FRAM Keys Low Energy Use
March 27, 2012, Design West Conference, San Jose, CA—Scott Emily from Ramtron posited that their F-RAM (ferro-electric RAM) is better suited for many applications than flash. The technology uses a different storage mechanism than most memories
The storage element is a thin ferroelectric film of lead zirconate titanate [Pb(Zr,Ti)O3], commonly referred to as PZT. The crystal has two stable states. When an electric field is applied, the zirconium (Zr) or titanium (Ti) atom changes position. The read circuit detects the polarity of the atom as a difference in voltage, which determines the 0 or 1. Each orientation remains in place even after the electric field is removed.
The advantages of the PZT cell is a much faster write cycle than flash, since a voltage only needs to be applied once. Fast is a relative term, as it still takes about 10 microseconds for a write. The technology is lower power because it doesn't need a charge pump to get a higher voltage and can come up to operating from a sleep mode in 20 microseconds. Read and write are symmetrical and most efficient in low duty cycle operating environments. The RAMs are gamma radiation and electro-magnetic immune and can operate in harsh environments.
Projected applications for the FRAMs are in engine and body electronics in vehicles, smart meters where the ability to power down and quickly power up reduces total energy use. The gamma immunity allows the devices to be used in medical equipment that needs radiation sterilization. In high security applications like point of sales terminals, the ability to completely wipe the data in a 10 microsecond cycle ensures greater security.
Ramtron has a number of products using this technology. The FM25e64 natively operates on energy efficient 1.5- or 1.8-volt power rails, offers low 20-microamps active current operation, and only requires about 20-microseconds to start up, write data, and shut down the memory. For more information, visit www.ramtron.com.