Infineon Technologies STK14CA8-RF35I

Overview

STK14CA8-RF35I from Cypress Semiconductor is a 128K × 8 (1 Mb) nonvolatile static RAM with integrated QuantumTrap storage, operating at 3.0V ±10%, delivering 35 ns read/write cycle time, automatic power-loss STORE and power-up RECALL, and 20-year data retention at 55°C. It serves as a drop-in SRAM replacement in industrial control modules requiring persistent memory without external backup.

For engineers reviewing the STK14CA8-RF35I datasheet, STK14CA8-RF35I pinout, STK14CA8-RF35I application, or STK14CA8-RF35I equivalent, key selection criteria include AutoStore timing (12.5 ms), HSB hardware busy signaling, VCAP capacitor interface (17–120 µF), and industrial temperature support (–40°C to +85°C).

Technical Context

The STK14CA8-RF35I integrates a 1024 × 1024 SRAM array with per-cell QuantumTrap nonvolatile elements, enabling monolithic STORE/RECALL without external controllers. Its dual-mode operation supports both automatic power-loss detection and software- or hardware-triggered STORE via HSB pin assertion.

It uses standard parallel SRAM timing with E/G/W control logic, maintains full SRAM read/write endurance (>10¹² cycles), and isolates nonvolatile operations via dedicated VCAP supply - decoupling STORE current (3 mA avg.) from main VCC rail during power collapse.

Key Specifications

Pinout & Package

STK14CA8-RF35I is packaged in a 48-pin SSOP (RF package), footprint-optimized for high-density PCB layouts while maintaining thermal performance (θja = 41.8°C/W at 500 fpm airflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK14CA8-RF35I, the SOIC variant sacrifices HSB flexibility for smaller area, while the FM1808 demands more complex power management - making the RF35I optimal for new industrial designs prioritizing robustness and ease of integration.

Availability

STK14CA8-RF35I is available at Aetrix Electronics and suitable for industrial PLCs, medical instrumentation, telecom infrastructure, and smart metering systems requiring stable component supply and guaranteed long-term availability.

Supply support for STK14CA8-RF35I 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 U.S.-based semiconductor company specializing in high-reliability memory, PSoC, and USB solutions for industrial and automotive markets.

The STK14CA8 belongs to Cypress's nvSRAM product line, engineered specifically to replace battery-backed SRAM and EEPROM in mission-critical systems where data persistence must survive uncontrolled power events without external supervision.

FAQ

What is the role of the VCAP pin and how is its capacitance value determined?

The VCAP pin connects an external capacitor (17–120 µF, 5V rated) that supplies energy to complete the nonvolatile STORE operation when VCC drops below 2.65 V. Capacitance is selected based on worst-case VCC droop rate and required STORE duration (12.5 ms); larger values extend hold-up time but increase board area and cost.

Can STK14CA8-RF35I be used as a direct replacement for standard SRAMs?

Yes - it is pin- and function-compatible with standard 128K × 8 SRAMs using E/G/W control, but requires adding a VCAP capacitor and observing STORE/RECALL timing constraints. No firmware changes are needed for basic read/write, though leveraging AutoStore requires minimal initialization code.

How does the HSB pin function during STORE and RECALL operations?

HSB is an open-drain output that goes low during STORE or RECALL to signal active nonvolatile operation. It can also be driven low externally to initiate a hardware STORE. Internal weak pull-up holds it high when unused, making connection optional unless hardware triggering is required.

Is STK14CA8-RF35I recommended for new designs despite the "Not Recommended" note in the datasheet?

No - Cypress explicitly marks STK14CA8 as "Not Recommended for New Designs" due to obsolescence planning; however, Aetrix Electronics maintains active inventory and supply chain support for legacy industrial programs requiring continuity, with documented migration paths to Infineon's newer nvSRAM families upon request.