FM31256-G

The FM31256 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 any other purpose. The FM31256 is a 64-Kbit/256-Kbit nonvolatile memory employing an advanced ferroelectric process. A ferroelectric random access memory or F-RAM is nonvolatile and performs reads and writes similar to a RAM. This memory is truly nonvolatile rather than battery backed. It provides reliable data retention for 151 years while eliminating the complexities, overhead, and system-level reliability problems caused by other nonvolatile memories. The FM31256 is capable of supporting 1014 read/write cycles, or 100 million times more write cycles than EEPROM. The real time clock (RTC) provides time and date information in BCD format. It can be permanently powered from an 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 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 comparator on PFI compares an external input pin to the onboard 1.2 V reference. This is useful for generating a power-fail interrupt (NMI) but can be used for any purpose. The family als

• 64-Kbit/256-Kbit ferroelectric random access memory (F-RAM)
• Logically organized as 8 K × 8 (FM3164) / 32 K × 8 (FM31256)
• High-endurance 100 trillion (1014) read/writes
• 151-year data retention (See the Data Retention and Endurance table)
• NoDelay™ writes
• Advanced high-reliability ferroelectric process
• 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 counter
• Serial number with write-lock for security
• Real-time Clock/Calendar
• Backup current at 2 V: 1.15 ?A at +25 ?C
• Seconds through centuries in BCD format
• Tracks leap years through 2099
• Uses standard 32.768 kHz crystal (6 pF)
• Software calibration
• Supports battery or capacitor backup
• Processor Companion -pin small outline integrated circuit (SOI