Cypress’ FM25V20A – RAM’s speed, Flash’s robustness

After Maxim bought Dallas Semiconductor, their once-ubiquituous battery-backed SRAM chips became more and more expensive. Cypress – mainly known for its PSoC microcontrollers – offers an alternative in its FRAM technology.

Parts like the FM25V20A use ferromagnetic random access memory technology: think of it as a new kind of RAM using a ferromagnetic layer for data storage. The idea has been around for more than thirty years, which makes the FM25V20A’s appearance in our search trends all the more fascinating.

Either way, Cypress promises a high endurance of 100 trillion (10^14) read/writes, along with a 151-year data retention – as with normal DRAM, write cycles can be done at full bus speed without any delays or similar wait states. Furthermore, no paging needs to be observed – each of the 256 K × 8 cells can be adressed in a peace-meal fashion.

Hunting in familiar grounds

SPI flash is an old classic – it is only natural that Cypress decided to deploy its FRAM technology in this market. Figure one shows the block diagram of a FM25V20A – experienced chip designers should immediately recognize the SPI transciever needed for communication with the memory array.

The SPI transciever lets periphery communicate with the FRAM array

Cypress adds two custom pins to the normal SPI layout. First of all, HOLD forces a temporary shutdown of the logic – when set, transitions of the SCK pin are ignored. This feature lets you “kill” the memory if the CPU needs to handle another, more urgent task. Interesting aspect number two is a pin dedicated to write protection – if it is activated, data on the FM25V20A is write protected as if it were in a normal ROM cell.

In terms of SPI modes, the FM25V20A supports both SPI Mode 0 and SPI Mode 3. The maximum bus speed of the FM25V20A is 40 MhZ, no wait states are required due to the ferromagnetic structure.
FRAM’s power consumption is quite humane. The part can live with 2.0 to 3.6 Volts of inpout, and needs at worst 3mA when working at 40MhZ. If your system can make do with a serial clock of just 1 MhZ, a maximal current consumption of 0.30mA is stated.

FM25V20A-G comes in a SOIC housing, while the FM25V20A ships in a DFN case. Both parts are qualified over the industrial temperature range – the only problem is the quite exorbitantly high price.

Recent Articles
Go with OPTO! Watch this free Webinar about Broadcom’s Isolation Products in Electrical Chargers
Broadcom Webinar: Isolation Products for High Speed Inverters/Converters in Electrical Chargers DC fast chargers shorten charging time from hours to mere minutes. Such high-powered equipment requires... Read Article
Efficient DC Power Distribution in Data Centres
The consistent use of direct current in a data centre makes sense. Losses can be massively reduced. On the power side, the IEC has defined the... Read Article
AC/DC Power Supplies 15 – 450 W from Traco Power
Engineered to stay cool High performance, ultra-compact AC/DC power supplies with minimal heat dissipation. Available in four different mechanical packages, these high-efficiency power supplies utilize industrial grade... Read Article
Bluetooth Mesh Solutions for IoT Based Designs
Cypress Best-in-class Bluetooth Mesh Cypress’ Bluetooth Mesh Eval Kit is a multi-node platform featuring a certified Bluetooth 5 module, sensors, and multiple mesh example projects with... Read Article
Check out the newly expanded TE Connectivity Online Store!
Buy Now with PayPal The TE Store now accepts PayPal! This feature gives you a wider range of payment options and the ability to pay for... Read Article
Compact, low power microphone with IC Interface.
This high performance MEMS audio sensor from STMicroelectronics is desigined with an IC Interface and capacitive sensing element. Ideal for a number of applications such as... Read Article