Infineon Technologies CY14B256I-SFXI

Overview

CY14B256I-SFXI from Infineon Technologies (formerly Cypress) is a 256-Kbit serial I²C nonvolatile SRAM with integrated real-time clock, organized as 32 K × 8, supporting AutoStore on power-loss via VCAP capacitor, Power-Up RECALL, and full RTC functions including alarm, watchdog timer, and programmable square-wave output (1 Hz to 32.768 kHz). It operates across 2.7–3.6 V and targets industrial data-logging systems requiring deterministic nonvolatile write-back without external controllers.

For engineers reviewing the CY14B256I-SFXI datasheet, CY14B256I-SFXI pinout, CY14B256I-SFXI application, or CY14B256I-SFXI equivalent, key selection criteria include I²C speed support up to 3.4 MHz, RTC backup current (0.45 µA typ), STORE endurance (1 million cycles), data retention (20 years at 85 °C), and hardware STORE/RECALL via HSB pin - all critical for battery-backed instrumentation and edge-node time-stamped storage.

Technical Context

This device integrates two independent functional blocks: a 32 K × 8 nvSRAM using QuantumTrap nonvolatile storage technology and a fully autonomous RTC subsystem with dedicated registers, counters, interrupt logic, and oscillator circuitry. The memory supports zero-cycle-delay reads/writes and three STORE initiation methods (AutoStore, Software STORE, Hardware STORE), while the RTC provides calibrated timekeeping, alarm-triggered interrupts, and configurable square-wave output without host CPU intervention.

The I²C interface complies with standard, fast, fast-plus, and high-speed modes (up to 3.4 MHz), with slave address selectable via A2–A0 pins and write protection enabled by WP pin or software block lock. RTC backup is supported either by capacitor (VRCTcap) or battery (VRCTbat), and INT/SQW serves dual-purpose as interrupt output or programmable clock source.

Key Specifications

Pinout & Package

16-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 nvSRAM+RTC applications.

Compared with STK14CA8-NF55I and DS1347Z+, CY14B256I-SFXI uniquely combines I²C-accessible nvSRAM and autonomous RTC in one SOIC-16 package, eliminating inter-IC timing dependencies and reducing firmware validation scope for time-critical data capture.

Availability

CY14B256I-SFXI is available at Aetrix Electronics and suitable for industrial data loggers, smart metering endpoints, medical diagnostic devices, and PLC I/O modules requiring stable component supply with guaranteed 20-year data retention and deterministic power-loss data preservation.

Supply support for CY14B256I-SFXI 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, automotive MCUs, and secure connectivity solutions.

CY14B256I belongs to Infineon's legacy Cypress nvSRAM product line, designed specifically for applications demanding simultaneous high-speed volatile access, automatic nonvolatile backup, and autonomous real-time timekeeping - bridging the gap between conventional SRAM and battery-backed RTC systems.

FAQ

What is the minimum VCAP capacitance required for reliable AutoStore operation?

The datasheet specifies a minimum 4.7 µF tantalum or ceramic capacitor on VCAP to ensure sufficient energy for complete STORE during VCC dropout. Lower values risk incomplete data transfer; derating to 10 µF is recommended for designs operating near 85 °C or with rapid power decay profiles. Capacitor ESR must be ≤ 1 Ω to meet tSTORE timing requirements.

Can the RTC operate independently while the nvSRAM is in sleep mode?

Yes - the RTC continues running in sleep mode (8 µA typical) as long as VCC or backup power (VRTCcap/VRTCbat) is present. The nvSRAM core is gated, but RTC registers, counters, and alarm logic remain fully active and responsive to I²C reads or interrupt generation.

How does the HSB pin function during a Hardware STORE sequence?

When HSB is pulled LOW externally, the device initiates STORE immediately and drives HSB LOW until completion (tHHHD ≈ 12 ms max). Upon finish, HSB transitions HIGH via internal weak pull-up. This status signal allows host systems to synchronize subsequent actions without polling or fixed delays.

Is the 8-byte serial number factory-programmed and permanently locked?

Yes - the 8-byte serial number is programmed at wafer test and permanently locked after initial write. Once locked via I²C command, it cannot be altered or erased, providing traceability for calibration records or regulatory documentation in medical and industrial deployments.