08-28-2016 08:38 AM
I have an USB osciloscope of 25 MHz of Bandwidth and Record length of 5000 samples, what I want to do is to take measurements of the voltage with a shunt resistor in serie with the power supply of the board BASYS2, if my code inside the ROM is working at 25MHz, 50MHz, 100MHz, it could be possible to take correct measurements with this oscilloscope, or it will be necesary an osciloscope with more bandwidth?, I hope not.
I understand the power supply have fluctuations when the code is running but I want to know if these fluctuations are related with the frecuency at my code is working, I need to justify in case it could be possible, thanks in advance!
08-28-2016 02:24 PM
08-28-2016 10:58 AM
08-28-2016 12:05 PM
I'm using the LM2596 regulator, that is exactly what I want to know if my 25MHz bandwidth scope could get correct measurements at 100 MHz or 50 MHz or 25MHz BASYS2 working frecuencies, c'ause as we know the Nyquist-Shannon theorem say that you need at least the double of sampling frecuency to take correct samples an avoid the Aliasing problem, but the regulator maybe work at lower frecuency than the BASYS 2.
In this video you can see how I'm taking voltage measurements over the shunt resistor in serie with the regulator , you can notice how is my system (The shunt, the board, and the regulator) and how is the scope earth referenced as well.
How can I justify the use of this scope with BW= 25MHz, maybe it could be better to use the DCM to decrease the BASYS2 working frecuencies and asure the correct measurements!, that would be catastrophic for me but please let me know if 25MHz bandwith could be enoung to take correct measurements, really thanks! . .
08-28-2016 01:56 PM
LM2596 SIMPLE SWITCHER® Power Converter 150-kHz 3-A Step-Down Voltage Regulator <== the regulator caracteristic say something about 150KHz, it could be the maximun working frecuency for the regulator, I also found in the datasheet this grafic:
that means the regulator can't work under frequencies greater than 150 KHz!, am I right??????????¡! . .
08-28-2016 02:24 PM
08-28-2016 03:13 PM
As you can notice at the video the scope probe is on the shunt resistor in serie with the regulator, I need to take measures about the variations in the (Power supply-regulator) voltage, my task has nothing to do with any pin in the BASYS2 apart from the battery conector pins:
Of course the shunt resistor is in serie with the negative battery conector pin.
In spite of that I accepted your answer as a solution if you notice something wrong in my arguments please let me know! because I need to finish my whole tasks in around 2 weeks, thanks! . .
08-28-2016 03:28 PM