Infineon Technologies STK17T88-RF45I

Overview

STK17T88-RF45I from Cypress Semiconductor is a 32K × 8 (256 Kb) nonvolatile SRAM with integrated real-time clock, watchdog timer, alarm, and power monitor. It operates from a single 2.7–3.6 V 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 metering, industrial PLCs, and network infrastructure where deterministic nonvolatile storage and accurate timekeeping coexist.

For engineers reviewing the STK17T88-RF45I datasheet, STK17T88-RF45I pinout, STK17T88-RF45I application, or STK17T88-RF45I equivalent, key selection criteria include nvSRAM endurance (unlimited reads/writes), RTC backup options (capacitor or battery), HSB-controlled hardware STORE timing, interrupt routing via INT pin, and SSOP-48 package compatibility with legacy board layouts.

Technical Context

The STK17T88-RF45I integrates a QuantumTrap-based nvSRAM array (512 × 512) with a fully autonomous RTC subsystem featuring leap-year compensation, programmable oscillator calibration, and dual-mode alarm (one-time or periodic). Its power control logic monitors VCC drop to trigger automatic STORE within 10 µs, using charge stored on the external VCAP capacitor (17–57 µF).

RTC registers are memory-mapped at A14–A0 addresses 0x0000–0x000F, accessible via the same DQ0–DQ7 bus as SRAM. The INT pin supports active-high push-pull or active-low open-drain configuration and can assert on alarm expiry, watchdog timeout, or VCC brownout-enabling system-level event coordination without CPU polling.

Key Specifications

Pinout & Package

Package: 48-pin 300-mil SSOP (RoHS compliant), body size 15.4 mm × 7.6 mm, pitch 0.635 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STK17T88-RF45I, the STK17C88-25I offers faster timing but sacrifices industrial reliability, while the DS1248W-120+ reduces component count at the cost of serviceability and real-time system responsiveness.

Availability

STK17T88-RF45I is available at Aetrix Electronics and suitable for smart metering, industrial PLCs, network infrastructure, and medical data loggers requiring stable component supply and long-term obsolescence management.

Supply support for STK17T88-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) designs high-reliability mixed-signal ICs for industrial, automotive, and communications systems, with emphasis on integration, longevity, and functional safety.

The STK17T88 belongs to Cypress's AutoStore nvSRAM product line, engineered to eliminate flash wear-out and battery dependency in mission-critical data logging and time-stamped control applications.

FAQ

What is the purpose of the VCAP pin?

The VCAP pin connects to an external 17–57 µF capacitor that supplies energy during VCC collapse to complete the nonvolatile STORE operation. This capacitor charges to VCC during normal operation and discharges into the nvSRAM storage circuitry when power drops, ensuring reliable data transfer to QuantumTrap cells within 10 µs - no battery or external power source is needed for STORE functionality.

Can the RTC operate independently of the nvSRAM function?

Yes. The RTC runs continuously from either VRTCcap or VRTCbat, even when VCC is absent or the nvSRAM is disabled. Its oscillator, calendar logic, alarm, and watchdog functions remain fully operational as long as backup power is applied - enabling timekeeping and interrupt generation during system sleep or power-off states.

How does the HSB pin function in hardware STORE mode?

In hardware STORE mode, pulling HSB low externally initiates a nonvolatile STORE operation. During STORE, HSB remains low to signal busy status; it returns high upon completion. The pin has an internal weak pull-up, so it defaults high when unconnected - eliminating need for external pull-up resistors unless actively driven by external logic.

Is the STK17T88-RF45I suitable for new designs despite "Not Recommended for New Designs" in the datasheet?

While Cypress marked the STK17T88 as "Not Recommended for New Designs" in 2009 due to newer nvSRAM generations, it remains actively stocked and supported by authorized distributors. Its mature qualification, full industrial temperature rating, and proven field reliability make it viable for long-lifecycle industrial and medical applications where redesign risk outweighs marginal feature gains.