LM7805

[1] The LM7085 or 7805 is a fixed positive linear voltage regulator (VR) IC of the 78xx.

Values

• [2] Usual Vout: 5V, some provide 4.8V to 5.2V.

• Load regulation: A load is often regulated within 10mV and below 50mV.

• Peak Vout: The TO220 version of 7805 delivers 1 A with a normal heatsink, but it can deliver up to 1.5 A by mounting it to an appropriate heatsink.

• Internal overload and short circuit current protection: If the 7805 regulator IC operates over too much and starts to overheat. A special thermal overload circuit will automatically turn off the chip until the temperature returns to a safe level.

• The minimum input voltage to deliver 5 V output: 7.3V. below 7.3V the chip may not provide a stable 5 V.

• Operating current (IQ): 5 mA.

• Junction temperature max 125 °C.

• Available in TO-220 and KTE package.

• Max Vin: 30 VDC, but at higher voltage, it needs to hold current and more power on itself, hence becoming too hot.

• Min Vout (if Vin = 5 V): 7V AC or 9V DC

[2] Pinout The 7805 has many versions. The TO-3 version comes in an all-metal can for better heat sinking. A small plastic TO-92 version can provide up to 100 mA for low-power circuits.

[2] At the present date, we will often see DPARK, since it is a small size. Therefore, it becomes suitable for SMD PCB work.

Operation

[2] 3 crucial things to note:

1. Vin must be above 7.3 V to keep the regulation. Any higher and the temperature will also rise up.

2. Enough heatsink — The simplest way to test the heatsink's heat transfer is to hold your finger on it for at least 30 s or so. If it is unbearable, increase the heatsink's size.

3. Close enough wiring — Connection of capacitors to the 7805 regulators must be as close as possible to remove oscillations.

[2] Vin must be above Vout to allow some voltage to drop across the bridge and VR.

References

• [1] 78xx - Wikipedia

• [2] How to Use 7805 Voltage Regulator IC | Pinout, Specs & Circuits - ElecCircuit