Agilent Technologies manual Overview of Agilent E3633A and Agilent E3634A Operation, 147

Chapter 7 Tutorial

Overview of Agilent E3633A and Agilent E3634A Operation

Overview of Agilent E3633A and Agilent 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.

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