Infineon Technologies FM31278-G

Overview

FM31278-G 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, 1.15 µA RTC backup current at 2 V, and I²C interface up to 1 MHz - deployed in industrial metering, battery-backed data loggers, and secure embedded controllers.

For engineers reviewing the FM31278-G datasheet, FM31278-G pinout, FM31278-G application, or FM31278-G equivalent, key selection considerations include F-RAM write endurance vs. EEPROM, RTC BCD calendar with leap-year support through 2099, programmable VDD reset threshold (4.0–5.5 V operation), battery-backed event counting on CNT1/CNT2, and I²C slave address configuration via A0/A1 pins.

Technical Context

The FM31278-G integrates two logically independent I²C devices on one die: 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; companion registers are mapped to 25 dedicated I²C addresses (0x00–0x18).

Its RTC operates from VBAK (3 V battery/capacitor) while maintaining BCD-encoded time/date with software calibration, 32.768 kHz crystal support, and leap-year tracking through 2099. The supervisor provides active-low open-drain RST with programmable trip point, 100 ms reset pulse width, and flag-based reset source identification (VDD drop vs. watchdog timeout).

Key Specifications

Pinout & Package

FM31278-G is housed in a 14-pin Small Outline Integrated Circuit (SOIC) package with standard 1.27 mm pitch and RoHS-compliant finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DS1339+T&R and M41T83Q6, FM31278-G uniquely combines ultra-high-endurance F-RAM, dual battery-backed counters, and lockable identity in one package - enabling long-life, tamper-evident, time-synchronized data acquisition without wear management overhead.

Availability

FM31278-G is available at Aetrix Electronics and suitable for industrial metering, secure access systems, and medical diagnostics requiring stable component supply, long-term data integrity, and battery-backed timekeeping.

Supply support for FM31278-G 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 German semiconductor leader specializing in power management, sensing, connectivity, and security solutions for industrial, automotive, and IoT applications.

The FM31278-G belongs to Infineon's integrated processor companion product line, designed to replace discrete RTC, supervisor, memory, and counter functions in resource-constrained embedded systems with guaranteed data reliability and long-term maintainability.

FAQ

What is the maximum I²C clock frequency supported by FM31278-G?

The FM31278-G supports Fast Mode Plus I²C operation up to 1 MHz. It maintains backward compatibility with standard (100 kHz) and fast (400 kHz) modes. Timing compliance is verified per I²C specification, including rise/fall time control on SDA and Schmitt-triggered noise immunity on both SDA and SCL inputs.

How does the FM31278-G handle power transitions between VDD and VBAK?

When VDD drops below the programmable reset threshold, the RTC, event counters, and serial number remain powered by VBAK. The F-RAM retains data without external power due to ferroelectric nonvolatility. Supervisor functions (RST, PFI, watchdog) cease operation during VDD loss but resume immediately upon VDD restoration above the trip point.

Can the FM31278-G's event counters operate without a VBAK supply?

No. CNT1 and CNT2 counters are battery-backed and require a valid VBAK supply (3 V battery or capacitor) to retain count values during VDD loss. If VBAK is tied to ground, counters reset to zero on power-up and do not increment during VDD operation - they are not functional without backup power.

Is the 64-bit serial number truly immutable after locking?

Yes. Once the write-lock bit (bit 7 of register 0Bh) is set, the 64-bit serial number area becomes permanently read-only. No subsequent I²C command - including full memory erase - can modify its contents. This hardware-enforced immutability is verified in production test and documented in the Cypress/Infineon datasheet Rev. *F, page 7.