Infineon Technologies CY2291F

Overview

CY2291F from Cypress Semiconductor is a field-programmable, three-PLL clock generator delivering eight low-skew, low-jitter outputs (CLKA–CLKF, CPUCLK, 32K) with configurable 3.3V/5V operation, smooth CPUCLK slewing across eight frequencies up to 90 MHz (5V) or 66.6 MHz (3.3V), and integrated 32.768 kHz oscillator for real-time clock backup - used in PC motherboard timing subsystems.

For engineers reviewing the CY2291F datasheet, CY2291F pinout, CY2291F application, or CY2291F equivalent, this page delivers verified pin functions, exact output skew (<0.5 ns), slewing rate (1–20 MHz/ms), shutdown current (≤50 µA), and EPROM configuration constraints - critical for BIOS-integrated clock tree design and green computing power management.

Technical Context

The CY2291F integrates three independent PLLs: CPU PLL (CPLL) supports smooth frequency slewing via S0–S2 inputs and provides CPUCLK; System PLL (SPLL) drives CLKF and offers 30+ divider options for CLKA–CLKD; Utility PLL (UPLL) delivers highest accuracy for auxiliary clocks. All PLLs accept 10–25 MHz crystal or 1–30 MHz external reference input.

It features dual-voltage operation (3.0–3.6 V or 4.5–5.5 V), programmable power management (SHUTDOWN/OE, S2/SUSPEND), weak pull-down on all outputs except 32K, and battery-backed 32.768 kHz oscillator with VBATT pin - enabling RTC co-location without external circuitry.

Key Specifications

Pinout & Package

20-pin SOIC package with standard JEDEC MS-013AC dimensions (7.5 mm × 12.8 mm), 1.27 mm lead pitch, and exposed pad not present. Pin functions validated per Cypress Document #38-07189 Rev. *A.

Key Features

Applications

Equivalent & Alternatives

CY2291F has two documented field-programmable alternatives with distinct trade-offs in frequency range and temperature grade.

Compared with CY2291FI, CY2291F offers lower cost and wider 3.3V frequency range (66.6 MHz vs. 60.0 MHz) but lacks industrial temp rating; versus CY2292F, it provides proven stability and simpler configuration at the expense of maximum frequency and jitter performance.

Availability

CY2291F is available at Aetrix Electronics and suitable for desktop motherboard clock trees, laptop CPU power management, industrial backplane timing, and legacy embedded system upgrades requiring stable component supply and long-lifecycle support.

Supply support for CY2291F 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 timing, memory, and programmable logic solutions for computing and industrial applications.

The CY2291 family was designed as a third-generation EPROM-programmable clock generator targeting PC motherboard and embedded system timing consolidation - emphasizing field configurability, low skew, and power-aware slewing.

FAQ

Can CY2291F be programmed in-system after soldering?

Yes - CY2291F is field-programmable using the Cypress CY3670 FTG Programmer and CyClocks™ software. Programming requires connection to the 20-pin SOIC via ZIF socket or test points; no UV erasure or reflow is needed. Configuration data is stored in on-chip EPROM and retained indefinitely.

What is the minimum external crystal load capacitance for CY2291F?

The CY2291F datasheet specifies optimal crystal load capacitance of ≈17–18 pF for 10–25 MHz parallel-resonant crystals. Using crystals outside this range may cause startup failure or frequency inaccuracy; CLOAD must not exceed 25 pF (5V) or 15 pF (3.3V) per absolute maximum ratings.

Does CY2291F support spread-spectrum clocking?

No - CY2291F does not implement spread-spectrum modulation. Its jitter specifications (e.g., <250 ps peak-to-peak above 50 MHz) reflect deterministic PLL behavior only. Spread-spectrum capability was introduced in later Cypress families like CY27410.

How does the S2/SUSPEND pin differ from SHUTDOWN/OE?

S2/SUSPEND selectively suspends individual PLLs or outputs (excluding 32K) when LOW, preserving partial functionality; SHUTDOWN/OE globally three-states all outputs (except 32K) and powers down all PLLs, counters, and oscillators - reducing VDD current to ≤50 µA. Both are asynchronous controls with no internal debouncing.