Infineon Technologies STK12C68-PF45I

Overview

STK12C68-PF45I from Cypress Semiconductor is a 64 Kbit (8K × 8) nonvolatile static RAM with QuantumTrap technology, delivering 45 ns access time, single 5V±10% operation, and automatic STORE on power loss using an external 68 µF capacitor. It integrates SRAM and nonvolatile storage in each cell for mission-critical data retention in industrial control, metering, and telecom infrastructure.

For engineers reviewing the STK12C68-PF45I datasheet, STK12C68-PF45I pinout, STK12C68-PF45I application, or STK12C68-PF45I equivalent, key selection criteria include AutoStore timing behavior, HSB-controlled hardware STORE latency, VCAP capacitor sizing requirements, and software STORE/RECALL address sequence compliance.

Technical Context

The STK12C68-PF45I implements a dual-cell architecture: standard fast SRAM (8K × 8) paired with parallel QuantumTrap nonvolatile elements per bit. STORE and RECALL operate at the full memory array level-not page- or byte-wise-enabling atomic data persistence without firmware overhead.

AutoStore triggers when VCC drops below VSWITCH (~3.6 V), disconnecting VCAP and initiating a 10 ms STORE cycle powered solely by the external capacitor. Hardware STORE via HSB is conditional: it only executes if at least one SRAM write occurred since the last STORE or RECALL, preventing spurious nonvolatile writes.

Key Specifications

Pinout & Package

STK12C68-PF45I is packaged in a 28-pin Plastic Dual In-line Package (PDIP), 600 mil width, with through-hole mounting and industry-standard 0.3 inch row spacing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK12C68-CF45I, the PF45I offers extended temperature support critical for outdoor or industrial use; versus FM1808-40-TG, it trades higher endurance and capacitor-free operation for proven AutoStore behavior under uncontrolled brownouts.

Availability

STK12C68-PF45I is available at Aetrix Electronics and suitable for industrial programmable logic controllers, smart electricity meters, and telecom base station control modules requiring stable component supply and long-term obsolescence support.

Supply support for STK12C68-PF45I 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 connectivity solutions for industrial and automotive markets.

The STK12C68 belongs to Cypress's nvSRAM product line, designed specifically to replace battery-backed SRAM in applications where maintenance-free, long-life nonvolatile storage is mandatory.

FAQ

What is the minimum VCAP capacitor value required for reliable AutoStore operation?

The STK12C68-PF45I requires a minimum 68 µF ±20% tantalum or aluminum electrolytic capacitor rated for 6 V. This value ensures ≥10 ms of regulated power delivery to complete the STORE cycle when VCC drops below VSWITCH (3.6 V). Using less capacitance risks incomplete STORE and data corruption.

Can STK12C68-PF45I be used in place of a standard 28-pin 64 Kbit SRAM without circuit modification?

Yes-pinout and AC timing are fully compatible with JEDEC-standard 28-pin 64 Kbit SRAMs (e.g., AS6C62256, CY62167). However, VCAP must be added externally, and HSB should be pulled up or left open; unused pins like HSB do not require termination beyond standard SRAM practice.

How does the STK12C68-PF45I prevent unintended STORE operations during power-up or noise events?

The device inhibits STORE unless at least one valid SRAM write has occurred since the last STORE or RECALL. Additionally, AutoStore only activates after VCC crosses below VSWITCH with monotonic decay; fast transients or ripple below threshold are ignored. HSB-driven STORE also requires tDELAY (100 ns) to confirm intent.

Is software STORE supported on all operating voltages and temperatures?

Yes-the six-address software STORE sequence (0x0000 → 0x0F0F) functions across the full specified range: 4.5–5.5 V and –40°C to +85°C. The internal logic validates address transitions regardless of voltage or temperature, and tSTORE (10 ms) is guaranteed under worst-case conditions per datasheet AC specs.