18. External Clock Drive Waveforms
AT89C2051
19. External Clock Drive
Symbol
1/tCLCL
tCLCL
tCHCX
tCLCX
tCLCH
tCHCL
Parameter
Oscillator Frequency
Clock Period
High Time
Low Time
Rise Time
Fall Time
VCC = 2.7V to 6.0V
Min
Max
0
12
83.3
30
30
20
20
VCC = 4.0V to 6.0V
Min
Max
0
24
41.6
15
15
20
20
Units
MHz
ns
ns
ns
ns
ns
()
20. Serial Port Timing: Shift Register Mode Test Conditions
VCC = 5.0V ± 20%; Load Capacitance = 80 pF
12 MHz Osc
Variable Oscillator
Symbol
Parameter
Min
Max
Min
Max
tXLXL
tQVXH
tXHQX
tXHDX
tXHDV
Serial Port Clock Cycle Time
Output Data Setup to Clock Rising Edge
Output Data Hold after Clock Rising Edge
Input Data Hold after Clock Rising Edge
Clock Rising Edge to Input Data Valid
1.0
12 tCLCL
700
10 tCLCL-133
50
2 tCLCL-117
0
0
700
10 tCLCL-133
Units
µs
ns
ns
ns
ns
13
0368G–MICRO–6/05