Transmeta has licensed its LongRun2 power management technology to Fujitsu, the second customer to purchase rights to the technology.
LongRun2 improves on an earlier Transmeta technology that managed transistor frequency according to an application's workload. Although the earlier technology controlled power consumption when the transistor was active, it did not address the growing problem of power leakage when the transistor was inactive.
The ever-shrinking size of transistors has exacerbated the problem of current leakage. Transistors are now so small that current can escape even when not actively flowing through the transistor. The problem is known as passive or standby leakage, and is expected to become even worse in the future.
LongRun2 specifically targets passive leakage by controlling the transistor's threshold voltage (the amount of power required to turn the transistor on or off).
Other power management technologies must raise or lower the threshold voltage in step with changes in frequency. As a result, an idle transistor can send the threshold voltage down until it reaches the point where very low levels of current can activate the transistor and cause power to leak.
Transmeta's LongRun2 prevents this by setting the threshold voltage high enough to prevent an idle transistor from turning on inadvertently in the presence of small amounts of power.
NEC was the first company to license the technology, which is also found in the 90-nanometer version of Transmeta's Efficeon processors.
Transmeta uses Fujitsu as a foundry for its 90-nanometer Efficeon processors, whil eFujitsu uses Transmeta processors in some of its notebooks and tablet PCs. Despite the improved performance of its Efficeon processors, Transmeta is still having a tough time getting its chips into ultraportable notebooks outside the Japanese market.
Tom Krazit writes for IDG News Service