FM3204

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only, and the functional operation of the device at these or any other conditions above those listed in the operational section of this specification is not implied. Exposure to absolute maximum ratings conditions for extended periods may affect device reliability.

FM32xx is a family of integrated devices that include the most commonly needed functions for processor-based systems. Major features include nonvolatile memory available in various sizes, 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 FM32xx family operates from 2.7 to 5.5V.

The FM32xx family is software and pinout compatible with the FM31xx family which also includes a real-time clock. The common features allow a system design that easily can be assembled with or without timekeeping by simply selecting the FM31xx or FM32xx, respectively.

Each FM32xx 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 processor companion includes commonly needed CPU support functions. Supervisory functions of FM32xx 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 FM32xx 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. FM32xx is useful for generating an early warning 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 the FM32xx offers a dual event counter that tracks the number of rising or falling edges detected on dedicated input pins. The counter can optionally be battery backed and even battery operated by attaching a backup power source to the VBAK pin. If VBAK is connected to a battery or capacitor, then events will be counted even in the absence of VDD.