FM25CL64
CS
0
1
2
3
4
5
6
7
0
1
2
3
4
5
3
4
5
6
7
0
1
2
3
4
5
6
7
SCK
op-code
13-bit Address
12 11 10
Data
X
X
X
4
3
2
1
0
7
6
5
4
3
2
1
0
SI
0
0
0
0
0
0
1
0
MSB
LSB MSB
LSB
SO
Figure 9. Memory Write
CS
0
1
2
3
4
5
6
7
0
1
2
3
4
5
3
4
5
6
7
0
1
2
3
4
5
6
7
SCK
SI
op-code
13-bit Address
12 11 10
X
X
X
4
3
2
1
0
0
0
0
0
0
0
1
1
MSB
LSB MSB
7
LSB
0
Data
SO
6
5
4
3
2
1
Figure 10. Memory Read
corrupted. The fast write of FRAM is complete
within a microsecond. This time is typically too short
for noise or power fluctuations to disturb it.
Applications
The versatility of FRAM technology fits into many
diverse applications. The strength of higher write
endurance and faster writes make FRAM superior to
EEPROM in all but one-time programmable
applications. The advantage is most obvious in data
collection environments where writes are frequent
and data must be nonvolatile.
4. Time to market. In a complex system, multiple
software routines may need to access the nonvolatile
memory. In this environment the time delay
associated with programming EEPROM adds
complexity to the software development. Each
software routine must wait for complete
programming before allowing access to the next
routine. When time to market is critical, FRAM can
eliminate this simple obstacle. As soon as a write is
issued to the FM25CL64, it is effectively done -- no
waiting.
The attributes of fast writes and high write endurance
combine in many innovative ways. A short list of
ideas is provided here.
1. Data collection. In applications that collect and
save data, FRAM provides a superior alternative to
other solutions. It is more cost effective than battery
backup for SRAM and provides better write attributes
than EEPROM.
5. RF/ID. In the area of contactless memory,
FRAM provides an ideal solution. Since RF/ID
memory is powered by an RF field, the long
programming time and high current consumption
needed to write EEPROM is unattractive. FRAM
provides a superior solution. The FM25CL64 is
suitable for multi-chip RF/ID products.
2. Configuration. Any nonvolatile memory can
retain a configuration. However, if the configuration
changes and power failure is a possibility, the higher
write endurance of FRAM allows changes to be
recorded without restriction. Any time the system-
state is altered, the change can be written. This avoids
writing to memory on power-down when the
available time is short and power scarce.
6. Maintenance tracking. In sophisticated systems,
the operating history and system-state during a failure
is important knowledge. Maintenance can be
expedited when this information has been recorded.
Due to the high write endurance, FRAM makes an
ideal system log. In addition, the convenient interface
of the FM25CL64 allows memory to be distributed
throughout the system using minimal additional
resources.
3. High noise environments. Writing to EEPROM
in a noisy environment can be challenging. When
severe noise or power fluctuations are present, the
long write time of EEPROM creates a window of
vulnerability during which the write can be
Rev. 2.1
Apr. 2003
Page 8 of 13
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
