Why do we choose LSE capacitance low?
STM32H7B3I-DK - Discovery kit use NX3215SA-32.768KHZ-EXS00A-MU00525 Crystal. Crystal Load Capacitance is 6, 9, 12.5 pF but STM32H7B3I-DK - Discovery kit use 1.5pF. Why it use different load capacitance.

STM32H7B3I-DK - Discovery kit use NX3215SA-32.768KHZ-EXS00A-MU00525 Crystal. Crystal Load Capacitance is 6, 9, 12.5 pF but STM32H7B3I-DK - Discovery kit use 1.5pF. Why it use different load capacitance.

First, you must be sure that your crystal is compatible with the selected STM32 LSE. Then, it is highly recommended to use a crystal with low pullability, that is with CL ≥ 6 pF:
7 pF is a good compromise between low drift and moderate power consumption
9 and 12.5 pF can be used in noisy environments, but impact the power consumption.
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