78L05 Voltage Regulator : Pin Configuration & Its Applications

Generally, a voltage regulator within various electronic circuits is very common as they provide a fixed output voltage for a different input voltage. The 78L05 voltage regulator from the L78Lxx series uses thermal shutdown & internal current limiting to make them fundamentally indestructible. Once a sufficient heat sink is provided to this regulator then it delivers output current upto100 mA.

These types of voltage regulators are fixed in a wide range of applications. Additionally, they can also be used through power pass elements to build voltage regulators with high-current. This article discusses an overview of the 78L05 voltage regulator, pin configuration, circuit, and its applications.

What is a 78L05 Voltage Regulator?

In the 78L05 voltage regulator, the first two numbers like ‘78’ is a positive voltage, 05 is the output voltage which is generated by this IC like 5V and the letter ‘L’ in between 78 & 05 is low current like 0.1A. This voltage regulator is used in most electronics projects.

The output current of this type of voltage regulator is up to 100mA however, this regulator suffers from a huge loss of heat. So, a Heat sink is suggested for electronic projects because that uses more current. One more popular type voltage regulator is 7805 but its size is bulkier & it has 1A of the high current rating. As a result, if you are seeking a voltage regulator in the smaller package then this regulator is suitable.

Pin Configuration

The pin configuration of the 78L05 voltage regulator is shown below. This regulator includes three pins where each pin with its function is discussed below.

78L05 Voltage Regulator Pin Out
78L05 Voltage Regulator Pin Out
  • Pin1 (Output (Vo)): This pin gives regulated +5V
  • Pin2 (Ground/GND): This pin is connected to GND
  • Pin3 (Input (V+)): This is a fixed input voltage

Features & Specifications

The features and specifications of the 78L05 voltage regulator include the following.

  • Input voltage (max) is 30V
  • Output current is 100mA
  • Voltage regulator positive voltage is 5V
  • The operating current is 5mA
  • Available packages are SO-8, SOT-89 & TO-92
  • It has the protection of short circuit current limiting & internal thermal overload

Alternative 78L05 voltage regulators are; LM7809, LM7806, LM317, LM7912, XC6206P332MR, LM7905, LM7812 & LM117V33. Equivalent 78L05 voltage regulators are AMS7111 & LM7805.

The testing of this regulator can be done by taking the positive probe from the i/p pin & situate it on the o/p pin. You can put down the negative probe over the GND pin. So, the output voltage must be 5 V due to the voltage associated with this regulator is 05.

How to use 78L05 Voltage Regulator/Circuit Diagram

The 78L05 voltage regulator application circuit is shown below. This circuit is used to regulate the 12V input voltage to 5V output voltage. In this circuit, a 78L05 voltage regulator plays a key role.


We have already discussed in the pin diagram above that is, this regulator includes three terminals namely i/p, o/p & GND. So this IC is very simple to use by connecting the input pin to the Vin whereas the GND pin is to system GND.

78L05 Voltage Regulator Circuit
78L05 Voltage Regulator Circuit

The input voltage like 12V is regulated to 5V with the help of the voltage regulator IC. So this output voltage is very useful to activate small loads and is rated below 100mA. The max current supplied by this regulator IC is up to 100mA.

In the above circuit, both the capacitors like C1 7 C2 are connected at the ends of input and output. The main function of these capacitors is to filter the noise which is available with the input voltage.

These capacitors are used to filter the noise from the input voltage. It is not compulsory to utilize the precise capacitor value but a 10uF of ‘C1’ value & and 1uF of ‘C2’ value would be a perfect selection. These voltage regulators can restrict the current & defend once the temperature surpasses ahead of junction temperature.

If you connect this circuit to high current loads then this may get heat & will stop working ultimately. So using a suitable regulator is a perfect choice. Apart from using this like a regulator, it can also be used like short-circuit protector, variable voltage regulator, current regulator, booster circuit.


The advantages of the 78L05 voltage regulator include the following.

  • The tolerance of output voltage is +/-5% on the range of temperature
  • Protection of safe area for o/p transistor
  • Protection of thermal overload
  • Full military temperature range
  • Protection from short circuits
  • No additional components are necessary

Where to use/Applications

78L05 voltage regulator is a three-terminal and fixed voltage regulator, so used in several applications. The characteristics of the 78L05 voltage regulator are; thermal shutdown & outstanding internal current which will make it to use in overload applications. Once this regulator is used to change the usual Zener diode then its o/p impedance is enhanced efficiently, however, the bias current is reduced highly.

Like a single point voltage regulator which needs to limit the noise and solve the distribution problem, it can also be used with other power transfer devices to form a stable voltage power supply with a large current, such as a stable output current of up to 100 mA.

The applications of the 78L05 voltage regulator mainly include the following.

  • Current limiter
  • Variable output voltage
  • LED lighting
  • Portable instruments
  • Microcontroller applications
  • Different circuits like power supply, battery charger, output booster, step down voltage.
  • Small loads can be powered under 100mA

In most situations, the 78L05 voltage regulator is replaced through a 7805 however they have some differences. The functions of both the ICs are the same but their pins are reversed. For the 78L05 voltage regulator, pins 1, 2, 3 are used for o/p, GND & i/p whereas for the 7805 regulators, pins 1, 2, 3 are used for i/p, GND & o/p.

This IC is available in the To-92 package whereas the 7805 IC is available in TO-220. For both the regulators, the output voltage is similar but its output current changes like 0.1A for 78L05 IC and 1A for 7805 IC. As compared to 7805 IC, 78L05 IC is smaller & dissipates less power.

Thus, this is all about an overview of the 78L05 voltage regulator datasheet which includes its pin configuration, specifications, features, a circuit with applications. Here is a question for you, which type of regulator is mostly used?