An audio power amplifier is a type of amplifier that amplifies low-power audio signals to a high level which is sufficient to drive headphones or loudspeakers. So these amplifiers are versatile and broadly used ICs that are well known for their capability to deliver better audio amplification with a compact design. It is a significant component in an audio system which is located normally between a sound source & a passive loudspeaker. Thus, these amplifiers can also be utilized for signal processing like filtering to eliminate interfering signals (or) limit audio bandwidth. In addition, they provide a stable high-voltage output, even when there are variations within frequency response or impedance. Thus, this article discusses an overview of one of the types of audio power amplifier IC like LM380 IC, pinout, specifications, and applications.
What is LM380 IC?
The LM380 is an audio power amplifier IC from National Semiconductor used in low-power audio amplification applications. So this is a 2.5Watts power audio amplifier IC with fixed gain at 34 dB to hold system cost to the lowest. The output of LM380 IC is short-circuit proof by internal thermal limiting. So it delivers moderate power to drive headphones or small speakers. Thus this is a popular audio power amplifier IC that is designed to provide less distortion audio amplification through a wide input signal range.
LM380 IC is a low-power audio amplifier that provides output power in a few watts ranging from 2 to 3 watts, designed to be used in low to moderate-power applications. It can also used frequently in DIY audio projects because of its robust performance & simplicity. So this amplifier IC drives speakers directly to make it perfect for small audio applications like intercoms, phonographs & radio receivers.
Working
The LM380 IC works by amplifying weak input signals into very strong output signals: So this IC has fixed gain internally and its output centers automatically at half of the voltage supply. Its unique input stage allows inputs to be AC-coupled or ground-referenced. This IC operates with a single power supply so that it simplifies circuit design. Thus it is designed mainly to provide less distortion & high-quality audio output. This IC can be configured to enhance the output power within BTL mode.
LM380 IC Pin Configuration:
The pin configuration of the LM380 IC is shown below. This IC includes 14 pins which are discussed below.
LM380 IC Pin Configuration
- Pin-1 (Bypass): This pin is used to connect a decoupling capacitor.
- Pin-2 (Non-Inverting Input (IN+)): This is a Non-Inverting pin of the amplifier and is provided by the audio signal.
- Pins – 3, 4, 5, 7, 10, 11, 12( GND): These are ground pins.
- Pin-6 (Inverting Input (IN-)): This is an Inverting Pin of an amplifier that is normally grounded.
- Pin-8 (VOUT): This is an o/p pin of the amplifier which is connected to the load.
- Pin-14 (VCC): It is a power supply pin.
- Pins – 9, 13 (NC): It is a Not Connected pin.
Features & Specifications:
The LM380 IC features and specifications include the following.
- LM380 is an audio power amplifier IC.
- This IC includes 14 pins.
- It is available in the standard DIP package.
- Its voltage supply ranges from 10 to 22V.
- Quiescent power at 18V is 0.13 watts.
- Its voltage gain is 50.
- Its high input impedance is 150kΩ.
- Its high peak current ability is 1.3Amps.
- This IC has less distortion.
- Its quiescent o/p voltage is at one-half of the voltage supply.
- Its storage and junction temperature ranges from -65 to 150°C.
Equivalents & Alternatives
Equivalent LM380 ICs are; LM317, LM311, LM318, LM324N, LM324, LM335, LM348, LM339, LM386 & LM358. Thus, alternative ICs are LM4871, IC6283, AD620, JRC45558, etc.
Simple Intercom Circuit with LM380 IC
An intercom is a type of communication system, that allows people to communicate with each other from various locations using a loudspeaker or a microphone. So these systems can be found in several places like; ships, airplanes & buildings. These can be used in door entry systems to control building access, car parking systems, lockdown alerts, flight announcements, etc.
Here a simple intercom circuit is designed with LM380 IC shown below. So the required components to make this simple intercom circuit mainly include; LM380 IC, 8ohm transformer, 8ohm speakers, switches A & B, 1M ohm potentiometer & 500uF 25V capacitor. Thus, connect this circuit as per the diagram shown below.
