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What are the required voltage levels for the OSC-IN pin for the HSE clock when using an external crystal resonator.

JEsko
Associate II

I see that if using an external CMOS oscillator on just the OSC-IN pin that 0.3*VDD and 0.7VDD input levels or better are required. My external crystal oscillator using OSC-IN and OSC-OUT has a smaller voltage swing than 0.3VDD to 0.7VDD. Do the same levels apply in both cases? ST app note for oscillator design provides many other guidelines but not voltage levels.

1 REPLY 1
T J
Lead

usually its a small sine wave

this one H743,

is 0.3V peak to peak centered at 1.6V

8.0003MHz