This is one of the regulator types.
Part Number: LD33CV
This product has 3.3V Voltage Regulator functions.
Package: TO-220 Type
The manufacturer of the product is STMicroelectronics.
A voltage regulator is an electronic device that is used to maintain a constant voltage level, regardless of changes in load or input voltage.
This is the basic LD33CV, LD1117V33 voltage regulator, a low drop positive regulator with a 3.3V fixed output voltage. This fixed regulator provides a great amount of stability and protection for your project and with its on ship trimming this regulator is able to reach an output voltage tolerance within ±1%. Each one of these voltage regulators can output a max current of 800mA. High efficiency is assured by NPN pass transistor. In fact in this case, unlike than PNP one, the Quiescent Current flows mostly into the load. Only a very common 10μF minimum capacitor is needed for stability.
1. LOW DROPOUT VOLTAGE (1V TYP.)
2. OUTPUT CURRENT UP TO 800 mA
3. FIXED OUTPUT VOLTAGE OF: 3.3V
4. INTERNAL CURRENT AND THERMAL LIMIT
5. SUPPLY VOLTAGE REJECTION: 75dB (TYP.)
Reference site : https://www.sparkfun.com/products/526