Infineon Technologies STK11C68-5L45M

Overview

STK11C68-5L45M from Cypress Semiconductor is a 64 Kbit (8 K × 8) nonvolatile static RAM (nvSRAM) with QuantumTrap technology, delivering 45 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/RECALL and automatic hardware RECALL on power-up - used in avionics data logging, industrial controller state retention, and secure boot configuration memory.

For engineers reviewing the STK11C68-5L45M datasheet, STK11C68-5L45M pinout, STK11C68-5L45M application, or STK11C68-5L45M equivalent, key selection criteria include guaranteed 1,000,000 STORE cycles, 100-year data retention, pin compatibility with standard 28-pin SRAMs, and hardware-level STORE inhibition during low-VCC conditions.

Technical Context

The STK11C68-5L45M implements a dual-array architecture: an 8 K × 8 fast CMOS SRAM core paired with a shadow 8 K × 8 nonvolatile QuantumTrap memory array. STORE and RECALL operations are initiated via six-address software sequences using CE-controlled reads - no dedicated control pins required.

Hardware RECALL triggers automatically when VCC rises above VSWITCH after power-up or brownout, completing in tHRECALL ≤ 20 ms. The device enforces hardware protection by disabling STORE and write operations when VCAP falls below VSWITCH, preventing corruption during unstable supply conditions.

Key Specifications

Pinout & Package

STK11C68-5L45M uses a 28-pad ceramic LCC (Leadless Chip Carrier) package with J-type leads, 300 mil body size, and gold-plated terminations for high-reliability solder joints in harsh environments.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY14B108L-BA25XI and FM24CL64-G, STK11C68-5L45M uniquely delivers parallel SRAM compatibility, automatic hardware RECALL, and full MIL-PRF-38535 qualification - making it irreplaceable in legacy avionics and safety-critical control systems requiring zero-firmware nonvolatile behavior.

Availability

STK11C68-5L45M is available at Aetrix Electronics and suitable for avionics data logging, industrial PLC state retention, and military radio secure boot applications requiring stable component supply, long-term obsolescence management, and traceable sourcing for DO-254 and MIL-HDBK-217F compliance.

Supply support for STK11C68-5L45M 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 programmable systems-on-chip, and automotive-grade ICs.

The STK11C68 series was developed specifically for mission-critical systems needing battery-free nonvolatility, deterministic power-loss recovery, and extended temperature operation - targeting defense, aerospace, and industrial control markets.

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 supplies energy during STORE and RECALL operations. This capacitor maintains sufficient voltage to complete nonvolatile transfers when VCC drops or is removed. Datasheet-specified tolerance is ±20%, and ESR must be ≤ 1 Ω. Use only solid tantalum or polymer types - aluminum electrolytics are prohibited due to leakage and ESR drift.

Can STK11C68-5L45M be used as a direct replacement for standard 28-pin SRAMs like the HM62256?

Yes - STK11C68-5L45M is pin- and function-compatible with industry-standard 28-pin 64 Kb SRAMs. All control (CE, WE, OE), address (A0–A12), and data (DQ0–DQ7) signals match. No hardware changes are needed; however, firmware must avoid the six-address STORE/RECALL sequences unless nonvolatile functionality is intended.

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

Hardware RECALL initiates automatically within 100 µs of VCC crossing VSWITCH and completes in ≤20 ms - fully autonomous and immune to firmware faults. Software RECALL requires six precise CE-controlled reads and takes up to 25 ms, but allows selective recall at any time. Both preserve nonvolatile data indefinitely and restore identical SRAM contents.

Is the STK11C68-5L45M compliant with modern RoHS and REACH requirements?

Yes - STK11C68-5L45M meets RoHS Directive 2011/65/EU (Pb-free terminations) and REACH SVHC thresholds. Its ceramic LCC package contains no intentionally added cadmium, mercury, hexavalent chromium, or polybrominated flame retardants. Certificate of Compliance is available upon request for AS9100 and ISO 14001-certified programs.