Infineon Technologies CY2291FI

Overview

CY2291FI from Cypress Semiconductor is a field-programmable, industrial-temperature, three-PLL clock generator with EPROM-based configuration, supporting 8 configurable outputs, 3.3V/5V dual-voltage operation, and smooth CPUCLK slewing across 8 user-selectable frequencies up to 60 MHz at 3.3V - deployed in PC motherboards and embedded timing subsystems requiring low-jitter, low-skew synchronization.

For engineers reviewing the CY2291FI datasheet, CY2291FI pinout, CY2291FI application, or CY2291FI equivalent, this page delivers verified package mapping (20-pin SOIC), validated PLL architecture (CPLL/SPLL/UPLL), confirmed industrial-temp electrical specs (−40°C to +85°C), and real-world slewing behavior (1–20 MHz/ms) critical for green computing and processor clock management.

Technical Context

The CY2291FI integrates three independent PLLs: the CPU PLL (CPLL) enables smooth frequency transitions between eight user-selectable outputs with slew rates of 1–20 MHz/ms; the System PLL (SPLL) provides fixed-frequency outputs with up to 10 divider options; and the Utility PLL (UPLL) delivers highest-accuracy clocks for auxiliary timing needs. All PLLs operate under programmable 3.3V or 5V supply conditions.

It accepts either a 10–25 MHz parallel-resonant crystal (XTALIN/XTALOUT) or a 1–30 MHz external reference clock, and includes a dedicated 32.768 kHz oscillator (32XIN/32XOUT/VBATT) with battery backup. Output skew between identical or related clocks is guaranteed <500 ps, and all configurable outputs (CLKA–CLKD, CLKF, CPUCLK) support three-state control via SHUTDOWN/OE and S2/SUSPEND pins.

Key Specifications

Pinout & Package

Package: 20-pin SOIC (Small Outline Integrated Circuit), industry-standard footprint compatible with automated PCB assembly and thermal management for high-density motherboard layouts.

Key Features

Applications

Equivalent & Alternatives

CY2291FI has two verified functional alternatives with documented differences in programmability, temperature range, and frequency limits.

Compared with CY2291I and CY2291F, CY2291FI uniquely combines field-programmability, industrial temperature range, and 60 MHz 3.3V output capability - making it the only option for ruggedized, upgradable timing in edge-computing and industrial IoT platforms.

Availability

CY2291FI is available at Aetrix Electronics and suitable for desktop motherboard design, industrial control backplane timing, and laptop power-managed clocking requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CY2291FI 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 timing, memory, and programmable logic solutions for computing, industrial, and automotive markets.

The CY2291 family belongs to Cypress's EPROM-programmable clock generator product line, designed specifically to replace legacy clock ICs (e.g., ICD2023) in PC motherboards and provide flexible, low-jitter, multi-output timing with field-upgrade capability.

FAQ

What is the maximum 3.3V output frequency for CY2291FI?

The CY2291FI supports up to 60.0 MHz at 3.3V operation, as specified in the Selector Guide and confirmed in the Electrical Characteristics tables for Industrial 3.3V operation. This is lower than the 66.6 MHz limit of CY2291F/CY2291I due to tighter industrial-grade timing margining and thermal derating.

Can CY2291FI be programmed after soldering to the PCB?

Yes - CY2291FI is field-programmable using the Cypress FTG Programmer (CY3670) and CyClocks™ software. Programming occurs via standard SOIC socket or in-circuit through the device's dedicated programming interface, requiring no de-soldering or rework.

Does CY2291FI retain its 32.768 kHz RTC output during main power loss?

Yes - when VBATT (2.0–5.5 V) is connected, the 32K output remains active even if VDD is removed or SHUTDOWN/OE is asserted. The internal 32.768 kHz oscillator continues running from battery power, preserving real-time clock functionality during system sleep or power failure.

How does CPUCLK slewing work without losing PLL lock?

CY2291FI's CPLL uses analog-controlled VCO tuning and phase interpolation to transition smoothly between frequencies while maintaining continuous phase alignment. Lock time after slewing is negligible (<50 ms), and downstream PLLs remain locked - satisfying Pentium® and 486 slewing compliance requirements.