Write Endurance to Write Home About

Radiation tolerance, power efficiency, and fast write performance also characterize F-RAM non-volatile storage technology.

Ferroelectric Random Access Memory (F-RAM) is a non-volatile storage technology that offers low power, fast write performance, and a greater write endurance when compared to EEPROM or flash technologies. For example, the write endurance of F-RAM from Cypress Semiconductor is 10^14 (100 trillion) write cycles. Presuming the device takes 4 ms to rewrite every cell, it would take a minimum of 126 years for a failure to occur. However, EEPROM and NOR Flash have write endurance of just 10^6 (1 million) write cycles. Additionally, F-RAM data retention is very robust, supporting a minimum of 10 years, and more than 121 years of data retention at + 85 °C, depending on the individual product.

Figure 1: Technologic Systems is now offering single board computers with an added Ferroelectric Random Access Memory (F-RAM) from Cypress Semiconductor.
Figure 1: Technologic Systems is now offering single board computers with an added Ferroelectric Random Access Memory (F-RAM) from Cypress Semiconductor.

The high-speed nature of the device combined with its non-volatility and data retention makes this memory device useful in many applications. The F-RAM used in Technologic Systems’ products is an AT25 compatible SPI device. The TS-7553-V2 board support package implements the F-RAM as an extra EEPROM-like memory and presents the whole device as a flat file.

Use Cases for F-RAM

Attached as a simple memory device, F-RAM can be used to store any data an application may need to retain in either traditional RAM or non-volatile memory. Having a secondary memory device can be useful for applications such as per-unit configuration/calibration data, non-secure storage of unique serial numbers or IDs, and boot flags. Applications that can take advantage of the high write endurance of F-RAM memory include temporary storage that needs to remain non-volatile, counters that require frequent writes, or data logging applications that need to store local data logs that will be read or transmitted later.

F-RAM has also proven to be highly tolerant to radiation effects that may be experienced in airborne and space applications. Typical memories retain state using various techniques that are susceptible to corruption from alpha particles, cosmic rays, heavy ions, and gamma- and x-rays. For instance, Dynamic Random Access Memory (DRAM) stores charge in a capacitor. Static Random Access Memory (SRAM) sets a latch. And EEPROM typically stores charge in an insulated floating gate. Each of these can experience a bit-flip, or soft error, as a result of a radiation event. Because the F-RAM cell stores the state as a lead zirconate titanate (PZT) polarization, an alpha particle or heavy ion hit is very unlikely to cause the polarization to change a given cell’s state, resulting in a robust tolerance to these events.

As the number of high altitude and low earth orbit projects continues to grow, especially for small-sat/cube-sat style projects, single board computers will rely on serial I/O boot code and data logging memories. F-RAM is the robust choice for these harsh environments.

Construction and Operation

The ferroelectric in F-RAM refers to a type of crystal material that is made of tiny electric dipoles where the positive and negative charges have a slight separation. This electric polarization is a natural spontaneous state of particular types of crystals and can be controlled via the application of an external electric field. The ferroelectric property is a phenomenon observed in a class of materials such as the PZT used in Cypress’ F-RAM (Figure 2).

Figure 2: Ferroelectric PZT Crystal
Figure 2: Ferroelectric PZT Crystal

Applying an electric field across the crystal causes the position to be aligned in the direction of the field and, conversely, when the electric field is reversed the crystal will be aligned in the opposite position. The polarization will remain in its last state until an electric field is applied, allowing reliable, non-volatile memory to be constructed from these crystals.

F-RAM Operation

FRAM is constructed of ferroelectric crystals used as a capacitor dielectric in a structure similar to DRAM. Where flash or EEPROM technologies rely on a charge being trapped on a floating gate, DRAM captures its charge in a capacitor. The capacitor in the FRAM cell uses a ferroelectric material, typically lead zirconate titanate, as the dielectric. By using a ferroelectric polarized dielectric, the cell is able to maintain its current state without the constant charge current required by DRAM, and the state is able to persist even without power.

The ferroelectric capacitor symbol (Figure 3) indicates that the capacitance is variable and is not a traditional linear capacitor. If a ferroelectric capacitor is not switched when an electric field is applied (no change in polarization state), it behaves like a linear capacitor. If it is switched, there is an additional charge induced, therefore, the capacitance must increase. The ferroelectric capacitor is combined with an access transistor, a bit line, and a plate line to form the memory cell as shown in Figure 3.

Figure 3: F-RAM Memory Cell
Figure 3: F-RAM Memory Cell

The operation of an F-RAM cell is also similar to DRAM. Writing is accomplished by applying a field across the ferroelectric layer in the capacitor by charging the plates on either side of it. The direction of the charge orients the dipoles in the ferroelectric layer one way or the other. This is how logical “0” and “1” are represented.

