LMX2820: Query on IO Logic of SPI (LMX2820 naad LMX2595

Tool/software:

We are using the LMX2595 and LMX2820 synthesizers in our design and would like your clarification on the following SPI interface and logic level compatibility points:

1. LMX2595 – SPI with 1.8V Logic:

   • If we are using 1.8V logic for the SPI interface, do we need to connect any power input (such as VIO) externally to 1.8V to ensure proper logic level matching?

   • What logic level is supported on the MUXOUT pin in this case?

2. LMX2820 – SPI and Logic Level Considerations:

   • Does the LMX2820 require an external 1.8V supply to support 1.8V SPI logic?

   • We are planning to connect the SDI, SCLK, and CS pins to the 1.8V logic bank of the MCU, while connecting the MUXOUT (used for SPI readback) to a 3.3V logic domain.

     • Will this logic level mismatch cause any issue or damage? 

     • Is there any provision or configuration available to make the MUXOUT pin output 1.8V logic to match the rest of the SPI lines?

3. General SPI Interface (for both parts):

   • Are there any recommended pull-up or pull-down resistors needed on the SPI lines?

   • Can the SPI bus be used in shared mode (multi-slave configuration) with other devices, and are there any precautions required for this?