DocID17659 Rev 10
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STM32L151x6/8/B, STM32L152x6/8/B
Functional overview
46
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.
!("
0RESCALER
!0"
0RESCALER
0#,+
(#,+
TO!("BUSCORE
MEMORYAND$-!
PERIPHERALS
TO!0"
0ERIPHERAL#LOCK
%NABLE
%NABLE
0ERIPHERAL#LOCK
!0"
0RESCALER
0#,+
TO4)-AND
PERIPHERALSTO!0"
0ERIPHERAL#LOCK
%NABLE
%NABLE
0ERIPHERAL#LOCK
-(ZMAX
-(ZMAX
TO#ORTEX3YSTEMTIMER
#LOCK
%NABLE
393#,+
4)-X#,+
4)-X#,+
&#,+#ORTEX
FREERUNNINGCLOCK
TO4)-AND
)F!0"PRESCALER X
ELSEX
)F!0"PRESCALER X
ELSEX
-(ZMAX
(3%/3#
-(Z
/3#?).
/3#?/54
(3)2#
-(Z
XXXX
XXX
0,,-5,
0,,#,+
(3)
(3)
(3%
0,,32#
37
#33
XX
-(Z
53"#,+
TO53"INTERFACE
0,,$)6
TO!$#
0ERIPHERALCLOCK
ENABLE
!$##,+
-(Z MAX
/3#?).
/3#?/54
,3%/3#
K(Z
,3)2#
K(Z
TO)NDEPENDENT7ATCHDOG)7$'
-#/
0,,#,+
(3)
(3%
,3%
,3)
TO24#
-#/3%,
24##,+
24#3%,;=
)7$'#,+
393#,+
-3)
,3%
,3)
TO,#$
TO
4IMER%42
(3%(IGHSPEEDEXTERNALCLOCKSIGNAL
,3%,OWSPEEDEXTERNALCLOCKSIGNAL
,3),OWSPEEDINTERNALCLOCKSIGNAL
(3) (IGHSPEEDINTERNALCLOCKSIGNAL
,EGEND
AIC
-3)-ULTISPEEDINTERNALCLOCKSIGNAL
0,,6#/
-3)2#
-3)