LM4912MMX/NOPB

Audio Amplifiers Overview

The LM4912MMX/NOPB is a stereo audio power amplifier delivering 40mW per channel into a 16Ω load or 25mW into a 32Ω load at 1% THD from a 3V supply. It operates on a 2.0V to 5.5V supply with a typical quiescent current of 1.5mA to 5mA depending on voltage. The device features ultra-low noise (10µV A-weighted), high PSRR (65dB), and shutdown current under 2µA. It utilizes an MSOP-10 package, includes thermal protection, and supports external gain setting via resistors.

Audio Amplifiers Feature Summary

• Capacitor-less output configuration eliminates the need for large output coupling capacitors by utilizing a buffered bias voltage.
• Micro-power shutdown mode reduces supply current to under 2µA for extended battery life in portable devices.
• Fast turn-on mute function minimizes output pop and click transients during activation.
• Internal thermal shutdown protection safeguards the device against overheating.

Audio Amplifiers Applications

• Portable CD players
• Personal Digital Assistants (PDAs)
• Portable electronic devices

Audio Amplifiers Procurement Notes

Verify the specific ordering suffix and package variant against the manufacturer's latest documentation to ensure compatibility with design requirements. Confirm RoHS compliance status and lead times directly with authorized distributors or the manufacturer. Ensure the selected component matches the required operating temperature range and electrical specifications for the intended application environment.

Audio Amplifiers Selection Notes

Select this amplifier for low-voltage portable applications requiring high-quality stereo audio output without bulky output capacitors. Consider the external gain-setting resistors to match input signal levels and desired output power. Evaluate the trade-off between input capacitor size and turn-on time when designing the circuit bandwidth. Ensure adequate power supply bypassing to maintain low noise performance.

Audio Amplifiers Part Context

The LM4912 belongs to the Boomer family of audio power amplifiers designed by National Semiconductor, now part of Texas Instruments. This series focuses on providing high-quality output power with minimal external components, making it suitable for space-constrained portable electronics. The MMX/NOPB designation indicates a tape-and-reel MSOP package with lead-free and halogen-free construction.

Audio Amplifiers Replacement Considerations

LM4911MMX/NOPB: Similar stereo headphone amplifier but delivers lower output power (145mW into 16Ω at 5V vs 40mW at 3V) and may have different pinout or control logic. Verify electrical characteristics and pin compatibility before substitution.

Audio Amplifiers FAQ

How does the LM4912 eliminate the need for output coupling capacitors?

The LM4912 uses three internal operational amplifiers. Two drive the loads differentially while the third acts as a unity-gain buffer providing a bias voltage equal to half the supply voltage. This configuration ensures no net DC voltage exists across the load, removing the requirement for output coupling capacitors.

What is the maximum output power specification for the LM4912?

The LM4912 delivers 40mW per channel into a 16Ω load or 25mW per channel into a 32Ω load at 1% THD+N from a 3V power supply.