Pre-Production
This is a product in pre-production phase of development. Device
Ramtron International Corporation
characterization is complete and Ramtron does not expect to change
1850 Ramtron Drive, Colorado Springs, CO 80921
the specifications. Ramtron will issue a Product Change Notice if
(800) 545-FRAM, (719) 481-7000
any specification changes are made.
http://www.ramtron.com
Rev. 2.0
Jan. 2011
Page 1 of 26
FM31278/276/274/272
5V Integrated Processor Companion with Memory
Features
High Integration Device Replaces Multiple Parts
Serial Nonvolatile Memory
Real-time Clock (RTC)
Low Voltage Reset
Watchdog Timer
Early Power-Fail Warning/NMI
Two 16-bit Event Counters
Serial Number with Write-lock for Security
Ferroelectric Nonvolatile RAM
4Kb, 16Kb, 64Kb, and 256Kb versions
Virtually Unlimited Read/Write Endurance
38 year Data Retention (+75
°C)
NoDelay Writes
Real-time Clock/Calendar
Backup Current under 1.4
A
Seconds through Centuries in BCD format
Tracks Leap Years through 2099
Uses Standard 32.768 kHz Crystal (12.5pF)
Software Calibration
Supports Battery or Capacitor Backup
Processor Companion
Active-low Reset Output for VDD and Watchdog
Programmable VDD Reset Trip Point
Manual Reset Filtered and Debounced
Programmable Watchdog Timer
Dual Battery-backed Event Counter Tracks
System Intrusions or other Events
Comparator for Early Power-Fail Interrupt
64-bit Programmable Serial Number with Lock
Fast Two-wire Serial Interface
Up to 1 MHz Maximum Bus Frequency
Supports Legacy Timing for 100 kHz & 400 kHz
Device Select Pins for up to 4 Memory Devices
RTC, Supervisor Controlled via 2-wire Interface
Easy to Use Configurations
Operates from 4.0 to 5.5V
14-pin “Green”/RoHS SOIC package (-G)
Low Operating Current
-40
°C to +85°C Operation
Underwriters Laboratory (UL) Recognized
Description
The FM3127x is a family of integrated devices that
includes the most commonly needed functions for
processor-based systems. Major features include
nonvolatile memory available in various sizes, real-
time clock, low-VDD reset, watchdog timer,
nonvolatile event counter, lockable 64-bit serial
number area, and general purpose comparator that
can be used for an early power-fail (NMI) interrupt or
other purpose. The family operates from 4.0 to 5.5V.
Each FM3127x provides nonvolatile RAM available
in sizes including 4Kb, 16Kb, 64Kb, and 256Kb
versions. Fast write speed and unlimited endurance
allow the memory to serve as extra RAM or
conventional nonvolatile storage. This memory is
truly nonvolatile rather than battery backed.
The real-time clock (RTC) provides time and date
information in BCD format. It can be permanently
powered from external backup voltage source, either
a battery or a capacitor. The timekeeper uses a
common external 32.768 kHz crystal and provides a
calibration mode that allows software adjustment of
timekeeping accuracy.
The processor companion includes commonly needed
CPU support functions. Supervisory functions
include a reset output signal controlled by either a
low VDD condition or a watchdog timeout. /RST
goes active when VDD drops below a programmable
threshold and remains active for 100 ms after VDD
rises above the trip point. A programmable watchdog
timer runs from 100 ms to 3 seconds. The watchdog
timer is optional, but if enabled it will assert the reset
signal for 100 ms if not restarted by the host before
the timeout. A flag-bit indicates the source of the
reset.
A general-purpose comparator compares an external
input pin to the onboard 1.2V reference. This is
useful for generating a power-fail interrupt (NMI) but
can be used for any purpose. The family also includes
a programmable 64-bit serial number that can be
locked making it unalterable. Additionally it offers a
dual battery-backed event counter that tracks the
number of rising or falling edges detected on
dedicated input pins.