.1 V
V
LOAD
- 0.1 V