Re: Power (current) measurement of Virtex 5 on ML505 (XUPV5-LX110T)

mcgett · ‎01-03-2008

> Lift the regulator pin and squeeze an SMT resistor of appropriate value between the pin and the pad :)

The pin can't be lifted as it is a through hole pin and access to cut it as the OP wants to do is mostly blocked by other components. The pin in question has been highlight in RED here:

If the pin was cut then a 3mOhm sense resistor (an SMT 0402 wouldn't be precise enough or have the necessary wattage rating) wouldn't fit between the power module and the board. Pulling the whole regulator off of the board is likely the easiest and quickest approach with the least chance of damage, but the OP is free to do as they please with their board.

> Ed, where's your sense of adventure?!

Sorry, I'm a bit of a kill joy. I said "nearly impossible" and maybe I should have said "extremely hard".

------------------------------------------------------------------
Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com

stuartdu · ‎10-13-2011

If I pull the whole regulator off and source the 1V0 VCCint with an external source, is there anything else I need to worry about? Would I need a source that can provide up to 16A? I know the regulator has a lot of other pins (track, SYNC, TT, +/- Sense, Inhibit). Would I still need to worry about these?

bassman59 · ‎02-25-2008

mcgett wrote:

> Lift the regulator pin and squeeze an SMT resistor of appropriate value between the pin and the pad :)

The pin can't be lifted as it is a through hole pin and access to cut it as the OP wants to do is mostly blocked by other components. The pin in question has been highlight in RED here:

If the pin was cut then a 3mOhm sense resistor (an SMT 0402 wouldn't be precise enough or have the necessary wattage rating) wouldn't fit between the power module and the board. Pulling the whole regulator off of the board is likely the easiest and quickest approach with the least chance of damage, but the OP is free to do as they please with their board.

> Ed, where's your sense of adventure?!

Sorry, I'm a bit of a kill joy. I said "nearly impossible" and maybe I should have said "extremely hard".

Hah, I didn't check to see how the regulator was installed.

"Extremely hard."

If it was easy, everyone would be doing it.

How about drilling out the pin? YEAH!

Every engineer has tales of heroic rework.

----------------------------------------------------------------
Yes, I do this for a living.

mcgett · ‎01-03-2008

> Would I need a source that can provide up to 16A?

You would need to have a source that can provide all of the current that your design needs. How much that is only you can know.

> I know the regulator has a lot of other pins (track, SYNC, TT, +/- Sense, Inhibit). Would I still need to worry about these?

Only GND and VCC are needed. If you have remote sense power supply then connecting the sense pins to +/- Sense would make sense. :-)

@bassman:

> How about drilling out the pin? YEAH!

The pin is fairly large (larger than a 100mil header), so I would be worried about drill wander and destroying the module. You can't tell from the image, but the pin is larger under the module than the hole it is in, so it isn't possible to just desolder pin and pull it out.

Now, if you removed the whole module from the board then it would be easy to desolder and remove the pin and the resolder the module into the board, but then you are back to figuring out how to squeeze a sense resistor into the board. Inserting an amp meter between the module and the board would be a reasonable option in this case, but I still like the external power supply.

------------------------------------------------------------------
Have you tried typing your question into Google? If not you should before posting.
Too many results? Try adding site:www.xilinx.com

stuartdu · ‎10-13-2011

I don't think using an Ammeter would be a good idea, because typically the burden voltage is too high. The VCCint has to stay between 0.95 and 1.05 V.

I was just going to solder leads onto each end of the pin (after I had cut it) and insert a shunt resistor to measure the current across. I wasn't going to squeeze a tiny resistor in there because that sounds too hard. Hopefully the leads don't have too much resistance.

vinathabadam · ‎06-14-2010

Hi,

I have experimented similar current measurement using clamp meter. I have removed the power module and cut the out put pin and soldered a thick wire with 1.5 inch length to the power module so that the clamp meter goes in the wire loop and soldered back the module on to the PCB. With clamp meter i am able to mesure the current on the VCCint.

regards