Infineon Technologies FM31256-GTR

Overview

FM31256-GTR from Infineon Technologies (formerly Cypress) is a 256-Kbit integrated processor companion IC combining ferroelectric RAM (F-RAM), real-time clock (RTC), low-VDD supervisor, watchdog timer, dual event counter, and 64-bit lockable serial number in a single 14-pin SOIC package. It delivers 10¹⁴ read/write endurance, 151-year data retention, and I²C interface up to 1 MHz - deployed in industrial metering, medical data loggers, and battery-backed control systems requiring deterministic nonvolatile storage and time-stamped event tracking.

For engineers reviewing the FM31256-GTR datasheet, FM31256-GTR pinout, FM31256-GTR application, or FM31256-GTR equivalent, key selection criteria include F-RAM write endurance vs. EEPROM/Flash, RTC BCD calendar with leap-year support through 2099, programmable VDD reset threshold (2.55 V / 2.75 V / 2.95 V / 3.15 V), battery-backed event counting on CNT1/CNT2, and I²C slave address configuration via A0/A1 pins.

Technical Context

The FM31256-GTR implements two logically independent I²C devices on one die: a 32K × 8 F-RAM array (slave address 0x50–0x53) and a companion peripheral block (slave address 0x68) housing RTC registers, supervisor control, event counters, and serial number. The F-RAM uses ferroelectric capacitor technology enabling true RAM-like random access with no write cycle delays and no wear leveling.

RTC operation is maintained by VBAK backup power (battery or capacitor), supporting seconds-to-centuries BCD calendar with software calibration, 32.768 kHz crystal input (X1/X2), and automatic leap-year correction through year 2099. Supervisor functions include active-low open-drain RST with 100 ms reset pulse width, programmable watchdog timeout (100 ms to 3 s), and PFI comparator referenced to internal 1.2 V.

Key Specifications

Pinout & Package

FM31256-GTR is housed in a 14-pin Small Outline Integrated Circuit (SOIC) package with standard 1.27 mm pitch, RoHS-compliant lead finish, and moisture sensitivity level (MSL) 3 per J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar integrated processor companion applications.

Compared with DS3231M+ and STM32H743VI, FM31256-GTR uniquely combines ultra-endurance nonvolatile memory, battery-backed timekeeping, and tamper-aware counting in one I²C device - reducing component count, PCB area, and qualification effort for legacy MCU-based systems.

Availability

FM31256-GTR is available at Aetrix Electronics and suitable for smart metering, medical data logging, industrial PLC controllers, and building automation gateways requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.

Supply support for FM31256-GTR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Infineon Technologies is a global semiconductor leader headquartered in Munich, Germany, delivering power systems, microcontrollers, sensors, and security solutions for automotive, industrial, and IoT applications.

The FM31256-GTR belongs to Infineon's legacy Cypress processor companion product line, designed specifically to reduce bill-of-materials and improve reliability in resource-constrained embedded systems requiring persistent time-stamped data capture.

FAQ

What is the maximum I²C clock frequency supported by FM31256-GTR?

The FM31256-GTR supports I²C operation up to 1 MHz under standard conditions (VDD ≥ 2.7 V, temperature −40 °C to +85 °C). It maintains backward compatibility with 100 kHz and 400 kHz modes, and all timing parameters-including tBUF, tHD:STA, and tSU:DAT-are fully specified in the datasheet for each speed grade. No external components are required to achieve 1 MHz operation.

How does the FM31256-GTR handle power failure during an F-RAM write?

The FM31256-GTR guarantees atomic write completion: if VDD drops below the reset threshold during an I²C write transaction, the internal state machine completes the ongoing byte write before asserting RST. No partial writes occur - the F-RAM cell either receives the full data byte or retains its prior value. This behavior is inherent to ferroelectric memory physics and requires no firmware intervention or checksum validation.

Can the RTC operate independently while the F-RAM is being accessed?

Yes. The FM31256-GTR presents two independent I²C slave addresses: 0x50–0x53 for F-RAM and 0x68 for RTC/companion registers. Concurrent access is not permitted, but rapid interleaving is supported - for example, reading RTC seconds (0x68) then writing sensor data to F-RAM (0x50) in successive transactions without bus contention or register corruption.

Is the 64-bit serial number truly one-time programmable?

Yes. The 64-bit serial number region (registers 0x20–0x27) can be permanently locked via the SNLOCK bit (bit 7 of register 0x0B). Once set, the serial number becomes read-only and cannot be altered even with VBAK applied. This lock is irreversible and survives power cycling, making it suitable for cryptographic key binding and anti-counterfeiting applications.