Zero-Power or NOT Zero-Power: That Is the Question
Having a great base technology is only the first block in building the ultimate low-power application. We need to take that technology and build it into the perfect device just for your design, which might require a certain number of I/Os, logic gates, clock resources, SRAM, and FIFOs. So Actel has created a range of devices to fit every need, or at least a good cross-section.
Since power matters, we can start there. The IGLOO devices start at 30 k gates, with static current of just 4 µA, and operate at 1.2 V. For faster performance, with low-power features still built in, the ProASIC3L family offers the balance of power and performance. The ProASIC3 family is the speed family for extra processing power, and still benefits from the inherently low-power flash technology. This doesn't mean much until you look at a specific area or application. We have been talking about replacing your old FPGA, so let's go head-to-head.
Low-Density Devices — Actel vs. "Zero-Power" MAX® IIZ
If you are currently using a MAX II, let's assume your next step would be an upgrade to the new MAX IIZ device. Our equivalent part would be an IGLOO device with 30 k gates.
| LEs | Max. User I/Os | Voltage Supply | Standby Current | Power | |
|---|---|---|---|---|---|
| AGL030 | 341 | 81 | 1.2 V | 4 µA | 5 µW |
| EPM240Z | 240 | 80 | 1.8 V | 29 µA | 52 µW |
So, using the datasheet numbers above, IGLOO has about 40%
more logic, with 10 times lower power than the "Zero-Power"
MAX IIZ device. In addition, since IGLOO FPGAs operate from a
1.2 V core voltage, the dynamic power consumption is also
significantly lower.
Mid-Density Devices — Actel vs. Spartan™-3 or Cyclone® III
In this case, all the devices can operate from 1.2 V, so compare basic power consumption at, say, 10,000 logic elements.
The standby current is hundreds of times higher in Cyclone III and Spartan-3AN than in the IGLOO device, and the active current is 2 or 3 times higher. Not what you would look for in a power-sensitive application. In a battery-powered application, this can lead to 10 or even 20 times longer battery life with IGLOO FPGAs.
| Standby Current | Active Current at 100 MHz | |
|---|---|---|
| AGL1000 | 0.148 mW | 94 mW |
| EP3C16 | 42 mW | 161 mW |
| XC3S700AN | 96 mW | 254 mW |
Low-Power Modes That Go One Step Further
Many FPGA vendors have talked about low-power modes of operation. Few truly deliver what has been claimed. Actel looked at ProASIC3 technology and thought about what an engineer truly wants to do when the device is in a static mode. From this development effort, the Flash*Freeze technology and IGLOO family were created. With a single pin, the device can enter Flash*Freeze mode and instantly drop power. Internal clocks automatically switch off, inputs continue to toggle, and the low power is controlled. Other vendors claim x number of microamps if you prevent toggling on the I/O, with single-pin control. Well, it's not really single-pin control if you have to find a way to disable every input. Enter Flash*Freeze mode in 1 µs and the competitors' mode in 250 µs. At Actel we have chosen to take power seriously and do not try to fake low-power modes to market our products. Actel delivers truly power-smart devices. The device family members range from 30 k gates to 3 million gates. Device choices include 1 to 6 PLLs, SRAM and FIFO, on-board user flash memory, flexible clock networks, 4x4 mm packaging, and 620 user I/Os.
