The FM30C256 is a 256-kilobit data collection
subsystem including nonvolatile RAM, timekeeping,
CPU supervisor, and system tamper detection. Nonvolatile
RAM is provided by FRAM technology,
which is ideal for collection data and requires no
battery backup for nonvolatile storage. In other
respects, it provides the same features as SRAM.
FRAM performs write operations at bus speed with
no write delays. Write cycles can be continuous
without block limitations. In addition, it offers much
higher write endurance than other nonvolatile
memories. The FM30C256 supports up to 1010
read/write cycles.
The FM30C256 also includes timekeeping with
external battery backup. The timekeeper consists of
registers that represent time and date information in
BCD format. The clock includes a calibration mode
that allows a software adjustment for timekeeping
accuracy.
To maintain system data integrity, the FM30C256
provides a reset signal asserted when VDD is out of
tolerance. /RST remains active for 100 ms after VDD
returns to proper levels. The FM30C256 also
provides a battery-backed tamper detect circuit that
records a rising edge on the TIN input. A batterybacked
flag is set when the event occurs, but can only
be cleared by software.
The FM30C256 is provided in a 20-pin SOIC
package and is guaranteed over an industrial
temperature range of –40°C to +85°C.