FM33256B
3V Integrated Processor Companion with F-RAM
Features
High Integration Device Replaces Multiple Parts
•
Serial Nonvolatile Memory
•
Real-time Clock (RTC) with Alarm
•
Low V
DD
Detection Drives Reset
•
Watchdog Window Timer
•
Early Power-Fail Warning/NMI
•
16-bit Nonvolatile Event Counter
•
Serial Number with Write-lock for Security
Ferroelectric Nonvolatile RAM
•
256Kb F-RAM
•
High Endurance 100 Trillion (10
14
) Read/Writes
•
38 year Data Retention (+75°C)
•
NoDelay™ Writes
Real-time Clock/Calendar
•
Backup Current at 2V, 1.15
µA
(max.) at +25C
•
Seconds through Centuries in BCD format
•
Tracks Leap Years through 2099
•
Uses Standard 32.768 kHz Crystal
•
Software Calibration
•
Supports Battery or Capacitor Backup
Processor Companion
•
Active-low Reset Output for V
DD
and Watchdog
•
Programmable Low-V
DD
Reset Thresholds
•
Manual Reset Filtered and Debounced
•
Programmable Watchdog Window Timer
•
Nonvolatile Event Counter Tracks System
Intrusions or other Events
•
Comparator for Power-Fail Interrupt or Other Use
•
64-bit Programmable Serial Number with Lock
Fast SPI Interface
•
Up to 16 MHz Maximum Bus Frequency
•
RTC, Supervisor Controlled via SPI Interface
•
SPI Mode 0 & 3 (CPOL, CPHA=0,0 & 1,1)
Easy to Use Configuration
•
Operates from 2.7 to 3.6V
•
Small Footprint “Green” 14-pin SOIC (-G)
•
Low Operating Current
•
-40°C to +85°C Operation
•
Underwriters Laboratory (UL) Recognized
Description
The FM33256B device integrates F-RAM memory
with the most commonly needed functions for
processor-based systems. Major features include
nonvolatile memory, real-time clock, low-V
DD
reset,
watchdog timer, nonvolatile event counter, lockable
64-bit serial number area, and general purpose
comparator that can be used for a power-fail (NMI)
interrupt or other purpose. The device operate from
2.7 to 3.6V.
The FM33256B provides 256Kb memory capacity of
nonvolatile F-RAM. 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 V
DD
condition or a watchdog timeout. /RST goes
active when V
DD
drops below a programmable
threshold and remains active for 100 ms (max.) after
V
DD
rises above the trip point. A programmable
watchdog timer runs from 60 ms to 1.8 seconds. The
timer may also be programmed for a delayed start,
which functions as a window timer. The watchdog
timer is optional, but if enabled it will assert the reset
signal for 100 ms if not restarted by the host within
the time window. A flag-bit indicates the source of
the reset.
A comparator on PFI compares an external input pin
to the onboard 1.5V 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 an
event counter that tracks the number of rising or
falling edges detected on a dedicated input pin. The
counter can be programmed to be non-volatile under
V
DD
power or battery-backed using only V
BAK
. If
V
BAK
is connected to a battery or capacitor, then
events will be counted even in the absence of V
DD
.
Ramtron International Corporation
1850 Ramtron Drive, Colorado Springs, CO 80921
(800) 545-FRAM, (719) 481-7000
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
Aug. 2012
www.ramtron.com
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RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
