AS3501-EQFP

Overview

The AS3501-EQFP is a low-power ambient noise-cancelling speaker driver designed for handsets, headphones, and ear pieces. It features a fully analog implementation to minimize power consumption and system BOM cost while enhancing received voice quality by reducing background ambient noise. The device supports feed-forward topology for effective low-frequency noise reduction and includes an internal OTP-ROM for storing microphone gain calibration settings. It operates on a single cell or fixed 1.0-1.8V supply with an internal charge pump generating VNEG. Key electrical parameters include a headphone amplifier delivering 2x34mW at 0.1% THD into 16Ω with a 100dB SNR, and a microphone input with 128 gain steps of 0.375dB. The typical quiescent current is 5mA in stereo ANC mode.

Feature Summary

• Fully analog ambient noise cancellation using feed-forward topology to reduce low-frequency background noise without DSP complexity.
• Integrated high-efficiency headphone amplifier with bridged mode capability for driving high impedance loads like 300Ω headsets.
• Programmable microphone gain stage with automatic gain control (AGC) and limiter functions to optimize dynamic range.
• Internal one-time programmable (OTP) memory for permanent storage of microphone gain calibration and system configuration.

Applications

• Ear pieces
• Headsets
• Hands-Free Kits
• Mobile Phones
• Voice Communicating Devices

Procurement Notes

Verify the specific package marking and revision level against the manufacturer's latest datasheet before procurement. Ensure that the ordering suffix corresponds to the required tape and reel quantity if applicable. Confirm compatibility with the target PCB footprint and soldering profile specifications provided in the official documentation.

Selection Notes

Select the AS3501 when a feed-forward noise cancellation architecture is sufficient for the application requirements. This model provides a single operational amplifier stage suitable for basic filtering needs. Compare against the AS3500 and AS3502 variants if additional feedback filtering stages or different pin counts are necessary for complex mechanical designs.

Part Context

The AS3501 belongs to the AS3500/01/02 family of low-power audio processors from AMS (now ams-OSRAM). These devices share a common functional core but differ in package options and available operational amplifier stages. The AS3501 specifically utilizes a QFN24 package with a 0.5mm pitch, offering a balance between feature set and physical size for compact mobile devices.

Replacement Considerations

Public confirmed substitute part numbers: AS3500, AS3502.