Analog Device’s latest SHARC DSPs combine big performance and on-chip memory with small prices and power numbers.  This unique combination makes the new ADSP-2148x and ADSP-2147x DSPs a compelling choice for high-performance audio, industrial, automotive, and medical applications.  Here’s what you get in the new DSPs:

• Up to 400 MHz of 32-bit floating-point performance—that’s 33% faster than the competing TI ‘C674x DSPs, and it’s nearly as fast as the fastest SHARCs already on the market.
• Up to 5 Mb of on-chip memory—2.5X the memory on the ‘C674x, and as much as you’ll find on other SHARCs.
• Power as low as 363 mW—this is a whopping 3X improvement over past SHARCs, and it compares favorably to TI’s power numbers (more on that in a moment).
• Prices starting at $7.85 in 1,000-unit quantities—a price that’s hard to beat in this class of DSP.

Before today’s launch, Analog Devices’ SHARC DSP was already a big hit in high-end audio applications thanks to its top-notch floating-point performance and audio-friendly features such as its large on-board memory.  The new 2148x and 2147x make these features available to a much broader market through cost and power optimization.  Let’s take a look at how ADI optimized the parts by comparing them to the flagship ADSP-21469.

On the cost front, the biggest changes are in the realm of IO.  The high-speed DDR2 interface on the 21469 is replaced by a slower SDRAM interface, and the 2194x’s multiprocessor link port is removed altogether.  The new SHARC parts also come in lower-cost packaging.   Instead of the 2194x’s 324-pin BGA package, the new parts come in 196-pin BGA and 176-pin LQFP packages.  The LQFP packages add additional saving by enabling OEMS to use low-cost assembly methods and PCBs with fewer layers.  The nice thing about these optimizations is that they dramatically cut costs without cutting into the performance or big memories that make the SHARC such a great fit for high-performance audio apps.

The new SHARCs also integrate a variety of new peripherals that help reduce system costs.  These include a thermal diode and (on the 2147x) a real-time timer and watchdog timer.  The thermal diode is an unusual addition.  This diode senses the chip’s internal temperature, allowing the SHARC to shut down safely if safe temperatures are exceeded—a very real risk in automotive environments, among other places.

To get power down, ADI switched to a low-leakage fabrication process.  Instead of the TSMC 65G process used in the 21469, the 2147x uses the low-leakage TSMC 65LP process.  (The 2148x sticks with the leakier but faster 65G process.)  The switch resulted in an impressive 3X reduction in absolute power and a 2X improvement in performance per Watt.

So how do the new SHARCs stack up against the competition?  Overall the numbers look pretty good.  Here’s a chart comparing select 2147x and 2148x parts against a competing TI C674x part:

*TI did not provide 1000-unit pricing, but this part probably costs less than $10 in 1000-unit quantities.

On a rough comparison of MMACs, the 21489 SHARC has a clear advantage over the C6745, while the other SHARCS are roughly at parity with TI’s DSP.  There is more to the story than MMACs, though.  The SHARC DSPs include a FIR/IIR/FFT accelerator that greatly boosts the SHARC’s performance on many applications.  Just how big of boost this is I can’t say.

SHARC has a less ambiguous advantage in on-chip memory.  TI’s part offers only 2 Mb, compared to as much as 5 Mb on SHARC.  However, it’s worth noting that the C674x integrates some features that are not available on the SHARC DSPs.  To name just a few examples, the TI parts are available with a 10/100 Ethernet MAC, USB ports, and a LCD controller.  In addition, the TI family is pin-compatible with the OMAP-L1x, which adds an ARM9 alongside the DSP.  The bottom line here is that SHARC has better features for high-performance audio, but the C674x is more attractive for consumer devices.

Looking at power, the 21478 is clearly a winner whether you look at absolute power or MMACS/mW.  I can’t say the same for the 2148x SHARCs, which burn considerably more power than the competition.   Pricing is harder to judge, but all of the SHARC parts look like good bargains considering the large amount of on-chip memory.

In the final analysis, the new SHARC DSPs are the best options I’ve seen for audio applications that need high-end performance without high-end cost and power.  The 2148x and 2147x also have many attractive features for the automotive, industrial, and medical markets.  If you have a project that needs floating -point performance, you should definitely give the new SHARC DSPs a look.