Table of Contents
Introduction
The TDA7387 is a 4 x 41W quad bridge amplifier designed for high-performance audio applications, particularly in car audio systems. It is a Class AB amplifier manufactured by STMicroelectronics, capable of delivering powerful and clear sound output with low distortion. The TDA7387 operates on a single power supply (12V-14.4V) and features low standby current consumption, making it an efficient choice for automotive and home entertainment systems. With built-in over-temperature and short-circuit protection, it ensures safe and reliable operation.
Components Details
Below is a table listing the key components required to build a TDA7387 amplifier circuit:
| Component | Value | Description |
|---|---|---|
| TDA7387 | – | Quad Bridge Amplifier IC |
| R1 | 10KΩ | Standby Control Resistor |
| R2 | 47KΩ | Mute Control Resistor |
| C1, C2, C3, C4 | 0.1µF | Input Coupling Capacitors |
| C5 | 0.1µF | Stability Capacitor |
| C6 | 47µF | Voltage Regulator Capacitor |
| C7 | 2200µF | Power Supply Filtering Capacitor |
| C8 | 0.1µF | Decoupling Capacitor |
| C9, C10 | 1µF | Standby and Mute Capacitors |
Pinout Description
The TDA7387 IC has 25 pins, each with a specific function. Below is a brief description:
| Pin | Name | Description |
|---|---|---|
| 1 | TAB | Ground connection |
| 2 | P-GND2 | Power Ground for Channel 2 |
| 3 | OUT2- | Negative Output Channel 2 |
| 4 | ST-BY | Standby Control |
| 5 | OUT2+ | Positive Output Channel 2 |
| 6 | VCC | Power Supply |
| 7 | OUT1- | Negative Output Channel 1 |
| 8 | P-GND1 | Power Ground for Channel 1 |
| 9 | OUT1+ | Positive Output Channel 1 |
| 10 | SVR | Supply Voltage Regulator |
| 11 | IN1 | Audio Input Channel 1 |
| 12 | IN2 | Audio Input Channel 2 |
| 13 | S-GND | Signal Ground |
| 14 | IN4 | Audio Input Channel 4 |
| 15 | IN3 | Audio Input Channel 3 |
| 16 | AC-GND | AC Ground |
| 17 | OUT3+ | Positive Output Channel 3 |
| 18 | P-GND3 | Power Ground for Channel 3 |
| 19 | OUT3- | Negative Output Channel 3 |
| 20 | VCC | Power Supply |
| 21 | OUT4+ | Positive Output Channel 4 |
| 22 | MUTE | Mute Control |
| 23 | OUT4- | Negative Output Channel 4 |
| 24 | P-GND4 | Power Ground for Channel 4 |
| 25 | HSD | High Side Driver |
Circuit Diagram
Working Principle
The TDA7387 is a quad bridge amplifier, meaning it has four independent output channels. Each channel can deliver 41W of power when operating at 14.4V with 4Ω speakers. The amplifier employs a Class AB topology, ensuring a balance between efficiency and sound quality.
The working mechanism includes:
- Audio Input Processing: The audio signals from external sources pass through input capacitors (C1-C4) to remove unwanted DC components.
- Amplification Stage: The signal is amplified within the IC using four independent bridge amplifiers.
- Output Stage: The amplified signal is fed to the speakers through OUT1, OUT2, OUT3, and OUT4 pins.
- Control Features: The Standby (ST-BY) and Mute (MUTE) pins allow external control to enable or disable the amplifier operation.
- Protection Mechanisms: Built-in thermal shutdown, short-circuit, and overload protection ensures reliability and safety.
Circuit Explanation
The TDA7387 amplifier circuit consists of various components that ensure smooth operation:
- Power Supply: The amplifier operates within a 12V-14.4V DC power supply, suitable for automotive applications. Capacitors C7 (2200µF) and C8 (0.1µF) help stabilize and filter the power input.
- Audio Input Section: The audio signals enter the amplifier through capacitors C1, C2, C3, and C4, which block DC noise and allow only the AC audio signal to pass.
- Control Circuit: The Standby (ST-BY) and Mute (MUTE) pins are controlled using R1 (10KΩ) and R2 (47KΩ) resistors along with C9 and C10 (1µF capacitors) to enable or disable the amplifier.
- Output Stage: The amplified signal is fed to four speakers through OUT1, OUT2, OUT3, and OUT4.
- Grounding and Stability: Proper grounding is maintained using signal ground (S-GND) and power ground (P-GND), ensuring noise-free operation and stability.
Applications
The TDA7387 audio amplifier is widely used in various high-power audio applications, including:
- Car Audio Systems – Used in vehicle entertainment systems to drive four speakers efficiently.
- Home Theater Systems – Ideal for multi-channel surround sound applications.
- Portable Audio Amplifiers – Can be used in high-power portable speaker systems.
- Public Address Systems – Suitable for medium-scale PA system applications.
- Multimedia Speaker Systems – Provides enhanced audio quality for TVs, computers, and home entertainment.
Conclusion
The TDA7387 is a powerful 4 x 41W quad bridge amplifier, offering high-fidelity sound output, low distortion, and built-in protection features. Its ease of integration and efficiency make it an ideal choice for car audio systems and home theater applications. With its robust design and high performance, the TDA7387 remains one of the most popular choices for multi-channel amplifier designs.
