Renesas Boasts of New Spin-Torque MRAM Tricks to Dramatically Lower IoT RAM Power Consumption

Semiconductor specialist Renesas has announced two new technologies designed to dramatically improve the efficiency of embedded devices built for the Internet of Things — by reducing the power required to write into RAM.

"With the accelerated spread of IoT technology in recent years, there has been strong demand for reduced power consumption in microcontroller units (MCUs) used in endpoint devices," the company claims in its technology announcement. "MRAM requires less energy for write operations than flash memory, and is thus particularly well suited for applications with frequent data updates."

"However, as demand for data processing capability surges for MCUs, the need to ameliorate the trade off between performance and power consumption increases. Therefore, further power consumption reduction remains a pressing issue."

Building on its existing spin-transfer torque magnetic random-access memory (STT-MRAM) technology platform, Renesas has made two breakthroughs that combine to offer a claimed 72 percent reduction in the energy required to write into RAM and a 50 percent reduction in the time a voltage needs to be applied — both confirmed via testing on a prototype 20Mb chip built on a 16nm FinFET process node.

The first change: A self-termination write scheme designed around slope pulses, in place of the usual fixed-voltage operation, which allows a successful write operation to be detected earlier. On top of this, the company has developed an optimization technique for allowing up to 10 percent of bits written to fail — dropping the need for an power-hungry charge pump operation in what the company claims to be "the great majority of bits."

Renesas presented both technologies at the 2021 IEEE International Electron Devices Meeting (IEDM '21), but has not yet offered a timescale for commercialization.