Infineon Technologies STK12C68-PF25

Overview

STK12C68-PF25 from Cypress Semiconductor is a 64 Kbit (8K × 8) nonvolatile static RAM with QuantumTrap technology, providing automatic STORE on power loss using an external 68 µF capacitor, 25 ns access time, single 5V ±10% supply, and 100-year data retention. It serves as a drop-in SRAM replacement in mission-critical industrial control, metering, and telecom infrastructure where data persistence across power cycles is mandatory.

For engineers reviewing the STK12C68-PF25 datasheet, STK12C68-PF25 pinout, STK12C68-PF25 application, or STK12C68-PF25 equivalent, key selection criteria include AutoStore timing behavior, HSB-controlled hardware STORE latency, VCAP capacitor sizing constraints, and software STORE/RECALL address sequence compliance.

Technical Context

The STK12C68-PF25 integrates parallel SRAM and QuantumTrap nonvolatile cells per bit, enabling simultaneous STORE/RECALL of all 8,192 bytes. It supports three STORE initiation modes: AutoStore (triggered by VCC drop below VSWITCH), hardware STORE (via HSB pin assertion), and software STORE (six-address CE-controlled read sequence).

RECALL occurs automatically at power-up or via software sequence; both operations inhibit SRAM access for tSTORE (max 10 ms) or tRECALL (max 10 ms). The device enforces write-before-store logic: AutoStore and HSB STORE are ignored unless at least one SRAM write has occurred since last STORE/RECALL.

Key Specifications

Pinout & Package

STK12C68-PF25 is packaged in a 28-pin 300-mil plastic DIP (PDIP) with through-hole mounting and standard 0.3-inch width. Pin layout follows JEDEC MS-001, supporting socket-based prototyping and wave-soldered production.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY14B108L-SP25XI and FM24CL64-G, STK12C68-PF25 delivers true hands-off AutoStore with parallel interface compatibility, eliminating protocol translation and external supervision-critical for deterministic, legacy-system upgrades.

Availability

STK12C68-PF25 is available at Aetrix Electronics and suitable for smart metering, industrial data logging, telecom line card configuration, and medical device audit trail storage requiring stable component supply over extended product lifecycles.

Supply support for STK12C68-PF25 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 fabless semiconductor company specializing in memory, microcontrollers, and programmable solutions for industrial, automotive, and communications markets.

The STK12C68 belongs to Cypress's QuantumTrap nvSRAM product line, designed specifically to replace battery-backed SRAM in applications where maintenance-free, long-term data retention under unpredictable power conditions is essential.

FAQ

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

The STK12C68-PF25 requires a minimum 68 µF capacitor on the VCAP pin, rated at ≥6 V and ±20% tolerance. This value ensures sufficient stored energy to complete the 10 ms STORE cycle even with worst-case VCC droop rates up to 20 µs/V. Lower values risk incomplete STORE and data corruption; larger values (up to 220 µF) improve margin but increase board area and inrush current.

Can STK12C68-PF25 be used without the VCAP capacitor?

Yes, but only in AutoStore Inhibit mode: tie VCC to ground and apply +5 V directly to VCAP. In this configuration, AutoStore is disabled and STORE must be initiated exclusively via software sequence or HSB assertion. All references to VCC in the datasheet then apply to VCAP. This mode is used when deterministic STORE timing is required or when board space prohibits large capacitors.

How does the STK12C68-PF25 prevent unintended STORE during brownout conditions?

The device implements write-before-store logic: AutoStore and HSB-triggered STORE are ignored unless at least one valid SRAM write has occurred since the last STORE or RECALL. This prevents spurious STOREs during transient undervoltage events where the host may not have updated critical data, thereby conserving QuantumTrap endurance and ensuring only meaningful data is preserved.

Is the software STORE sequence compatible with all bus timing configurations?

Yes-the six-address software STORE sequence uses CE-controlled reads and is timing-agnostic: it functions correctly regardless of whether the host uses address-strobe, transparent, or multiplexed bus protocols. Each read must be a valid CE-low access; OE state is irrelevant. Intervening writes or address changes abort the sequence, ensuring robustness against bus noise or timing violations.