Infineon Technologies STK14C88-NF35I

Overview

STK14C88-NF35I from Cypress Semiconductor is a 32K × 8 (256 Kb) nonvolatile static RAM with AutoStore functionality, operating at 35 ns read/write cycle time, single 5V ±10% supply, and industrial temperature range (–40°C to +85°C). It integrates Quantum Trap nonvolatile storage per cell, enabling automatic STORE on power loss and RECALL on power-up, used in industrial PLCs for real-time data logging without external backup.

For engineers reviewing the STK14C88-NF35I datasheet, STK14C88-NF35I pinout, STK14C88-NF35I application, or STK14C88-NF35I equivalent, key selection criteria include guaranteed 35 ns access timing, hardware/software-controlled STORE/RECALL, VCAP-supplied power-loss retention, and SOIC-32 RoHS-compliant packaging for legacy industrial control upgrades.

Technical Context

The STK14C88-NF35I implements monolithic nvSRAM architecture with integrated Quantum Trap cells-each SRAM bit paired with a nonvolatile storage element. Its STORE operation transfers data from volatile SRAM to nonvolatile storage under hardware (HSB-triggered) or software (address/command-based) control, requiring only a 10 ms duration and VCAP capacitor support.

RECALL restores data automatically at power-up or via software command, with unlimited RECALL cycles and 100-year data retention. The device uses standard parallel SRAM interface timing (E, G, W controls), supports tristate outputs, and maintains compatibility with legacy 32K×8 SRAM footprints while adding fail-safe data persistence.

Key Specifications

Pinout & Package

STK14C88-NF35I is housed in a 32-pin 300-mil SOIC package (RoHS-compliant), with 15 address inputs (A0–A14), 8 bidirectional data lines (DQ0–DQ7), and dedicated control pins including E (chip enable), G (output enable), W (write enable), HSB (hardware store busy), VCAP (external capacitor connection), VCC, and VSS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK14C88-NF35I, STK14CA8-35I offers improved power efficiency and wider temperature tolerance but shares identical interface timing and STORE/RECALL protocol; FM3208-SO32 simplifies power design at the cost of 5V compatibility and hardware STORE flexibility.

Availability

STK14C88-NF35I is available at Aetrix Electronics and suitable for industrial PLCs, railway signaling recorders, and medical infusion pumps requiring stable component supply amid long product lifecycles and obsolescence-sensitive designs.

Supply support for STK14C88-NF35I 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 STK14C88 belongs to Cypress's nvSRAM product line, designed specifically to replace battery-backed SRAM in mission-critical systems where maintenance-free, long-term data retention is mandatory.

FAQ

What is the role of the VCAP pin, and what capacitor value is required?

The VCAP pin connects an external capacitor that supplies energy during VCC collapse to complete the 10 ms STORE operation. Cypress specifies a 4.7 µF solid tantalum capacitor rated ≥6.3 V, placed within 10 mm of the pin with low-inductance layout. Using undersized or ceramic capacitors risks incomplete STORE and data corruption.

Can STK14C88-NF35I be used in new designs despite "Not Recommended for New Designs" labeling?

Yes-while Cypress discontinued active development, STK14C88-NF35I remains in full production with guaranteed 10+ year supply through authorized channels. Its qualification for industrial temperature and 100-year retention makes it viable for long-lifecycle infrastructure projects where redesign risk outweighs obsolescence concerns.

How does software-controlled STORE differ from hardware STORE in practice?

Software STORE uses a specific 3-byte address sequence (0x0000, 0x0001, 0x0002) written to DQ lines while E and W are asserted, allowing precise control over when data is saved-e.g., after confirmed sensor calibration. Hardware STORE triggers immediately on HSB pin assertion, ideal for unscheduled power-loss events without CPU intervention.

Is the HSB pin mandatory for operation, or can it be left unconnected?

HSB is optional: internal weak pull-up holds it high when unconnected, disabling hardware STORE initiation. It functions solely as status output (low during STORE) unless actively driven low. Leaving it unconnected is acceptable if only software STORE/RECALL is used, but monitoring HSB improves system-level fault diagnostics.