ST10F272M-4Q3 STMICROELECTRONICS [STMicroelectronics], ST10F272M-4Q3 Datasheet - Page 142

• Manufacturer Part Number: ST10F272M-4Q3
• Description: 16-bit MCU with 256 Kbyte Flash memory and 20 Kbyte RAM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Electrical characteristics
24.8.3
142/176
Figure 45. Generation mechanisms for the CPU clock
Clock generation modes
The next
generation mode.
Table 61.
1. The external clock input range refers to a CPU clock range of 1...40 MHz. Moreover, the PLL usage is
2. The maximum depends on the duty cycle of the external clock signal: when 40 MHz is used, 50% duty
3. The limits on input frequency are 4-8 MHz since the usage of the internal oscillator amplifier is required.
1
1
1
1
0
0
0
0
limited to 4-8 MHz. 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).
cycle is granted (low phase = high phase = 12.5ns); when 20 MHz is selected a 25% duty cycle can be
accepted (minimum phase, high or low, again equal to 12.5ns).
Also when the PLL is not used and the CPU clock corresponds to f
must be used: It is not possible to force any clock though an external clock source.
(P0H.7-5)
P0.15-13
1
1
0
0
1
1
0
0
Table 61
On-chip clock generator selections
Phase locked loop operation
Direct Clock Drive
Prescaler Operation
1
0
1
0
1
0
1
0
f
f
f
f
f
f
XTAL
CPU
XTAL
CPU
XTAL
CPU
associates the combinations of these three bits with the respective clock
CPU frequency
f
CPU
f
f
f
f
f
f
f
XTAL
XTAL
f
XTAL
XTAL
XTAL
XTAL
XTAL
XTAL
= f
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 8 MHz
6.4 to 8 MHz
4 to 6.4 MHz
1 to 64 MHz
4 to 8 MHz
4 to 8 MHz
4 to 8 MHz
4 MHz
(1)(3)
XTAL
Default configuration
Direct Drive (oscillator bypassed)
CPU clock via prescaler
/2, an external crystal or resonator
TCL
TCL
TCLTCL
TCLTCL
Notes
ST10F272M
(3)
(2)