Commonly used audio amplifier chips

As the name implies, power amplifier is the abbreviation of power amplification. Compared with voltage or current amplification, power amplifier requires a certain power without distortion, and generally works under large signal conditions. Therefore, power amplifier circuits generally contain special problems that voltage amplification or current amplification circuits do not have, specifically: ① The output power is as large as possible; ② It usually works under large signal conditions; ③ The nonlinear distortion is prominent; ④ Improving efficiency is an important concern; ⑤ The safety of power devices. For audio power amplifier circuits, the above issues also need to be paid attention to.

According to the different conduction methods of the amplifying circuit, audio power amplifier circuits are classified into two types: analog and digital. Analog audio power amplifiers usually include Class A, Class B, Class AB, Class G, and Class H TD amplifiers, while digital circuit amplifiers are divided into Class D and Class T.

The power amplifier chip is like the "heart" of multimedia playback equipment. It is the component that provides power for the playback equipment and is also one of the important links related to sound quality. Its importance is self-evident. Therefore, many beginners of audio power amplifier chips are curious about how to choose the right chip. What are the commonly used audio power amplifier chips? The following is a collection of several most commonly used audio power amplifier chips and power amplifier integrated circuits on Huaqiangbei IC Purchasing Network. I hope it will be helpful for everyone's audio circuit design.

Commonly used audio amplifier chips

1. LM1875

LM1875 is one of the most commonly used power amplifier chips. It is a mono design. It not only has the advantages of rich sound quality and high power, but also has a complete protection circuit. It is a high-end model among the same type of chips.

2. LM3886

LM38863TF is a high-power audio amplifier chip launched by NS (National Semiconductor) in the early 1990s. The main parameters of this chip are: the working voltage is ±9V~±40V (recommended ±25V~±35V) and the continuous output power reaches 68W (peak 135W) when RL=8Ω. If it is connected to BLT, the output power can reach 100W, and its distortion is less than 0.03%. Its internal design has a very complete over-consumption protection circuit. I am also using this chip. Its tone is very sweet, the sound quality is mellow, and it has the charm of a tube. It is suitable for playing softer music. NS also has LM1875, LM1876, LM4766 and other chips that everyone is familiar with. Among them, LM4766 is the latest, with a dual-channel design, and contains overvoltage, undervoltage, overload, overtemperature and other protection circuits. Its output power is not less than 2×40W. The bass is deep and elastic, and it has the style of a tube amplifier.

It is also a mono design with a total of 11 pins. Compared with LM1875, LM3885 has greater power, wider dynamics, and advantages in other parameters. Therefore, only the highest-end multimedia speakers will use LM3886 as the audio amplifier chip.

3.LM4766

It is commonly said on the Internet that the LM4766 is equivalent to two LM3886s packaged together. Why is that? From the performance parameters, the LM4766 is exactly the same as the LM3886, and even the tone and color are exactly the same. However, due to the large number of pins of the LM4766, people in the industry often call it a "centipede chip", which is difficult to solder.

TDA1521/TDA1514A are two chips designed by Philips of the Netherlands for low distortion and high stability of digital audio during playback. Therefore, the sound quality of the direct output of the CD player is particularly good. The parameters are: when the voltage of TDA1521 is ±16V and the impedance is 8Ω, the output power is 2×15W, and the distortion is only 0.5%. The working voltage of TDA1514A is ±9V~±30V. When the voltage is ±25V and RL=8Ω, the output power reaches 50 W and the total harmonic distortion is 0.08%. The input impedance is 20KΩ, the input sensitivity is 600mV, and the signal-to-noise ratio reaches 85dB. The circuit is equipped with waiting and quiet noise states, overheating protection, low offset voltage and high ripple suppression, and extremely low thermal resistance, with excellent high-frequency resolution and low-frequency strength. The sound is transparent and pure, the bass is full and thick, the treble is clear and bright, and it has the charm of a tube. The above two amplifiers have relatively few peripheral parts. They are "fool-proof" amplifier chips, which are very suitable for junior audiophiles to assemble. As long as you follow the circuit diagram, you can get a good effect without debugging. Because the input level of the chip is relatively low, we do not need a preamplifier in production, just connect it directly to our computer sound card, optical drive, and Walkman. The famous computer multimedia speaker Edifier also uses these two chips.

