Agilent Technologies E364XA Series, User Manual

Page: 34 / 220

Chapter 2 General Information
Output Connections
33
2
Voltage Drops
The load wires must also be large enough to avoid excessive voltage drops due
to the impedance of the wires. In general, if the wires are heavy enough to carry
the maximum short circuit current without overheating, excessive voltage
drops will not be a problem. The voltage drops across the load wires should
be limited to less than two volts. Refer to Table 2-1 to calculate the voltage drop
for some commonly used AWG copper wire.
Load Consideration
Capacitive Loading
The power supply will be stable for almost any size load capacitance. However,
large load capacitors may cause transient response ringing. Certain
combinations of load capacitance, equivalent series resistance, and load lead
inductance may result in instability (oscillation). If this occurs, the problem
may often be solved by either increasing or decreasing the size of the capacitive
load.
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.