Infineon Technologies FM31278-GTR

Overview

FM31278-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 battery-backed event counters, and 64-bit lockable serial number in a single 14-pin SOIC package. It operates from 4.0 V to 5.5 V, supports I²C up to 1 MHz, and retains data for 151 years with 10¹⁴ write endurance - deployed in industrial metering, backup-critical embedded controllers, and secure logging systems.

For engineers reviewing the FM31278-GTR datasheet, FM31278-GTR pinout, FM31278-GTR application, or FM31278-GTR equivalent, key selection considerations include its NoDelay™ F-RAM write capability, programmable reset threshold (VTP), RTC BCD calendar with leap-year support through 2099, battery-backed event counting on CNT1/CNT2, and dual I²C device addressing for memory vs. companion register access.

Technical Context

The FM31278-GTR implements two logically independent I²C slave devices on one die: a 32K × 8 F-RAM array (slave address 0x50–0x53) and a companion peripheral block (slave address 0x68) containing RTC, supervisor, comparator, and counters. All timekeeping and nonvolatile state persist under VBAK backup power (3 V battery/capacitor), decoupled from main VDD operation.

Its supervisor uses a programmable voltage threshold (VTP bits in register 0Bh) to trigger RST assertion at 4.63 V, 4.38 V, 4.00 V, or 3.07 V; the watchdog timer offers 100 ms to 3 s timeout with software restart; and the PFI comparator compares external voltage to an internal 1.2 V reference to generate early power-fail interrupts.

Key Specifications

Pinout & Package

FM31278-GTR 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 MCP79410-I/SN, FM31278-GTR uniquely combines ultra-high-endurance F-RAM, battery-backed dual counters, and lockable identity in one I²C device - reducing BOM count, eliminating write latency, and enabling secure, long-life embedded logging without compromise.

Availability

FM31278-GTR is available at Aetrix Electronics and suitable for industrial metering, medical diagnostics, and secure firmware boot applications requiring stable component supply, long-term data integrity, and guaranteed 151-year retention without battery dependency.

Supply support for FM31278-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 memory solutions for automotive, industrial, and IoT markets.

The FM31278-GTR belongs to Infineon's integrated processor companion product line - designed specifically to consolidate nonvolatile memory, real-time clock, and system supervision into a single, reliable, low-power device for mission-critical embedded applications.

FAQ

What backup power sources are supported for VBAK?

VBAK accepts either a 3 V lithium coin cell (e.g., CR2032) or a high-capacitance backup capacitor. The integrated UL-recognized trickle charger regulates charging current to prevent overcurrent with lithium batteries. If no backup is used, VBAK must be tied to ground and the VBC bit cleared in RTC register 0Bh to disable charging circuitry.

How does the FM31278-GTR handle I²C bus contention between memory and companion functions?

The FM31278-GTR uses two distinct I²C slave addresses: 0x50–0x53 for F-RAM access and 0x68 for RTC/supervisor registers. This separation prevents bus contention - memory reads/writes and RTC register updates occur independently, enabling concurrent timestamping and data logging without arbitration delay.

Can the event counters operate without VDD applied?

Yes - CNT1 and CNT2 remain fully functional under VBAK-only power. When VDD drops below operational threshold, the counters continue incrementing on detected edges, preserving intrusion or maintenance event counts across power cycles. Their 16-bit values are retained in battery-backed RAM until explicitly read or reset via I²C.

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

Yes - once the LOCK bit in register 0Bh is set, the 64-bit serial number area becomes permanently read-only. No software command or hardware condition can clear or rewrite it. This hardware-enforced lock ensures cryptographic binding of firmware to a unique, immutable device identity for anti-cloning and secure boot validation.