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Altera_Forum's avatar
Altera_Forum
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13 years ago

Combining LVDS RXs and CMOS I/Os in one bank

Hi,

We are using Stratix IV E development kit (dk-dev-4se530n) as a part of a larger design and need to connect other PCBs to it with flex cables going to two HSMC connectors. One of those extra PCBs has 32 LVDS outputs, which need to be connected to Stratix. Those signals take up all LVDS RXs of banks 5 and 6 connected to the HSMCs. We have other 50+ CMOS I/Os to connect from another PCB to Stratix. Can we use LVDS TXs in the same banks for those CMOS signals? Both standards are 2.5V.

Another option is to remove the Ethernet 88E1111 IC from the board and replace it with some BCC (bump chip carrier) adapter to get access to the pads. Does anyone know, if such an adapter exist?

Thank you!

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    You can use mixed single ended and differential IOs in a bank. Pin placement rules for the device possibly require a few pads distamce between both IO standards. You can either review the device manual or "ask" the Quartus Pin Planner tool for a valid pin assignment, which is the convenient option.

    Besides device IO constraints, you should provide sufficient ground connections for the single ended signals in the wiring, otherwise ground bounce might threaden signal integrity. I remember this has been a problem with some HSMC breakout boards. The HSMC specification is prepared for alternative single ended usage of the LVDS pins.