Overview
The LM4766, produced by Texas Instruments, is a high-performance stereo audio power amplifier. It is part of the Overture™ Audio Power Amplifier Series and is designed to deliver exceptional audio quality with minimal external components. The LM4766 is capable of providing 40W per channel for the non-isolated NDL package and 30W per channel for the isolated NDB package, with a continuous average output power into an 8Ω load and less than 0.1% Total Harmonic Distortion plus Noise (THD+N) at 1kHz. This amplifier features a wide supply range of 20V to 78V, making it versatile for various audio applications.
Key Specifications
| Parameter | Conditions | Typical Value | Limit |
|---|---|---|---|
| Power Supply Voltage | VCC = +30V, VEE = −30V | 20V to 60V | 20V to 60V |
| Output Power (Continuous Average) | f = 1kHz, RL = 8Ω | 40W/ch (NDL), 30W/ch (NDB) | 40W/ch (NDL), 30W/ch (NDB) |
| THD+N at 1kHz | PO = 2 x 30W into 8Ω | 0.009% (Typ), 0.1% (Max) | 0.1% (Max) |
| Input Noise (IHF-A Weighting Filter) | RIN = 600Ω | 2.0 μV (Max) | 2.0 μV (Max) |
| Signal-to-Noise Ratio (A-Weighted) | PO = 25W, RS = 25Ω | 112 dB | 112 dB |
| Junction Temperature | 150°C | 150°C | |
| Thermal Resistance (θJC) | NDL Package | 1°C/W | 1°C/W |
| Thermal Resistance (θJC) | NDB Package | 2°C/W | 2°C/W |
Key Features
- SPiKe Protection: The LM4766 is safeguarded against overvoltage, undervoltage, overloads, and instantaneous temperature peaks, ensuring safe operation.
- Quiet Fade-In/Out Mute Mode: Independent smooth transition fade-in/out mute for each amplifier, minimizing output pops.
- Minimal External Components: Requires a minimal amount of external components, simplifying the design process.
- Wide Supply Range: Operates with a supply voltage range of 20V to 78V, providing flexibility in various applications.
- Low Noise Floor and THD+N: Extremely low noise floor of 2µV and a low THD+N value of 0.06% at rated power, making it ideal for high-end audio systems.
- Under-Voltage Protection: Prevents DC output spikes during power-up and ensures the output is brought to ground before power-down.
- Over-Voltage Protection: Limits output current and provides voltage clamping to protect the device.
Applications
- High-End Stereo TVs: Suitable for high-quality audio in television systems.
- Component Stereo Systems: Ideal for component stereo systems requiring high fidelity audio.
- Compact Stereo Systems: Used in compact stereo systems where space and performance are critical.
Q & A
- What is the maximum output power of the LM4766?
The LM4766 can deliver up to 40W per channel for the non-isolated NDL package and up to 30W per channel for the isolated NDB package.
- What is the typical THD+N at 1kHz for the LM4766?
The typical THD+N at 1kHz is 0.009% for an output power of 2 x 30W into an 8Ω load.
- What is the input noise level of the LM4766?
The input noise level is 2.0 μV (max) with an IHF-A weighting filter and RIN = 600Ω.
- How does the mute function work on the LM4766?
The mute function is activated by drawing more than 0.5mA out of each mute pin. This can be achieved using a resistor and switch setup as described in the datasheet.
- What is the thermal resistance of the NDL and NDB packages?
The thermal resistance (θJC) is 1°C/W for the NDL package and 2°C/W for the NDB package.
- What is the junction temperature limit for the LM4766?
The junction temperature limit is 150°C.
- How does the under-voltage protection work?
The under-voltage protection circuitry ensures that the power supplies and their corresponding capacitors reach their full values before turning on the LM4766, preventing DC output spikes.
- What is the purpose of the SPiKe Protection Circuitry?
The SPiKe Protection Circuitry safeguards the device against instantaneous peak-temperature stressing of the power transistor array.
- What are the common applications of the LM4766?
The LM4766 is commonly used in high-end stereo TVs, component stereo systems, and compact stereo systems.
- How can you minimize clicks and pops during power-up and power-down?
Using the mute mode and ensuring the input terminals are at the same potential can significantly reduce clicks and pops. Additionally, the under-voltage protection and stable half-supply potential help in achieving transient-free power-up and power-down.
