st10f273m STMicroelectronics, st10f273m Datasheet - Page 148

• Manufacturer Part Number: st10f273m
• Description: 16-bit Mcu With 512 Kbyte Flash Memory And 36 Kbyte Ram
• Manufacturer: STMicroelectronics

Electrical characteristics
24.8.3
148/182
Figure 46. Generation mechanisms for the CPU clock
Clock generation modes
The next
generation mode.
Table 62.
1. The external clock input range refers to a CPU clock range of 1...40 MHz. Moreover, the PLL usage is
2. The limits on input frequency are 4 to 12 MHz since the usage of the internal oscillator amplifier is required.
3. The maximum depends on the duty cycle of the external clock signal: When 40 MHz is used, 50% duty
1
1
1
1
0
0
0
0
limited to 4 to 12 MHz input frequency range. 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).
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.
cycle shall be 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).
(P0H.7-5)
P0.15-13
1
1
0
0
1
1
0
0
Phase locked loop operation
Direct clock drive
Prescaler operation
Table 62
f
f
f
f
f
f
1
0
1
0
1
0
1
0
XTAL
CPU
XTAL
CPU
XTAL
CPU
On-chip clock generator selections
f
CPU frequency
CPU
associates the combinations of these three bits with the respective clock
f
f
f
f
f
f
XTAL
f
XTAL
XTAL
XTAL
XTAL
XTAL
XTAL
= f
-
XTAL
x 10
x 4
x 3
x 8
x 5
x 1
/ 2
x F
External clock input range
Main OSC (MHz)
5.3 to 10.6
6.4 to 8
1 to 40
4 to 12
4 to 8
4 to 5
4
-
XTAL
/2, an external crystal or resonator
(1)(2)
TCL
Default configuration
Direct drive
(oscillator bypassed)
CPU clock via prescaler
Reserved
TCL
TCL TCL
TCL TCL
Notes
ST10F273M
(3)
(2)