Infineon Technologies STK14C88-3NF35I

Overview

STK14C88-3NF35I from Cypress Semiconductor is a 256 Kbit (32K × 8) nonvolatile static RAM with AutoStore functionality, QuantumTrap nonvolatile cell architecture, 35 ns access time, single 3.3 V ±0.3 V supply, and industrial temperature range (–40°C to +85°C). It performs automatic STORE on power loss and RECALL on power-up, used in mission-critical data logging systems where volatile SRAM persistence is required without external backup circuitry.

For engineers reviewing the STK14C88-3NF35I datasheet, STK14C88-3NF35I pinout, STK14C88-3NF35I application, or STK14C88-3NF35I equivalent, key selection factors include VCAP capacitor sizing (68–220 µF), HSB hardware store synchronization, software STORE/RECALL address sequence integrity, and compatibility with 32-pin SOIC footprint in industrial control and telecom infrastructure designs.

Technical Context

The STK14C88-3NF35I integrates standard SRAM array (512 × 512) with parallel QuantumTrap nonvolatile cells per bit, enabling simultaneous STORE/RECALL across all 32,768 bytes. Its dual-mode operation supports both autonomous power-loss-triggered STORE and deterministic software- or hardware-initiated STORE/RECALL cycles.

Control logic enforces strict sequencing: software STORE requires six exact CE-controlled READs at addresses 0x0E38, 0x31C7, 0x03E0, 0x3C1F, 0x303F, and 0x0FC0; RECALL uses identical sequence ending at 0x0C63. During STORE/RECALL, SRAM read/write is inhibited, and HSB asserts open-drain LOW to signal busy status.

Key Specifications

Pinout & Package

STK14C88-3NF35I is housed in a 32-pin SOIC (300-mil width) package with standard JEDEC MS-012AC footprint. Pin assignments are electrically identical to PDIP variant but optimized for surface-mount assembly and thermal performance in dense PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK14C88-3NF35I, STK14CA8-3AF35I offers improved supply margin without changing board layout, while FM24V02A-G trades deterministic nonvolatile persistence for zero-latency writes-making it suitable only where STORE cycle blocking cannot be tolerated.

Availability

STK14C88-3NF35I is available at Aetrix Electronics and suitable for industrial PLC data logging, telecom base station configuration storage, and medical infusion pump runtime state retention requiring stable component supply and long-lifecycle support.

Supply support for STK14C88-3NF35I 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 STK14C88 product line delivers nonvolatile SRAMs optimized for deterministic data persistence in safety-critical systems where battery-free, long-retention memory is mandatory.

FAQ

What is the minimum VCAP capacitor value required for reliable AutoStore operation?

The STK14C88-3NF35I requires a minimum 68 µF tantalum or polymer capacitor rated at 4.7 V on the VCAP pin. Values below this threshold may cause incomplete STORE cycles during rapid VCC dropout. Capacitor ESR must remain under 1 Ω to ensure sufficient discharge current for full 256 Kbit transfer within tSTORE (max 20 ms).

Can STK14C88-3NF35I be used in place of standard SRAM without modifying existing firmware?

No-direct substitution is not possible without firmware changes. The device requires explicit handling of HSB status polling before critical writes, and software STORE/RECALL sequences must be implemented. Standard SRAM read/write timing is preserved, but nonvolatile operations introduce mandatory inhibit windows where bus access is blocked.

How does the HSB pin behave during multi-device STORE synchronization?

When multiple STK14C88-3NF35I devices share a common HSB net and VCAP capacitor, any device detecting VCC dropout pulls HSB LOW, triggering STORE in all connected parts. Each device independently verifies whether a WRITE occurred since last nonvolatile cycle before executing STORE-ensuring atomicity without centralized arbitration logic.

Is STK14C88-3NF35I still recommended for new designs?

No-Cypress documentation explicitly marks STK14C88-3 as "Not Recommended for New Designs." While fully supported for existing production, Infineon recommends migrating to STK14CA8-3AF35I for new projects due to enhanced voltage tolerance, updated qualification, and continued long-term supply assurance.