Just as silicon replaced tubes in computers by stuffing transistors into a space few thought possible in, say, 1950, it's doing its bit to replaced parts in consumer devices. While chips initially saved space by reducing the number of transistors, they're now moving on to reducing the cost of gadgets by combining the capabilities of multiple chips onto a single chip. This week, Texas Instruments took the wraps off two stereo analog-to-digital converters (ADC) that support home audio entertainment systems, the Direct Stream Digital (DSD) specification, and the Super Audio CD format (SACD). Super Audio Compact Disc (SACD) is an audio format that provides for six-channel sound and supports discs that can contain three different versions of the same material. Direct Stream Digital (DSD) converts an analog waveform to a 1-bit signal for direct recording, instead of the pulse code modulation (PCM) and filtering used by standard CDs. (Thanks to whatis.com for these definitions. It's a good resource for deciphering acronyms and turning them back into information.) TI thinks this family of widgets is a good fit for consumer audio equipment like DVD, CD, and MD players, as well as higher-end audio/video amplifiers and receivers since they can handle the different formats. The new 24-bit devices are called the PCM1804 and the smaller PCM1802.

The PCM1804 is a differential input 24-bit ADC with a 192 kHz maximum sampling rate, a dynamic range of 112dB and THD+N at -102dB. The PCM1804 uses a proprietary architecture and analog circuitry to provide direct 64fs 1-bit streaming data from the modulator output, enabling it to meet the DSD specification. The PCM1804 contains a built-in anti-aliasing digital filter with -100dB stop-band attenuation and +/- 0.005dB pass band ripple. The device uses a dual- voltage power supply at 5V analog and 3.3V digital with a +/- 2.5 V differential inputs and has a selectable master/slave audio interface and system clock speeds of 128, 256, 512 and 786 fs. The lower-end PCM1802 stereo ADC uses single-ended input with 24-bit sampling and a 96 kHz maximum sampling rate. Both ADCs are available now. The PCM1804 is packaged in a 28-pin SSOP and is priced at $4.95 in quantities of 1,000 and the PCM1802 is packaged in a 20-pin SSOP and priced at $3.95 the same quantities.