3
Clocks
3.1
Introduction
The STM32H723/33, STM32H725/35 and STM32H730 microcontrollers support several possible clock sources:
•
Two external oscillators (this will require external components):
–
High-speed external oscillator (HSE)
–
Low-speed external oscillator (LSE).
•
Four internal oscillators:
–
High speed internal oscillator (HSI)
–
High speed internal 48MHz oscillator (HSI48)
–
Low-power internal oscillator (CSI)
–
Low speed internal oscillator (LSI)
•
Three embedded PLLs can be used to generate the high frequency clocks for the system and peripherals.
For both the HSE and LSE, the clock can also be provided from an external source using the OCS_IN and
OSC32_IN pins (HSE bypass and LSE bypass modes)
Figure 10. Clock generation and clock tree
schematic shows the clock generation and clock tree architecture.
For detail explanation refer to reference manual
STM32H723/733, STM32H725/735 and STM32H730 advanced
Arm
®
-based 32-bit MCUs
(RM0468).
The choice of clocks depends strongly on the application use case .
Refer to the
STM32H72x/ and STM32H73x datasheet
for the electrical characteristics (range and accuracy)
AN5419
Clocks
AN5419
-
Rev 2
page 18/50