Alc271x Datasheet -

The Realtek ALC271X is a 4-channel high-definition audio codec designed primarily for laptop and desktop computers. It is part of the ALC269 series family and is commonly used in portable multimedia devices due to its high-performance digital-to-analog (DAC) and analog-to-digital (ADC) conversion capabilities. Technical Specifications

Based on documentation from Jotrin Electronics and Veswin, the ALC271X features: Package Type: 48-pin QFN (7x7 mm). Resolution: Supports 16/20/24-bit PCM formats. Sample Rates: Up to 48 kHz for playback and recording. Operating Temperature: Specified for an extended range of -40∘Cnegative 40 raised to the composed with power C 105∘C105 raised to the composed with power C

Compliance: Meets Windows Logo Program (WLP) audio requirements for legacy systems like Windows 7 and Vista. Key Features

Multi-Streaming: Supports independent stereo sound outputs and inputs simultaneously. alc271x datasheet

Output/Input: Features integrated headphone amplifiers and supports microphone array inputs with noise reduction.

Digital Support: Includes an S/PDIF output for digital audio transmission.

Jack Detection: Designed with jack detection pins that can sense up to 4 jacks each. Common Applications & Ecosystem ALC271X REALTEK QFN-48 Other Components The Realtek ALC271X is a 4-channel high-definition audio

The Realtek ALC271X (often ALC271X-VB6-CG) is a 48-pin MQFN High Definition Audio Codec frequently used in mobile computing platforms, sharing high architectural overlap with the ALC269 series. It supports Intel HDA links and features specific, often paired with "alc271-dmic" Linux kernel workarounds for digital microphone support. For detailed technical specs, review the Realtek ALC269 Datasheet. Realtek ALC269 DataSheet 1.5

This document is intended for the hardware and software engineer's general information on the Realtek ALC269 codec IC. Infania Networks ALC271X-VB6-CG REALTEK Audio ICs - Jotrin Electronics

✅ Jack detection details (Section 4.3)

Uses Unsolicited Response capability.
Set UNSOL_ENABLE in pin widget to get jack events.

The Definitive Guide to the ALC271X Datasheet: Pinouts, Specifications, and Legacy Audio Design

5. Practical example (Linux/ALSA)

The driver is snd-hda-codec-realtek. In alc271x_bind you’ll see: ✅ Jack detection details (Section 4

/* alc271x specific setup */
snd_hda_codec_write(codec, 0x20, 0, AC_VERB_SET_PROC_STATE, 0x01);

That enables internal processing. The datasheet won’t explain that – you need Realtek’s application note.

Chapter 1: What is the ALC271X? A Historical Context

The Realtek ALC271X is a 48-pin LQFP (Low-profile Quad Flat Package) audio codec. To understand its datasheet, one must first understand its mode.

Unlike later pure-HD Audio codecs, the ALC271X is a dual-mode chip. According to the datasheet, it can operate in two distinct states:

AC’97 Mode: Backward compatible with the older AC’97 2.3 specification.
Azalia (HD Audio) Mode: Compliant with the Intel High Definition Audio Specification 1.0.

Why does this matter? When reviewing the pinout in the datasheet, the function of certain pins (specifically EAPD, GPIOs, and SDATA_OUT) changes depending on which mode the BIOS configures. Many failed repairs occur because a technician assumes a pin function based on standard HD Audio behavior, ignoring the AC’97 fallback defined in the alc271x datasheet.

Chapter 5: Application Circuit – Reference Design

Page 45 of the standard alc271x datasheet shows the reference design. For a functional audio section, you need five external components besides the codec:

Crystal (X2): 24.576 MHz parallel resonant. The datasheet lists: Fox FS4B, ECS ECS-240-20-5PXDN-TR, or equivalent with 20pF loading caps.
Analog Power Filter: A 10uF tantalum + 0.1uF ceramic on AVDD (Pin 48).
VREF Filter: 2.2uF capacitor (low ESR, X7R) on Pin 2.
HP_DET (Jack Detection): This is optional but recommended. The datasheet uses a mechanical switch inside the headphone jack to pull Pin 33 (HP_DET) to ground.
ACZ_CAP (Analog Coupling): For the headphone output, a 220uF electrolytic capacitor in series with each channel (if DC-coupled headphone amp is not used).

ALC271X Audio Codec — Deep Dive and Practical Guide

Driver integration

Linux: ALC271-family codecs typically supported by snd_hda_intel / HDA codec drivers or ASoC machine drivers for SoC platforms. Use the codec’s pin widgets and DAPM paths in the ASoC driver. Implement jack detection callbacks and quirks for notebook-specific routing.
- Confirm supported model ID; add quirk entries if platform wiring differs from reference.
- Use ALSA mixer controls to expose mic boost, playback volume, and input muxing.
Windows: Many OEMs use vendor-supplied HD-Audio drivers; customization done in driver INF and vendor-supplied codec module. Use vendor tools to map pins and define default routing.