At NEC Corp, we have developed the nonvolatile (NV) magnetic flip-flop (MFF), which we position as a constituent technology essential in the realization of system-on-chips (SoC) with zero standby dissipation. This technology makes it possible to significantly reduce power consumption in standby mode for digital consumer electronics, mobile gear and other products. For a standard Blu-ray Disc or digital videodisc (DVD) recorder, for example, standby power consumption can be cut to a few percent.
The MFF is an implementation of nonvolatile logic circuit in an SoC, based on an application of magnetic random access memory (MRAM) technology. If embedded static RAM (SRAM) is replaced by MRAM in addition to utilizing MFF for the logic, the entire chip can be made nonvolatile (Note 1). Performance drops very little as a result of these changes, and the only manufacturing process modification is inserting a magnetic layer between the metallization layers of the integrated circuit (IC).
Note 1: The SoC also has analog circuits, but they can be turned off because they do not require data retention.
The use of MRAM technology means that there are no limitations on the number of times memory can be rewritten, and it is relatively easy to design for operation at supplies of 1V or less, as required in cutting-edge process technology. This characteristic is not found in other nonvolatile flip-flop technologies, and is supposed to open up a host of applications. We plan to prototype SoCs with zero standby dissipation, utilizing MFFs, within a few years.
We think these SoCs will make it possible to control power on/off as often as needed, each time the keyboard is touched on a personal computer (PC), for example. When the user touches a key, the power is instantaneously turned on, any processing is executed, and then the power is turned off again. If the equipment executes these operations fast enough so that the user does not even notice them, it will be possible to significantly cut power consumption even while the equipment is in use.
Power consumption in consumer electronics continues to rise as a result of trends toward larger display sizes and constant Internet connection. Statistics released by the Agency for Natural Resources & Energy point up the steady rise in energy consumption in the consumer sector, and the urgency of reducing equipment power consumption there 1). In portable equipment, however, battery-drive time is a key selling point, and manufacturers need to minimize power consumption to lengthen the per-charge operating time.
Reflecting the changing environment, development of equipment stressing low power consumption is accelerating, such as liquid crystal display (LCD) televisions that detect when the room is empty and turn off automatically, and mobile gear with lower power requirements made possible by higher-efficiency wireless power amps 2-3).
A look at the usage of digital consumer electronics and mobile equipment shows that in both cases, such equipment is in standby mode for most of the time - turned off by the remote in the case the former, or in call-waiting state in the case of the latter 4). It is therefor clear that reducing standby power consumption is crucial in cutting total equipment power consumption 5). One good example of a component that consumes power even in standby is the SoC, the heart of the equipment.
A standard LCD TV has two standby modes, namely (1) fast-start mode and (2) low-power consumption mode. The fast-start mode (1) is designed to shorten the time needed to "wake up" the set, and requires that the SoC and other components be constantly powered up. Even the latest TVs (40-inch) consume about 15W in fast-start. The low-power consumption mode (2), on the other hand, drops power consumption down to about 0.1W in standby, but it takes several seconds for the screen image to appear. This is because power to the electronic components, including the SoC, is shut off. For Blu-ray Disc and DVD recorders, which do not have displays, the principle difference between (1) and (2) is SoC dissipation, and in most products this works out to about 6W.
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