FM30C256
256Kb Data Collector
Features
Real-time Clock/Calendar
256K bit Ferroelectric Nonvolatile RAM
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Backup Current under 1 µA
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Organized as 32,768 x 8 bits
High Endurance 10 Billion (1010) Read/Writes
10 year Data Retention
Tracks Seconds through Centuries (BCD format)
Tracks Leap Years through 2099
Uses Standard 32.768 kHz Crystal (6pF)
Software Calibration
NoDelay™ Writes
Advanced High-Reliability Ferroelectric Process
System Supervisor
Fast Two-wire Serial Interface
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Active-low Reset Output for VDD Out-of-Tolerance
Tamper Detect Input with Battery Backup and
Time Stamp
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Up to 1 MHz Maximum Bus Frequency
Supports Legacy Timing for 100 kHz & 400 kHz
Clock Registers Accessed via 2-wire Interface
Description
Pin Configuration
The FM30C256 is a 256-kilobit data collection
subsystem including nonvolatile RAM, timekeeping,
CPU supervisor, and system tamper detection. Non-
volatile 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.
1
2
20
19
18
17
16
15
14
13
12
11
VDD
SCL
SDA
NC
TIN
A0
3
A1
4
A2
5
NC
NC
NC
CAL
NC
6
NC
7
NC
8
X2
9
RST
VSS
X1
10
VBAK
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.
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
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 battery-
backed flag is set when the event occurs, but can only
be cleared by software.
Serial Clock
Supply Voltage 5V
Battery-Backup input
Ground
The FM30C256 is provided in a 20-pin SOIC
package and is guaranteed over an industrial
temperature range of –40°C to +85°C.
Ordering Information
FM30C256-SA 20-pin SOIC
This product conforms to specifications per the terms of the Ramtron
standard warranty. Production processing does not necessarily in-
clude testing of all parameters.
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, (719) 481-7000, Fax (719) 481-7058
www.ramtron.com
Rev 2.1
Dec. 2002
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