Infineon Technologies CY14B256K-SP45XIT

Overview

CY14B256K-SP45XIT from Cypress Semiconductor is a 256 Kbit (32K × 8) nonvolatile SRAM with integrated real-time clock, operating at 3V ±10%, featuring 45 ns access time, 350 nA RTC standby current, and QuantumTrap™ nonvolatile storage. It performs automatic STORE on power loss using VCAP capacitor backup and supports software/hardware-initiated STORE/RECALL cycles in industrial control and metering systems.

For engineers reviewing the CY14B256K-SP45XIT datasheet, CY14B256K-SP45XIT pinout, CY14B256K-SP45XIT application, or CY14B256K-SP45XIT equivalent, key selection criteria include RTC accuracy with leap-year support, AutoStore timing under voltage drop (VSWITCH = 2.7 V), infinite SRAM read/write endurance, and HSB-controlled hardware store coordination with microprocessor reset sequencing.

Technical Context

The device integrates a standard fast SRAM array (512 × 512) with parallel-coupled QuantumTrap nonvolatile cells, enabling simultaneous STORE/RECALL of all 32K bytes. Its RTC includes programmable alarm (seconds to days), watchdog timer, and temperature-compensated 32.768 kHz oscillator with calibration register at 0x7FF8.

STORE operations are triggered by power-down (via VCAP discharge below VSWITCH), HSB pin assertion, or six-address software sequence (0x0E38 → 0x0FC0); RECALL occurs automatically on power-up or via software sequence ending at 0x0C63. All SRAM accesses are inhibited during STORE/RECALL, with tSTORE = 20 ms and tRECALL = 15 ms typical.

Key Specifications

Pinout & Package

48-pin SSOP (ROHS compliant), 0.300-inch body width, 0.025-inch pitch. Package supports automated optical inspection and reflow-compatible thermal profile.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK17T88-35I and FM31L278, CY14B256K-SP45XIT uniquely combines 45 ns SRAM speed, full RTC feature set (alarm, watchdog, leap year), and capacitor-based AutoStore-enabling maintenance-free operation in harsh, frequently cycled environments.

Availability

CY14B256K-SP45XIT is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, medical infusion pumps, and automotive event recorders requiring stable component supply and long-term data integrity.

Supply support for CY14B256K-SP45XIT 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 computing applications, with emphasis on nonvolatile memory and timing solutions.

The CY14B series targets applications demanding seamless SRAM functionality plus guaranteed data retention during power failure-designed specifically for metering, control, and safety-critical logging where battery maintenance is impractical.

FAQ

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

The datasheet specifies 100 µF as the typical value for VCAP, with minimum 47 µF and maximum 220 µF. Using >220 µF risks excessive inrush current that may degrade the internal pass transistor. At 2.7 V VCC dropout threshold, 100 µF ensures ≥20 ms STORE time with margin for aging and temperature drift.

How does the CY14B256K-SP45XIT handle power-up sequencing with an external microcontroller?

On power-up, the device performs automatic RECALL before releasing HSB HIGH. The MCU must hold WE inactive (e.g., via 10 kΩ pull-up) until RECALL completes (~15 ms). If the MCU asserts WE before RECALL finishes, writes are inhibited until VCC exceeds VSWITCH and RECALL completes-preventing partial or corrupted data writes.

Can the RTC operate independently while the SRAM is disabled?

Yes-the RTC runs continuously from VRTCcap or VRTCbat regardless of VCC state or SRAM enable status. Its 350 nA current draw allows >10-year operation on a 220 mAh CR2032 cell. The RTC maintains time, date, alarm, and watchdog functions even when CE/OE/WE are all HIGH and the SRAM is fully deselected.

Is the software STORE sequence susceptible to bus contention or noise-induced corruption?

Yes-interruption of the six-address READ sequence (e.g., by an unintended WRITE or address glitch) aborts STORE initiation. To mitigate, execute the sequence with CE-controlled reads only, disable interrupts during the sequence, and ensure stable VCC (>2.7 V) and clean clock edges. No retry mechanism exists; firmware must verify post-STORE SRAM content if critical.