FM30C256
256Kb Data Collector
Features
256K bit Ferroelectric Nonvolatile RAM
• Organized as 32,768 x 8 bits
• High Endurance 10 Billion (1010) Read/Writes
• 10 year Data Retention
• NoDelay™ Writes
• Advanced High-Reliability Ferroelectric Process
Real-time Clock/Calendar
• Backup Current under 1 µA
• Tracks Seconds through Centuries (BCD format)
• Tracks Leap Years through 2099
• Uses Standard 32.768 kHz Crystal (6pF)
• Software Calibration
D
E
D S
N N 8
E G 27
M SI 31
M E FM
O D e:
C
Us
E W ns
R E ig
T N Des
O R w
N O Ne
F or
Fast Two-wire Serial Interface
• Up to 1 MHz Maximum Bus Frequency
• Supports Legacy Timing for 100 kHz & 400 kHz
• Clock Registers Accessed via 2-wire Interface
Description
System Supervisor
• Active-low Reset Output for VDD Out-of-Tolerance
• Tamper Detect Input with Battery Backup and
Time Stamp
Pin Configuration
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.
F
The FM30C256 is provided in a 20-pin SOIC
package and is guaranteed over an industrial
temperature range of –40°C to +85°C.
This product conforms to specifications per the terms of the Ramtron
standard warranty. Production processing does not necessarily include testing of all parameters.
Pin Names
TIN
A0-A2
CAL
/RST
X1, X2
SDA
SCL
VDD
VBAK
VSS
Function
Tamper Detect input
Device Select inputs
Clock Calibration output
Reset Output
Crystal Connections
Serial Data
Serial Clock
Supply Voltage 5V
Battery-Backup input
Ground
Ordering Information
FM30C256-S * 20-pin SOIC
FM30C256-G
20-pin “Green”/RoHS SOIC
* End of Life. Last time buy June 2009.
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, (719) 481-7000, Fax (719) 481-7058
www.ramtron.com
Rev. 2.5
Nov. 2008
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