CY8C21x34 Final Data Sheet
3. Electrical Specifications
3.4.7
AC External Clock Specifications
The following tables list guaranteed maximum and minimum specifications for the voltage and temperature ranges: 4.75V to 5.25V
and -40°C ≤ TA ≤ 85°C, or 3.0V to 3.6V and -40°C ≤ TA ≤ 85°C, respectively. Typical parameters apply to 5V, 3.3V, or 2.7V at 25°C
and are for design guidance only.
Table 3-24. 5V AC External Clock Specifications
Symbol
Description
Min
0.093
Typ
Max
24.6
Units
MHz
Notes
F
–
–
–
Frequency
High Period
Low Period
–
–
–
–
OSCEXT
20.6
20.6
150
5300
ns
ns
µs
–
–
Power Up IMO to Switch
Table 3-25. 3.3V AC External Clock Specifications
Symbol
Description
Min
Typ
Max
Units
Notes
F
F
Frequency with CPU Clock divide by 1
0.093
–
–
MHz
Maximum CPU frequency is 12 MHz at 3.3V.
With the CPU clock divider set to 1, the external
clock must adhere to the maximum frequency
and duty cycle requirements.
12.3
OSCEXT
Frequency with CPU Clock divide by 2 or greater
0.186
24.6
MHz
If the frequency of the external clock is greater
than 12 MHz, the CPU clock divider must be set
to 2 or greater. In this case, the CPU clock
divider will ensure that the fifty percent duty
cycle requirement is met.
OSCEXT
–
–
–
High Period with CPU Clock divide by 1
Low Period with CPU Clock divide by 1
Power Up IMO to Switch
41.7
41.7
150
–
–
–
5300
ns
ns
µs
–
–
Table 3-26. 2.7V AC External Clock Specifications
Symbol
Description
Min
Typ
Max
Units
Notes
0
F
F
Frequency with CPU Clock divide by 1
0.093
–
–
MHz
Maximum CPU frequency is 3 MHz at 2.7V.
With the CPU clock divider set to 1, the external
clock must adhere to the maximum frequency
and duty cycle requirements.
3.08
OSCEXT
Frequency with CPU Clock divide by 2 or greater
0.186
6.35
MHz
If the frequency of the external clock is greater
than 3 MHz, the CPU clock divider must be set
to 2 or greater. In this case, the CPU clock
divider will ensure that the fifty percent duty
cycle requirement is met.
OSCEXT
–
–
–
High Period with CPU Clock divide by 1
Low Period with CPU Clock divide by 1
Power Up IMO to Switch
160
160
150
–
–
–
5300
ns
ns
µs
–
–
January 12, 2007
Document No. 38-12025 Rev. *K
29
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