A read operation is destructive to both DRAM and F-RAM. This means that after a read a rewrite must occur for the data to remain in the cell. In a DRAM read, the cell is drained to a sense amplifier. Next, it is determined if the cell contained a charge or not.

F-RAM is read by setting the cell to a known logical state, for example a “0.” If the cell is already in this state, then the output from the cell shows no change, and it is known that the cell was in a “0” state. However, if the cell is in the opposite state, the output from the cell is a brief current pulse as electrons are pushed out during the ferroelectric polarity switch. The internal controller will then reset the cell to the correct value to be stored back, and the read data is transferred out of the IC.

F-RAM Benefits Over Other Non-Volatile Memory

Traditional writable non-volatile memories that use floating gate technology such as EEPROM or Flash use charge pumps to develop high voltages on-chip (10 V or more) thus forcing carriers through the gate oxide. With charge pumps there are long write delays and high power consumption for write or erase operations. Additionally, the write operation is destructive to the memory cell, which limits the operating life. F-RAM’s crystalline structure does not have this sort of wear out mechanism from forcing carriers through oxides, ensuring a longer operating life. Also, the switching speed of the F-RAM’s crystalline structure supports an “instant write,” guaranteeing that when data is presented to the device the data is stored without any internal chip delay. This eliminates “data at risk” in case of a sudden power loss. The mechanism used to apply an electric field to the F-RAM structure also requires significantly less power than the power used by the charge pumps in floating gate technologies.


By Kris Bahnsen and Eliza Schaub, Technologic Systems

Originally published on eecatalog.com:
http://eecatalog.com/storage/2018/08/29/write-endurance-to-write-home-about/

The Obligatory CES Wrap Article

CES 2018 is in the bag. There were some highs and lows as the show continues to grow and slowly encompass the entire Vegas Strip. This is my unofficial awards ceremony for this years CES.

Most Omni-Present Tech

Google. Google, everywhere. This CES was definitely the battle of the virtual assistant market share and “hey google” was making a big splash. From wrapping the monorail to banners covering entire buildings to the oompa-loompah like assistants running all around the show it was hard to get away from Google. However, while Google had the crown for the most marketing materials it seemed like developers were leaning more towards Alexa in the vendor booths.

Runner Up (tie)

Screens. It’s no surprise for a show that started partially as a showcase for televisions that screens are still king at CES. From the massive LG OLED canyon to wafer thin screens that worn as watches, there were screens of all shapes, sizes and clarity were everywhere.

Robots. Every shape, style and size of robot was on display. From autonomous two wheel “tank” bots cruising the aisles to small desktop balancing robots responding to voice commands the robots were at CES in a big way this year. My personal favorite was Buddy, who looked like he came straight out of a Pixar movie.

Coolest Product

Yamaha Motoroid Motorcycle. Straight out of Akira and looking stupid fast even sitting still that bike was the slickest thing I saw at CES and I found myself constantly walking back to it.

Line I Wish I Stood In

Teslasuit. There were a lot of VR/AR experiences and a line to go with everyone of them. However, the standout seemed to be the Teslasuit full haptic feedback suit and I wish I would have experienced that one first hand. Next year.

Loudest Exhibit

BMW Driving Experience. Serving up more donuts than Dunkin, the perpetual drift track was as loud as it was impressive.

Most Impressive Demonstration

MyDevices.
For this one you had to go to the mydevices suite in Mandalay Bay. If you were lucky enough to get invited you saw Benny Estes, product manager for mydevices put together a complete working sensor suite from scratch. Using auto-discovery and QR codes Benny took devices out of the box and had them online and reporting to a central dashboard in a matter of seconds. Truly inspiring to see how quickly you could deploy and the variety of sensors you can have available.

Party Crasher

Mother Nature.  In the first two days of CES Vegas get one quarter of their annual rainfall. Flooded parking garages, puddles and disabled outdoor escalators were just some of the downsides to this water show. Soggy shoes and walking 18,078 steps is a bad combo. The power outage in north hall on day 3 was also attributed to the rains.

Favorite Swag

There was a lot of the typical swag at CES this year, as to be expected, but for me a few booths stood out. CNET provided hand screened canvas bag made to order while you wait. I went with the timeless 70s logo, mainly because my other selection “so many gadgets, so little time” was too popular.

Strangest Product

A pill you ingest to help you predict and notify you when you are going to experience flatulence. Not sure if you get a text, or how you are notified of the pending eruption. Taking the Internet of Things a bit too far?

