Low-power 24bit Stereo CODEC with Microphone/Speaker/Video amplifiers and LDO


Tokyo Japan, November 1 2013, Asahi Kasei Microdevices Corporation today launched the AK4958, the newest product in the AKM Audio 2 Go (TM) family. The AK4958 is an enhanced version of the AK4957 that is widely used for sound processing in digital still and video cameras. This 24-bit stereo CODEC integrates microphone, speaker and cap-less video amplifiers in addition to an LDO, saving significant board space and design complexity. An advanced automatic wind noise reduction filter is effective during outdoor recordings and is a key new feature in the AK4958. A five-band notch filter and an ALC circuit are included for added noise reduction to greatly reduce the motor noise while maximizing the microphone signal level during recording.

Designed for low power, the AK4958 features an outstanding performance to power consumption ratio, merely consuming 10mW (AVDD =3.3V, D/TVDD = 1.8V) for recording and 8.5mW (AVDD =3.3V, D/TVDD = 1.8V) for playback. The stereo ADC achieves 96dB dynamic range and 85dB S/(N+D), and the stereo DAC (lineout mode) achieves 92dB dynamic range and 85dB S/(N+D) at a very low supply current, making the AK4958 an ideal solution for portable applications such as digital still and video cameras. The AK4958 has a capacitor-less video amplifier that outputs a 50mV at typical clamp level. This video amplifier eliminates large AC-coupling capacitors, reducing cost and space, both key requirements for portable devices. The microphone input circuit includes an optional digital microphone interface, converting 1-bit data (PDM) into 24-bit linear PCM data. The ADC output and digital microphone output are automatically adjusted by the ALC circuit, and high quality sound recording can be realized using an internal five-band equalizer.

The AK4958 integrates a low noise stereo microphone preamplifier that supports single-ended inputs, a power supply circuit for two sets of stereo microphones, an ALC circuit for recording and playback, a digital volume control, a three-band dynamic range control circuit for playback, a bass boost circuit for playback, a cap-less video amplifier supporting 50mV typical clamp level outputs, a mono speaker amplifier with a maximum output of 400mW, and a stereo lineout amplifier. An integrated PLL generates all required audio clocks internally, ensuring a simple interface to external processors. The PLL includes an internal loop filter, eliminating traditional external circuitry. Functions are controlled through serial control, either 3-wire or I2C bus interfaces. The AK4958 supports sampling rates from 7.35kHz to 48kHz, and the operating voltage ranges from 2.8V to 3.6V for the analog block, from 1.6V to 2.0V for the digital block, and from 1.6V to 3.6V for the digital interface. The AK4958EG is housed in a space saving small 32-pin BGA package (3.5mm x 3.5mm, 0.5mm pitch) and the AK4958ECB is housed in an ultra-small 25-pin CSP package (2.2mm x 2.2mm, 0.4mm pitch).


Evaluation boards and samples are available now.

To obtain more information about the AK4958, please visit here for the AK4958EG and here for the AK4958ECB.



About “Audio 2 Go (TM)
Audio 2 Go(TM) products are designed for portable audio applications, including mobile phones and media players, which provide feature-rich, single chip solution with low power consumption and high audio fidelity.


[Note] AKM and Audio 2 Go are trademarks of Asahi Kasei Microdevices Corporation.