Keysight E3633A, User Manual

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7 Tutorial
182 Keysight E3633A and E3634A User’s Guide
Overview of Keysight E3633A and Keysight E3634A Operation
The basic design technique, which has not changed over the years, consists of
placing a control element in series with the rectifier and load device. Figure 7-1
shows a simplified schematic of a series regulated supply with the
phase-controlled pre-regulator described as a power switch and the series
element depicted as a variable resistor. The phase-controlled pre-regulator
minimizes the power dissipated at the series element by maintaining the voltage
drop across the series element at a low and constant. Feedback control circuits
continuously monitor the output and adjust the series resistance to maintain a
constant output voltage. Because the variable resistance of Figure 7-1 is actually
one or more power transistor operating in the linear (class A) mode, supplies with
this type of regulator are often called linear power supplies. Linear power supplies
have many advantages and usually provide the simplest most effective means of
satisfying high performance and low power requirements.
Figure 7-1 Diagram of simple series power supply
This power supply has two ranges, allowing more voltage at a lower current. To
maintain the voltage across the pre-regulator efficient in accordance with the
demands imposed by the DC output voltage and current of the supply, this power
supply also uses the pre-regulator which is controlled by transformer tap
switching before the rectifier bridge in the Figure 7-1 . This is one of several
techniques using semiconductors for preregulation to reduce the power
dissipated across the series element.