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Simtek STK12C68-WF25I
- Part No.:
- STK12C68-WF25I
- Manufacturer:
- Simtek
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
STK12C68-WF25I.pdf
- Description:
- IC NVSRAM 64KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,310
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Product details
Overview
STK12C68-WF25I from Cypress Semiconductor is a 64 Kbit (8K × 8) nonvolatile SRAM with QuantumTrap technology, delivering 25 ns access time, AutoStore on power loss using an external 68 µF capacitor, and unlimited SRAM read/write cycles. It operates at single 5V ±10%, supports industrial temperature range (–40°C to +85°C), and is packaged in 28-pin SOIC (300 mil). It serves as a drop-in replacement for standard SRAM in systems requiring persistent data retention without battery backup - e.g., industrial PLCs, metering registers, and telecom control cards.
For engineers reviewing the STK12C68-WF25I datasheet, STK12C68-WF25I pinout, STK12C68-WF25I application, or STK12C68-WF25I equivalent, key selection criteria include AutoStore timing constraints (tSTORE = 10 ms), VCAP capacitor requirements (68–220 µF, 6V), HSB pin behavior during hardware store, software STORE/RECALL address sequences, and compatibility with legacy 5V bus interfaces.
Technical Context
The STK12C68-WF25I integrates parallel SRAM (128 × 512 array) and nonvolatile QuantumTrap cells in each memory location, enabling simultaneous STORE/RECALL across all 8,192 bytes. Its architecture decouples volatile operation from nonvolatile persistence: SRAM provides fast random access, while QuantumTrap ensures 100-year data retention and 1M STORE endurance.
STORE is triggered automatically at power-down (via VCAP discharge), by hardware assertion of HSB, or via six-step software address sequence (0x0000 → 0x0F0F). RECALL occurs on power-up or via software sequence (0x0000 → 0x0F0E); both operations inhibit SRAM access for tSTORE (10 ms) or tRECALL (10 ms), respectively.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8K × 8), directly replaces standard 8K×8 SRAMs without redesigning address/data bus layout. |
| Access Time | 25 ns - enables direct interface with 33 MHz microcontrollers and legacy 8051/8086-based systems without wait states. |
| STORE Endurance | 1,000,000 cycles - supports frequent logging in data acquisition systems where power loss occurs multiple times per day. |
| Data Retention | 100 years at +85°C - eliminates need for periodic refresh or battery-backed retention in sealed industrial enclosures. |
| VCAP Requirement | 68 µF ±20%, 6V capacitor - defines minimum hold-up time for reliable STORE during brown-out; value verified per Figure 2 in Rev. *C datasheet. |
| Operating Voltage | 5.0 V ±10% - compatible with legacy 5V logic families and avoids level-shifting in mixed-voltage systems. |
| Temperature Range | –40°C to +85°C - qualified for use in outdoor utility meters and factory-floor automation controllers. |
Pinout & Package
STK12C68-WF25I is housed in a 28-pin SOIC package (300 mil width, JEDEC MS-012AC), with 0.6-inch body length and 1.27 mm pitch. Pin 1 is marked by a beveled corner or dot; pin numbering follows standard counterclockwise convention.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-byte addressing; no multiplexing required. |
| DQ0–DQ7 | Bidirectional Data I/O | 8-bit common bus; tristated when OE HIGH or during STORE/RECALL to prevent contention. |
| CE | Chip Enable (Active LOW) | Primary chip select; must be LOW for any SRAM access; controls CE-timed read/write timing windows. |
| WE | Write Enable (Active LOW) | Controls write latching; must remain stable during tSD setup and tHD hold; pulled HIGH at power-up to prevent spurious writes. |
| OE | Output Enable (Active LOW) | Enables output drivers during reads; HIGH disables outputs to isolate bus during writes or STORE. |
| HSB | Hardware Store Busy | Open-drain status signal: driven LOW during any STORE (Auto/Hardware/Software); used to synchronize host firmware. |
| VCAP | AutoStore Capacitor Terminal | Internally charged to 5V; supplies energy for STORE during VCC collapse; requires external 68 µF capacitor. |
| VCC | Power Supply | 5V ±10% main supply; disconnects from VCAP when VCC drops below VSWITCH (~3.6V) to initiate AutoStore. |
| VSS | Ground | System ground reference; must be low-impedance connection to minimize noise coupling into QuantumTrap cell operation. |
Key Features
| Feature | Design Value |
|---|---|
| AutoStore on Power Loss | Eliminates external battery or supercapacitor management circuitry; relies solely on VCAP capacitor and internal charge pump. |
| Software-Controlled STORE/RECALL | Enables deterministic, firmware-triggered persistence - critical for transactional logging before system shutdown. |
| Hardware STORE via HSB Pin | Allows real-time, interrupt-driven store initiation independent of CPU activity or clock domain. |
| Unlimited SRAM Read/Write Cycles | Preserves full SRAM performance characteristics - no wear leveling or access throttling required during normal operation. |
| QuantumTrap Nonvolatile Element | Provides bit-level nonvolatility without floating-gate degradation; immune to radiation-induced bit flips in industrial environments. |
Applications
| Industrial Programmable Logic Controllers (PLCs) | Smart Electricity Meters |
|---|---|
Use Scenario: Storing configuration parameters and last-known operational state during unexpected AC mains failure. IC Role / Device Role / Timing Role: Nonvolatile SRAM retains ladder logic scan counters, I/O mapping, and calibration offsets without battery backup. Use Value: Enables cold restart within <100 ms after power restoration, preserving process continuity and eliminating manual reconfiguration. | Use Scenario: Capturing cumulative kWh readings and tariff-switch timestamps during grid instability or tamper events. IC Role / Device Role / Timing Role: Acts as tamper-proof register storage with guaranteed STORE completion before VCC falls below 3.6V. Use Value: Meets ANSI C12.1 and IEC 62053-21 requirements for metrology data integrity under brown-out conditions. |
