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Single-supply audio DACs deliver ground-referenced 2-Vrms output

Asahi Kasei EMD Corporation (AKM) has announced the AK4420 and AK4421 single-supply stereo audio 2-Vrms-output DACs with integrated charge pumps. According to the company, the devices' high integration level reduces external component requirements, simplifying system design and reducing cost for consumer audio applications such as set-top boxes, televisions, DVD players and recorders, and A/V receivers.

The AK4420 operates from a +5-V nominal power supply, while the AK4421 operates on +3.3 V. The integrated charge pump supplies the negative rail for the output buffer.

Since the output buffer operates off of an internal dual-rail supply, the output signal is ground-referenced, and audible pop noise is suppressed without any external mute circuits on power-up or when clocks are stopped. The output signal is 2 Vrms, centered around ground.

Specifications include a 24-bit resolution at sampling rates up to 192 kHz, a dynamic range of 105 dB, and THD+N of -92 dB. An automatic power-on reset circuit eliminates the need to reset the DAC on power-up or after the clocks are stopped. No external controller is needed to set the data interface format or the audio sampling rate.

The DACs include a switched-capacitor filter, and the output buffer features a continuous-time filter. With these two internal filters, a simple first-order RC external filter is all that is recommended.

The AK4420/21 are housed in 16-pin TSSOPs. The AK4420 is now in mass production, and samples are available for the AK4421.

Asahi Kasei Microsystems , +81-3-5908-2716, http://www.akm.com

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