Specifications

CY8C21123/CY8C21223/CY8C21323
Document Number: 38-12022 Rev. *Y Page 28 of 46
AC External Clock Specifications
The following tables list the guaranteed maximum and minimum specifications for the voltage and temperature ranges: 4.75 V to
5.25 V and –40 °C  T
A
 85 °C, or 3.0 V to 3.6 V and –40 °C  T
A
 85 °C, respectively. Typical parameters apply to 5 V, 3.3 V, or
2.7 V at 25 °C and are for design guidance only.
Table 30. 5-V AC External Clock Specifications
Symbol Description Min Typ Max Units Notes
F
OSCEXT
Frequency 0.093 –24.6MHz
– High period 20.6
– 5300 ns
– Low period 20.6
– –ns
– Power-up IMO to switch 150
– –µs
Table 31. 3.3-V AC External Clock Specifications
Symbol Description Min Typ Max Units Notes
F
OSCEXT
Frequency with CPU clock divide by 1 0.093 – 12.3 MHz Maximum CPU frequency is 12 MHz at
3.3 V. With the CPU clock divider set to
1, the external clock must adhere to the
maximum frequency and duty cycle
requirements.
F
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 ensures
that the fifty percent duty cycle
requirement is met.
– High period with CPU clock divide by 1 41.7
– 5300 ns
– Low period with CPU clock divide by 1 41.7
– –ns
– Power-up IMO to switch 150
– –µs
Table 32. 2.7-V AC External Clock Specifications
Symbol Description Min Typ Max Units Notes
F
OSCEXT
Frequency with CPU clock divide by 1 0.093 –6.06
0
MHz Maximum CPU frequency is 3 MHz at
2.7 V. With the CPU clock divider set to
1, the external clock must adhere to the
maximum frequency and duty cycle
requirements.
F
OSCEXT
Frequency with CPU clock divide by 2 or
greater
0.186 – 12.12 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 ensures
that the fifty percent duty cycle
requirement is met.
– High period with CPU clock divide by 1 83.4
– 5300 ns
– Low period with CPU clock divide by 1 83.4
– –ns
– Power-up IMO to switch 150
– –µs