LMK05318B: OSC input

Part Number: LMK05318B
Other Parts Discussed in Thread: LMK05318,

Tool/software:

Hi Expert,

In the LMK05318 manual, there is a "3.3-V LVCMOS OSC EXAMPLE (XO, TCXO)". I would like to know what the network of C29, R3, and R1 (should be capacitors) is for? Is it necessary? Thank you.

Regards,

Hailiang

  • Hi Hailiang,

    A direct connection between a 3.3V LVCMOS oscillator and the XO input pin of the LMK05318B is not supported because the required swing must be between 1V and 2.6V.

    To meet the spec with a 3.3V LVCMOS input, a voltage divider must be used. You may recommend the following network:

    C29 and R3 caps of the above schematic are not necessary. R2 and R3 are required to bring the voltage down within spec.

    Regards,

    Jennifer