Tektronix IsoVu TIVM Series, User Manual

Page: 38 / 82

Operating information
Output clamping
The measurement system has a selectable output clamping feature. Push the
button on the controller to enable or disable the output clamping feature. When
enabled (indicator is on), the output clamping limits the output voltage swing of
the measurement system into the oscilloscope input. It allows you to increase the
vertical sensitivity without over-driving or saturating the oscilloscope input.
Sensor tip loading
Each of the sensor tip cables (IVTIP1X, IVTIP5X, IVTIP10X, IVTIP25X,
IVTIP50X) has a differential input resistance listed on the bottom labels as shown
in the following
fi gure.
Figure 14: Bottom sensor tip labels
It is important to understand the impact of the tip loading on the DUT. For
example, the IVTIP5X tip has a differential input resistance of 250
Ω . If you
choose the IVTIP25X tip, the differential input resistance increases to 1.25 k Ω .
Refer to the Input resistance/capacitance section in the speci fi cations table for
more information. The sensor tip cables are specially designed to act as a common
mode choke that helps reduce the common mode loading.
NOTE.
The coaxial (common) shield of the sensor tip cable should always be
connected to the lowest impedance point (usually a circuit common or power
supply rail) in the circuit-under-test (relative to the sensor tip cable/center
conductor) to obtain the most accurate waveform.
20 TIVM Series Measurement System User Manual