FM31T372 Datasheet, PDF (1/26 Pages) Ramtron International Corporation – System Supervisor & Temperature Compensated RTC(TCXO) with Embedded Crystal

Preliminary
FM31T372/374/376/378
System Supervisor & Temperature Compensated RTC
(TCXO) with Embedded Crystal
Features
High Integration Device Replaces Multiple Parts
 Real-time Clock (RTC)
o Embedded 32.768kHz Crystal
o Temperature Compensated
 32.768 kHz Clock Output
 Low-V_DD Detection Drives Reset
 Watchdog Timer
 Early Power-Fail Warning/NMI
 Two 16-bit Event Counters with Event Driven
Interrupt Output
 Serial Number with Write-lock for Security
Ferroelectric Nonvolatile RAM
 4Kb, 16Kb, 64Kb, and 256Kb versions
 Unlimited Read/Write Endurance
 10 year Data Retention
 NoDelay™ Writes
Real-time Clock/Calendar
 Temp-Compensated Using On-Chip Sensor
o  5 ppm over -40°C to +85°C
o Accuracy  2 ½ min. per year
 Backup Current 1.4 A (max.) at +25C
 Seconds through Centuries in BCD format
 Tracks Leap Years through 2099
 No External Crystal Required
 Offset Register to Correct for Crystal Aging
 Supports Battery or Capacitor Backup
Processor Companion
 32.768 kHz Clock Output
 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
 Event Counter Driven Interrupt Output
 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 2.7 to 5.5V
 Small Footprint 14-pin “Green” SOIC (-G)
 Low Operating Current
 -40C to +85C Operation
Description
The FM31T37x is a family of integrated devices that
includes the most commonly needed functions for
processor-based systems. Major features include
nonvolatile F-RAM memory available in various
sizes, temperature-compensated real-time clock with
embedded crystal, 32.768kHz clock output,
low-VDD reset, watchdog timer, battery backed
event counter, event driven interrupt output, lockable
64-bit serial number area, general purpose
comparator that can be used for an early power-fail
(NMI) interrupt or other purpose, and 2-wire serial
interface to a host microcontroller. The family
operates from 2.7 to 5.5V.
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 an
internal 32.768 kHz crystal which is factory-
calibrated for excellent timekeeping accuracy over
the industrial temperature range.
This is a product that has fixed target specifications but are subject
to change pending characterization results.
Rev. 1.1
Apr. 2011
The FM31T37x devices integrate 4Kb, 16Kb, 64Kb,
and 256Kb of F-RAM memory. F-RAM offers
superior write speed and unlimited endurance. This
allows the memory to provide system data collection
and as read/write RAM storage. This memory is truly
nonvolatile rather than battery-backed.
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.
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, [phone]
http://www.ramtron.com
Page 1 of 26