Audio Amplifiers


Audio Amplifier ICs (integrated circuits) is a type of audio amplifier that is built into the chassis of the main product. More generally, audio amplifiers are devices that increase, control and amplify the audio signal strength, or amplitude, of audio signals, to make the sound louder and premium quality.IC Audio amplifiers are useful because they can vastly decrease the size of amplification devices, making it possible to create sophisticated amplification within a small package. Unlike power amplifiers, they are not standalone devices.What are the IC audio amplifiers used for?Audio amplifier ICs are used in a range of commercial products. They are found in car stereos, televisions, electronic keyboards, and many other devices in which amplification capacity is in-built.Types of audio amp ICsAudio amplifier ICs can be differentiated by several traits: amplifier type, such as digital, operational, or headphone amps maximum power, in watts, depending on the size and scope of amplification you need input and output signal type, depending on whether you want stereo or mono sound

LA4440 LA4440 is a two channel audio power amplifier IC with inbuilt in dual channels enables it for stereo and bridge amplifier applications. In dual mode it gives 6 W per channel and in bridge mode 19 W output. It has good ripple rejection of 46dB, small residual noise, built in over voltage and surge voltage protection etc. ideal feature of the IC is its pin-to-pin protection. Here LA4440 is wired in Stereo configuration using both inputs and outputs. A link to make one of them can be found here.
Click on the pic below to open



A complete casing of that same amplifier with an additional bass treble board
LM380 The LM380 is a power audio amplifier (2.5W) for consumer applications. In order to hold system cost to a minimum, gain is internally fixed at 34 dB. A unique input stage allows ground referenced input signals. The output automatically self-centers to one-half the supply voltage. The output is short circuit proof with internal thermal limiting. The package outline is standard dual-in-line. The LM380N uses a copper lead frame. The center three pins on either side comprise a heat sink. This makes the device easy to use in standard PC layouts. Two links can be found below to make on of them.
Audio amplifier using LM380
Bluetooth Audio amplifier using LM380

8002C The 8002 is an audio power amplifier primarily designed for demanding applications in low-power portable systems. It is capable of delivering 3 watts of continuous average power to an 3Ω BTL load with less than 10% distortion (THD) from a 5VDC power supply. the 8002 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement.the 8002 features a low-power consumption shutdown mode.the 8002 contains advanced pop and click circuitry which eliminates noise which would otherwise occur during turn-on and turn-off transitions. The 8002 is unity-gain stable and can be configured by external gain-setting resistors
8002 8002
8002C on a milled PCB
LM386 The LM386 is a power amplifier designed for use in low voltage consumer applications with power output of 1W approx. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200.

PAM8403 The PAM8403 is a 3W, class-D audio amplifier. It offers low THD+N, allowing it to achieve high-quality sound reproduction. The new filterless architecture allows the device to drive the speaker directly, requiring no low-pass output filters, thus saving system cost and PCB area.

Stereo speakers for PC using PAM8403

LA4225 LA4225 is a 5W monaural power amplifier intended for television audio output. This IC requires only two external components (capacitors) to construct amplifiers and is ideal for realizing substantial cost reduction of electronic devices.

TDA2822 The TDA2822M is a monolithic integrated circuit in 8 lead Minidip package. It is intended for use as dual audio power amplifier in portable cassette players and radios.This has become obsolete now.

TDA1558Q The TDA1558Q is a monolithic integrated class-B output amplifier in a 17-lead single-in-line (SIL) plastic power package. The device contains 4 x 11 W single-ended or 2 x 22 W BTL amplifiers and has been primarily developed for car radio applications

Obviously there are huge number of audio ICs available in market. Some have obsolete now and many new technogies have arrived. Class D, G, H amplifiers are now common in market with very good efficiency. the list is endless. You can have a list of common class AB audio amplifiers in the PDF below.

Now there available BJT based audio amplifiers too.Below are some popular transistors. Popular transistors are 5200/1943 pair, 3055/2955 pair, etc. also popular are 2n3773. They can dissipate large power and are easily replacable. professional class G/H amplifier uses such transistors and mosfets to provide high power.

Some points to keep in mind while designing audio amplifiers

  1. Always read Datasheet before using a particular IC or transistor and don't blindly copy other's design.
  2. Use large capacitor banks and always prefer good transformers with sufficient high current rating (depend on your amplifier)
  3. Design Star Grounding and avoid long power tracks on PCB.
  4. Use Zobel,Theile Networks and Boucherout Cell
  5. Use audio rated capacitors,metal film resistors and log potentiometer
  6. Use thick wires and heatsinks with heatpaste

Large capacitor to be used at power supply and should be placed as close to the amplifier as possible

An Active crossover made using Opamps and testing it using LA4225 amplifier with different types of speakers(Woofer and tweeters)

Audio IC amplifiers

Speaker Speakers are transducers that convert electromagnetic waves into sound waves. The speakers receive audio input from a device such as a computer or an audio receiver. This input may be either in analog or digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Below are some speakers you may like to see

40w 6in.
The specification of the same speaker
5w 3in.
20w 5in.
5w 6in.
5w 4in.
5w 4in.

Audio IC suggester tool:

This tool will help you to choose an audio IC for home audio type of TDA series class AB type. Maximum wattage available here is 250w. For example, if you need an amplifier IC of 15w power output then enter upper value as 20 and lower value as 10. You will get all relevant IC of nearly equal wattages. Do note that many of such TDA ic have been discontinued and one need to look out for authentic ICs.

Lower limit

Upper limit

An interesting IC you may like to see - UM66/BT66x

Datasheet link UM66 datasheet
A video below demonstrates it.

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