temperature sense diodes in Xilinx 7 series

Has anybody used these?
We have two FPGAs on a board, a Zynq and an Artix7. We want to use the
internal ADCs to read chip temperatures. We have been advised to
ground the temp sense diode pins DXP and DXN "if they are not being
used".
Unless the XADC has a separate temp sense diode, seems to me that
shorting the external diode pins might kill our ability to acquire
temperature internally.
I don't see any big downside to not grounding those pins.
--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
 Click to see the full signature
Reply to
John Larkin
Loading thread data ...
After too much research, it seems that there are independent temp sensors, the external-pin one and another inside the XADC.
--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
 Click to see the full signature
Reply to
John Larkin
And they recommend grounding DXP and DXN to improve the ESD rating. IIRC there's no functional issue caused by leaving them open.
Regards, Allan
Reply to
Allan Herriman
Right, the esd thing makes no sense at all.
--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
 Click to see the full signature
Reply to
John Larkin
Why do you say it makes no sense? A lot of devices have an improved ESD rating when their more sensitive pins are connected to low impedance sources (as opposed to being open).
Of course, if those pins are on a via-less pad under a BGA on a PCB with good planes, the difference may be hard to measure.
Regards, Allan
Reply to
Allan Herriman
Do you ground every unused pin on every FPGA?
--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
 Click to see the full signature
Reply to
John Larkin
Of course not, but I do ground pins that the manufacturer says to ground.
Last century (using QFP packages) I would sometimes ground extra IO pins to help with ground bounce on IO banks that had more O than I.
Allan
Reply to
Allan Herriman

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.