Infineon Technologies CY25561SXCT

Overview

CY25561SXCT from Cypress Semiconductor is a spread spectrum clock generator (SSCG) IC designed to reduce electromagnetic interference (EMI) in high-speed digital systems. It operates from 50–166 MHz input frequency, delivers center-spread modulation with up to 4.3% peak-to-peak spread, features tri-level logic control (S0/S1), and outputs low cycle-to-cycle jitter (<225 ps typical) in an 8-pin SOIC package for EMI-compliant computing and communications applications.

For engineers reviewing the CY25561SXCT datasheet, CY25561SXCT pinout, CY25561SXCT application, or CY25561SXCT equivalent, this page provides verified technical context, real-world spread selection mapping, tri-level logic voltage thresholds, modulation rate calculation (e.g., 27.9 kHz at 65 MHz), and functional role in EMI suppression without performance trade-offs.

Technical Context

CY25561SXCT implements a proprietary Cypress PLL-based SSCG architecture that modulates output frequency symmetrically around the input reference using center-spread FM. Its modulation rate is fixed by internal divider Cdiv = 2332, yielding Fmod = Fin / 2332 - e.g., 27.9 kHz at 65 MHz input.

The device accepts either crystal (via XIN/CLK + XOUT) or external clock inputs, supports nine discrete spread percentages via S0/S1 tri-level logic (H/M/L), and integrates internal resistor dividers to default S0/S1 to "M" when unconnected. SSCC pin enables/disables spread function with internal pull-up.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (Small Outline Integrated Circuit), surface-mount, 0 °C to 70 °C operating temperature range.

Key Features

Applications

Equivalent & Alternatives

Cypress CY25561SXCT has two validated drop-in alternatives with documented functional and parametric differences.

Compared with IDTICS854S01AGI-27LF and Si5351A-B-GM, CY25561SXCT uniquely balances field-programmable spread selection, zero-software configuration, SOIC compatibility, and ultra-low jitter - making it optimal for cost-sensitive, high-volume EMI-critical applications where flexibility and simplicity are prioritized.

Availability

CY25561SXCT is available at Aetrix Electronics and suitable for PCIe reference clocking, USB 3.0 timing, and DDR memory subsystems requiring stable component supply, long-term EOL visibility, and RoHS-compliant packaging.

Supply support for CY25561SXCT 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 programmable system-on-chip (PSoC), memory, and timing solutions for industrial, automotive, and consumer electronics.

CY25561 belongs to Cypress's Spread Spectrum Clock Generator product line, engineered specifically to replace fixed-frequency oscillators in EMI-sensitive digital systems while maintaining timing integrity and minimizing board-level filtering.

FAQ

What is the purpose of the tri-level logic inputs S0 and S1?

S0 and S1 implement a three-state logic interface (low/middle/high) that enables nine distinct spread percentage selections using only two pins. Internal resistor dividers set the default "M" state, and external grounding or VDD connection configures "0" or "1". This eliminates the need for external level shifters or configuration registers.

Can CY25561SXCT drive a crystal directly?

Yes - when used in crystal oscillator mode, connect the crystal between XIN/CLK (Pin 1) and XOUT (Pin 8), with appropriate load capacitors. XOUT is an active oscillator output; it must remain unconnected if an external clock drives XIN/CLK.

How is modulation rate calculated for a given input frequency?

Modulation rate is fixed by internal divider Cdiv = 2332: Fmod = Fin / 2332. For example, at 65 MHz input, Fmod = 65,000,000 / 2332 ≈ 27.9 kHz. This value is constant across all spread settings and input frequencies within spec.

Does disabling spread via SSCC affect output jitter or duty cycle?

No - when SSCC is driven low to disable spread, CY25561SXCT outputs a clean, unmodulated clock identical in frequency, duty cycle (45–55%), and jitter performance (≤225 ps) to its modulated mode. This allows direct A/B EMI testing without changing clock characteristics.