An Introduction to TDA7266SA Dual Bridge Amplifier
07 October 2023
Ⅱ. Symbol, footprint and pin connection of TDA7266SA
Ⅴ. How to configure the gain of TDA7266SA?
Ⅵ. How is the short circuit protection of TDA7266SA implemented?
Ⅷ. What issues should be paid attention to when applying TDA7266SA?
TDA7266SA is a Class AB dual-bridge audio power amplifier IC. It is suitable for a variety of applications such as computer motherboards, LCD monitors, televisions, and portable wireless devices. The device adopts the Clipwatt-15 package process, has a gain of up to 26 dB, has two channels, and is equipped with multiple functions such as standby, mute functions, short circuit protection, and thermal overload protection. Its operating voltage range is 3V to 18V, ensuring stable performance.
Replacement and equivalent：
• TDA7294V
• TDA7297
Its pin functions are as follows:
Pin 1 (OUT1+): Left channel positive output
Pin 2 (OUT1-): Negative output of left channel
Pin 3 (Vcc): Power supply
Pin 4 (IN1): Right channel input
Pin 5 (N.C.): Empty feet
Pin 6 (MUTE): Mute
Pin 7 (ST-BY): Standby
Pin 8 (PW-GND): Ground
Pin 9 (S-GND): Ground
Pin 10 (N.C.): Empty feet
Pin 11 (N.C.): Empty foot
Pin 12 (IN2): Left channel input
Pin 13 (Vcc): Power supply
Pin 14 (OUT2-): Right channel positive output
Pin 15 (OUT2+): Right channel negative output
• Fixed gain Gv=26 dB
• Equipped with complete protection functions
• Has a wide supply voltage range
• Equipped with MUTE function: the mute function can be realized through the control pin
• With standby function: compatible with COMS level, can maintain low power consumption in standby state
• Po=8.0W×2 (Vcc=12V, R=8Ω, BTL, THD=10%)
• At 11V operating voltage and 8Ω load, its output power is 7W×2 (THD = 10%)
The gain of the TDA7266SA can be configured through external components. Generally, we can set the gain using an external resistor connected to its pin. The gain is calculated as follows:
Gain (G) = 1 + (Rf/Ri)
Among them, Rf is the resistance of the feedback resistor, and Ri is the resistance of the input resistor. By choosing different resistor values, it can achieve different gain settings to suit specific application needs.
The TDA7266SA incorporates internal circuitry and safety features to safeguard against short circuits. Specifically, if a short circuit occurs either at the output terminal, between the output terminal and the power source, or with the ground, the chip's built-in protection system will identify instances of excessive current or voltage. It will then take automatic measures such as cutting off the power supply or reducing the output power to prevent potential harm from overcurrent or overvoltage, which could otherwise damage the circuits and speakers. Furthermore, the chip is equipped with a thermal protection mechanism to prevent functional failures or damage that might arise due to excessive heat. It is important to bear in mind that when a short circuit fault arises, the root cause of the issue should be resolved before restarting the power supply to ensure the circuit and speakers remain safe.
• TV: The audio system of the TV requires a high-quality audio amplifier to ensure sound quality. TDA7266SA can provide stable audio output and enhance the viewing experience.
• LCD display: TDA7266SA can be used as a dual-bridge amplifier in an LCD display, responsible for driving the two channels of the LCD display to improve the sound quality.
• Portable wireless applications: Portable wireless devices such as Bluetooth headsets, speakers, etc. require high-quality audio amplifiers to ensure sound quality. TDA7266SA can provide stable audio output and improve music playback effect.
• Computer motherboard: The audio output on the computer motherboard requires a high-quality audio amplifier to drive it. TDA7266SA can provide stable audio output and ensure computer audio experience.
• Microprocessor application
To prevent the occurrence of disruptive "Pop-Noise" during the activation or deactivation phases, it is vital to ensure the correct sequence of standby and mute signals. Achieving this functionality is straightforward with the use of a microprocessor, as shown in the picture. Initially, the St-by signal, originating from the microprocessor, goes high, causing the voltage across the St-by terminal (Pin 7) to gradually increase. An external RC network is employed to facilitate a slow turn-on of the amplifier's biasing circuits. This gradual activation helps prevent undesirable "POP" and "CLICK" sounds at the outputs.
Once the voltage reaches the St-by threshold level, the amplifier turns on, and the external capacitors connected in series to the input terminals (C3, C53) begin to charge.
It is crucial to keep the mute signal low until these capacitors are completely charged to prevent the device from entering play mode, which could result in a loud "Pop Noise" through the speakers. A delay of 100-200 milliseconds between the St-by and mute signals is recommended for proper operation.
When using TDA7266SA, we should pay attention to the following points.
1. Ground resistance
The audio amplifier's ground resistance should be as low as possible to minimize the effects of ground potential differences and ground loop currents. To achieve this, we can use multiple ground springs or copper strips to connect the audio amplifier to the earth. This ensures good grounding to avoid noise interference and signal attenuation.
2. Stability of power supply voltage
The supply voltage range of TDA7266SA is 3V to 18V. We need to ensure that the supplied power voltage is within this range to ensure normal operation.
3. Use of mute
When mute is required, we should use the relevant control pins or signal lines correctly to avoid equipment damage or sound quality impairment.
4. Impedance matching between signal input and output
The input and output impedance of the audio signal need to accurately match the input and output impedance of the TDA7266SA to achieve high-quality audio signal transmission and ensure system stability. This matching minimizes signal distortion and noise interference, providing clear sound quality.
5. Heat dissipation design
Under continuous operation, the TDA7266SA may generate slight heat, so it requires a good heat dissipation design to prevent overheating from causing equipment damage.
6. Electrostatic protection
Audio amplifiers are delicate electronic devices that are susceptible to static electricity. Accumulation of static electricity can cause discharges, potentially causing damage to equipment. To ensure the reliability and stability of the equipment, we must take effective electrostatic protection measures. These include using an anti-static work surface and gloves, avoiding working on carpets, and ensuring the air is dry. In addition, during the transportation and storage of equipment, we should take anti-static packaging and measures to avoid equipment being damaged by static electricity during transportation.
Frequently Asked Questions
1. What is the TDA7266SA?
The TDA7266SA is an integrated circuit (IC) that functions as a dual bridge amplifier. It is designed to amplify audio signals and is often used in audio applications where a compact and efficient amplifier is required.
2. What type of amplification does the TDA7266SA provide?
The TDA7266SA is a bridge amplifier, which means it can amplify both positive and negative phases of the audio signal. This allows for improved efficiency and better audio quality.
3. What is the operating temperature range of TDA7266SA?
The operating temperature of TDA7266SA ranges from 0°C to 70 °C.
4. How many channels does the TDA7266SA support?
The TDA7266SA is a dual bridge amplifier, meaning it can drive two independent audio channels. It can be used for stereo audio amplification.
5. Is thermal protection included in the TDA7266SA?
Yes, the TDA7266SA usually includes thermal protection circuitry to prevent the IC from overheating. When the temperature exceeds a certain threshold, the IC will shut down to protect itself from damage, and it will automatically restart when it cools down.
