As part of power supply testing we are measuring the current profiles of various regulators.

Startup profiles includes current bursts with different current amplitudes and widths.

i want to understand the accuracy of the current probe*(MINIMUM CURRENT WHICH CAN BE MEASURED ACCURATELY UPTO 1% to 3%)* in measuring currents.

For example in my case, I have TCP0030A current probe from Tek-

it has 2 ranges 5A and 30A.

1. whether in both ranges the accuracy differs or same

It has different specifications like

DC gain accuracy <3%(1% typical) - i am not sure what is this exactly?

Displayed RMS noise <75uArms

1mA sensitivity- Is this directly relates to Minimum current can be measured with this probe

If i want to find the accuracy of the measurement, how i can derive error from all above error sources.


1 Answer 1


The sensitivity (1 mA) is the smallest current that can be consistently sensed by the instrument, i.e. it is guaranteed that you will get some reading with anything above 1 mA.

The gain accuracy tells you your measurement accuracy as a percentage of the measurement itself, so if you are sensing 1 A you can expect +-3%, typically +-1%.

The figures above are true for a properly calibrated, degaussed, warmed up and auto zeroed probe.

  • \$\begingroup\$ :Thanks. If i measure 1.5A using probe in scope, it means 1.5A+/-45mA (with 3%). Will it be same for whole range (30A or 5A)?I believe the probe mentioned is a hybrid probe which uses transformer for Higher currents and Hall effect sensor for Low currents - even though both are different sensors is the accuracy remains same? \$\endgroup\$
    – user19579
    Commented Sep 6, 2019 at 10:37
  • \$\begingroup\$ That is a question that is answered on the datasheet... If they only give 3% figure both for 5 A and 30 A then yes, the error is the same. \$\endgroup\$ Commented Sep 7, 2019 at 5:48
  • \$\begingroup\$ Thanks. Is there any specific reason behind mentioning the accuracy as "DC Gain Accuracy" \$\endgroup\$
    – user19579
    Commented Sep 9, 2019 at 8:45
  • \$\begingroup\$ Yes, it is gain accuracy only. Total accuracy depends on gain, offset, linearity, noise... Probably there is a tempco as well. \$\endgroup\$ Commented Sep 9, 2019 at 14:44

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