ST72F324BJ STMICROELECTRONICS [STMicroelectronics], ST72F324BJ Datasheet - Page 28

• Manufacturer Part Number: ST72F324BJ
• Description: 8-bit MCU, 3.8 to 5.5 V operating range with 8 to 32 Kbyte Flash/ROM, 10-bit ADC, 4 timers, SPI, SCI
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Supply, reset and clock management
6.3.2
6.3.3
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Crystal/ceramic oscillators
This family of oscillators has the advantage of producing a very accurate rate on the main
clock of the ST7. The selection within a list of four oscillators with different frequency ranges
has to be done by option byte in order to reduce consumption (refer to
172
resonator and the load capacitors have to be placed as close as possible to the oscillator
pins in order to minimize output distortion and start-up stabilization time. The loading
capacitance values must be adjusted according to the selected oscillator.
These oscillators are not stopped during the reset phase to avoid losing time in the oscillator
start-up phase.
Internal RC oscillator
This oscillator allows a low cost solution for the main clock of the ST7 using only an internal
resistor and capacitor. Internal RC oscillator mode has the drawback of a lower frequency
accuracy and should not be used in applications that require accurate timing.
In this mode, the two oscillator pins have to be tied to ground.
In order not to exceed the maximum operating frequency, the internal RC oscillator must not
be used with the PLL.
Table 8.
for more details on the frequency ranges). In this mode of the multi-oscillator, the
ST7 clock sources
C
Hardware configuration
L1
External
source
OSC1
OSC1
OSC1
capacitors
Load
ST7
ST7
ST7
OSC2
OSC2
OSC2
C
L2
Section 14.1 on page
ST72324B