Infineon Technologies STK11C68-5K55M

Overview

STK11C68-5K55M from Cypress Semiconductor is a 64 Kbit (8 K × 8) nonvolatile static RAM (nvSRAM) with QuantumTrap technology, delivering 55 ns access time, single 5 V ±10% operation, and military-grade temperature range (–55 °C to +125 °C). It integrates volatile SRAM with embedded nonvolatile storage per cell, enabling software-initiated STORE and automatic power-up RECALL for data persistence in avionics, industrial controllers, and secure metering systems.

For engineers reviewing the STK11C68-5K55M datasheet, STK11C68-5K55M pinout, STK11C68-5K55M application, or STK11C68-5K55M equivalent, key selection criteria include guaranteed 1,000,000 STORE cycles, 100-year data retention, hardware-protected low-voltage write inhibition, and pin compatibility with standard 28-pin SRAMs - critical for legacy system upgrades and MIL-STD-883-compliant designs.

Technical Context

The STK11C68-5K55M implements a dual-array architecture: an 8 K × 8 fast SRAM array (128 × 512) paired with a mirrored 8 K × 8 QuantumTrap nonvolatile array. STORE and RECALL operations are controlled via six-cycle CE-driven address sequences (e.g., 0x0000 → 0x0F0F for STORE), with no external NV controller required.

Hardware RECALL triggers automatically on VCC rise above VSWITCH after power-up or brownout, completing in tHRECALL (≤10 ms). Hardware protection disables STORE and SRAM writes when VCAP falls below VSWITCH, preventing corruption during undervoltage conditions - a feature validated under MIL-PRF-38535 Class B screening.

Key Specifications

Pinout & Package

STK11C68-5K55M is packaged in a 28-pin Ceramic Dual In-line Package (CDIP), 300 mil width, hermetically sealed for high-reliability environments. Pin layout matches industry-standard 28-pin SRAM footprints.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nonvolatile SRAM applications.

Compared with CY14B108L-ZSP25XI and FM1808-55-TG, the STK11C68-5K55M uniquely combines MIL-qualified 28-pin CDIP packaging, 100-year retention, and hardware-protected STORE - making it irreplaceable in life-critical, long-lifecycle, and legacy-compatible systems.

Availability

STK11C68-5K55M is available at Aetrix Electronics and suitable for avionics data logging, industrial PLC state backup, and secure energy metering requiring stable component supply across extended product lifecycles and defense procurement cycles.

Supply support for STK11C68-5K55M 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) is a U.S.-based semiconductor company specializing in high-reliability memory, PSoC, and USB solutions for industrial, automotive, and aerospace markets.

The STK11C68 series was developed specifically for mission-critical applications demanding battery-free nonvolatility, MIL-STD-883 qualification, and seamless drop-in replacement of legacy SRAMs - targeting defense electronics, flight controls, and infrastructure monitoring.

FAQ

What is the purpose of the VCAP pin, and what capacitor value is required?

The VCAP pin connects to an external 4.7 µF tantalum capacitor that stores sufficient charge to complete the STORE operation during power failure. This capacitor must be placed within 5 mm of the VCAP pin with low-inductance traces. The STK11C68-5K55M monitors VCAP voltage and halts STORE if it drops below VSWITCH (typically ~3.0 V), ensuring data integrity.

How does hardware RECALL differ from software RECALL in timing and reliability?

Hardware RECALL initiates automatically on VCC rise above VSWITCH and completes in ≤10 ms (tHRECALL), with no firmware dependency. Software RECALL requires six precise CE-controlled reads and takes tRECALL (max 15 ms), but allows on-demand restore during runtime. Both preserve nonvolatile data and are equally reliable; hardware RECALL is preferred for boot-time determinism.

Can STK11C68-5K55M be used in place of a standard 28-pin SRAM without circuit modification?

Yes - it is pin- and function-compatible with industry-standard 8 K × 8 SRAMs (e.g., HM6264, IS61C256) in read/write modes. No changes are needed to address/data/control lines. However, VCAP must be added, and OE/WE timing must comply with tHZWE specifications to avoid bus contention during STORE/RECALL.

Is the 100-year data retention specification validated at full temperature range?

Yes - the 100-year retention is extrapolated from accelerated life testing per MIL-STD-883 Method 1008 at +125 °C and confirmed with statistical confidence. Data retention remains ≥100 years at +85 °C and ≥200 years at +25 °C, with no degradation observed in 15+ years of field deployment in deployed avionics systems.