Infineon Technologies STK12C68-WF45I

Overview

STK12C68-WF45I from Cypress Semiconductor is a 64 Kbit (8K × 8) nonvolatile static RAM with QuantumTrap technology, operating at 5 V ±10%, featuring 45 ns access time, AutoStore on power-down, and hardware/software-controlled STORE/RECALL. It serves as a drop-in SRAM replacement in industrial control systems requiring persistent data retention without battery backup.

For engineers reviewing the STK12C68-WF45I datasheet, STK12C68-WF45I pinout, STK12C68-WF45I application, or STK12C68-WF45I equivalent, key selection criteria include VCAP capacitor support (68 µF), HSB-driven hardware store timing, tSTORE/tRECALL cycle durations, and compatibility with legacy 28-pin SOIC footprints in mission-critical embedded systems.

Technical Context

The STK12C68-WF45I integrates an 8K × 8 SRAM array with parallel-connected QuantumTrap nonvolatile cells per bit, enabling simultaneous STORE/RECALL across all memory locations. Its architecture decouples volatile read/write performance (25–45 ns access) from nonvolatile endurance (1M STORE cycles, 100-year retention).

STORE is triggered automatically at VCC dropout below VSWITCH using charge stored on the external VCAP capacitor, or via HSB assertion or six-address software sequence. RECALL occurs automatically on power-up or via identical six-address sequence ending in 0x0F0E, with SRAM cleared before loading nonvolatile data.

Key Specifications

Pinout & Package

STK12C68-WF45I uses a 28-pin SOIC (300-mil width) package with standard DIP-compatible footprint. Pin functions are electrically and mechanically defined per Cypress Document 001-51027 Rev. *C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK12C68-WF45I, the -WF35I offers faster access but identical reliability and feature set, while FM16W08-SG trades AutoStore simplicity for density and serial interface-requiring new driver development and losing hands-off power-loss protection.

Availability

STK12C68-WF45I is available at Aetrix Electronics and suitable for industrial PLC data logging, medical device configuration storage, and avionics black box memory requiring stable component supply and long-term lifecycle support.

Supply support for STK12C68-WF45I 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 industrial, automotive, and communications markets.

The STK12C68 product line delivers battery-free nonvolatile SRAM for mission-critical systems where data persistence during uncontrolled power loss is mandatory-targeting factory automation, medical electronics, and aerospace applications.

FAQ

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

The STK12C68-WF45I requires a minimum 68 µF capacitor on the VCAP pin, rated at 6 V with ±20% tolerance. This value ensures sufficient stored energy to complete one full STORE cycle when VCC drops below VSWITCH (~3.6 V). Using less capacitance risks incomplete STORE and data loss; larger values (up to 220 µF) improve margin but do not extend endurance or retention.

Can STK12C68-WF45I be used in place of standard SRAM without design changes?

Yes-STK12C68-WF45I is pin- and function-compatible with standard 28-pin 8K × 8 SRAMs (e.g., AS6C8008, IS61LV256AL), provided VCAP is added and WE is pulled up during power-up. No address/data bus or timing changes are needed; AutoStore operates transparently unless explicitly disabled via VCC/VCAP reconfiguration.

How does the software STORE sequence prevent accidental activation?

The six-address software STORE sequence (0x0000 → 0x0F0F) requires consecutive CE-controlled reads with no intervening writes or address violations. Any deviation-such as a write access or incorrect address order-aborts the sequence. This prevents spurious STOREs from noise or firmware errors, ensuring nonvolatile updates occur only under deliberate, validated control flow.

Is STK12C68-WF45I RoHS compliant and halogen-free?

Yes-STK12C68-WF45I meets RoHS Directive 2011/65/EU requirements and is manufactured as a lead-free, halogen-free device per Cypress Document 001-51027 Rev. *C. The 28-pin SOIC package uses matte tin lead finish and complies with JEDEC J-STD-020 moisture sensitivity level 3 (MSL-3) handling guidelines.