FM33256B-G Integrated Circuit Chip 3V Integrated Processor Companion with F-RAM

Features

High Integration Device Replaces Multiple Parts

Serial Nonvolatile Memory

Real-time Clock (RTC) with Alarm

Low VDD 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 (1014) 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 VDD and Watchdog

Programmable Low-VDD 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-VDD 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 VDD condition or a watchdog timeout. /RST goes active when VDD drops below a programmable threshold and remains active for 100 ms (max.) after VDD 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 VDD power or battery-backed using only VBAK. If VBAK is connected to a battery or capacitor, then events will be counted even in the absence of VDD.

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