LM4851LQ/NOPB

Audio Amplifiers Overview

The LM4851LQ/NOPB is an obsolete integrated audio amplifier system by Texas Instruments. It delivers 1.1W (typ) into a mono 8Ω BTL load and 115mW (typ) per channel into stereo 32Ω BTL loads using a 5V supply. The device features a 32-step digital volume control (-40.5dB to +6dB) and eight distinct output modes programmed via SPI. Key specifications include 1% THD+N at 1.5W into 4Ω, single supply operation from 2.6V to 5.0V, and low shutdown current of 0.1µA.

Audio Amplifiers Feature Summary

• Integrates a 32-step digital volume control with programmable gain ranging from -40.5dB to +6dB.
• Offers eight distinct output modes for flexible audio routing and mixing via SPI interface.
• Includes click and pop suppression circuitry to minimize audible transients during power-up and shutdown.
• Provides thermal shutdown protection to safeguard the device under high-power or high-temperature conditions.

Audio Amplifiers Applications

• Mobile phones
• Personal Digital Assistants (PDAs)
• Portable handheld applications

Audio Amplifiers Procurement Notes

This component is marked as obsolete in official documentation. Verify availability through authorized distributors or secondary markets. Confirm that the specific LQ package variant matches your PCB footprint requirements. Ensure compliance with RoHS standards if applicable to your manufacturing process. Review datasheet revisions for any critical parameter updates before finalizing designs.

Audio Amplifiers Selection Notes

Select this part for space-constrained portable devices requiring high output power from a small surface-mount package. Consider the thermal resistance characteristics of the LLP package when designing the PCB copper heat sink area. Evaluate the SPI interface compatibility with your host controller for volume and mode configuration. Assess the need for external components like input coupling and bypass capacitors based on your specific frequency response and noise requirements.

Audio Amplifiers Part Context

The LM4851 belongs to Texas Instruments' Boomer family of audio amplifiers. It is designed as a complete audio subsystem, integrating power amplification, volume control, and signal processing in a single micro-SMD or LLP package. This integration reduces the bill of materials and simplifies layout compared to discrete solutions.

Audio Amplifiers Replacement Considerations

Public confirmed substitute part numbers are not available in the provided source material. As the device is obsolete, consult Texas Instruments directly for potential end-of-life notifications or recommended upgrades within the Boomer family.

Audio Amplifiers FAQ

How is the digital volume control configured?

The volume control is programmed via a three-wire SPI serial interface, allowing selection of 32 steps with a step size of 1.5dB, ranging from -40.5dB to +6dB.

What is the purpose of the exposed-DAP in the LQ package?

The exposed die attach paddle (DAP) provides a low thermal resistance path to the PCB, facilitating rapid heat transfer to the copper ground plane and preventing thermal shutdown.

Can the LM4851 drive both headphones and a speaker simultaneously?

Yes, it features multiple output pairs (SPKROUT, ROUT, LOUT) and eight configurable output modes to drive different loads such as handsfree speakers and stereo headphones concurrently.