SL28PCIE25ALCT

Clock Generators, PLLs, Frequency Synthesizers Overview

The SL28PCIE25ALCT is a programmable clock generator from Skyworks Solutions Inc., designed for PCI Express Gen 2 and Gen 3 applications. It operates at a maximum frequency of 100 MHz with a 1:5 input-to-output ratio. The device features one differential input and five differential outputs, utilizing EProClock technology for non-volatile configuration via an SMBus interface. It accepts a 25 MHz crystal or clock input and provides four 100 MHz differential PCIe reference clocks alongside a buffered 25 MHz single-ended output. Powered by a 3.3V supply (3.135V to 3.465V), it supports triangular spread spectrum modulation for EMI reduction and operates within a commercial temperature range of 0°C to 85°C in a 32-pin QFN package.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• EProClock non-volatile programmable technology allows configuration via SMBus or hard coding without board redesigns.
• Integrated low power push-pull differential output buffers with integrated resistors on differential clocks.
• Supports triangular Spread Spectrum Clocking (SSC) profile for electromagnetic interference reduction.
• Includes an integrated voltage regulator and dual-function CKPWRGD/PD# pin for power management.

Clock Generators, PLLs, Frequency Synthesizers Applications

• PCI Express Gen 2 and Gen 3 system designs
• Motherboard clock distribution networks
• Server and workstation platforms requiring low jitter reference clocks

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify the specific ordering suffix against the manufacturer's current datasheet before procurement. The 'T' suffix indicates tape and reel packaging, while 'C' denotes the commercial temperature range. Confirm that the component status remains active or acceptable for new designs, as timing products may undergo lifecycle changes. Ensure the required package type matches the PCB footprint specifications provided in the official documentation.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select this model when designing for PCI Express Gen 2 or Gen 3 interfaces requiring a 100 MHz differential reference clock. Choose the ALCT variant specifically if tape and reel manufacturing processes are required rather than tray packaging. Verify that the commercial temperature range (0°C to 85°C) aligns with the system environment; otherwise, consider the industrial grade alternative. Ensure the design accommodates the 32-pin QFN exposed pad thermal requirements and SMBus connectivity for configuration.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This component belongs to the SL28PCIe25 family of EProClock generators. The base part number SL28PCIE25 identifies the core silicon functionality. The suffixes define physical attributes: 'A' typically indicates lead-free composition, 'L' specifies the 32-QFN package, 'C' defines the commercial temperature range, and 'T' specifies tape and reel shipping. Variants like SL28PCIE25ALI exist for industrial temperature ranges.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

SL28PCIE25ALI serves as the industrial temperature range equivalent. SL28PCIE25AL is the tray-packaged version of the same commercial device. Direct functional replacements should be verified against updated Skyworks portfolios, as older generations may have successors with enhanced jitter performance.

Clock Generators, PLLs, Frequency Synthesizers FAQ

What is the function of the CKPWRGD/PD# pin?

It is a dual-function pin. During initial power-up, it acts as CKPWRGD (Power Good). Once sampled HIGH, it functions as PD#, an asynchronous active-LOW input used to cleanly shut off all clocks before powering down the device.

How is the device configured?

Configuration is achieved through the SMBus serial interface (SDATA/SCLK) or by hard-coding the settings. The EProClock technology stores over 4000 bits of configuration data non-volatiles.

What is the power-up latency for this clock generator?

The power-up latency is less than 1.8 ms, measured from the deassertion of the PD# pin or the ramping of the power supply until stable clocks are generated.