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Robert_PIN_ASAP's avatar
Robert_PIN_ASAP
Icon for Occasional Contributor rankOccasional Contributor
2 months ago

Agilex 3 VCCLSENSE and GNDSENSE

Hello, For Agilex 3, what is the recommendation for VCCLSENSE and GNDSENSE  if our regulator for VCC does not provide remote sense inputs?    Can we just leave these two device outputs as no connect...
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Ash_R_Altera's avatar
Ash_R_Altera
Icon for Regular Contributor rankRegular Contributor
2 months ago

Hi,

First thing is that whether the regulator that you choose is from a recommended list or not. Refer to 

https://docs.altera.com/r/docs/853726/current/pcb-design-guidelines/pcb-voltage-regulator-recommendation-for-pcb-power-rails

 

Secondly, the VCCLSENSE and GNDSENSE are recommended to be a must connected pins for VCC core. These pins compensates for the DC IR drop associated with the PCB and device package from the VCC power.

 

Altera strongly recommends to follow the guidelines provided for a smooth operation of the device. Any design outside the recommendations will not be supported. It will be at user risk.

 

Regards,

Altera support

Ash_R_Altera's avatar
Ash_R_Altera
Icon for Regular Contributor rankRegular Contributor
2 months ago

Hi,

I recommend that you choose the regulator that suites your current requirement from the vendor list that we have validated with, as it is crucial for the regulators to be SmartVID compatible with the FPGA devices.

https://docs.altera.com/r/docs/853726/current/pcb-design-guidelines/fpga-core-fabric-vcc-voltage-regulator-selection

 

For the SENSE, pin it is a strong recommendation to connect to the regulator pins and do not leave them unconnected.

 

Regards

  • Robert_PIN_ASAP's avatar
    Robert_PIN_ASAP
    Icon for Occasional Contributor rankOccasional Contributor
    2 months ago

    Thank you for the reply and information, but the Agilex 3 datasheet states that Vcc is a fixed voltage. 

    It's nice to have recommendations, but if we choose a regulator that meets the requirements stated in the datasheet, then that should be sufficient.  

    The Agilex 3 Pin Connection Guideline states that the sense pins are outputs.  If these are truly outputs, then I would think it's OK to leave them floating if our regulator doesn't support remote sense.  

    In the case of our very small PCB with a power plane, I believe we can ensure that we will meet the VCC requirements without using a more expensive regulator that supports remote voltage sense.