Infineon Technologies STK22C48-NF45TR

Overview

STK22C48-NF45TR from Cypress Semiconductor is a 16-Kbit (2 K × 8) nonvolatile SRAM with AutoStore™ functionality, integrating QuantumTrap™ nonvolatile elements in each memory cell. It operates at 5 V ±10%, delivers 45 ns access time, supports unlimited SRAM read/write cycles, and guarantees 1,000,000 STORE cycles and 100-year data retention. Used in industrial control modules where power-loss resilience and deterministic recall timing are critical.

For engineers reviewing the STK22C48-NF45TR datasheet, STK22C48-NF45TR pinout, STK22C48-NF45TR application, or STK22C48-NF45TR equivalent, key selection criteria include AutoStore initiation method (power-down vs. HSB), VCAP capacitor requirements (68 µF), hardware store busy signaling, and compatibility with legacy 28-pin SOIC-based memory interfaces.

Technical Context

The STK22C48-NF45TR implements a dual-cell architecture: a standard fast SRAM array (32 × 512) paired with parallel QuantumTrap nonvolatile storage. STORE transfers data from SRAM to nonvolatile cells using charge stored on the external VCAP capacitor; RECALL restores data on power-up without external intervention.

AutoStore triggers automatically when VCC drops below VSWITCH (~3.6 V), while hardware STORE is initiated by pulling HSB low - both operations inhibit concurrent SRAM reads/writes. The device uses CMOS-compatible inputs, supports TTL-level OE/CE/WE, and includes built-in low-voltage write inhibition to prevent corruption during brown-out conditions.

Key Specifications

Pinout & Package

STK22C48-NF45TR is housed in a 28-pin 300-mil Small Outline Integrated Circuit (SOIC) package with gull-wing leads and RoHS-compliant finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY14B101PA-SP25XI and FM24CL64B, STK22C48-NF45TR offers the only pin-compatible, parallel-interface nvSRAM with dedicated HSB signaling and proven 45 ns performance in legacy 5 V industrial designs - making it irreplaceable for drop-in upgrades of aging SRAM-based systems.

Availability

STK22C48-NF45TR is available at Aetrix Electronics and suitable for industrial control panels, medical device configuration storage, and energy meter firmware tables requiring stable component supply and long-lifecycle support.

Supply support for STK22C48-NF45TR 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 memory, microcontrollers, and programmable solutions for industrial and automotive markets.

The STK22C48 belongs to Cypress's AutoStore 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 minimum VCAP capacitor value required for reliable AutoStore operation?

The STK22C48-NF45TR requires a minimum 68 µF tantalum or polymer capacitor on the VCAP pin, rated for ≥6 V and ±20% tolerance. This value ensures sufficient energy to complete the 10 ms STORE cycle when VCC collapses from 5 V to below VSWITCH (~3.6 V). Using less capacitance risks incomplete STORE and data loss; values up to 220 µF are supported for extended hold-up time.

Can STK22C48-NF45TR be used without the VCAP capacitor?

No - the VCAP capacitor is mandatory for AutoStore functionality. In AutoStore Inhibit mode (VCC grounded, +5 V applied to VCAP), the capacitor is still required to power the STORE operation triggered by HSB. Omitting VCAP disables all nonvolatile STORE capability, reducing the device to a standard volatile SRAM with no power-loss protection.

How does the HSB pin behave during a STORE operation?

During any STORE (AutoStore, HSB-triggered, or software-initiated), the HSB pin is driven LOW by an internal open-drain driver. It remains LOW until STORE completes (~10 ms), then releases to HIGH via its weak internal pull-up. An external 10 kΩ pull-up to VCAP is required if HSB is used as a system BUSY indicator to ensure clean logic-level signaling.

Is STK22C48-NF45TR suitable for new designs?

Cypress explicitly states "Not Recommended for New Designs" - this part is maintained in production solely to support ongoing manufacturing of legacy systems. For new designs, Infineon recommends migrating to the CY14B series nvSRAMs with enhanced density, SPI/I²C interfaces, and integrated capacitors. However, STK22C48-NF45TR remains fully supported for obsolescence mitigation and repair programs.