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FMC V1 Power

Former Member

Hi,

   FMC V1 - PCIe power question.

  Is it ok to have the main power supply (via J14) connected when the board is installed in a PC.

 Both J14 and the PCIe connector will be providing a 12V supply. 

 D22/23 seem to provide isolation but I'm just being

super cautious.

Regards,

   Elwyn

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    Hi Elwyn,

     

    Does the PC you are using have a spec compliant PCIe slot?  The reason I ask is if I'm not mistaken the PCIe spec states that the interface can provide up to 75W.  The PicoZed and carrier should draw nowhere near that.  I'd expect less than 8W, realistically around 5W or less.  That being said, perhaps you are running into an inrush limiting situation where the supply is going into overcurrent at startup.  Can you look at the startup and see if when the supply starts ramping that it starts smoothly and doesn't glitch or turn off?  I would look at the 12V feeding the FMC carrier.  That should at least tell us if the FMC load is impacting boot up.

    Thanks

    Chris

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  • 0

    Hi Elwyn,

     

    Does the PC you are using have a spec compliant PCIe slot?  The reason I ask is if I'm not mistaken the PCIe spec states that the interface can provide up to 75W.  The PicoZed and carrier should draw nowhere near that.  I'd expect less than 8W, realistically around 5W or less.  That being said, perhaps you are running into an inrush limiting situation where the supply is going into overcurrent at startup.  Can you look at the startup and see if when the supply starts ramping that it starts smoothly and doesn't glitch or turn off?  I would look at the 12V feeding the FMC carrier.  That should at least tell us if the FMC load is impacting boot up.

    Thanks

    Chris

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