Supply, reset and clock management
6
Supply, reset and clock management
ST72324xx-Auto
6.1
Introduction
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 Figure 10.
For more details, refer to the dedicated parametric section.
Main features
● Optional Phase Locked Loop (PLL) for multiplying the frequency by 2 (not to be used
) with internal RC oscillator in order to respect the max. operating frequency)
t(s ● Multi-Oscillator clock management (MO)
c – 5 crystal/ceramic resonator oscillators
u – 1 Internal RC oscillator
rod ● Reset Sequence Manager (RSM)
P ● System Integrity management (SI)
te – Main supply low voltage detection (LVD)
le – Auxiliary voltage detector (AVD) with interrupt capability for monitoring the main
o supply
Obs 6.2
roduct(s) - Caution:
PLL (phase locked loop)
If the clock frequency input to the PLL is in the range 2 to 4 MHz, the PLL can be used to
multiply the frequency by two to obtain an fOSC2 of 4 to 8 MHz. The PLL is enabled by option
byte. If the PLL is disabled, then fOSC2 = fOSC/2.
The PLL is not recommended for applications where timing accuracy is required.
Furthermore, it must not be used with the internal RC oscillator.
P Figure 9. PLL block diagram
Obsolete fOSC
PLL x 2
/2
0
fOSC2
1
PLL option bit
32/193
Doc ID 13841 Rev 1