
149
AT89C51ID2
4289C–8051–11/05
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 VIL 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/VOL level
occurs. I
OL/IOH ≥ ± 20 mA.
Clock Waveforms
Valid in normal clock mode. In X2 mode XTAL2 must be changed to XTAL2/2.
INPUT/OUTPUT
0.2 V
CC + 0.9
0.2 V
CC - 0.1
V
CC -0.5V
0.45V
FLOAT
V
OH - 0.1V
V
OL + 0.1V
V
LOAD
V
LOAD + 0.1V
V
LOAD - 0.1V