If external crystal waveform abnormal, whether OSC module will automatically shut down XTAL and EXTAL voltage?

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If external crystal waveform abnormal, whether OSC module will automatically shut down XTAL and EXTAL voltage?

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larryyang
NXP Employee
NXP Employee

The MCU type is MC56F84763, if environment temperature is higher than 70 degree Celsius, one of the prototype external crystal stop working, there is no waveform output of XTAL and EXTAL pin. If replace the crystal with another one and this crystal is proved to be good, the issue still exists. It seems like not crystal issue. My question is if MCU detects external crystal output abnormal or PLL loss of lock failure, whether OSC module will automatically shut down XTAL and EXTAL voltage, make the external crystal stop oscillating?

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johnlwinters
NXP Employee
NXP Employee

There is no automatic action.

It is up to the firmware to detect this and switch over to the internal relaxation osc.

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larryyang
NXP Employee
NXP Employee

Get it. Thanks a lot!

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