Measure low current (micro-Amp) using PCI-6259

[vinhnguyen]

Hi,

I'm using PCI-6259 to do power measurement on my board. Everything looks good when the current is at mA levels (5mA - 30mA). However, at lower current measurement (uA), I get a lot of negative values. I'd like to know if PCI-6259 can handle low current measurement?

Thanks,

Vinh 

[Ima U]

Hi Vinh,

The 6259 is not meant for micro-amp current measurements.  Keep in mind that the voltage output is dependent on the resolution of the card.  The minimum voltage range sensitivity for your 6259 is 6uV and the minimum voltage range accuracy is 52uV.  This allows you to measure down into the mA range with a very large shunt resistor.  You also should keep in mind that most large resistors are not accurate enough for what you are trying to do.  They often have any where from 1%-20% off. 

We make high precision cards for accurate current measurements.  You can take a look at some or the National Instrument DMMs if you are interested in making more precise measurements.  For example our NI 4071 can measure current down to the pA range.

I hope this helps!