Infineon Technologies STK11C68-5C45M

Overview

STK11C68-5C45M from Cypress Semiconductor is a 64 Kbit (8 K × 8) nonvolatile static RAM (nvSRAM) with QuantumTrap technology, offering 45 ns access time, single 5 V ±10% operation, and automatic hardware RECALL on power-up. It functions as a drop-in replacement for standard SRAMs in mission-critical systems requiring data persistence across power cycles, such as avionics black boxes and military telemetry recorders.

For engineers reviewing the STK11C68-5C45M datasheet, STK11C68-5C45M pinout, STK11C68-5C45M application, or STK11C68-5C45M equivalent, key selection criteria include STORE/RECALL cycle timing (tSTORE = 10 ms typ., tRECALL = 10 ms typ.), 1,000,000 nonvolatile STORE endurance, 100-year data retention, and compatibility with military temperature range (–55 °C to +125 °C).

Technical Context

The STK11C68-5C45M integrates a standard 8 K × 8 SRAM array with a parallel nonvolatile memory array using QuantumTrap cell technology. Each SRAM byte has a dedicated nonvolatile shadow cell, enabling independent read/write cycling (unlimited) and discrete STORE/RECALL operations without shared wear mechanisms.

STORE is initiated via a six-address software sequence (0x0000 → 0x1555 → 0x0AAA → 0x1FFF → 0x10F0 → 0x0F0F) using CE-controlled reads; RECALL uses identical sequencing ending at 0x0F0E. Hardware RECALL triggers automatically when VCC rises above VSWITCH after power loss, completing in tHRECALL ≤ 15 ms.

Key Specifications

Pinout & Package

STK11C68-5C45M is packaged in a 28-pin Ceramic Dual In-line Package (CDIP), 300 mil width, hermetically sealed for high-reliability military use. Pin layout follows JEDEC MS-011AC standard.

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, STK11C68-5C45M uniquely delivers parallel-bus compatibility, hardware-triggered RECALL, and built-in voltage-monitoring protection - making it the sole choice for retrofitting legacy military computing platforms requiring zero-firmware nvRAM behavior.

Availability

STK11C68-5C45M is available at Aetrix Electronics and suitable for avionics data logging, tactical radio configuration storage, and military vehicle engine control units requiring stable component supply across extended product lifecycles.

Supply support for STK11C68-5C45M 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 memory and programmable solutions for aerospace, defense, and industrial markets, with focus on radiation-tolerant and extended-temperature operation.

The STK11C68 series was developed specifically for military and avionics applications demanding guaranteed data retention without batteries or external support components - emphasizing deterministic STORE/RECALL timing and hardware-level fault containment.

FAQ

What is the minimum VCC required to complete a STORE operation?

STORE requires VCC ≥ 4.5 V to guarantee proper QuantumTrap cell programming voltage margin. Below this threshold, hardware protection inhibits STORE initiation, and the device enters standby mode. The datasheet specifies that STORE is only valid across the full military operating range (4.5 V to 5.5 V), with tSTORE = 10 ms typical at VCC = 5.0 V and TA = 25 °C.

Can STK11C68-5C45M be used in place of a standard 28-pin SRAM without design changes?

Yes - it is pin- and function-compatible with industry-standard 28-pin 8 K × 8 SRAMs (e.g., HM6264, IS61C256). All control signals (CE, WE, OE), address (A0–A12), and data (DQ0–DQ7) pins match exactly. No PCB or firmware modifications are needed for basic SRAM operation; STORE/RECALL features remain inactive unless explicitly invoked.

How does hardware RECALL interact with ongoing SRAM writes during power-up?

If a write cycle is active when VCC crosses VSWITCH, SRAM data may be corrupted because RECALL clears the SRAM before reloading nonvolatile content. Cypress recommends pulling CE or WE high via a 10 kΩ resistor to VCC to force chip disable during power ramp, ensuring RECALL completes before any host access. This is documented in the Hardware RECALL section (Page 4).

Is VCAP pin required for normal operation, and what value capacitor is recommended?

VCAP is mandatory for nonvolatile STORE operation - it supplies charge for QuantumTrap programming. A 4.7 µF tantalum or low-ESR ceramic capacitor must be connected between VCAP and VSS, placed within 10 mm of the package. Without VCAP, STORE fails silently; RECALL remains functional using VCC alone. Datasheet Figure 5 shows recommended layout and decoupling.