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LMX2615-SP: Use ACMOS signal from reference oscillator or do we need sine wave output version of a crystal reference oscillator?

JLA
Intellectual 2525 points
Part Number: LMX2615-SP

Hi Team, 

As customer of mine has been asked by their TCXO supplier if they can use CMOS output.

We are to select a TCXO to provide the reference frequency to TI LMX2615 synthesizer and have to decide the most suitable waveform for LMX2615. We were wanting to have sine wave output from the reference oscillator, but now the TCXO supplier is asking can we use CMOS output. 

 LMX2615 PIN-mode 23 (reference doubler is enabled): Can we use ACMOS signal from reference oscillator, having specified duty cycle 45…55%  - or do we need sine wave output version of a crystal reference oscillator?

For the PIN modes it is specified that the supply rise time should always be <50ms. Slow rise times did not seem to cause issues when testing the evaluation board. For our design testing purposes, should we use some more specific supply rise conditions for our design robustness validation?

Best regards

Jorgen

  • 0
    TI__Guru** 107380 points

    Hi Jorgen,

    What is the TCXO frequency?

    At low frequency, such as 10MHz, we will definitely go for a CMOS reference clock as the slew rate of a 10MHz sine wave signal is going to be very bad.

    BTW, TCXO output waveform is usually clipped sine wave or CMOS.