TDA7294

TDA7294 is a rather innovative DMOS high-power integrated amplifier circuit introduced to the Chinese mainland by the famous European SGS-THOMSON STMicroelectronics Company in the 1990s. It swept away the raw, cold and hard sound of previous linear integrated amplifiers and thick film integration, and is widely used in the HI-FI field: such as home theaters, active speakers, etc. The design of this chip focuses on the sound quality, and has the advantages of bipolar signal processing circuits and power MOS. It has the characteristics of high voltage resistance, low noise, low distortion, and extremely friendly playback sound quality; short-circuit current and overheating protection functions make its performance more perfect. The main parameters of TDA7294: Vs (power supply voltage) = ±10~±40V; Io (peak output current) is 10 amperes; Po (RMS continuous output power) is 70W when Vs=±35V, 8Ω, 70W when Vs=±27V, 4Ω; music power (effective value) is 100W when Vs=±38V, 8Ω, 100W when Vs=±29V, 4Ω. The total harmonic distortion is extremely low, only 0.005%. In addition, SGS-THOMSON STMicroelectronics has several representative power amplifier chips, such as: TDA7295 TDA7296 TDA7264, TDA2030A (our commonly used Mai Lan subwoofer uses this chip), etc.

Power amplifier circuit diagram made by TDA7294

The TDA7294 integrated amplifier circuit is a Hi-Fi high-power DMOS integrated amplifier circuit launched by the famous European company SGS-THOMSON. Today, we will introduce three amplifier circuits made using the TDA7294 integrated amplifier block.

1. OOL circuit

The OCL circuit diagram is shown in Figure 1. This circuit is a dual-channel 70W power amplifier composed of two TDA7294 chips. There are few peripheral components and a simple circuit. When the power supply voltage is ±35V, a continuous output power of 70W can be obtained on an 8-ohm load. It is very suitable for playing sound in an environment of less than 30 square meters. The rectifier circuit is shown in Figure 4. If the speaker impedance is less than 8 ohms, the power supply voltage should be reduced accordingly.

2. BTL circuit

The BTL circuit is shown in Figure 2, and the rectifier circuit is shown in Figure 4. Using two TDA7294s to form a BTL amplifier circuit, the output power can reach more than 150W, which is suitable for places such as dance halls that require high power. Four TDA7294s are required for stereo. When the power supply voltage is ±25V, a continuous output power of 150W can be obtained on an 8-ohm load. When the power supply voltage is ±35V, a continuous output power of 180W can be obtained on a 16-ohm load. When using TDA7294 as a BTL amplifier, the load must not be less than 8 ohms.

3. Constant current amplifier

The constant current amplifier circuit is shown in Figure 3, and the rectifier circuit is shown in Figure 4. This amplifier circuit is somewhat different from the previous two structures. Its feedback circuit is current sampling and voltage summing negative feedback. This circuit structure is what people often call a constant current amplifier. The specific analysis of the circuit is not described in detail, and only the more prominent advantages compared with the traditional constant voltage amplifier are introduced.

① The output current of the power amplifier has nothing to do with the load impedance. Even if the load is short-circuited, it will not cause the amplifier block to overheat.

②The output power increases with the increase of load impedance. Driving the speaker load within a certain power reserve can well ensure the bass strength and high-frequency resolution of the original music signal.

③The force acting on the speaker voice coil depends only on the current. Using the current-controlled oscillation method to drive the speaker must be faster than the voltage-controlled oscillation method, making the speaker vibration system

④ Input and output impedances are easy to match. The constant current amplifier circuit is actually a controlled current source controlled by the input signal voltage. Its internal feedback circuit is current sampling and voltage summing negative feedback, and has the characteristics of high input and output impedances. High input impedance is exactly what the previous constant voltage amplifier circuit needs, which is conducive to sending the signal voltage to the amplifier input without loss. High output impedance can reduce the shunt of the signal by the internal resistance, which is conducive to adding the output signal current to the load. In Figure 3, the power supply voltage is selected as ±35V, and its amplification factor is determined by the ratio of the speaker to R6.