Infineon Technologies FM31L276-GTR

Overview

FM31L276-GTR from Infineon Technologies (formerly Cypress) is a 64-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 operates from 2.7 V to 3.6 V, delivers 1.15 µA RTC backup current at 2 V/25 °C, supports 1-MHz I²C interface, and retains data for 151 years with 10¹⁴ read/write endurance - deployed in industrial metering and battery-backed control systems.

For engineers reviewing the FM31L276-GTR datasheet, FM31L276-GTR pinout, FM31L276-GTR application, or FM31L276-GTR equivalent, key selection criteria include F-RAM write endurance vs. EEPROM, RTC BCD calendar accuracy with software calibration, programmable VDD reset threshold, dual battery-backed event counting on CNT1/CNT2, and I²C slave address configuration via A0/A1 pins.

Technical Context

The FM31L276-GTR implements two logically independent I²C devices on one die: an 8K × 8 F-RAM array (slave address 0x50–0x53) and a companion peripheral block (slave address 0x68) housing RTC, supervisor, counters, and comparator. All timekeeping and supervision functions remain active during VDD brownout using VBAK-supplied power.

Its RTC uses a 32.768 kHz crystal (6 pF/12.5 pF load), stores time/date in BCD format through year 2099 including leap-year correction, and supports ±1 ppm software calibration via CAL/PFO output. The supervisor provides active-low open-drain RST with 100 ms reset pulse width, programmable trip point (2.55 V to 2.95 V), and manual reset debouncing.

Key Specifications

Pinout & Package

FM31L276-GTR is housed in a 14-pin small outline integrated circuit (SOIC) package with standard 1.27 mm pitch, RoHS-compliant, UL-recognized trickle charger for lithium backup batteries.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231M+ and RV-3032-C3, FM31L276-GTR uniquely combines high-endurance F-RAM, full supervisor suite, dual event counters, and lockable serial number in one SOIC package - reducing component count by ≥3 while enabling deterministic, long-life data logging in safety-critical systems.

Availability

FM31L276-GTR is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical infusion pumps, and building HVAC controllers requiring stable component supply, long-term data integrity, and battery-backed reliability.

Supply support for FM31L276-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, specializing in power management, sensing, connectivity, and security solutions for automotive, industrial, and IoT applications.

The FM31L276-GTR belongs to Infineon's legacy Cypress processor companion family, designed to replace multiple discrete supervisory, timing, and nonvolatile memory components in resource-constrained embedded systems with high data-integrity demands.

FAQ

What is the maximum I²C clock frequency supported by FM31L276-GTR?

The FM31L276-GTR supports I²C operation up to 1 MHz, with full backward compatibility for legacy 100 kHz and 400 kHz timings. This allows high-speed parameter uploads and timestamped event capture while maintaining interoperability with older controllers. The SDA line features slope control and Schmitt-trigger input for robustness on noisy industrial buses.

How does the FM31L276-GTR handle power failure detection and system reset?

FM31L276-GTR uses its internal 1.2 V reference to compare against the external supply on the PFI pin, generating an early power-fail interrupt (NMI). Simultaneously, its supervisor monitors VDD and asserts the open-drain RST pin when voltage drops below a programmable threshold (2.55–2.95 V), holding reset active for ≥100 ms after recovery - ensuring reliable MCU reset during brownouts.

Can the 64-bit serial number be reprogrammed after initial write?

No - the 64-bit serial number area can be permanently locked via a dedicated hardware bit in register 0Bh. Once locked, the serial number becomes read-only and cannot be altered, providing cryptographic-grade device identity for firmware binding, secure boot, or anti-counterfeiting. Unlocking is not supported in hardware or firmware.

What crystal specifications are required for the RTC to operate correctly?

The FM31L276-GTR requires a standard 32.768 kHz tuning-fork crystal with load capacitance of either 6 pF or 12.5 pF, connected between X1 and X2. The device supports software calibration to compensate for crystal tolerance and aging, achieving ±1 ppm accuracy. External oscillators may be used by driving X1 with a CMOS-level signal and biasing X2 to VDD/2.