
RM0453 Rev 2
281/1454
RM0453
Reset and clock control (RCC)
363
Figure 27. Clock tree
1. For full details about the internal and external clock source characteristics, refer to the electrical characteristics section in
the device datasheet.
2. The ADC clock can additionally be derived from the AHB clock of the ADC bus interface, divided by a programmable factor
(1, 2 or 4). When the programmable factor is 1, the AHB prescaler must be equal to 1.
7.2.1
HSE32 clock with trimming
The HSE32 32 MHz external oscillator has the advantage of producing a very accurate rate
on the main clock. The HSE32 furthermore provides on-chip trimming capability.
The high-speed external clock signal (HSE32) can be generated from the following clock
sources:
•
HSE32 external crystal
•
HSE32 external clock
–
external clock source
–
external TCXO
The clock source must be placed as close as possible to the oscillator pins in order to
minimize output distortion and startup stabilization time.
MSv62604V2
LSI RCC 32 kHz
LSE OSC
32.768 kHz
LSCO
to IWDG
HSE32 OSC
32 MHz
HSE CSS
OSC_IN
OSC_OUT
HSI16 RC
16 MHz
MSI RC
100 kHz - 48 MHz
MCO
/1 - 16
/32
LSE CSS
PLL
/P
/R
/Q
/M
SYSCLK
MSI
MSI
HSI16
HSI16
HSE32
HSE32
PLLRCLK
PLLRCLK
LSE
LSI
SYS clock
source
control
SYSCLK
MSI
HSI16
CPU1
HPRE
/1,2,...,512
HCLK1
HCLK2
HCLK3
APB1
PPRE1
/1,2,4,8,16
to CPU1, AHB1, AHB2
to CPU1 FCLK
/8
to CPU1 system timer
APB2
PPRE2
/1,2,4,8,16
PCLK1
PCLK2
to CPU2
to CPU2 FCLK
/8
to CPU2 system timer
to AHB3, Flash, SRAM1, SRAM2
to APB1 TIMx
to APB2 TIMx
to USART1
to LPTIM1
to LPUART1
to ADC
to RTC
x1 or
x2
x1 or
x2
to I2C1
PCLKn
SYSCLK
HSI16
HSI16
HSI16
PCLKn
LSI
LSE
PLLPCLK
SYSCLK
PCLKn
LSE
to APB2
to APB1
to RF
SYSCLK
MSI
to RNG
PLLQCLK
PLLRCLK
OSC32_IN
OSC32_OUT
LSI
LSE
LSI
LSE
HSEPRE
/1,2
xN
to I2C2
to I2C3
to LPTIM3
to LPTIM2
PCLK3
to APB3
to USART2
HSI16
to SPI2S2
I2S_CKIN
HSI16
PLLPCLK
PLLQCLK
LSIPRE
/1,128
CPU2
C2HPRE
1,2,...,512
AHB3
SHDHPRE
/1,2,...,512
LSI
DAC