Simple Intercom Circuit with LM380 IC
Working
This simple intercom circuit is based on the LM380 IC. Here, a power supply is provided to pin-14 whereas all pins 3,4,5,10,11 & 12 should be grounded. So this circuit uses a double pole double throw (DPST) switch, indicated with Switch 1. In this circuit, there are two positions the talk position and the listen position.
The switch in the above circuit is in the talk position for the left speaker. So talking at the speaker generates a signal to the LM380 IC through the T1 matching transformer. On the right side, the output from the chip goes toward the speaker. Thus, if you place the switch in the other place then the right-side speaker is the talking unit whereas the left-side speaker listens. The volume of the speaker can be controlled by the 1M ohm potentiometer in the circuit. So this simple intercom circuit is basic for beginners or anyone to get started with electronics.
Phase Shift Oscillator Circuit with LM380 IC
The phase shift oscillator circuit with LM380 IC is shown below. This is a linear electronic circuit that generates a sine wave output. This circuit includes an inverting amplifier element like an operational amplifier or a transistor. So its output is given as feedback to its input throughout a phase-shift network. This network includes resistors & capacitors within a ladder network.
The required components to make this phase shift oscillator circuit include; LM380 IC, 1k resistors, 2.7 resistors, 0. 1uF capacitors, 250uF capacitors, and a speaker. Thus, connect this circuit as per the phase shift oscillator circuit diagram shown below.
Phase Shift Oscillator Circuit with LM380 IC
Working
A phase shift oscillator circuit works by generating a sine wave with low to medium preferred frequency. So the LM380 IC in this circuit is used to generate 180° of a phase shift. An RC network with three resistors & capacitors can be connected in the feedback lane. Thus, every RC element in this circuit gives 60° of a phase shift and all of them make a 180° complete phase shift.
Advantages & Disadvantages
The advantages of LM380 ICs include the following.
- The LM380 IC is a single-channel audio amplifier chip with a compact and simple design.
- It is well known for its high-quality audio amplification.
- These are versatile ICs.
- It has less harmonic distortion.
- The LM380 IC has internal compensation circuitry.
- These ICs have short circuits and thermal protection.
- These ICs are available in simple to use DIP package.
- It has a 34 dB fixed gain setting internally.
- It has a unique i/p stage that permits inputs to be GND referenced.
- This IC output is self-centering automatically to one-half of the voltage supply.
The disadvantages of LM380 ICs include the following.
- The LM380 IC is designed only for low to medium-power audio amplification so it is not suitable for high-power applications.
- It is suggested to mount the amplifier IC on a heat sink when operating at higher power ranges or in limited ventilation environments.
- These ICs cannot operate at a high range of voltages.
- These are delicate and have a limited power rating.
- They produce more noise throughout the operation.
Applications
The applications of LM380 ICs include the following.
- The LM380 IC is used frequently in portable audio devices like; portable radios, MP3 players, portable speakers, headphones, or small built-in speakers.
- This IC is used in intercom systems to amplify voice signals by allowing communication between various rooms (or) areas in a building.
- It is used in different electronic toys to amplify the effects of sound & provide audio o/p from in-built speakers.
- This IC is used in home automation projects wherever audio signals need to be changed for alarms.
- It is used in educational electronic kits for teaching fundamental audio amplifier circuits & principles.
- These ICs are used in small audio systems like DIY audio projects or mini hi-fi setups wherever modest audio power is enough.
- It can be used within walkie-talkies to increase the audio signals for clear communication.
- It is used in small communication devices wherever audio signals need amplification to get clear audio sound.
Please refer to this link for the LM380 IC Datasheet.
Thus, this is an overview of the LM380 IC, pinout, features, specifications, circuit, working, advantages, disadvantages, and its applications. So the LM380 IC is a versatile and low-cost audio power amplifier chip. This IC generates very clean and low-distortion audio signals with fewer components making it a preferred choice among beginners & professionals. Thus, here is a question for you, what is LM317 IC?