CY25819SXCT

Clock Generators, PLLs, Frequency Synthesizers Overview

The CY25819SXCT is a Spread Spectrum Clock Generator (SSCG) manufactured by Cypress Semiconductor, now part of Infineon Technologies. It operates within an input frequency range of 16 MHz to 32 MHz and accepts clock, crystal, or ceramic resonator inputs. The device provides separate modulated (SSCLK) and unmodulated reference (REFCLK) outputs at the same frequency as the input. It features down spread modulation with selectable percentages via the S0 pin: -0.7%, -2.2%, or -3.0% for 16–20 MHz inputs; -0.6%, -1.9%, or -2.7% for 20–24 MHz; -0.6%, -1.8%, or -2.5% for 24–28 MHz; and -0.5%, -1.7%, or -2.3% for 28–32 MHz. Power dissipation is typically 36 mW at 16 MHz and 63 mW at 32 MHz. Cycle-to-cycle jitter is typically 250 ps for SSCLK and 275 ps for REFCLK. It functions on a single supply voltage ranging from 2.97 V to 3.63 V.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Generates separate modulated and unmodulated clock outputs from a single input source.
• Utilizes proprietary phase-locked loop technology to reduce electromagnetic interference through down spread frequency modulation.
• Supports flexible input sources including external clocks, crystals, and ceramic resonators.
• Includes a dedicated power-down control function to minimize energy consumption.

Clock Generators, PLLs, Frequency Synthesizers Applications

• Printers and multifunction printers (MFPs)
• LCD panels and notebook PCs
• Digital copiers and scanners
• Automotive embedded systems
• Networking and LAN/WAN equipment

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify that the component matches the specific CY25819SXCT designation, noting the 'T' suffix indicates tape and reel packaging. Confirm the manufacturer origin, as Cypress Semiconductor was acquired by Infineon Technologies. Ensure the device meets commercial temperature requirements of 0°C to +70°C. Check for lead-free compliance and RoHS certification status prior to procurement.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select the CY25819SXCT when an input frequency between 16 MHz and 32 MHz is required. Choose this model over the CY25818 if the application demands higher frequency operation, as the CY25818 supports only 8–16 MHz. Consider the separate REFCLK output requirement; if only modulated output is needed, other variants may suffice. Verify that the 8-pin SOIC package dimensions fit the PCB layout constraints.

Clock Generators, PLLs, Frequency Synthesizers Part Context

The CY25819SXCT belongs to the CY2581x series of Spread Spectrum Clock Generators produced by Cypress Semiconductor. This series is designed specifically for EMI reduction in high-speed digital systems. The SXCT variant denotes the 8-pin SOIC package configuration supplied in tape and reel format for automated assembly processes.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

The CY25818SXCT serves as a functional substitute for lower frequency applications requiring 8–16 MHz input. For identical performance specifications but different packaging, the CY25819SXC tube version is available. No direct cross-manufacturer replacements are documented in the official datasheet.

Clock Generators, PLLs, Frequency Synthesizers FAQ

How is the modulation percentage selected on the CY25819?

The modulation percentage is selected using the S0 digital input pin, which supports three logic levels: HIGH (connected to Vdd), LOW (connected to GND), and MIDDLE (left floating). Each level corresponds to a specific down spread percentage based on the input frequency range.

What is the difference between the SSCLK and REFCLK outputs?

SSCLK is the modulated Spread Spectrum Clock output used for EMI reduction, while REFCLK is the unmodulated Reference Clock output. Both outputs operate at the same frequency as the input clock signal.

Can the CY25819 accept a crystal input directly?

Yes, the XIN/CLKIN pin (Pin 1) can accept an external clock signal, a crystal, or a ceramic resonator. If an external clock is used, the XOUT pin (Pin 8) should be left unconnected.