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Altera_Forum
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16 years ago

Using LVDS Rd, StratixIII 1v8 VCCIO

I get an error message when trying to apply a differential OCT (Rd) to an LVDS clock input which is on a bank with VCCIO=1v8 in a SIII part: Error: I/O bank 1C contains I/O pin p_rclk3 with Te...
Altera_Forum's avatar
Altera_Forum
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16 years ago

OCT = On Chip Termination. OCT Calibration blocks are instantiated by the user for calibrating on chip series and parallel termination. You are using differential termination, so you do not need to instantiate them.

OCT blocks are still used for differential termination, and unfortunately OCT blocks always utilize VCCIO. So while you only need VCCPD for differential inputs, you still need VCCIO for differential inputs with termination.

I know this is far from ideal, but perhaps you can turn off differential termination and place an external 100-ohm resistor across two vias on the differential pair?