7805 Voltage Regulator IC

Here is the commonly used 7805 voltage regulator IC. I am shining a bright spotlight on the device so that the identification can be clearly seen in the video. Otherwise I find it difficult to get a good view of the number very often. It is a three terminal positive voltage regulator integrated circuit which provides a fixed output voltage of +5V. 7805 can be used to power devices like microcontrollers and logic chips which require a stable 5V supply. It has built-in thermal overload protection to prevent overheating. Internal short circuit protection can limit the current in case of a short circuit.

In this video clip which was taken initially, you can see how much I am struggling to get a good view of the IC number clearly. But the pins of the IC are seen much better in this clip. In the 78xx series of fixed linear voltage regulators, the xx indicates output voltage it provides.

According to the specifications, the minimum voltage input needed is 7V. So a couple of 18650 Lithium-ion batteries can provide the required input voltage. Maximum input voltage rating is 35V and the current rating 1A. Maximum output voltage is 5.2V and minimum output voltage 4.8V.

Pinout diagram of the 7805 IC is as shown in the image, with input, ground and output terminals. Input terminal receives the unregulated voltage and the output pin gives the regulated voltage. Ground pin is equally neutral for input and output. Though there is a high range for input voltage, the voltage dropped will be wasted as heat. Higher input voltages will have more heat generation and need better heat sinks. Hence it is better to give 7-8V as input to avoid heating and unnecessary power wastage.

Here is a typical circuit diagram of a regulated power supply. Step down transformer feeds the bridge rectifier circuit with four diodes. Output of the bridge rectifier is fed to the regulator IC. Input and output filter capacitors are useful in filtering the AC ripple in rectified DC. Generally filter capacitors are of high value like 1000 or 2000 microfarads. Voltage regulators work better with pure DC. Regulated output is delivered to the load. Mobile phone chargers and logic circuits require a nice clean DC signal.