Infineon Technologies CY14B256K-SP25XC

Overview

CY14B256K-SP25XC from Cypress Semiconductor is a 256 Kbit (32K × 8) nonvolatile SRAM with integrated real-time clock, supporting 25 ns access time, 3.0 V ±10% operation, and QuantumTrap™ nonvolatile storage. It performs automatic STORE on power loss using VCAP capacitor backup, delivers 350 nA RTC standby current, and integrates alarm, watchdog timer, and hardware/software-initiated STORE/RECALL - deployed in industrial data loggers for persistent timestamped sensor memory.

For engineers reviewing the CY14B256K-SP25XC datasheet, CY14B256K-SP25XC pinout, CY14B256K-SP25XC application, or CY14B256K-SP25XC equivalent, key selection criteria include VCAP-based AutoStore timing, RTC interrupt routing via INT pin, HSB-controlled hardware store arbitration, and compatibility with STK17T88 in legacy 48-pin SSOP designs.

Technical Context

The device integrates SRAM and QuantumTrap nonvolatile cells in a single die, enabling parallel STORE/RECALL across all 32K bytes without byte-level latency. Its RTC includes leap-year correction, programmable oscillator calibration, and alarm interrupts configurable for seconds-to-days periodicity.

STORE operations are triggered by three independent mechanisms: software address sequence (six specific CE-reads), hardware assertion of HSB pin, or autonomous voltage-drop detection at VSWITCH (≈2.0 V). RECALL occurs automatically on power-up or via software sequence, with tHRECALL ≤ 20 ms and tSTORE ≤ 25 ms (typical).

Key Specifications

Pinout & Package

48-pin SSOP (ROHS compliant), 0.300-inch body width, 0.025-inch pitch. Package meets JEDEC MS-012AC, thermal resistance θJA = 120°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nvSRAM with RTC applications.

Compared with STK17T88-35I and MAX6900A, CY14B256K-SP25XC uniquely combines fast SRAM, autonomous power-loss STORE, and full-featured RTC in one package - reducing component count, eliminating external STORE control circuitry, and enabling deterministic data recovery without host firmware dependency.

Availability

CY14B256K-SP25XC is available at Aetrix Electronics and suitable for industrial data loggers, medical patient monitors, smart utility meters, and PLC configuration storage requiring stable component supply and long-term lifecycle support.

Supply support for CY14B256K-SP25XC 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

Cypress Semiconductor (now part of Infineon Technologies) designs high-reliability mixed-signal ICs for industrial, automotive, and IoT applications, with expertise in nonvolatile memory and timing solutions.

The CY14B series targets systems needing persistent memory with precise timekeeping - specifically engineered for applications where data loss during power interruption is unacceptable and RTC integration reduces design complexity.

FAQ

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

The datasheet specifies a nominal 10 µF tantalum or polymer capacitor on VCAP, with ±20% tolerance. Using less than 8 µF risks incomplete STORE execution under worst-case voltage droop; exceeding 12 µF increases inrush current stress on the internal charge pump transistor, potentially degrading long-term reliability. Cypress recommends verifying VCAP discharge profile with oscilloscope during actual power-fail testing.

Can the RTC operate independently while the SRAM is disabled?

Yes. The RTC continues running from VRTCcap or VRTCbat even when VCC is absent or CE is HIGH. Its 350 nA current draw allows continuous timekeeping for over a decade on a 1 µF capacitor. The SRAM remains powered down and inaccessible, but RTC registers, alarm settings, and oscillator remain fully functional and retain state.

How does the CY14B256K-SP25XC prevent accidental STORE during brownout conditions?

It uses dual protection: (1) STORE operations are inhibited when VCC falls below VSWITCH (≈2.0 V), and (2) software STORE sequences are aborted if any intervening READ/WRITE occurs between the six required addresses. Additionally, WRITE operations are blocked during low-voltage conditions, preventing corrupted data from being latched into SRAM before RECALL completes.

Is the HSB pin mandatory for system design?

No. HSB is optional: if unused, it may be left unconnected (internal weak pull-up holds it HIGH). When used, it provides both STORE initiation and real-time busy indication - allowing the host MCU to pause writes during STORE and avoid data loss. Its omission simplifies layout but removes hardware-triggered STORE capability and real-time STORE progress visibility.