Last August, LSI Logic announced a new member of its LSI40x DSP processor chip family, the LSI403LP. The new chip targets cost- and power-sensitive applications, particularly audio and voice processing. LSI says that at 150 MHz and 1.2 volts the LSI403LP burns just 55 mW of power—an impressively low figure. According to LSI, the chip has now reached production and is available at 150 MHz for about $10 in 10K quantities.
The LSI403LP is based on LSI’s ZSP400 DSP core, a superscalar, 16-bit fixed-point, dual-MAC architecture that is capable of executing up to four instructions in parallel. (The ZSP400 is the predecessor to LSI’s ZSP500, which was announced in September of 2002 and is not yet available in chip form.) In addition to being offered in off-the-shelf chips, the ZSP400 core is also available from LSI as licensable IP and as a building block for customer-designed SoCs fabricated by LSI. The core’s availability in these three forms is unique among DSP architectures and is a strong advantage. An OEM can start product development with an off-the-shelf LSI400 family chip, for example, and then migrate to a custom SoC when volumes justify the costs of a custom chip design.
The LSI403LP’s main competitors are TI’s ’C55xx family and Analog Devices’ Blackfin (ADSP-2153x) family. The LSI403LP is not as fast as the fastest versions of these two competitors; at 150 MHz, it has a BDTImark2000™ score of 700, compared to a score of 1690 for the 300 MHz ADSP-21535 and 970 for the 200 MHz ’C5509. (Detailed benchmark results and analysis for the ZSP400 are available in two of BDTI’s reports, Buyer’s Guide to DSP Processors and Inside the LSI Logic ZSP500.)
The LSI403LP shines in terms of energy efficiency, however. At 150 MHz, its BDTImark2000/mW energy-efficiency score is 12.8. The ’21535 (operating in its reduced speed/reduced voltage mode) and the ’C5509 both have energy efficiency scores that are about half as good as that of the LSI403LP; the ’21535’s result at full speed is even worse. The LSI403LP’s energy-efficiency advantage may be short lived, however; a forthcoming chip from ADI, the ’21532, is expected to close the gap and offer similar energy efficiency. Until then, the LSI403LP will enjoy a coveted spot as the most energy-efficient chip—by far—in this field of competitors
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