CES MVP

Security. This show is massive. Almost unimaginably massive. It has a footprint spanning from the LVCC to the Aria with stops everywhere in between, and is even larger if you count vendor suites. The security was amazing. Omnipresent, but not intrusive you were never far from help but also never standing in long lines for bag searches. Incredibly well choreographed and coordinated from the K9, to LVPD, to the convention center security they were hitting on all cylinders. #vegasstrong

Runner Up

Monorail.  My personal favorite mode of travel the monorail kept whisking attendants away to the next venue or to the after parties on a smooth schedule and even at peak hours never seemed over crowded.

Favorite Non-CES Moment

I ran into Caesar’s Forum shops to get out of the rain and saw an Optimus Prime sculpture in a storefront. I took a picture and sent it to my son, who is currently an Optimus fan. When I got home I asked if he got the picture and my son said that he had and asked me, “He’s not real, is he?” and thanks to being to CES 2018 I could answer the question truthfully, “Not yet.”

“HALT 2: Preparation is Everything” Published in EECatalog.com

EECatalog.com both published and featured the second of a multi-part article “HALT 2: Preparation is Everything“, written by our very own Alan Brown, Marketing Communications Manager.  In it, he covers tips, tricks, and lessons learned as Technologic Systems prepared for and underwent HALT.  Be sure to take a look!

HALT 2: Preparation is Everything

“What is HALT?” Published in EECatalog.com

EECatalog.com both published and featured the first of a multi-part article “What is HALT?“, written by our very own Alan Brown, Marketing Communications Manager.  In it, he introduces what HALT testing is, what it isn’t, and how it compares to other tests.  Be sure to take a look!

What is HALT?

Hot Off the Press: Working with I2C Sensor Devices

Nuts and Volts has published the article “Working with I2C Sensor Devices” in the July 2017 issue.  It walks you through how to interface with an I2C device using a single board computer.  Be sure to visit your local bookstore and pick up a copy while they’re available!

http://www.nutsvolts.com/magazine/article/working-with-i2c-sensor-devices

http://nutsvolts.texterity.com/nutsvolts/201707/?folio=36&pg=36#pg36

 

 

Deionized Water: The Gold Standard for Electronics Cleaning

When washing electronic boards, a common concern among technicians is the purity of their water. Rightfully so because technicians don’t want filthy trace deposits left under and around sensitive components. Some might ask, “If water is bad for electronics, why wash them in the first place?” Washing boards is a common process in the electronics industry because when a board is manufactured or reworked, there is a substance called flux that needs to be removed or it will cause corrosion and longevity issues. Water is a readily available and an effective solution for removing flux. However, technicians need to choose the water carefully.

There are several different levels of water purity. Starting with the least pure option, typical tap water can be used for washing boards. The next quality improvement is using carbon filtered water which marginally helps with the contaminants in the tap water. A quality level above that is Deionized water (DI water) which is commonly used in the board washing process at high quality electronics facilities. Using DI water for the board washing process is optimal due to the absence of contaminants in the water. Because DI water is the purest form of water, electronics manufacturers focused on quality use this as a standard for board washing.

Continue reading “Deionized Water: The Gold Standard for Electronics Cleaning”

Reach Out and Touch Something (Capacitive vs Resistive Touch Screens)

You only have to go as far as your corner coffee shop to realize the new human-machine interface (HMI) preference is screens. From the touchscreen Point of Sale systems to the multitude of people interacting with their phones and mobile devices, screens are king. Industry is following suit and the choice for HMI is quickly migrating away from the keyboard and mouse and towards the screen. With the abundance of touch screens on the market and the decrease in costs there has been a marked increase in their market share and penetration. When picking a screen it’s important to determine which is better for your purposes: capacitive or resistive?

Continue reading “Reach Out and Touch Something (Capacitive vs Resistive Touch Screens)”

Our Research in SLC NAND Endurance on EECatalog

This whitepaper is the result of many months of effort, working together with our customers in the field, in troubleshooting and coming up with an “smoking gun” explanation and solution for a decrease in SLC NAND flash endurance.  It’s valuable information for any embedded system users who rely on their data and filesystem to be free of corruption.  Be sure to read the full whitepaper at SLC NAND: Secrets Exposed at EECatalog.com.

While you’re at it, you may want to take a look at our related articles, featuring the solution we came up with for the decreased flash endurance, XNAND2: NAND Device Driver for Todays Lower Endurance SLC NAND, and how to further prevent data loss, Whitepaper: Preventing Filesystem Corruption in Embedded Linux.

NetBSD Toaster Powered by the TS-7200 ARM9 SBC

It has long been regarded that the UNIX-like OS NetBSD is portable to every type of machine except perhaps your kitchen toaster. Technologic Systems, however, has conquered this last frontier. Using the rugged, embedded TS-7200 single board computer housed inside the empty space of a standard two slice toaster, Technologic Systems has designed a functional NetBSD controlled toaster.

netbsd-toaster

Continue reading “NetBSD Toaster Powered by the TS-7200 ARM9 SBC”