SL28PCIE14ALI

Application Specific Clock/Timing Overview

The SL28PCIe14ALI is a PCI-Express Gen 2 & Gen 3 compliant clock generator and fan-out buffer utilizing EProClock® technology. It features four low-power push-pull differential output buffers with integrated resistors, operating at frequencies up to 100 MHz. The device supports a 25 MHz crystal or clock input and offers hardware-selectable buffered input or synthesizer modes. Key specifications include a 3.3V power supply, industrial temperature range (-40°C to 85°C), and SMBus programmability for frequency and spread spectrum control.

Application Specific Clock/Timing Feature Summary

• EProClock® non-volatile programmable technology allowing configuration via SMBus or hard coding.
• Four differential outputs supporting PCIe Gen 2 and Gen 3 standards with integrated series resistors.
• Hardware-selectable Spread Spectrum Control (SSC) via SS pins for EMI reduction.
• SMBus interface with readback capabilities for individual output enable/disable and amplitude adjustment.

Application Specific Clock/Timing Applications

• PCI-Express Gen 2 and Gen 3 system designs requiring compliant reference clocks.
• Industrial computing platforms needing wide temperature operation (-40°C to 85°C).
• Motherboards and expansion cards utilizing Intel Ultra Mobile Platform architectures.

Application Specific Clock/Timing Procurement Notes

Verify the specific ordering suffix against the datasheet table on page 12. The 'I' suffix denotes Industrial temperature range (-40°C to 85°C), while 'C' indicates Commercial range. The 'T' suffix specifies Tape and Reel packaging; absence of 'T' implies Tube packaging. Confirm package type is 32-pin QFN (5x5mm).

Application Specific Clock/Timing Selection Notes

Select based on required temperature range and packaging format. Ensure the input source matches either a 25MHz crystal or a 3.3V CMOS clock signal. Verify that the target application requires the specific jitter performance metrics defined for PCIe Gen 2/3 compliance, particularly the RMS phase jitter limits under specified PLL bandwidth conditions.

Application Specific Clock/Timing Part Context

This component belongs to the Skyworks SL28PCIe family of clock generators. It is distinct from other models in the series by its specific combination of four differential outputs, EProClock® programmability, and support for both synthesizer and fan-out buffer modes within a single 32-pin QFN package.

Application Specific Clock/Timing Replacement Considerations

Direct replacements must match the 32-pin QFN footprint and pinout. Consider Skyworks models such as SL28PCIe16ALIT or SL28PCIe26ALCT if higher output counts or different input configurations are acceptable, provided they meet the same PCIe Gen 2/3 electrical specifications.

Application Specific Clock/Timing FAQ

How is the Spread Spectrum profile selected?

The Spread Spectrum profile is selected using the SS1 and SS0 pins. Logic levels applied to these pins before CKPWRGD assertion determine the modulation percentage (OFF, -0.5%, +/-0.25%, or -0.75%).

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

It is a dual-function pin. During power-up, it acts as CKPWRGD to latch inputs. Once sampled HIGH, it functions as PD#, an asynchronous active-LOW input used to cleanly shut off all clocks before power removal.

Can the device operate without a crystal?

Yes. By setting IN_SEL high, the device operates in Fan-out Buffer mode, accepting an external differential serial reference clock input on DIFFIN/DIFFIN# instead of using the internal synthesizer with a crystal.