Simtek STK17TA8-RF25

Overview

STK17TA8-RF25 from Cypress Semiconductor is a 128k × 8 (1 Mb) nonvolatile SRAM with integrated real-time clock, watchdog timer, alarm, and power monitor. It operates from a single 3 V ±10% supply, delivers 25 ns read access time, supports automatic STORE on power loss and RECALL on power-up, and uses a 48-pin SSOP package for industrial temperature operation (–40°C to +85°C).

For engineers reviewing the STK17TA8-RF25 datasheet, STK17TA8-RF25 pinout, STK17TA8-RF25 application, or STK17TA8-RF25 equivalent, key selection considerations include nvSRAM endurance (unlimited read/write), RTC backup options (capacitor or battery), hardware STORE/RECALL control via HSB, interrupt-driven alarm/wdog signaling, and compatibility with legacy SRAM interfaces.

Technical Context

The STK17TA8-RF25 integrates a Quantum Trap-based nvSRAM array with a fully featured RTC subsystem. Its memory core provides SRAM-speed access (25 ns) and unlimited read/write cycles, while nonvolatile STORE/RECALL operations are triggered by power-loss detection, HSB assertion, or software command - all preserving data for ≥20 years at 55°C.

The RTC block includes a programmable 32.768 kHz oscillator with ±20 ppm accuracy, leap-year calendar support, minute/hour/day alarm modes, a 16-bit watchdog timer with reset output, and a power monitor flag. Interrupts (INT pin) are configurable as active-high push-pull or active-low open-drain for alarm, watchdog timeout, or VCC drop events.

Key Specifications

Pinout & Package

STK17TA8-RF25 is housed in a 48-pin, 300-mil SSOP (RF) RoHS-compliant package with 0.635 mm pitch and exposed thermal pad per Cypress specification.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nvSRAM+RTC applications.

Compared with STK17TA8-RF45 and DS1248-120+, the STK17TA8-RF25 delivers the fastest access (25 ns), full RTC feature set (alarm, wdog, power monitor), and lowest latency STORE initiation - making it optimal for real-time control systems requiring deterministic data persistence and precise timestamping.

Availability

STK17TA8-RF25 is available at Aetrix Electronics and suitable for industrial PLC data logging, medical device event timestamping, point-of-sale terminal configuration storage, and telecom base station clock holdover requiring stable component supply and long-term lifecycle support.

Supply support for STK17TA8-RF25 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 mixed-signal ICs for industrial, automotive, and communications infrastructure applications.

The STK17TA8 product line targets systems needing concurrent high-speed memory and precision timekeeping - specifically engineered to replace discrete SRAM + RTC + backup solutions in space-constrained, mission-critical embedded platforms.

FAQ

What backup power options does STK17TA8-RF25 support for the RTC?

STK17TA8-RF25 supports two mutually exclusive RTC backup sources: a 1.2–2.7 V capacitor on V_RTCcap (typical 2.4 V), or a 1.8–3.3 V battery on V_RTCbat (typical 3.0 V). Only one may be connected; the other must remain unconnected. Capacitor backup enables maintenance-free operation, while battery backup extends RTC uptime beyond capacitor discharge limits.

How does the AutoStore™ function detect power loss?

AutoStore™ uses an internal voltage monitor that continuously compares V_CC against a factory-trimmed threshold (~2.5 V). When V_CC drops below this threshold, the chip initiates STORE within 10 µs, using charge stored on the external V_CAP capacitor to complete the transfer to Quantum Trap cells. No external circuitry or host intervention is required.

Can STK17TA8-RF25 operate as a drop-in replacement for standard 25 ns SRAMs?

Yes - STK17TA8-RF25 uses industry-standard SRAM control signals (E, W, G), identical address/data bus timing (tAVAV = 25 ns), and pin-compatible 48-pin SSOP packaging. All SRAM read/write cycles function identically; nvSRAM and RTC features are accessed only via optional address ranges and do not affect baseline SRAM operation.

What is the maximum frequency of the integrated RTC oscillator?

The integrated RTC oscillator is fixed at 32.768 kHz - a standard low-power watch crystal frequency. It is not programmable to other frequencies. Startup time is ≤5 sec at 25°C and ≤10 sec at minimum operating temperature, with ±20 ppm accuracy over the industrial temperature range.