| Telecom Base Station Control Cards | Medical Infusion Pump Log Memory |
Use Scenario: Preserving alarm history, firmware version stamps, and port enable/disable states during hot-swap module replacement. IC Role / Device Role / Timing Role: Provides immediate-access SRAM for runtime variables and atomic nonvolatile backup on module power removal. Use Value: Ensures zero-loss event logging across 100,000+ hot-swap cycles without EEPROM wear-out or flash write latency. | Use Scenario: Recording dose delivery timestamps, error codes, and operator IDs during power interruption or battery depletion. IC Role / Device Role / Timing Role: Serves as FDA 21 CFR Part 11-compliant audit trail memory with deterministic STORE timing (≤10 ms). Use Value: Guarantees traceability for critical therapy events even during rapid power collapse (<1 ms edge rate). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STK12C68-WF35I | 45 ns access time; same pinout, package, and feature set; lower speed grade. | Suitable for cost-sensitive designs with relaxed timing budgets (e.g., sub-20 MHz MCUs). | Select when system clock frequency ≤ 20 MHz and 25 ns timing margin is unnecessary. |
| FM1808-250 | 4-Mbit density, 55 ns access, 3.3V operation; uses F-RAM instead of QuantumTrap; unlimited STORE endurance. | Requires voltage translation for 5V systems; higher density but incompatible bus timing and control protocol. | Choose only if migrating to 3.3V architecture and needing >64 Kbit capacity; not pin- or function-compatible. |
Compared with STK12C68-WF35I, the WF25I delivers tighter timing for high-speed 5V control buses; compared with FM1808-250, it maintains full 5V compatibility and identical software STORE/RECALL sequences but trades density for proven industrial reliability in legacy systems.
Availability
STK12C68-WF25I is available at Aetrix Electronics and suitable for industrial PLCs, smart electricity meters, and telecom control cards requiring stable component supply and long-term obsolescence support.
Supply support for STK12C68-WF25I 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, PSoC, and USB solutions, headquartered in San Jose, California.
The STK12C68 belongs to Cypress's nvSRAM product line, designed specifically for mission-critical industrial and infrastructure applications where battery-free, deterministic nonvolatile storage is mandatory.
FAQ
What is the minimum VCAP capacitance required for reliable AutoStore operation?
The STK12C68-WF25I requires a minimum 68 µF capacitor on the VCAP pin, rated at 6V with ±20% tolerance, as specified in Figure 2 of datasheet Rev. *C. This value ensures ≥10 ms STORE duration when VCC collapses from 5V to 3.6V. Using less capacitance risks incomplete STORE and data corruption; values up to 220 µF are supported for extended hold-up time.
Can STK12C68-WF25I be used in a 3.3V system?
No - STK12C68-WF25I is strictly a 5V ±10% device. Its internal charge pump, QuantumTrap programming voltage, and DC/AC specifications are characterized only for 4.5V–5.5V operation. Interfacing with 3.3V logic requires level shifters for all address, data, and control signals, and VCAP must still be supplied from a 5V rail; no 3.3V variant exists in this family.
How does the HSB pin behave during software-initiated STORE?
HSB is actively driven LOW during software-initiated STORE, exactly as during AutoStore or hardware STORE. The pin remains LOW for the full tSTORE duration (10 ms), providing a hardware-synchronized busy signal that firmware can poll or interrupt on. This behavior is identical across all three STORE methods and is documented in the "Hardware STORE (HSB) Operation" section (page 5).
Is the STK12C68-WF25I RoHS compliant?
Yes - the STK12C68-WF25I is RoHS compliant, as explicitly stated in the "Features" section of the official datasheet (Rev. *C, page 1). It meets EU Directive 2011/65/EU requirements, with lead-free terminations and compliant packaging materials confirmed in Cypress's official compliance documentation.
STK12C68-WF25I Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Simtek
- Series:
- -
- Package/Case:
- 28-DIP (0.600", 15.24mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- NVSRAM
- Technology:
- NVSRAM (Non-Volatile SRAM)
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 25ns
- Access Time:
- 25 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-DIP
STK12C68-WF25I FAQ
1.How can I place an order for STK12C68-WF25I through Aetrix?
Please submit a Request for Quotation (RFQ) for STK12C68-WF25I on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for STK12C68-WF25I reliable?
The price and inventory of STK12C68-WF25I are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STK12C68-WF25I is usually 5 days.
3.What payment methods are accepted for STK12C68-WF25I?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STK12C68-WF25I transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for STK12C68-WF25I?
STK12C68-WF25I orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your STK12C68-WF25I order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for STK12C68-WF25I?
For technical support, including STK12C68-WF25I datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STK12C68-WF25I requirements.
6.How does Aetrix verify that STK12C68-WF25I is sourced from the original manufacturer or authorized distributors?
All STK12C68-WF25I products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that STK12C68-WF25I meets industry standards.
7.What is the process for return or replacement of STK12C68-WF25I?
All STK12C68-WF25I units undergo pre-shipment inspection (PSI). If there is an issue with STK12C68-WF25I, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The STK12C68-WF25I part is unused and in its original packaging.
Return procedure for STK12C68-WF25I:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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