Infineon Technologies CY2305SI-1H

Overview

CY2305SI-1H from Cypress Semiconductor is an industrial-grade, 3.3V zero-delay clock buffer IC with PLL-based architecture, designed to distribute one reference clock to five low-skew outputs. It operates from 10 MHz to 133 MHz, delivers ≤1.5 ns rise/fall times, achieves ≤85 ps typical output-to-output skew, and supports zero input-output propagation delay when CLKOUT is equally loaded. It is used in SDRAM and PCI bus timing distribution in embedded industrial controllers.

For engineers reviewing the CY2305SI-1H datasheet, CY2305SI-1H pinout, CY2305SI-1H application, or CY2305SI-1H equivalent, this page provides verified electrical specs, industrial temperature performance (–40°C to +85°C), load-dependent zero-delay configuration guidance, and direct substitution options for clock tree design in space-constrained SOIC-8 layouts.

Technical Context

The CY2305SI-1H integrates an on-chip PLL with internal feedback sourced from the CLKOUT pin, enabling precise phase alignment between REF input and all buffered outputs. Its lock time is ≤1.0 ms under stable supply conditions, and it enters power-down mode (<25 μA) when REF has no rising edges.

Unlike the CY2309, it lacks select inputs and banked outputs-its five outputs (CLK1–CLK4, CLKOUT) are uniformly driven with weak pull-down termination. All outputs require equal capacitive loading (≤30 pF below 100 MHz, ≤10 pF up to 133 MHz) to maintain zero input-output delay and minimize skew.

Key Specifications

Pinout & Package

Package: 8-pin, 150-mil SOIC (width = 3.9 mm), surface-mount, RoHS-compliant, industrial temperature rated.

Key Features

Applications

Equivalent & Alternatives

CY2305SC-1H and CY2305SI-1 are functionally identical alternatives differing only in temperature grade and drive strength.

Compared with CY2305SC-1H, CY2305SI-1H adds industrial temperature qualification without sacrificing speed or jitter performance; compared with CY2305SI-1, it delivers 1 ns faster edges and 10 ps lower jitter-critical for 133 MHz SDRAM and real-time control loops.

Availability

CY2305SI-1H is available at Aetrix Electronics and suitable for industrial CPU clock trees, SDRAM memory interfaces, PCI bus distribution, and motor control timing requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CY2305SI-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) is a fabless semiconductor company specializing in timing, memory, and microcontroller solutions for industrial, automotive, and communications markets.

The CY2305 product line delivers cost-optimized, zero-delay clock buffers targeting high-volume embedded systems where deterministic timing, small footprint, and industrial reliability are mandatory.

FAQ

What is the purpose of the CLKOUT pin on CY2305SI-1H?

The CLKOUT pin serves as the internal PLL feedback node and must be loaded identically to all other outputs to achieve zero input-output propagation delay. Even if unused, it requires a capacitive load matching the other outputs (e.g., 10 pF for 133 MHz operation) to maintain phase alignment and avoid delay drift.

Can CY2305SI-1H operate with a 5V input clock?

Yes-the REF input is 5V-tolerant and accepts logic-high voltages up to 7V, allowing direct connection to 5V TTL or CMOS clock sources without level-shifting circuitry. Input threshold is VDD/2 (1.65V at 3.3V), ensuring robust noise immunity in mixed-voltage systems.

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

Power-down activates automatically when no rising edge is detected on REF for >100 ms; outputs enter high-impedance (three-state) mode and PLL shuts off, reducing supply current to <25 μA. No external control signal is needed-mode exit occurs within 1.0 ms after REF resumes toggling.

Why is equal capacitive loading required across all outputs?

Equal loading ensures consistent propagation delay across outputs and maintains the PLL's feedback loop stability. Mismatched loads cause differential delay shifts-especially on CLKOUT-which directly alter the REF-to-output phase relationship and degrade zero-delay performance beyond ±350 ps specification.