Keysight Technologies N6700C Serie Guide D'utilisation page 65

2 Installation
Note that Keysight Models N678xA SMU require remote sensing when using any of the High output
bandwidth modes discussed under
wiring restrictions as discussed under
When remote sensing on power modules with the 50 A sense connector, do not
connect the +LS and –LS terminals. These are dedicated for local sensing only.
Open Sense Leads
The sense leads are part of the output's feedback path. Connect them in such a way so that they do
not inadvertently become open circuited. The power system includes protection resistors that reduce
the effect of open sense leads during remote-sensing operation. If the sense leads open during
operation, the power system returns to the local sensing mode, with the voltage at the output
terminals approximately 1% higher than the programmed value.
Over-Voltage Protection Considerations
You must take into account any voltage drop in the load leads when setting the over-voltage trip
point. This is because the OVP circuit senses at the output terminals and not at the sense terminals.
Due to the voltage drop in the load leads, the voltage sensed by the OVP circuit could be higher than
the voltage being regulated at the load.
OVP for Keysight N678xA SMU (local OVP)
For Keysight Models N678xA SMU only, the OVP circuit senses at the 4-wire sense terminals rather
than at the output terminals. This allows for more precise overvoltage monitoring directly at the load.
Since incorrect sense terminal wiring could defeat this feature, there is also a local OVP function.
The Local OVP function tracks the programmed OVP setting and trips if the voltage at the + and -
output terminals rises more than 1.5 V above the programmed OVP setting. The local OVP also trips if
the voltage at the output terminals exceeds 7.5 V on the 6 V range and 21.5 V on the 20 V range.
Output Noise Considerations
Any noise picked up on the sense leads will appear at the output terminals and may adversely affect
CV load regulation. Twist the sense leads or use a ribbon cable to minimize the pickup of external
noise. In extremely noisy environments it may be necessary to shield the sense leads. Ground the
shield at the power system end only; do not use the shield as one of the sensing conductors.
The noise specifications documented in the
Specifications Guide apply at the output terminals when using local sensing. However, voltage
transients may be produced at the load by noise induced in the leads or by load current transients
acting on the inductance and resistance of the load lead. If it is desirable to keep voltage transient
levels to a minimum, place an aluminum or tantalum capacitor, with an approximate value of 10 µF per
foot (30.5 cm) of load lead, right across the load.
64
Set the Output Bandwidth. Also, these models have additional
Keysight N678xA SMU Wiring
Keysight N6700 Modular Power System Family
Requirements.
Keysight N6700C Series User's Guide