You should provide at least about 7 V input to get a regulated 5 V output. The L7805CV’s dropout voltage is roughly 2 V, meaning the input must stay approximately 2 V above 5 V under load. So for a stable 5.0 V out at maximum current, a 7 V (or higher) input is recommended. It can accept inputs up to around 30 V DC, but keep in mind that higher input voltages will cause more heat dissipation in the regulator.

The L7805CV is rated for up to 1.5 A output. In practice, without a heatsink it might only sustain a few hundred milliamps before overheating, depending on the voltage drop. If you plan to draw near an amp or more, a heatsink is highly recommended. With adequate heatsinking, it can deliver over 1 A continuously. The thermal shutdown will kick in if the device gets too hot, so use a heatsink (or lower the input voltage) for large currents.

Functionally, L7805CV is equivalent to other 7805 regulators. “7805” is the generic part number for a 5 V linear regulator. Different letters in the prefix/suffix indicate the manufacturer or package. For example, LM7805 is originally National Semiconductor (now TI)’s designation, MC7805 might be Motorola/ON Semi, and L7805 is STMicro’s. The “CV” suffix in ST’s part denotes the specific package (TO-220) and version (standard tolerance). Some variants like 7805A have a tighter output tolerance (2%). Overall, any standard 7805 will have similar pin-out and specs, but it’s good practice to check the datasheet if swapping between manufacturers. They are usually drop-in replacements for each other.

Yes. It’s important to use input and output capacitors with the L7805CV (and any 78xx regulator) for stability. The typical recommendation is to place a 0.33 µF capacitor on the input (between input pin and ground) and 0.1 µF on the output (between output pin and ground) as close to the regulator pins as possible. These are usually tantalum or ceramic capacitors. They help prevent oscillations and improve the transient response. In practice, many people also add a larger electrolytic (e.g. 10 µF) on the output to handle bigger load transients, but the small caps are the minimum requirement. Always refer to the specific datasheet’s recommendations.

The “CV” is part of STMicroelectronics’ internal naming for this series. ST uses prefixes like L78 for regulators and suffixes to denote package or revision. In this case, “C” often indicated the temperature range (0 °C to 125 °C commercial range) and packaging, and “V” indicates the TO-220 vertical package mounting. Essentially, L7805CV is ST’s TO-220 version. There are other variants like L7805CP (possibly different lead form) or L7805ACV (the A means 2% accuracy). So the letters aren’t an acronym one can easily translate, but they differentiate specific versions. If you are sourcing equivalents, just ensure the part is a 7805 in a TO-220 (or desired) package from a reputable maker.

No, not in that scenario – if your source is already 5 V (like USB), the L7805CV cannot regulate because it has a dropout of ~2 V. It would simply drop some voltage and you’d get less than 5 V out. Linear regulators always need the input higher than the desired output. For a USB 5 V source, you either use it directly or use a low-dropout regulator specifically designed for near-5V inputs (or a DC-DC converter). The L7805CV is intended to regulate a higher voltage (like 9V, 12V, etc.) down to 5V, not to clean or buffer an existing 5V rail (because it would drop voltage and waste power in doing so).