Keysight E3633A, User Manual

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Tutorial 7
Keysight E3633A and E3634A User’s Guide 191
Load consideration
Capacitive loading
In most cases, the power supply will be stable for almost any size load
capacitance. Large load capacitors may cause ringing in the power supply’s
transient response. It is possible that certain combinations of load capacitance,
equivalent series resistance, and load lead inductance will result in instability. If
this occurs, the problem may often be solved by either increasing or decreasing
the total load capacitance.
A large load capacitor may cause the power supply to cross into CC or
unregulated mode momentarily when the output voltage is reprogrammed. The
slew rate of the output voltage will be limited to the current setting divided by the
total load capacitance (internal and external).
Inductive loading
Inductive loads present no loop stability problems in constant voltage mode. In
constant current mode, inductive loads form a parallel resonance with the power
supply’s output capacitor. Generally this will not affect the stability of the power
supply, but it may cause ringing of the current in the load.
Pulse loading
In some applications the load current varies periodically from a minimum to a
maximum value. The constant current circuit limits the output current. Some peak
loading exceeding the current limit can be obtained due to the output capacitor.
To stay within the specifications for the output, the current limit should be set
greater than the peak current expected or the supply may go into CC mode or
unregulated mode for brief periods.
Table 7-2 Slew rate
Internal capacitance Internal bleed resistor Slew rate at no load and full scale current setting
470 μ F x 2 ea 3 K Ω 0.44 V/msec