Keysight Technologies RP7900 Serie Guide D'utilisation Et De Maintenance page 86

2 Installing the Instrument
Lead Inductance Considerations in Constant Current (CC) Operation
In CC operation, both in current priority mode and in voltage priority mode (when in current limit), the
setup typically resembles that in the following figure where the DUT is of a low impedance or voltage
source nature. Sense lead measurements are still utilized to detect over/under voltage protection
events and when cross-over into CV operation occurs.
In CC operation, large inductive leads have the potential to create ringing in the output current when
undergoing current programming steps or load voltage changes. This effect increases as inductance
increases and lead resistance decreases. The
section shows the minimum amount of lead resistance to mitigate programming overshoot and
unstable programming response under two sets of load lead conditions. This is a function of the
current compensation mode. Note that lead and DUT resistance are indistinguishable in this context,
so any resistance in the DUT is added to the effective lead resistance as specified in the graphs.
Dynamic Current Programming with Large Inductive Loads
Additional constraints may be required when programming current steps with high inductance DUTs or
leads. Programming speed decreases with inductive loads greater than 1 μH. When programming
large current steps, further speed degradation and overshoots may occur due to inherent voltage
limitations of the RPS. Without lowering the inductance, the speed degradation cannot be improved.
However, the overshoot aspect can be mitigated or removed by gradually decreasing the
programming pole or slew rate
Excessive Current in Current Priority Mode
Excessive output current may damage the device under test under certain conditions.
This can occur, for example, if the DUT shorts the output of the instrument when the
lower voltage limit is set substantially above zero.
When operating in current priority mode, if the voltage of a low-impedance DUT, such as a battery or
short circuit, rises above the upper voltage limit setting or falls below the lower voltage limit setting,
current flow exceeding the RPS unit's steady state rating can occur, potentially damaging the DUT.
After a short delay, the excessive current flow will cause over-current protection to engage - disabling
the output of the RPS.
86
Inductive Load Boundary
setting until the desired level of performance is achieved.
graph in the Characteristics
Keysight RP7900 Series Operating and Service Guide