Measure high frequency switching current

[jatanp]

Hi,

I wish to measure high frequency switching current in my FPGA/CPLD core. How can I do that?

Thanks,
Jatan

 

[karesz]

Hi,
Do you wish to measure it intern the chip or "only" through int/aux parts?
k.

 

[jatanp]

Hi,

I want to measure the total switching current to the FPGA core. What kind of equipment do I need?

 

[karesz]

Hi,
you need a so called "high side" current sensing, IC + scaling to the ADC...
Some possibilities: Maxim, than Allegro, Lem...
But the FPGAs has min. 2 voltages and Multilayer PCB, these power planes are usual inside/burried...
If your layout isnt in accordance: you have not much chanse, or you must meausre system power.
K.

 

[jatanp]

My target is to measure the dynamic power of the FPGA core... is there any other way I could achieve it.

If not inst dynamic power, even Pavg would be sufficient. How could I do that. I wish to do that for asynchronous as well as synchronous designs.

Thanks,
Jatan

 

[karesz]

Hi Jatan,
Sorry, Im not a FPGA "doer", as I know is core=VccInt_am I correct Or is for you with VccAux too?
Otherwise, the first problem is physical acsessing & if you have it, than the over their writen "high side" current sensing; as Allegros ACS712 or others...
The ACS712 has onchip shunt resistor, nice small SMD IC, with 66 to 185 mV/A output sensitivity...(The ACS712 is provided in a small, surface mount SOIC8 package. the device is Pb-free, except for flip-chip high-temperature Pb-based solder balls, The device is fully calibrated prior to shipment from the factory. )
I think simplest physical access is at the dedicated voltage regulators outputs!, here have you to insert the sensings electronic.
Rest is SW, that you have in same puls (takt) to convert with the ADCor makes some LP-filtering/integrating (avrg) for easyer conversion and so on.
K.

 

[karesz]

Hi,
I found a (dynamically)better High-side current sensor, has a bandwidth of ca 300KHz(bei 10mV) & 2MHz bei 100mV_ZXCT1010....
K.

 

[jatanp]

Hi Karesz,

This is going to really helpful.

Thanks!!

 

[karesz]

Welcome!
Good luck, but give feedback pls...
Karesz