Figure 15. High-Speed External Clock Source Ac Timing Diagram - STMicroelectronics STM32L151CB Manual

STM32L151xx, STM32L152xx Electrical characteristics

Figure 15. High-speed external clock source AC timing diagram

High-speed external clock generated from a crystal/ceramic resonator
The high-speed external (HSE) clock can be supplied with a 1 to 24 MHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on characterization
results obtained with typical external components specified in Table 24. In the application,
the resonator and the load capacitors have to be placed as close as possible to the oscillator
pins in order to minimize output distortion and startup stabilization time. Refer to the crystal
resonator manufacturer for more details on the resonator characteristics (frequency,
package, accuracy).
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