Publicité
Les langues disponibles
Les langues disponibles
2 Installing the Instrument
reduce the amplitude of voltage deviation. It is likely an external parallel damping network, as
previously illustrated, would be needed in place of or in addition to a pure capacitor. Generally, a
capacitor with low ESR in parallel with a capacitor with high ESR allows for good stability, minimized
transient response voltage deviation, as well as good voltage noise filtering.
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.
RP797xAand RP798xA
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
minimum amount of lead resistance to mitigate programming overshoot and unstable programming
response. Note that if there is no bypass capacitor at the DUT, the lead and DUT resistance are
indistinguishable in this context so that 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. When programming large current steps, further speed degradation and overshoots may
occur due to inherent voltage limitations of the power supply. Without lowering the inductance, the
speed degradation cannot be improved. However, the overshoot aspect can be mitigated or removed
by gradually decreasing the
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 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 - thereby disabling
the output of the unit.
74
Inductive Load Boundary
programming pole
or
slew rate
Keysight RP7970 & RP7980 Series Operating and Service Guide
characteristic graphs show the
until the desired performance is achieved.
Publicité
