FM31L278/L276/L274/L272
3V Integrated Processor Companion with Memory
Features
Processor Companion
High Integration Device Replaces Multiple Parts
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Active-low Reset Output for VDD and Watchdog
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Serial Nonvolatile Memory
Programmable VDD Reset Trip Point
Real-time Clock (RTC)
Manual Reset Filtered and Debounced
Programmable Watchdog Timer
Low Voltage Reset
Watchdog Timer
Early Power-Fail Warning/NMI
Two 16-bit Event Counters
Serial Number with Write-lock for Security
Dual Battery-backed Event Counter Tracks
System Intrusions or other Events
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Comparator for Early Power-Fail Interrupt
64-bit Programmable Serial Number with Lock
Ferroelectric Nonvolatile RAM
Fast Two-wire Serial Interface
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4Kb, 16Kb, 64Kb, and 256Kb versions
Unlimited Read/Write Endurance
45 year Data Retention
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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
NoDelay™ Writes
Real-time Clock/Calendar
Easy to Use Configurations
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Backup Current under 1 µA
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Operates from 2.7 to 3.6V
Seconds through Centuries in BCD format
Tracks Leap Years through 2099
Uses Standard 32.768 kHz Crystal (12.5pF)
Software Calibration
14-pin “Green”/RoHS SOIC package (-G)
Low Operating Current
-40°C to +85°C Operation
Underwriters Laboratory (UL) Recognized
Supports Battery or Capacitor Backup
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.
Description
The FM31L27x 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 2.7 to 3.6V.
Each FM31L27x 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.
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.
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.
This product conforms to specifications per the terms of the Ramtron
standard warranty. The product has completed Ramtron’s internal
qualification testing and has reached production status.
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, (719) 481-7000
http://www.ramtron.com
Rev. 3.0
Feb. 2009
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