
49
TS8xCx2X2
4184I–8051–02/08
External Clock Drive
Characteristics (XTAL1)
External Clock Drive
Waveforms
Figure 23. External Clock Drive Waveforms
AC Testing Input/Output
Waveforms
Figure 24. AC Testing Input/Output Waveforms
AC inputs during testing are driven at VCC - 0.5 for a logic “1” and 0.45V for a logic “0”.
Timing measurement are made at VIH min for a logic “1” and VIL max for a logic “0”.
Float Waveforms
Figure 25. Float Waveforms
For timing purposes a 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 VOH/VOL level
occurs. IOL/IOH ≥ ± 20mA.
Table 36. AC Parameters
Symbol
Parameter
Min
Max
Units
TCLCL
Oscillator Period
25
ns
TCHCX
High Time
5
ns
TCLCX
Low Time
5
ns
TCLCH
Rise Time
5
ns
TCHCL
Fall Time
5
ns
TCHCX/TCLCX Cyclic ratio in X2 mode
40
60
%
VCC-0.5V
0.45V
0.7VCC
0.2VCC-0.1 V
TCHCL
TCLCX
TCLCL
TCLCH
TCHCX
0.45V
VCC-0.5V
0.2VCC+0.9
0.2VCC-0.1
INPUT/OUTPUT
VOL+0.1 V
VOH-0.1 V
FLOAT
VLOAD
VLOAD+0.1 V
VLOAD-0.1 V