FM31L278 Datasheet, PDF (1/25 Pages) Ramtron International Corporation – 3V Integrated Processor Companion with Memory

FM31L278/L276/L274/L272
3V 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
Processor Companion
• Active-low Reset Output for V_DD and Watchdog
• Programmable V_DD 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
Ferroelectric Nonvolatile RAM
• 4Kb, 16Kb, 64Kb, and 256Kb versions
• Unlimited Read/Write Endurance
• 45 year Data Retention
• NoDelay™ Writes
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
Real-time Clock/Calendar
• Backup Current under 1 µA
• 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
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.
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.
Easy to Use Configurations
• Operates from 2.7 to 3.6V
• 14-pin “Green”/RoHS SOIC package (-G)
• Low Operating Current
• -40°C to +85°C Operation
• Underwriters Laboratory (UL) Recognized
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.
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.
Rev. 3.0
Feb. 2009
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, [phone]
http://www.ramtron.com
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