Infineon Technologies STK17TA8-RF45I

Overview

STK17TA8-RF45I 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 3.0 V ±10% supply, delivers 45 ns read/write cycle time, supports automatic STORE on power loss and RECALL on power-up, and retains data for 20 years without power in industrial temperature range (–40°C to +85°C). It is used in industrial control systems requiring persistent time-stamped memory during brownouts.

For engineers reviewing the STK17TA8-RF45I datasheet, STK17TA8-RF45I pinout, STK17TA8-RF45I application, or STK17TA8-RF45I equivalent, key selection criteria include nvSRAM endurance (unlimited read/write), RTC accuracy with leap-year support, hardware STORE/RECALL timing, VCAP-backed nonvolatile write integrity, and SSOP-48 footprint compatibility with legacy board layouts.

Technical Context

The STK17TA8-RF45I integrates a quantum-trap-based nvSRAM array with a fully featured RTC subsystem. Its memory core provides SRAM-speed access (45 ns) while guaranteeing 200,000 STORE cycles and 20-year data retention via on-chip nonvolatile storage elements. The RTC includes programmable alarm (minutes/hours/days), watchdog timer, and power monitor with interrupt output.

It supports dual backup sources: capacitor (VRCTcap) or battery (VRCTbat), with typical backup current ≤350 nA. The device uses a 32.768 kHz crystal (X1/X2) and features dedicated pins for hardware STORE initiation (HSB), interrupt signaling (INT), and autostore capacitor coupling (VCAP), enabling deterministic power-loss response without external logic.

Key Specifications

Pinout & Package

STK17TA8-RF45I is housed in a 48-pin 300-mil SSOP (RoHS-compliant) package with 0.025" pitch and exposed thermal pad. Pin layout supports standard 8-bit parallel bus interfacing and dedicated RTC control signals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK17TA8-RF45I, the -25I variant trades lower latency for higher power, while the DS1248W-120+ sacrifices speed and flexibility for pin-for-pin compatibility with older Maxim-based designs - neither offers the same combination of 45 ns performance, capacitor-based RTC backup, and unified register architecture.

Availability

STK17TA8-RF45I is available at Aetrix Electronics and suitable for industrial control systems, smart metering platforms, and medical data loggers requiring stable component supply with guaranteed 20-year data retention and deterministic power-loss response.

Supply support for STK17TA8-RF45I 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 high-reliability memory, microcontrollers, and timing solutions for industrial and automotive markets.

The STK17TA8 product line was designed to replace discrete SRAM + RTC + backup controller combinations in mission-critical embedded systems where data integrity during power disruption is non-negotiable.

FAQ

What is the role of the VCAP pin, and how is its capacitance value determined?

The VCAP pin connects to an external 17–57 µF capacitor that supplies energy during VCC collapse to complete the nonvolatile STORE operation. Capacitance is selected based on worst-case voltage droop and required STORE duration: 57 µF supports longer hold-up at lower VCC thresholds, while 17 µF suffices for fast, shallow dips. Tantalum or polymer capacitors rated ≥5 V are recommended.

Can the STK17TA8-RF45I operate without a crystal, and what happens to RTC functionality?

No - the X1/X2 pins require a 32.768 kHz crystal for RTC operation. Without it, the oscillator remains inactive, and all RTC functions (clock, alarm, watchdog) are disabled. The nvSRAM portion continues full operation, but time-stamped logging and alarm-triggered actions become unavailable.

How does the HSB pin behave during a hardware-initiated STORE, and is external pull-up required?

During hardware STORE, HSB goes low within 100 ns of the external falling edge and remains low for the full STORE duration (typically <10 ms). The pin has an internal weak pull-up; no external resistor is required unless driving a long trace or heavy capacitive load where rise time must be controlled.

Is software STORE compatible with all operating modes, and what register sequence triggers it?

Yes - software STORE works in all valid operating modes (E/G asserted, W high). It is initiated by writing 0x20 to address 0x0000 followed by 0x20 to address 0x0001 within 100 µs. This two-byte sequence is latched and executed immediately, independent of bus activity - no wait states or polling needed.