st72324bk STMicroelectronics, st72324bk Datasheet - Page 25

• Manufacturer Part Number: st72324bk
• Description: 3 V/5 V Range 8-bit Mcu With 4/8 Kbyte Rom, 10-bit Adc, Four Timers And Spi
• Manufacturer: STMicroelectronics

ST72323 ST72323L
5
5.1
Caution:
Supply, reset and clock management
The device includes a range of utility features for securing the application in critical
situations (for example in case of a power brown-out), and reducing the number of external
components. An overview is shown in
Main features
●
●
Figure 10. Clock, reset and supply block diagram
Multioscillator (MO)
The main clock of the ST7 can be generated by three different source types coming from the
multioscillator block:
●
●
●
Each oscillator is optimized for a given frequency range in terms of consumption and is
selectable through the option byte. The associated hardware configurations are shown in
Table
The OSC1 and/or OSC2 pins must not be left unconnected. For the purposes of Failure
Mode and Effect Analysis, it should be noted that if the OSC1 and/or OSC2 pins are left
unconnected, the ST7 main oscillator may start and, in this configuration, could generate an
f
unsafe/undefined state. The product behaviour must therefore be considered undefined
when the OSC pins are left unconnected.
External clock source
In this external clock mode, a clock signal (square, sinus or triangle) with ~50% duty cycle
has to drive the OSC1 pin while the OSC2 pin is tied to ground.
OSC
RESET
OSC2
OSC1
Reset sequence manager (RSM)
Multioscillator clock management (MO)
–
–
an external source
4 crystal or ceramic resonator oscillators
an internal high frequency RC oscillator
clock frequency in excess of the allowed maximum (>16 MHz.), putting the ST7 in an
4. Refer to
5 crystal/ceramic resonator oscillators
1 Internal RC oscillator
Section 11: Electrical characteristics
Oscillator
Reset sequence
(MO)
Multi
manager
(RSM)
f
OSC
divider
Figure
/2
10.
f
OSC2
Supply, reset and clock management
for more details.
clock (MCC/RTC)
with real-time
timer (WDG)
Main clock
Watchdog
controller
to CPU and peripherals
f
CPU
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