User Manual

Section 2: General operation Series 2200 Programmable DC Power Supplies Reference Manual
2-16 2200S-901-01 Rev. A/November 2011
Configuring the instrument for your application
The configuration menus (see Configuration menus description (on page 2-9)) includes settings, like
OVP and Max Volt, that determine the maximum voltage output of the power supply. The menu
system also includes settings, like Save Last and Output Recall, that determine how the
instrument initializes itself when it is turned on.
This power supply features a constant voltage/constant current automatic crossover. This feature
permits continuous operation in the transition from constant-voltage mode to constant-current mode
as the load changes. The intersection of the constant-current and constant-voltage modes is called
the crossover point.
For example, if the load is such that the power supply is operating in constant-voltage mode, the
power supply provides a regulated output voltage. The output voltage remains constant as the load
increases until the preset current limit is reached. Then the crossover occurs. At that point, the output
current becomes constant and the output voltage drops in proportion to further load increases.
Crossover is indicated by the front panel CC and CV messages. If the CV message appears, the
instrument is operating in constant-voltage mode. If the CC message appears, the instrument is
operating in constant-current mode.
Crossover from the constant-current mode to the constant-voltage mode also occurs automatically in
response to a decrease in load. For example, suppose you are charging a 12 V battery. Initially, the
open circuit voltage of the power supply is preset for 13.8 V. A low-battery places a heavy load on the
power supply, and it operates in constant-current mode. You adjust the instrument to charge the
battery at the rate of 1 A. As the battery becomes charged and its voltage approaches 13.8 V, the
load decreases to the point where the battery no longer demands the full 1 A charging rate. The
power supply then crosses over to constant-voltage mode.