Functional overview
STM32L151xC STM32L152xC
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DocID022799 Rev 10
Figure 2. Clock tree
1. For the USB function to be available, both HSE and PLL must be enabled, with the CPU running at either
24 MHz or 32 MHz.
-36
,3)2#
,3%/3#
(3)2#
(3%
/3#
6
6
$$#/2%
6
LEVELSHIFTERS
LEVELSHIFTERS
0,,
8
6
LEVELSHIFTERS
,3%TEMPO
-(ZCLOCK
DETECTOR
6
,3
7ATCHDOG
CK?PLLIN
SOURCE
CONTROL
#LOCK
7ATCHDOG
ENABLE
24#ENABLE
CK?HSI
CK?HSE
(3%PRESENTORNOT
,3)TEMPO
CK?PLL
!("
PRESCALER
!0"
!0"
CK?USB6CO6COMUSTBEAT-(
Z
#+?4)-393
#+?#05
#+?&#,+
#+?072
#+?53"
#+?4)-4'/
#+?!0"
#+?!0"
USBENANDNOTDEEPSLEEP
TIMERENANDNOTDEEPSLEEP
APBPERIPHENANDNOTDEEPSLEEP
APBPERIPHENANDNOTDEEPSLEEP
NOTSLEEPOR
DEEPSLEEP
NOTSLEEPOR
DEEPSLEEP
NOTDEEPSLEEP
NOTDEEPSLEEP
3TANDBYSUPPLIEDVOLTAGEDOMAIN
3YSTEM
CLOCK
-#/
IF!0"PRESC X
ELSE
X
CK?LSE
#+?,#$
-(Z
6
$$#/2%
6
$$#/2%
6
$$#/2%
,#$ENABLE
-3)2#
6
6
$$#/2%
LEVELSHIFTERS
CK?MSI
CK?LSI
#+?!$#
!$#ENABLE
,3
,3 ,3
,3
,3
,3
PRESCALER
PRESCALER
2ADIO3LEEP4IMER
24#
2ADIO3LEEP4IMERENABLE