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What is FRAM?

FRAM inquiry Datasheet download

FRAM(Ferroelectric Random Access Memory) is also known as FeRAM. It is a type of memory that uses a ferroelectric film as a capacitor to store data. FRAM has the characteristcs of both ROM(Read Only Memory) and RAM(Random Access Memory), and advantages in high-speed writing,high endurance, low power consumption and tamper resistance.

 

About Ferroelectric

The figure below explains PZT crystal structure, which is commonly used as a typical ferroelectric material. There are zirconium and titanium in the lattice, which have two stabilization points. They can move between the points according to the external electric field. Once the position is settled, it will not move anymore even the absence of electric filed. Top and bottom electrodes structure a capacitor. Then, the capacitor plots bottom electrode voltage and polarization, which yields a hysteresis loop. Data is stored in the form of "1" or "0".

PZT Crystal Structure and Principles of FRAM

FRAM Cell pzt-1_cgi-bin_document_document_search    Crystal structure of PZT(FER) pzt-2_cgi-bin_document_document_search    Hysteresis Loop of PZT pzt-3_cgi-bin_document_document_search

  1. Polarization occurs when an electric field is applied. (Zr/Ti ions move upward or downward in the crystal)
  2. Electric polarization remains even in the absence of an applied electric field.
  3. Two stabilized states are stored in the form of "0" or "1" data.

FRAM in Memory Classification

FRAM in Memory Classification category_cgi-bin_document_document_search

* Non-Volatile: even when not powered, the stored information can be retained

Advantages

FRAM has following advantages over conventional memories;

Non-volatility

  • Even when not powered, the stored information can be retained
  • When compared to SRAM, Battery-free (Eco product)

Higher speed writing

  • Over-writable just like SRAM
    Rewrite command is not required
  • No waiting time for erase/write operation
    Write cycle time = Read cycle time
    Writing time: 1/30,000 of E2PROM

Higher endurance

  • Guarantee the endurance of Max. 1012cycles (1 trillion cycles) per bit
    Endurance: more than 1 million times of E2PROM

Lower power consumption

  • Charge Pump Circuit is not required
    Power consumption: below 1/400 of E2PROM

Table1 is a comparison table for specification differences between FRAM and other memory devices.

Table1.Features of FRAM compared with other memory products

FRAM E2PROM Flash SRAM
Memory type Non-volatile Non-volatile Non-volatile Volatile
Cell structure*1 1T1C/2T2C 2T 1T 6T
Data rewrite method Overwrite Erase+ Write Sector erase+ Write Overwrite
Write cycle time 150ns*2 5ms 10µs 55ns
Endurance Max. 1012(1 trillion cycles*3)*2 106(1million cycles) 105(100thousand cycles) Unlimited
Write operation current 5mA(Typ.)*2
15mA(Max.)*2
5mA(Max.) 20mA(Max.) 8mA(Typ.)
-
Standby current 5µA(Typ.)*2
50µA(Max.)*2
2µA(Max.) 100µA(Max.) 0.7µA(Typ.)
3µA(Max.)

*1) T=Transistor. C=Capacitor
*2) Specs of 256Kb stand-alone FRAM memory
*3) Total cycles of read and write operation

Fujitsu FRAM Integrated Products

Stand-alone Memory (I2C/SPI/Parallel interface products)

Fujitsu Semiconductor provides stand-alone memory which has FRAM's advantages including non-volatility, high-speed writing, low power consumption and high endurance. You can use it for various applications such as mobile, OA equipment, digital appliance, banking terminal.

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Stand-alone Memory (I2C/SPI/Parallel interface products)

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Applications

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