TDA7482 digital power amplifier circuit diagram

SGS-THOMSON has launched three single-chip Class D power amplifier ICs, namely TDA7480 (10W), TDA 7481C (18W) and TDA7482 (25W). This article takes the TDA7482, which has the largest output power, as an example to introduce it.

TDA7482 is a Class D pulse width modulation monolithic power amplifier IC for audio. This series of ICs is mainly designed for use in high-efficiency applications such as sound systems for large-screen color TVs and home stereo devices.

The main technical parameters of TDA7482 are:

1. Has a rated output power of 25W. Working conditions are: RL=4~8Ω, THD≤10%. In fact, according to the recommended electrical parameters, when RL =8Ω and P =1W, its THD is only 0.1%.

2. It has high output efficiency. When Vcc = ±21V, RL = 8Ω, P = 18W, the efficiency reaches 78%, so only a small radiator is needed for operation, or even no heat sink is needed.

3. Wide operating voltage range. The recommended value is ±10V~±25V, which is very suitable for car battery power supply.

4. There is an overcurrent protection device inside. When RL=0Ω, the protection action threshold is 3.5A ~ 5A.

5. There is an overvoltage protection device inside, and the protection threshold is 50V.

6. It has overheating and overload protection, and the overheating shutdown temperature is 150℃.

7. It has ST-BY and MUTE functions.

8. The recommended carrier frequency operating frequency of pulse width modulation is 100kHz ~ 200kHz.

9. Input noise (20Hz ~ 20kHz) is 7μF ~ 12μF.

10.The input impedance is 30kΩ.

11. Maximum power consumption is 3.8W.

The typical application circuit of TDA7482 is shown in the figure below

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Regarding the pulse width modulation Class D audio power amplifier, foreign magazines have continuously discussed and reported it in the past half century. The main attractive feature of this technology is its high output efficiency (generally above 85~90%), which is more important for amplifiers with larger output power. However, its distortion index is still far from high Hi-Fi requirements. The THD of all known Class D PWM power amplifiers is about 0.1% ~ 0.01%, but it is difficult to reach this range when the power is greater than 50W. Although the audio power amplifier produced by PWM is not very musical, it does not feel very musical. Secondly, the powerful PWM carrier frequency will inevitably cause serious electromagnetic interference in the medium and short wave bands. This is probably a problem that cannot be satisfactorily solved by existing filter designs. Nevertheless, in the sound output stage of large-screen color TVs, the audio part of multimedia computers and car stereo systems, the above shortcomings of PWM power amplifiers do not seem to be important, so they have found their uses. Moreover, large international companies such as SGS-THOMSON have launched this series of chips in the form of a single chip. You can expect them to work very reliably, so they are worth recommending.