|
|
|
| Part | Access Time | IDD@max | Organization | Package | Vdd |
 FM23MLD16 | 60ns | 14mA | 512K x 16 | 48-Ball FBGA | 2.7-3.6V |
| FM22L16 | 55ns | 12mA | 256K x 16 | TSOP-II-44 | 2.7-3.6V |
| FM22LD16 | 55ns | 12mA | 256K x 16 | 48-Ball FBGA | 2.7-3.6V |
| FM21L16 | 60ns | 12mA | 128K x 16 | TSOP-II-44 | 2.7-3.6V |
| FM21LD16 | 60ns | 12mA | 128K x 16 | 48-Ball FBGA | 2.7-3.6V |
| FM28V100 | 60ns | 12mA | 128K x 8 | TSOP-I-32 | 2.0-3.6V |
| FM28V020 | 70ns | 12mA | 32K x 8 | 28-pin SOIC, 32-pin TSOP-I | 2.0-3.6V |
| FM18W08 | 70ns | 12mA | 32K x 8 | 28-Pin SOIC | 2.7-5.5V |
| FM1808B | 70ns | 15mA | 32K x 8 | 28-Pin SOIC | 4.5-5.5V |
| FM16W08 | 70ns | 12mA | 8K x 8 | 28-Pin SOIC | 2.7-5.5V |
| FM1608B | 70ns | 15mA | 8K x 8 | 28-Pin SOIC | 4.5-5.5V |
|
|
|
|
Top Parallel Memory Products FAQs
|
|
|
質問：
Are F-RAM devices affected by magnetic fields?
|
|
|
|
答え：
F-RAM devices are ferroelectric memories and are not ferro-magnetic. They are not affected by external magnetic fields.
See also: F-RAM Technology Brief
|
|
|
|
質問：
Does /CE need to toggle for every access?
|
|
|
|
答え：
No, the new FM28V100 and FM28V020 devices as well as the FM21L16, FM22L16/22LD16, and FM23MLD16 have on-chip ATD circuits which allow the memory to access any location by simply changing the address. This feature is called Address Transition Detection and allows /CE to remain low. It is true that the FM1608 and FM1808 devices require /CE to toggle.
|
|
|
|
質問：
Is FeRAM the same as F-RAM?
|
|
|
|
答え：
Yes. FeRAM and F-RAM are synonymous. Ramtron does not hold a trademark on the word “F-RAM”. It may be freely used without restriction.
|
|
|
|
質問：
Is F-RAM affected by radiation or soft errors?
|
|
|
|
答え：
Volatile memories, DRAM and SRAM, use a capacitor to store charge or a simple latch to store state. These cells can be easily upset by a alpha particles, cosmic rays, heavy ions, gamma, x-rays, etc. which cause bits to flip to an opposite state. This is called a soft error, since a subsequent write will be retained. The rate at which this occurs is called the Soft Error Rate (SER) of the device. Because the F-RAM cell stores the state as a PZT film polarization, an alpha hit is very unlikely to cause the polarization to change a given cell’s state. The F-RAM terrestrial SER is not measurable.
|
|
|
|
質問：
What are parallel F-RAM devices?
|
|
|
|
答え：
Standard asynchronous SRAMs have been available in the market for many years. The interface is the simplest, and it is the type of memory that most designers think of when referring to “RAM.” It has a few control pins (/CE, /WE, /OE), an address bus, and a data bus. Ramtron offers x8 and x16 parallel parts.
|
|
|
|
質問：
What are the key advantages over EEPROM and Flash?
|
|
|
|
答え：
1) Speed. The “RAM” part of the F-RAM name tells us that it is a RAM, not a ROM. Of course, EEPROM and Flash are not truly ROMs but writing to them can be very slow. An F-RAM’s write cycles are completed immediately whereas an EEPROM/flash needs 5 to 10 ms.
2) Low Power Writes. Writes to the F-RAM cell occur at low voltage and very little current is needed to change the data. With EEPROM and Flash, high voltages (10V charge pump) are needed and writes require 5 ms to complete a page buffer write. The energy needed is much higher than F-RAM writes. If E=P*t, then 5ms of write time will necessarily require 200x more energy than F-RAM.
3) High Endurance. Writes are destructive – and floating gate devices eventually wear out; typical endurance is 100,000 to 1 million cycles. F-RAM experiences 1E12 read/write cycles or greater.
|
|
|
|
質問：
What is F-RAM?
|
|
|
|
答え：
F-RAM is a nonvolatile memory device that can hold data even after it is powered off. F-RAM is an acronym for ferroelectric random access memory. F-RAM is not ferromagnetic as there is no ferrous material (iron) in the chip. Ferroelectric materials switch polarity in an electric field, but are not affected by magnetic fields.
See also: Ferroelectric Technology Brief and What is F-RAM.
|
|
|
|
質問：
Why use a parallel F-RAM?
|
|
|
|
答え：
Today, Ramtron offers x8 (bytewide) and x16 (wordwide) memory devices. Traditionally SRAMs have been used in systems that use a x8 memory. Speed is an advantage of a parallel memory device over serial parts. All address lines are presented at once and an access can start immediately. Data is transferred into and out of the memory 8- or 16-bits at a time.
|
|
|
|
|
|
|
End-of-Life (EOL) or Not Recommended for New Design (NRND)
|
|
|
| Part | Access Time | IDD@max | Organization | Package | Vdd |
| FM1808 (NRND) | 70ns | 25mA | 32K x 8 | 28-Pin SOIC or PDIP | 4.5-5.5V |
| FM18L08 (NRND) | 70ns | 15mA | 32K x 8 | 28-Pin SOIC, PDIP or 32-Pin TSOP-I | 3.0-3.65V |
| FM1608 (NRND) | 120ns | 15mA | 8K x 8 | 28-Pin SOIC or PDIP | 4.5-5.5V |
|
|
|
|
|