ST10F271E STMICROELECTRONICS [STMicroelectronics], ST10F271E Datasheet - Page 147

• Manufacturer Part Number: ST10F271E
• Description: 16-bit MCU with 128 Kbyte Flash memory and 8/12 Kbyte RAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ST10F271B/ST10F271E
24.8.3
Figure 45. Generation mechanisms for the CPU clock
Clock generation modes
Next
generation mode.
Table 68.
1. The external clock input range refers to a CPU clock range of 1...64 MHz. Besides, the PLL usage is limited
2. The maximum depends on the duty cycle of the external clock signal: when 64MHz is used, 50% duty cycle
3. The limits on input frequency are 4-8MHz since the usage of the internal oscillator amplifier is required.
1
1
1
1
0
0
0
0
to 4-8MHz. All configurations need a crystal (or ceramic resonator) to generate the CPU clock through the
internal oscillator amplifier (apart from Direct Drive): vice versa, the clock can be forced through an external
clock source only in Direct Drive mode (on-chip oscillator amplifier disabled, so no crystal or resonator can
be used).
shall be granted (low phase = high phase = 7.8ns); when 32MHz is selected a 25% duty cycle can be
accepted (minimum phase, high or low, again equal to 7.8ns).
Also when the PLL is not used and the CPU clock corresponds to F
shall be used: it is not possible to force any clock though an external clock source.
(P0H.7-5)
Table 68
P0.15-13
1
1
0
0
1
1
0
0
On-chip clock generator selections
Phase locked loop operation
Direct Clock Drive
Prescaler Operation
associates the combinations of these three bits with the respective clock
1
0
1
0
1
0
1
0
f
f
f
f
f
f
XTAL
CPU
XTAL
CPU
XTAL
CPU
CPU Frequency
f
CPU
F
F
F
F
F
F
F
F
XTAL
XTAL
XTAL
XTAL
XTAL
XTAL
XTAL
= f
XTAL
XTAL
x 10
x 16
x 4
x 3
x 8
x 5
x 1
/ 2
x F
Input Range
External Clock
5.3 to 8MHz
6.4 to 8MHz
4 to 6.4MHz
1 to 64MHz
4 to 8MHz
4 to 8MHz
4 to 8MHz
4MHz
1) 3)
XTAL
Default configuration
See
Direct Drive (oscillator bypassed)
2)
CPU clock via prescaler
/2, an external crystal or resonator
TCL
Table 69
Electrical characteristics
TCL
TCLTCL
TCLTCL
Notes
3)
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