Infineon Technologies FM31L278-GTR

Overview

FM31L278-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 counters, and 64-bit lockable serial number in a single 14-pin SOIC package. It operates from 2.7 V to 3.6 V, retains data for 151 years, endures 10¹⁴ read/write cycles, and supports I²C up to 1 MHz - deployed in industrial metering, medical data loggers, and backup-critical embedded controllers.

For engineers reviewing the FM31L278-GTR datasheet, FM31L278-GTR pinout, FM31L278-GTR application, or FM31L278-GTR equivalent, key selection considerations include F-RAM endurance vs. EEPROM, battery-backed RTC/calendar with leap-year support through 2099, programmable reset threshold (VTP), dual edge-triggered event counters, and I²C address select pins (A0/A1) enabling up to four devices on one bus.

Technical Context

The FM31L278-GTR integrates two logically independent I²C slave devices: a 32K × 8 F-RAM memory block (slave address 0x50–0x53) and a companion peripheral block (slave address 0x68) hosting RTC, supervisor, counters, and comparator. Memory access uses standard two-byte addressing with NoDelay™ writes and software-configurable write protection via WP0/WP1 bits.

RTC functionality runs continuously from VBAK (battery/capacitor backup), maintaining BCD-encoded time/date (seconds to centuries), supporting crystal calibration, and tracking leap years through 2099. The supervisor provides active-low open-drain RST output triggered by either programmable VDD undervoltage or watchdog timeout, with 100 ms reset pulse width and source-flagging register.

Key Specifications

Pinout & Package

FM31L278-GTR is housed in a 14-pin small outline integrated circuit (SOIC) package with 1.27 mm pitch, RoHS-compliant, UL-recognized for trickle-charge operation with lithium batteries.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS3231M+ and MAX31341, FM31L278-GTR uniquely delivers 256-Kbit F-RAM, dual battery-backed event counters, and lockable serial number in one I²C device - reducing BOM count and PCB area while enabling secure, high-endurance, power-fail-resilient logging.

Availability

FM31L278-GTR is available at Aetrix Electronics and suitable for smart metering, industrial data logging, medical diagnostics, and POS terminal applications requiring stable component supply, long-life data retention, and robust power-fail handling.

Supply support for FM31L278-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 systems, sensors, and microcontrollers for industrial, automotive, and IoT applications.

The FM31L278-GTR belongs to Infineon's integrated processor companion product line, designed to replace discrete RTC, supervisor, nonvolatile memory, and event counter ICs in resource-constrained embedded systems requiring high reliability and extended data retention.

FAQ

What backup power sources are supported on VBAK?

VBAK accepts a 3 V lithium coin cell (e.g., CR2032) or a large-value tantalum/ceramic capacitor (≥0.1 F). The internal UL-recognized trickle charger limits current to safe levels for lithium chemistry. If no backup is used, VBAK must be tied to ground and the VBC bit cleared in RTC register 0Bh to disable charging.

How does the FM31L278-GTR handle I²C bus contention between memory and companion functions?

The FM31L278-GTR presents two independent I²C slave addresses: memory block (0x50–0x53) and companion block (0x68–0x6B). This separation allows concurrent access - e.g., reading RTC time while writing sensor data to F-RAM - without arbitration conflict or internal bus locking.

Can the event counters operate without VDD applied?

Yes. When VDD drops below operating range, the CNT1 and CNT2 inputs remain functional as long as VBAK ≥ 2.0 V. Each counter retains its value and increments on detected edges (programmable rising/falling), enabling tamper detection during main power loss.

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

Yes. After writing the 64-bit serial number, the LOCK bit in register 0Bh can be set to permanently disable further writes to that field. Once locked, the value cannot be altered - even by reprogramming or power cycling - providing hardware-enforced uniqueness for security or traceability.