PCB track current measurement
The unique feature of the I-prober 520 is
its ability to observe and measure currents flowing in PCB
tracks by acting as a "positional" current probe.
The magnitude of the signal is critically
related to its position relative to the conductor which means
that the probe tip must be positioned carefully. The size of the
conductor (e.g. the width of a PCB track) also has a significant
This means that the sensitivity of the I-prober
has to be adjusted to match the track width when quantitative
measurements are required. A calibrator within the control box
enables sensitivity adjustment in conjunction with a calibration
The measurement result will also include
other field effects present at the tip of the probe and not just
that coming from the current through the conductor. This may
include DC effects from adjacent magnetised components and from
the earths magnetic field, plus AC effects from transformers and
other field radiating sources.
Current in adjacent tracks, or tracks on the
opposite side of the PCB will also affect the measurement.
There are potential solutions to these
problems. The unwanted DC can be nulled out by observing the
measurement without power to the circuit, whilst AC interference
can be attenuated using bandwidth filters. The I-prober control
box includes a wide range DC offset control and switchable
Nevertheless, the use of the I-prober 520
requires interpretation based upon a proper understanding of
circuits and systems. It is a tool for the professional engineer
and is not suitable for use by just anyone.