• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 21 subscribers
  • Views 306 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

LMX2594: LMX2594 digital i/o connection to 1.8V fpga bank

LMX2594: Digital Interface compatibility

daniele sassaroli
Intellectual 650 points
Part Number: LMX2594

Dear Sirs,

I've understood that the serial input signals of the LMX2594 are 1.8V compatible. This info is reported 
in pag. 7 (SPI clock. High impedance CMOS input. 1.8-V to 3.3-V logic.) and pag. 11 (DIGITAL INTERFACE section)
of the datasheet.

I've understood also that the MUXout is not a 1.8V-logic compatible but only 3.3V-logic because the Voh min is Vcc-0.4 = 2.9.

Instead, the SYNC and SYSREFREQ input signals are defined CMOS and maybe 1.8V compatible reading
the pag. 11 (DIGITAL INTERFACE section) but in the pag. 7 is not defined 1.8-V to 3.3-V logic. Why? 
The same problem there is for CE signal.

Could you help me to clear the different definitions?

Is it possible to drive the serial channel signals in 1.8V logic and the SYNC/SYSREFREF in 3.3V logic?

Thanks in advance.

Daniele Sassaroli

  • 0
    TI__Genius 11900 points

    Hello Daniele,

    Page 11 is what you need to refer to for the electrical specifications, page 7 is only meant to be a table with all the pins listed along with their high level functions. In page 7 the input voltage of SYNC and SYSREFREQ is not mentioned. This is not a concern, refer to "DIGITAL INTERFACE Applies to SLK, SDI, CSB, CE, RampDir, RampClk, MUXout, SYNC (CMOS Mode), SysRefReq (CMOS Mode)" section of page 11.

    The SYNC and SYSREFREQ pins will register a high input when they see a voltage above 1.4 V.

    Thanks,

    Vibhu