Low-Power Advanced 32-bit Stereo DAC with HP-Amp / SRC


Low-power HiFi Headphone DAC for Bluetooth headphones


The AK4331 is an advanced 32-bit high sound quality stereo audio DAC with a built-in ground-referenced headphone amplifier. The AK4331 has four types of 32-bit digital filters for better sound quality, achieving low distortion characteristics and wide dynamic range. The AK4331 also has a jitter cleaner with a built-in SRC and a Crystal. The AK4331 is available in a 36-pin CSP package, utilizing less board space than competitive offerings. It is ideal for Bluetooth headphones.

Achieving THD+N = -100dB with 4.4mW ultra-low power

VELVET SOUND technology adopted for premium D/A converters for high-end audio equipment has been further optimized for portable devices. Newly developed low-power consumption technology has been implemented. Each circuit block such as the headphone amplifier or LDO maintains sound quality while reducing power consumption. The AK4331 achieves 4.4mW ultra-low power consumption, THD+N at -100dB, and 109dB SNR. Long playback time with Bluetooth headphones can be achieved.

Necessary headphone functions integrated in a small package

The AK4331 integrates necessary functions such as a headphone amplifier, digital microphone input, and LDO, into a compact 36-pin CSP package. A jitter cleaner, (sample rate converter), which is effective under a jittery clock input environment is also included.


Bluetooth Headphones

Key Features

  • Maximum Sampling Frequency/Resolution :  192kHz/32-bit
  • S/N (SNR) :  109dB
  • Distortion (THD+N) :  -100dB
  • Sound Color Digital Filter :  4 types
  • Power Consumption :  4.4mW (fs=48kHz)

Block Diagram


Main Specifications

Part Number
DAC  32-bit Stereo Portable
 Audio D/A Converter
 32-bit Mono Portable
 Audio D/A Converter
Sound Color  Four Types of Digital Filters
 - Acoustic Sound (Short Delay Sharp Roll-off, GD = 5.5/fs)
 - Acoustic Tone (Short Delay Slow Roll-off, GD = 4.5/fs)
 - Traditional Sound (Sharp Roll-off)
 - Traditional Tone (Slow Roll-off)
Headphone Amplifier  Ground Referenced Class-G Headphone Amplifier
 - Output Noise Level: -114dBV (Analog Volume = -10dB)
 - Analog Volume: +4 to -10dB, 2dB Step
Output Power: 70mW with 8Ω  Output Power: 88mW with 8Ω
THD+N (Total Harmonic Distortion Pulse Noise)  -100dB  -101dB
SNR  109dB
Sampling Rate  Maximum 192kHz Master/Slave Mode
Jitter Cleaning Function  Available
 Asynchronous Sample Rate Converter
 Crystal Oscillator
Low Jitter PLL  Available
Digital MIC Interface  Available  None
Digital Audio Interface  PCM Input  PCM Input
 PDM 1-bit Input
 DSD Input
Resolution  32-bit
Number of Channels  2ch  1ch
Microcontroller Interface  I2C (400kHz)
VELVET SOUND Technology  Low distortion Technology
 OSRD (Over Sampling Ratio Doubler) Technology
Power Consumption  4.4mW (fs = 48kHz)  2.8mW (fs = 48kHz)
Power Supply  AVDD = CVDD = LVDD = 1.7 to 1.9V
 TVDD = 1.65 to 3.6V
 AVDD = CVDD = LVDD = 1.7 to 1.9V
Operation Temperature Range  -40 to 85°C
Package  36-pin CSP
  (2.533 × 2.371mm, 0.4mm pitch)
 30-pin CSP
  (2.371 × 1.971mm, 0.4mm pitch)
Mass Production  Now  Summer, 2019

Related Contents

Datasheet Download



VELVET SOUND is a sound philosophy and brand concept for AKM’s next-generation audio devices, featuring new chip architectures and core technologies.

The new circuitry found in VELVET SOUND devices is designed to maximize dynamics and ensure pure, unaltered audio data, prioritizing the accurate capture and reproduction of the source material in order to achieve high performance and rich musicality. These devices were designed specifically for the high-resolution digital audio era.

* VELVET SOUND ™, VELVET SOUND | VERITA ™ and Audio 4 Pro ™ are trademarks of Asahi Kasei Microdevices Corporation in Japan, Europe and the United States.