Infineon Technologies STK22C48-NF45

Overview

STK22C48-NF45 from Cypress Semiconductor is a 16-Kbit (2 K × 8) nonvolatile SRAM with AutoStore™ functionality, integrating SRAM and QuantumTrap™ nonvolatile elements in each cell. It delivers 45 ns access time, operates at single 5 V ±10%, supports hardware STORE via HSB pin, and enables automatic power-loss data retention using an external 68 µF capacitor - deployed in industrial PLCs for real-time parameter backup.

For engineers reviewing the STK22C48-NF45 datasheet, STK22C48-NF45 pinout, STK22C48-NF45 application, or STK22C48-NF45 equivalent, key selection criteria include AutoStore timing behavior, VCAP capacitor sizing, HSB-driven STORE arbitration, and compatibility with legacy 5 V bus systems requiring guaranteed nonvolatile write-on-power-loss.

Technical Context

The STK22C48-NF45 implements a dual-cell architecture: a standard fast SRAM array (32 × 512) paired with parallel QuantumTrap nonvolatile storage (32 × 512). STORE transfers data from SRAM to nonvolatile cells either automatically on VCC drop below VSWITCH (~3.6 V), via software command, or by pulling HSB LOW; RECALL restores data on power-up or when VCC exceeds VSWITCH.

It enforces conditional STORE initiation - only after at least one SRAM write since last STORE/RECALL - and inhibits writes during low-voltage conditions (VCC < VSWITCH). The HSB pin serves dual roles: open-drain busy indicator during STORE and active-Low trigger input, with internal weak pull-up enabling optional external 10 kΩ pull-up to VCAP.

Key Specifications

Pinout & Package

STK22C48-NF45 is housed in a 28-pin 300-mil Small Outline Integrated Circuit (SOIC) package with gull-wing leads, RoHS-compliant, and rated for industrial temperature operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CY14B101PA-SP25XI and FM24CL16B-G, STK22C48-NF45 uniquely provides parallel 8-bit bus compatibility, 5 V operation, hardware-triggered STORE via HSB, and deterministic AutoStore timing - making it irreplaceable in legacy industrial control upgrades requiring zero firmware changes.

Availability

STK22C48-NF45 is available at Aetrix Electronics and suitable for industrial PLCs, medical infusion pumps, and telecom line cards requiring stable component supply with long-term lifecycle support.

Supply support for STK22C48-NF45 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 connectivity solutions for industrial, automotive, and consumer markets.

The STK22C48 belongs to Cypress's AutoStore nvSRAM product line, engineered specifically for systems demanding instantaneous, battery-free nonvolatile storage in 5 V parallel-memory architectures.

FAQ

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

The STK22C48-NF45 requires a minimum 68 µF tantalum or aluminum electrolytic capacitor on the VCAP pin, rated ≥6 V and +20% tolerance. This value ensures sufficient stored energy to complete the 10 ms STORE cycle even when VCC collapses from 5.5 V to 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-NF45 operate without the VCAP capacitor?

Yes - but only in AutoStore Inhibit mode, where VCC is tied to ground and +5 V is applied directly to VCAP. In this configuration, AutoStore is disabled and STORE operations require explicit HSB pin assertion or software command. Normal AutoStore functionality is impossible without the VCAP capacitor connected as specified in Figure 2 of the datasheet.

How does the STK22C48-NF45 prevent unintended STORE during brown-out conditions?

The device monitors VCC against VSWITCH (~3.6 V). When VCC drops below this threshold, all externally initiated STOREs and SRAM writes are automatically inhibited. Additionally, the conditional STORE rule - requiring at least one prior write since last STORE/RECALL - prevents spurious activation. The HSB pin remains HIGH unless actively driven LOW or pulled down by internal logic during valid STORE initiation.

Is STK22C48-NF45 pin-compatible with other Cypress nvSRAMs like STK14C88?

No - STK22C48-NF45 uses a 28-pin SOIC package with specific pin assignments including dedicated HSB and VCAP pins. STK14C88 is a 28-pin PLCC with different pinout (e.g., HSB at Pin 27 vs. Pin 6 in STK22C48), incompatible address/data mapping, and distinct AutoStore control logic. Direct replacement requires PCB redesign and firmware adaptation.