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Altera_Forum
Honored Contributor I
876 Views

LVDS termination resistors on Cyclone III or Stratix III DSP development kits

I am currently working on implementing a design on a Cyclone III dev board with the DAC5681zEVM and ADS5560EVM connected to the FGPA via the HSMC connectors. We are having to install external termination resistors on the FPGA board to send the LVDS signals between the FGPA board and the ADC / DAC.  

 

 

If I would have purchased the Cyclone III DSP development kit (which includes the data conversion HSMC board), would the external termination resistors for LVDS signals have already been installed? Does the Stratix III DSP development kit (which also includes the data conversion HSMC board) require external resistors or does it have on-chip termination?  

 

 

Thanks, 

Erin
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3 Replies
Altera_Forum
Honored Contributor I
52 Views

Hi Erin, 

 

You might want to check on the board schematic to see if there is any external termination resistors on the specific pins that you want to use.
Altera_Forum
Honored Contributor I
52 Views

Hi, 

As I understand, Stratix III devices support on chip termination for differential LVDS input buffers. 

You can get more details from the handbook - LVDS Input On-Chip Termination (RD) 

https://www.altera.com/content/dam/altera-www/global/en_us/pdfs/literature/hb/stx3/stx3_siii51007.pd...
Altera_Forum
Honored Contributor I
52 Views

Just to clarify that CIII devices do not support the on chip termination for LVDS. User will need to add external termination resistors for LVDS input. As for SIII devices, the OCR RD is supported.

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