Infineon Technologies STK12C68-SF45ITR

Overview

STK12C68-SF45ITR from Cypress Semiconductor is a 64 Kbit (8 K × 8) nonvolatile static RAM with QuantumTrap technology, delivering 45 ns access time, AutoStore on power-down using an external 68 µF capacitor, and 100-year data retention. It operates at single 5 V ±10%, supports unlimited SRAM read/write cycles, and performs STORE/RECALL via software, hardware (HSB), or automatic power-loss detection - used in industrial control systems requiring persistent memory without battery backup.

For engineers reviewing the STK12C68-SF45ITR datasheet, STK12C68-SF45ITR pinout, STK12C68-SF45ITR application, or STK12C68-SF45ITR equivalent, key selection considerations include AutoStore timing constraints (tSTORE = 10 ms), VCAP capacitor sizing (68–220 µF), HSB pin behavior during STORE busy state, and software STORE/RECALL address sequences (0x0000 → 0x0F0F / 0x0F0E).

Technical Context

The STK12C68-SF45ITR integrates parallel SRAM and QuantumTrap nonvolatile cells per bit, enabling simultaneous STORE/RECALL of all 8,192 bytes. Its architecture decouples volatile operation from nonvolatile persistence: SRAM provides standard fast random access (tAA = 45 ns), while QuantumTrap elements retain data without power.

STORE is triggered by power loss (via VCAP discharge), HSB assertion, or software sequence; RECALL occurs automatically at power-up or via software. During STORE/RECALL, SRAM I/O is disabled, and HSB asserts open-drain LOW to signal busy status - critical for system-level coordination of memory state transitions.

Key Specifications

Pinout & Package

STK12C68-SF45ITR uses a 28-pin SOIC (330 mil) package with gull-wing leads, JEDEC MS-012AC compliant, 1.27 mm pitch, and RoHS-compliant matte tin finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK12C68-SF35I, the -SF45ITR trades 10 ns speed for broader voltage margin tolerance; versus FM1808-45-SG, it offers deterministic HSB signaling and proven industrial temperature reliability but requires larger VCAP and has lower STORE endurance.

Availability

STK12C68-SF45ITR is available at Aetrix Electronics and suitable for industrial PLC data logging, medical device configuration storage, and avionics power-up state recovery requiring stable component supply and long-term lifecycle support.

Supply support for STK12C68-SF45ITR 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 STK12C68 belongs to Cypress's QuantumTrap nvSRAM product line, engineered specifically for systems needing instant-on memory persistence without batteries, capacitors, or complex firmware save protocols.

FAQ

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

The STK12C68-SF45ITR requires a minimum 68 µF capacitor on VCAP, rated ≥6 V and +20% tolerance, to guarantee successful STORE during a 10 ms power collapse. Lower values risk incomplete STORE due to insufficient charge retention; 100 µF is recommended for margin in industrial environments with >100 ms brownouts.

Can STK12C68-SF45ITR perform STORE while SRAM is actively being written?

No - the device inhibits AutoStore and Hardware STORE unless at least one SRAM write has occurred since the last STORE or RECALL cycle. This prevents unnecessary nonvolatile writes. Software STORE is exempt and executes regardless of recent write activity, enabling forced persistence on demand.

How does the HSB pin behave during a software-initiated STORE?

During software STORE, HSB asserts open-drain LOW exactly as during AutoStore or HSB-triggered STORE - providing consistent hardware signaling for system-level synchronization. The pin remains LOW for the full tSTORE duration (10 ms max) and releases only upon completion, enabling external logic to gate subsequent operations.

Is STK12C68-SF45ITR compatible with 3.3 V systems?

No - it is strictly a 5 V ±10% device (4.5 V to 5.5 V). Interfacing with 3.3 V microcontrollers requires level-shifting on all address, data, and control lines (A0–A12, DQ0–DQ7, CE, WE, OE, HSB). VCAP must still be connected to a 5 V source; direct 3.3 V operation will cause STORE failure and potential data corruption.