STMicroelectronics | LM317T

Linear regulators are Step-Down regulators only. There are 2 types of regulators, Shunt and series-pass regulators.

For IC linear voltage regulators, the regulator type determines the configuration of the pass device as well as the dropout voltage. Standard voltage regulators use an NPN Darlington configuration and have a dropout voltage between 1.5V and 2.2 V. Low dropout (LDO) regulators differ from standard regulators in that the pass device consists of a single PNP transistor.

Linear regulators provide significant advantages over switching regulators in simplicity, cost, and output noise.

The only difference between a 'normal' linear regulator and a LDO one is that, the LDO type can have a lower constant voltage-drop across the series-pass element.

This device is a monlithic integrated circuit in TO-220, ISOWATT220™, TO-3 and D2PAK. It is designed to supply more than 1.5A of load current with an output volatge adjustable over a 1.2 to 37V range. The nominal output voltage is selected by means of only a resistive divider, making the device exceptionally easy to use and eliminating the stocking of many fixed regulators.

The ST Micro LM317T is a 1.5 Amp Positive Adjustable Voltage Regulator. It comes in a TO 220 Tube Package.