Several types of voltage regulators have been produced to meet various needs. These regulators have been offered to many consumers by different names and catalog numbers. Briefly, let’s sort out some examples. MC 1560, SE 550, TL 1723, LM 117, LM 137, LM 317, LM 337, MC 723, L200 etc.
A voltage regulator is a system that maintains a constant voltage automatically. A voltage regulator can be simply feed-forward or have negative feedback. An electromechanical mechanism or electronic components may be used.
Although there are some differences in the internal construction and use of all these circuits, they are the same in all basic ideas. We will briefly introduce the LM317 and LM337 positive and negative adjustable voltage regulators which are commonly used in this section and are easily found on the electronic market. Figure-3.20 shows the positive voltage regulator circuit with LM317 that produces adjustable output. The output voltage of the inverter;
Typical values for the LM337 are;
In Figure-1.21, positive and negative voltage regulators giving adjustable output are given. In both circuits, the output voltage is set by resistor R2 set. The voltage values that the output voltage can take depending on the value of R2 are given in the table.
LM317 and LM337 are used together to provide a regulated voltage regulator with a regulated ± 20V symmetrical output voltage. The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25 V to 37 V. It requires only two external resistors to set the output voltage. The device features a typical line regulation of 0.01% and typical load regulation of 0.1%. It includes current limiting, thermal overload protection, and safe operating area protection. Overload protection remains functional even if the ADJUST terminal is disconnected.
In this circuit, the positive and negative output voltages can be set independently from 1.2V to 20V.