Infineon Technologies CY2305SC-1H

Overview

CY2305SC-1H from Cypress Semiconductor is a 3.3V zero-delay clock buffer IC with five low-skew outputs, PLL-based architecture, and 100–133 MHz operating range. It accepts one 5V-tolerant reference input (REF), delivers matched buffered clocks to CPU/PCI/SDRAM subsystems, and achieves ±350 ps input-output delay control via CLKOUT feedback loading. Designed for commercial-temperature (0°C to 70°C) embedded timing distribution.

For engineers reviewing the CY2305SC-1H datasheet, CY2305SC-1H pinout, CY2305SC-1H application, or CY2305SC-1H equivalent, this page provides verified pin functions, real-world skew/jitter performance, zero-delay configuration guidance, and validated alternatives for Pentium-compatible clock tree design.

Technical Context

The CY2305SC-1H integrates an on-chip PLL with internal feedback from the CLKOUT pin to achieve zero input-output propagation delay. Its output stage supports 12 mA drive strength (–1H suffix), delivering 1.5 ns rise/fall times under 10–30 pF loads.

All five outputs-CLK1 through CLK4 and CLKOUT-are buffered copies of the REF input with ≤85 ps typical output-to-output skew when equally loaded. The device enters power-down mode (<25 μA) when REF has no rising edges, three-stating all outputs and disabling the PLL.

Key Specifications

Pinout & Package

Package: 8-pin 150-mil SOIC (width = 3.9 mm), RoHS-compliant, surface-mountable with standard reflow profile.

Key Features

Applications

Equivalent & Alternatives

CY2305SC-1H has two functionally compatible alternatives with documented electrical and functional differences.

Compared with IDT74FCT807CTSO and ICS552MI-133, CY2305SC-1H uniquely combines zero-delay operation, 5V-tolerant input, and self-contained feedback-enabling simpler, more deterministic clock trees in Pentium-era and industrial SDRAM systems without external tuning components.

Availability

CY2305SC-1H is available at Aetrix Electronics and suitable for PCI bus clock distribution, SDRAM memory controller timing, and Pentium-compatible CPU clock tree applications requiring stable component supply across long-lifecycle industrial programs.

Supply support for CY2305SC-1H 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 timing, memory, and microcontroller solutions for industrial, automotive, and computing markets.

The CY2305 product line delivers cost-optimized, zero-delay clock buffers targeting legacy PC architectures and industrial control systems requiring deterministic, low-skew clock distribution at 3.3V.

FAQ

What is the purpose of the CLKOUT pin on CY2305SC-1H?

The CLKOUT pin serves as the internal PLL feedback node. Its capacitive load directly controls the input-to-output propagation delay: matching its load to that of CLK1–CLK4 achieves zero delay. Even if unused, CLKOUT must be loaded identically to other outputs to maintain timing accuracy-this is not optional per the datasheet's zero-delay calibration requirement.

Can CY2305SC-1H operate with a 5V input clock?

Yes. The REF pin is explicitly 5V-tolerant per Absolute Maximum Ratings and Electrical Characteristics tables. It accepts TTL/CMOS-level inputs up to 7V, enabling direct connection to legacy 5V oscillators or microcontrollers without level-shifting circuitry-critical for backward compatibility in Pentium-era designs.

How does power-down mode activate and what happens to outputs?

Power-down activates automatically when no rising edge occurs on REF for >100 ms (characterized). In this state, the PLL shuts off, all outputs (CLK1–CLK4 and CLKOUT) are three-stated, and supply current drops to ≤25 μA. Outputs remain high-impedance until REF resumes activity and PLL relocks (~1.0 ms).

Why is output loading critical for CY2305SC-1H timing performance?

Unequal loading causes unequal propagation delays across outputs, breaking zero-delay operation and increasing output-to-output skew. The datasheet mandates identical capacitive loads (e.g., 10 pF or 30 pF) on all outputs-including CLKOUT-to ensure matched delay paths and guarantee ≤85 ps typical skew. Mismatched loads degrade timing margins in synchronous buses like PCI and SDRAM.