This is a circuit diagram of one circuit variable regulator, this circuit controlled by the LM117 IC. LM117 Series 3-terminal adapted positive voltage regulator capable of supplying more than 1.5A is more than 1.2V to 37V output range. They are very easy to use, and requires only two external resistors to set the output voltage. Further, both line and load regulation are better than standard fixed regulators. In addition, the LM117 in the container in a standard transistor package easy to install and handle. Besides higher performance than fixed regulators, the LM117 series offers full overload protection available only in IC’s. Included on the chip are current limit, thermal load protection and protection of the safe area. All overload protection circuitry remains fully functional even if the adjustment terminal is lost. The following is a schematic drawing:

Usually, there is no capacitor is required unless this device is situated more than 6 inches from the input filter capacitors in this case an input bypass is needed. Optional output capacitor can be added to improve the response. The adjustment terminal can be ignored to achieve very high ripple rejection ratio are difficult to achieve with standard 3-terminal regulators. For applications requiring output current greater, see LM150 series (3A) and LM138 series (5A) data sheets. For the negative complement, see LM137 series data sheet.

Table LM117/LM317A/LM317

part Number suffix      package  rated       powerdissipation        design curent

k                                   TO-3                                        20 W                      1,5A
H                                 TO-39                                         2W                       0.5A
T                                  TO-220                                   20w                        1,5A
E                                  LCC                                           2W                        0,5A
S                                  TO-263                                    4W                         1,5A

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