Nippon Precision Circuits Inc. announces the development of SM5866AS, a high-performance DAC for DSD (Direct Stream Digital)^*and PCM (Pulse Code Modulation) playback with the ultra low THD+N (Total Harmonic Distortion + Noise).

SM5866AS is a mono-channel DAC for both DSD and 24-bit PCM audio playback. This DAC has both a DSD input and 24-bit PCM serial input, and by selecting input mode with external pins, either the DSD or 24-bit PCM is converted to a double-differential current-mode analog output. The THD+N is -109dB (0.00036%) in DSD playback mode and -106dB (0.00050%) in 24-bit PCM playback mode. This IC is suitable for professional and hi-end SACD/CD or DVD-Audio playback systems by combining the SM5866AS with the NPC's 8-times over-sampling digital filter SM5847AF and external I/V Op-amps.

DSD, the SACD signal format, is a high-order ΔΣ(delta-sigma) converted 1-bit signal of 64fs (fs=44.1kHz) sampling rate, which includes a high level of quantization noise at the frequency range above 100kHz. The SM5866AS, in DSD mode, incorporates a digital FIR filter ("DSD filter") to attenuate the DSD signal quantization noise, and this filtered multi-level output is converted to analog. The cutoff frequency of "DSD filter" is about 100kHz at -1dB attenuation. Using this internal digital filter enables an ultra low THD+N to be achieved at the analog output.

In PCM mode, the SM5866AS supports speeds from CD format (16-bit/44.1kHz) to the fastest standard in DVD-Audio format (24-bit/192kHz), when combined with NPC's SM5847AF, an 8-times over-sampling digital filter for DVD-Audio. In PCM mode the 8-times over-sampled PCM is converted to 23-level signal by a 3rd order noise-shaper, which has more than 120dB theoretical S/N in the 20kHz audio band.

The development of the SM5866AS draws upon NPC's CMOS technology and experience using the multi-level noise-shaping method, both of which have been fundamentally important in the development of NPC's ΣDECO^(R) product line. The ultra low THD+N was achieved in the SM5866AS as a result of applying a new method developed by NPC, a method named as the New Precision Dynamic Element Matching (NPDEM) method. Applying this method results in achieving a total harmonic distortion of -109dB (0.00036%) in DSD playback mode.

Precision matching analog elements such as resistors and capacitors on a chip is greatly increased when using NPDEM. This new method enabled a significant improvement in the signal-to-noise ratio (S/N), an increase in the dynamic range, and lowering of the total harmonic distortion. Therefore NPDEM enables high precision D/A conversion.

SM5866AS is the NPC's first device for DSD (SACD) playback system. NPC will continue to develop and release other new digital audio ICs in the field of DSD (SACD) and DVD-Audio playback systems.

*This SM5866AS has been developed based on DSD (Direct Stream Digital) technology supported by Sony Corporation.