Actel Powers Down – Again
New ProASIC3L Family

For a long time, the messages coming out of Actel were diverse – their two flavors of non-volatile programmable logic devices, some flash-based and others antifuse-based, had distinctive characteristics that differentiated them from mainstream SRAM-based FPGAs.  They tended to have better resistance to radiation and better design security, they were live at power-up, they were a true single-chip solution because they didn’t require configuration circuitry to support them…

Today, that’s all changed.  There is only one marketing word coming out of Actel these days, and it’s Power - less of it.  Actel has focused their development efforts, their messaging, and their minds on low-power programmable logic, and the other subtle differences have fallen by the wayside. 

Now, they’re fleshing out their low-power offerings with a new flash-based family - ProASIC3L - that fits in between their ProASIC3 family and the ultra-low-power Igloo family.  Igloo remains the no-holds-barred-microwatt-miser, and ProASIC3 is still the as-close-to-SRAM-speed-as-flash-can-get family.  ProASIC3L gives up a little bit of the speed of ProASIC3 in order to gain a lot of the power savings of Igloo.  It offers a nice compromise point and keeps customers from falling into the void between the other two families where they need more speed than Igloo, but less power than standard ProASIC3.

On static power, flash already has a significant advantage over its SRAM-based rivals.  For an SRAM FPGA to stay alive, it needs to power a lot of SRAM cells just to hold its configuration – the state of the routing and look-up-table (LUT) truth tables.  True flash-based FPGAs keep this same configuration information in flash cells which, of course, require no power to retain their state.  The majority of static power in a programmable logic device is consumed by keeping the configuration intact, so flash-based FPGAs can have a couple orders of magnitude advantage in static power over even the thriftiest of SRAM-based devices. 

Apparently Actel noticed this static power advantage and decided to ride that horse off into the land of mass-produced battery-powered devices.  Static power in the microwatts is certainly better for batteries than the tens of milliwatts required for a typical SRAM-based device, so they’ve got a good point.  Most portable devices spend a lot of time waiting around for the user to call them into action, and the battery juice they don’t drink during that period is crucial for “standby time” – the amount of time a device can sit on the hotel dresser when you left your charger at home.

When it comes to dynamic power – the power consumed when the device is actually engaged in useful work -- Actel’s flash-based devices have a somewhat smaller advantage, but they still have a slightly shallower slope on the power/frequency curve than typical FPGAs.  Here, SRAM-based FPGAs are a couple of process geometry nodes ahead, so their lower voltage swings help them get back in the game on dynamic power. 

Another nice feature that Actel has provided in the new family is the “Flash*Freeze” capability, which allows you to cycle the power on and off almost instantly, maintaining state and keeping circuit-friendly I/O behavior.  This makes putting your device in standby mode a snap and skips the time- and power-consuming reconfiguration required in an SRAM device when the power pipeline is shut down. 

At the same time, Actel is announcing an “M1” version of the new family as well.  In Actel parlance, M1 means that the device comes with a built-in license for an ARM Cortex M1 soft-core processor.  The royalties for the ARM core are included in the price of the silicon, so you just buy the device, drop on the Cortex, pick out a few peripherals, load up some embedded software, and you’ve got the world’s easiest ARM-based system-on-chip.

The ARM Cortex M1 is optimized for FPGA implementation, and it has a number of power-saving features of its own.  You can configure the processor core with just the features you need, saving real-estate and transistor toggles, you can mix 16- and 32-bit instructions, and with the Thumb-2 ARMv6-M instruction set, you can use less memory to store your code (requiring, therefore, less power) while enjoying better performance due to more efficient instruction fetch.  The M1 also features a nested vectored interrupt controller that shortens interrupt latency and saves power.

The new family includes four devices (or eight if you count the “M1” versions separately) ranging from 6144 to 75264 Actel “tiles”.  (A tile is kinda’ like a LUT3 or a DFF.)  The devices include from 36K to 504K bits of RAM, one to six PLLs, and from four to eight I/O banks.

Actel also continues to enhance their tool suite with power-related features – in line with their new power-miser mantra.  Their Libero Integrated Design Environment now includes power-driven place and route that the company claims reduces dynamic power consumption by as much as 30%.  They also include power analysis features that give you the ability to build profiles based on functional modes, cycle-accurate peak power and average power analysis, and battery life estimation.

The new ProASIC3L family is available immediately in a wide range of packages including VQ100, FG144, FG256, FG324, FG484, FG896, and PQ208.  In line with their target market of mass-produced portable devices, the pricing is mostly in the volume-friendly sub-$10 range (the company quotes pricing “from $3.95USD in 100KU quantities”).  The software tools are available in January 2008 – oh wait, that’s just about now.  The thing you really need to get rolling – the starter kits (M1A3600L and M1A3PL) are slated to be available this quarter.  The remaining devices in the family are scheduled for Q2 and Q3 of this year.

With power becoming a key differentiator for the expanding FPGA market in the high-volume domain and being absolutely critical in the handheld/battery powered arena, Actel’s strategy seems solid.  For years, the company has played the niche markets where the special characteristics of flash have extra value.  Now that one of those characteristics – power -- is moving to center stage in important new markets, Actel might move there right along with it.

January 15, 2008