A Comprehensive Guide to Harnessing the Power of the TDA7850 Audio Amplifier

Ⅰ. TDA7850 overview

Ⅱ. How does the TDA7850 perform in terms of sound quality?

Ⅲ. Specifications of TDA7850 audio amplifier

Ⅳ. Electrical characteristic curves of TDA7850 audio amplifier

Ⅴ. What kind of speakers can TDA7850 match?

Ⅵ. Precautions for using TDA7850 audio amplifier

Ⅶ. How to check the fault of TDA7850 audio amplifier?

When modifying CD host, we often use TDA7850 as a four-channel car audio dedicated amplifier chip. It adopts BTL output form and has specialized characteristics. Today, we will share the information about TDA7850 so that you can better understand and utilize this chip.

TDA7850 is a four-channel stereo amplifier chip made by STMicroelectronics. It uses a single power supply of 14.4V and has very few external components, but the sound quality is excellent, bringing users a good listening experience. Meanwhile, the TDA7850 adopts a 25-pin dual in-line package, making it easy to integrate in a variety of audio equipment. With an output power of 4×50W, the TDA7850 has a strong driving capability and is able to easily drive a variety of speakers and headphones. In addition, it has a strong anti-interference ability, which can effectively resist external interference and ensure the stable transmission of audio signals. In addition, the TDA7850 also features AC and DC output short circuit and temperature protection, further enhancing its stability and reliability.

Replacements and equivalents:

• TA8266HQ

• TDA7388

• TDA7377

• TDA7560

• TDA7851

• TDA8561Q

TDA7850 amplifier chip is equivalent to Harman Kardon stereo sound quality, and its effect is excellent. The chip uses a powerful processor, the Qualcomm Snapdragon 865 processor, and also supports 5G dual-mode full Netcom functionality. In addition, it has a built-in 5000 mAh battery and is equipped with stereo dual speakers which are comparable to the Harman Kardon stereo dual speakers in terms of outgoing sound. The main advantage of this speaker is that it avoids the unstable sound produced by reflecting the sound holes. Even if the volume is not large, it can obtain good sound radiation effect. As a result, its high sensitivity effectively reduces the speaker's operating irradiance. This is why it is called labyrinth or curve type.

• Product Type: Audio Amplifiers

• Length: 29.23 mm

• Width: 4.5mm

• Height: 15.7mm

• Gain: 26 dB

• Class: Class-AB

• Packaging: Tube

• Package / Case: Flexiwatt-25

• Power Supply Rejection Ratio: 75 dB

• Power Dissipation: 80 W

• Number of Channels: 4

• Supply Voltage: 8 V ~ 18 V

• Operating Temperature: -55°C to 150°C

• Mounting Style: Through Hole

• Manufacturer: STMicroelectronics

According to the technical parameters of TDA7850, the audio power amplifier has an output power of 4×50W and supports the parallel operation of two or four speakers. Different speakers can bring a diverse sound experience. For example, some speakers are better at expressing mid-range and high notes, while others are better at expressing bass. By choosing the right speaker, the music can be performed more perfectly and the listener can have a better listening experience. When choosing a speaker brand, we can consider well-known brands such as Q Acoustics, Tannoy, JBL, ELAC, and Bose. Each of them has unique sound quality and different prices. We can make a selection based on our personal preference and budget.

1. Standby and muting

Both standby and muting features are compatible with CMOS. If genuine CMOS ports or microprocessors are unavailable, a direct connection to the Vs of these two pins is acceptable, but a 470k equivalent resistance must be placed between the power supply and the muting and ST-BY pins. R-C cells must always be employed to ensure smooth transitions, preventing any audible transient noises. Regarding standby, the time constant assigned for achieving a virtually pop-free transition must be slower than 2.5 V/ms.

2. DC offset detector

The TDA7850 integrates a DC offset detector to avoid that an anomalous DC offset on the inputs of the amplifier may be multiplied by the gain and result in a dangerous large offset on the outputs which may lead to speakers damage for overheating. The feature is enabled by the MUTE pin (according to table 3) and works with the amplifier unmuted and with no signal on the inputs. The DC offset detection is signaled out on the HSD pin. To ensure the correct functionality of the offset detector, it is necessary to connect a pulldown 10 kW resistor between HSD and ground.

3. Input stage

The TDA7850's inputs are compatible with ground and can tolerate extremely high input signals (±8Vpk) without experiencing any degradation in performance. If the standard input capacitor value (0.1µF) is used, the low-frequency cut-off will be 16 Hz.

4. SVR

The SVR capacitor not only contributes to ripple rejection but also controls the sequence of turn ON/OFF times, thereby playing a crucial role in optimizing pop during ON/OFF transients. To effectively meet both requirements, a minimum recommended value of 10µF is advised.

First, we use a multimeter to measure the voltage at the power supply pins to verify that it is within the specified range, usually 12 V to 14.4 V. Next, we can test the input signal by connecting to another source and checking for problems with the connecting cables, plugs, and signal sources. In addition, we use an oscilloscope or multimeter to test the output signals of the TDA7850 to make sure that the output signals are within the normal range at the appropriate volume. If one or more outputs are found to be abnormal, then we may need to check the power amplifier for faults. To make sure that the speakers are connected properly and the load does not exceed the specified range, we check the speakers and coils for damage.

Checking the radiator is an important step to ensure that it is working properly. We check the fan and radiator surfaces to make sure there is no dust blockage and observe the status of the LED indicators. If the TDA7850 has a built-in fault indication function, different indicator states may indicate different types of faults. In addition, we check the power and ground wires to make sure they are firmly connected, as poor power and ground connections may cause the power amplifier to operate erratically. Finally, we check whether the capacitors are sufficient to ensure that the TDA7850 can work properly. By performing the above checking steps, we can effectively diagnose and solve potential fault problems that may occur with the TDA7850.

Frequently Asked Questions

1. What is the input voltage for TDA7850?

This TDA7850 module operates from a single supply voltage of 12~14Vdc which most suitable for car stereo application and DIY Hi-Fi System. 

2. What is the operating temperature range of TDA7850?

The operating temperature of TDA7850 ranges from -55°C to 150 °C.

3. What are the features of TDA7850?

TDA7850 features high output power, excellent 2Ω driving capability, low output noise, Hi-Fi class distortion, and MOSFET output power stage.

4. What is the equivalent of TDA7850?

Similar to the TDA7850, the TDA7388 is a 4-channel BTL audio amplifier IC designed for automotive applications. It is capable of delivering a maximum power output of approximately 40 watts per channel in BTL mode and around 20 watts per channel in the single-ended mode.