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LM567C: Behavior in the absence of any input signal

Part Number: LM567C

The datasheet of the LM567 describes how two input tones are used to let the output switch between 0 and 1. A tone within the PLLs detection bandwidth leads to output 0, and a tone outside the PLLs detection bandwidth leads to output 1.

But how will the device behave in case of absence of any tone signal at its input? Is there a risk that the output starts to float unpredictably?

  • Dear Kohl,

    I have not used this device but here is my recommendation.

    I would not not leave the input floating for sure. Leaving the input "floating" in not a good idea.

    If the input is held low then you will have a known output of the VCO in quadrature. A known state.

    I hope this helps,

    Regards, Simon.