GTL2014 VREF pin voltage, when DIR pin is set as HIGH (A to B)

[amith_krishna_b]

Hi,

I am using GTL2014 in our design and the Direction pin been set to High (1K pu to 3.3V) ie LVTTL to GTL translation. Currently I have set the VREF to 2/3 of VTT. I would like to know, whether VREF has any importance during LVTTL to GTL translation? as VREF is used as a threshold reference during GTL to LVTTL translation.

Please let me know the consequences of setting VREF to 2/3 VTT in such scenario (DIR= H).

Regards,

Amith K Bhat

[TomasVaverka]

Hi Amith,

Please find below the answer from our application engineer:

I do not see any problem with setting VREF to 2/3 of VTT . Voh and Vol of GTL output driver are much higher or low than VREF.

When DIR=H, the direction is from A to B so VREF is not referenced. When the DIR=L, the direction is from B to A so VREF is used for setting the input threshold.

Please let us know if there are any further questions.

Best regards,

Tomas