News and New Products

SHARC swims toward deeper, more fertile waters

By Brian Dipert -- EDN, 12/11/2003

Analog Devices’ 32-bit floating-point DSPs have achieved notable success in high-end consumer- and professional-audio applications, as a perusal of the plethora of SHARC logos on ads in publications such as Electronic Musician, Mix, Recording, and Stereophile attests. Melody 32, Analog Devices’ first stab at mainstream automotive- and home-audio success, netted limited results, due in part to its single-MAC (multiply-accumulate) and fixed-point-only temperaments. The company’s ensuing shot, in the form of four simultaneous product announcements, restores SHARC’s SIMD (single-instruction multiple-data) and floating-point features to match customers’ expectations and competitors’ capabilities but converts from a RAM-only internal-memory architecture to a blended RAM-plus-ROM approach to keep costs in line (see “Home theater attracts another DSP supplier, EDN, Sept 20, 2001, pg 22).

The 200-MHz, $14.95 (10,000) ADSP-21266, also available in a 150-MHz, $12.50 variant, has for six months been available for sampling and will enter volume production in the first quarter of 2004. This nonvolatile-memory-inclusive derivative of the in-production ADSP-21262 includes 2 Mbits of dual-port RAM and 4 Mbits of ROM. The $9.95 ADSP-21267 variant runs at 150 MHz and has 1 Mbit of SRAM and 3 Mbits of ROM. It is due to become available for sampling in the first quarter. It will house all of the ADSP-21266’s ROM-inclusive algorithms except for the 24-bit, 96-kHz variant DTS, for which you need to employ either internal RAM or external memory (see “Auditioning high-resolution surround-sound compression, EDN, July 10, 2003, pg 89). The ADSP-21267 also offers four serial ports versus six in the ADSP-21266 and 14 “zero-overhead” DMA channels versus 22 in the ADSP-21266.

The $19.95 ADSP-21365 and $24.95 ADSP-21364, scheduled to begin appearing in sample form in the first and second quarters of 2004, respectively, represent a more extensive revamping of Analog Devices’ SHARC architecture. From memory- and processing-performance standpoints, they’re identical, both containing 3 Mbits of RAM and 4 Mbits of ROM and running at 300 MHz. The devices achieve the boost in clock speed by moving from the three-stage pipeline of ADSP-2126x products to a five-stage approach. They differ in the mix of audio-tuned peripherals surrounding the DSP and memory cores. The ADSP-21365 integrates an S/PDIF (Sony/Philips digital interface) transmitter-and-receiver combo, DTCP (digital-transmission content protection), AKE (authentication and key exchange) and cipher hardware, and an eight-channel ASRC (asynchronous sample-rate converter) with claimed 110-dB dynamic range.

The ADSP-21364 drops its sibling’s S/PDIF and DTCP capabilities but boosts the ASRC SNR specs to 142 dB with input-sample sizes as large as 24 bits, input-sample rates to 192 kHz, and input-to-output sample rate ratios ranging from 7.75-to-1 to 1-to-8. Both chips carry forward the ADSP-21266’s six serial ports, boost the number of SPI (serial-peripheral-interface) channels to two and DMA channels to 24, and add 16 PWM (pulse-width modulation) channels. All four DSPs are pinout-compatible with each other in the 136-bump BGA package; their flexible signal-to-pin-routing capabilities enhances this feature; the 2126x variants also come in 144-lead LQFPs. They include four-output clock-generation capability deriving from subdivisions of a single input-crystal frequency and support decoding of Microsoft’s (www.microsoft.com) eight-channel, high-resolution Windows Media Audio Professional format.

Analog Devices, 1-408-222-2500, www.analog.com.