Nonvolatile SRAM (nvSRAM) combines Cypress's industry leading SRAM technology with best-in-class SONOS nonvolatile technology. Under normal operation, nvSRAM behaves like a conventional asynchronous SRAM using standard signals and timing. nvSRAM performs parallel random access reads and writes as fast as 20 ns.
On a power glitch or failure, nvSRAM automatically saves a copy of the SRAM data into nonvolatile memory cells, where the data stays protected for over 20 years. The transfer between SRAM and nonvolatile memory cells is completely parallel (cell for cell) allowing the operation to complete in 8 ms or less, without any user intervention. On power-up, nvSRAM returns the data back to the SRAM and system operation can continue from where it left off. nvSRAM also provides user controlled software STORE and RECALL initiation commands, as well as a user controlled hardware STORE command in most versions.
Cypress's nvSRAMs are offered in industry-standard, RoHS-compliant packaging options such as TSOP, FBGA, SSOP, and SOIC packages.
Cypress nvSRAM's nonvolatile cells are based on SONOS technology. They take advantage of Fowler-Nordheim Tunneling (FN Tunneling) to store data by trapping charge in a sandwiched nitride layer. A key advantage of FN Tunneling is that it results in vastly higher NV endurance and much slower wear out. Another advantage of SONOS technology is its ease of integration in CMOS (only two additional masks). This allows the NV cell to be located immediately adjacent to the 6T SRAM cell in each memory bit making the transfers between SRAM to NV all happen in parallel and at very low power levels.
Cypress Serial F-RAM (Ferroelectric RAM) combines nonvolatile data storage with the high performance of RAM.
Serial F-RAM provides fast writes at full interface speed. Serial F-RAM does not have any write delays and data is instantly nonvolatile. Traditional nonvolatile memories have delays of 5 or more milliseconds before data becomes nonvolatile. If power is disrupted, pending data is lost unless the system has extra capacitance or batteries to keep the system on until data is stored.
Serial F-RAM offers virtually unlimited endurance of 100 trillion read/write cycles. Traditional nonvolatile memories typically have less than 1 million cycle endurance, forcing system designers to use complex wear-leveling routines and up to 4x more density to prolong the lifetime of these memories.
Serial F-RAM consumes as low as 300 µA active and 6 µA standby current. Because of fast write speeds, Serial F-RAM stays active for short periods of time, yielding very low energy consumption. Traditional nonvolatile memories with write delays must stay active for longer periods of time, resulting in higher energy consumption.
Serial F-RAM offers a pin-to-pin and footprint compatible EEPROM replacement with minor firmware changes.
Cypress F-RAM is built on ferroelectric technology. The F-RAM chip contains a thin ferroelectric film of lead zirconate titanate, commonly referred to as PZT. The atoms in the PZT change polarity in an electric field, thereby producing a power efficient binary switch. However, the most important aspect of the PZT is that it is not affected by power disruption, making F-RAM a reliable nonvolatile memory. A common misconception is that ferroelectric crystals are ferromagnetic or have similar magnetic properties. In fact, ferroelectric materials switch in an electric field and are not affected by magnetic fields.