SIT92211AI-N

Clock Buffers, Drivers Overview

The SiTime SIT92211AI-N is a 2.1 GHz, 10-output ultra-low jitter clock fan-out buffer designed for high-frequency clock distribution and level translation. It features three selectable clock inputs: two universal differential or single-ended inputs (CLKin0/1) supporting up to 2.1 GHz, and one crystal input (OSCIN) for 8 MHz to 50 MHz crystals or single-ended clocks. The device distributes the selected clock to two independent output driver banks (A and B), each providing five differential outputs, plus one synchronized LVCMOS reference output (REFOUT). Output drivers can be independently configured as LVPECL, LVDS, HCSL, or Hi-Z. The core supply operates at 3.3 V or 2.5 V, while differential outputs support 3.3 V or 2.5 V, and the LVCMOS output supports 3.3 V, 2.5 V, or 1.8 V.

Clock Buffers, Drivers Feature Summary

• Ultra-low additive jitter performance of 55 fs RMS with PSRR up to -73 dBc.
• Supports 3:1 input selection from two universal clock inputs (up to 2.1 GHz) or one crystal input (8-50 MHz).
• Provides 10 differential outputs across two programmable banks (LVPECL, LVDS, HCSL, or Hi-Z) and one glitch-free LVCMOS reference output.
• Typical output skew between clock outputs is 30 ps.

Clock Buffers, Drivers Applications

• PCI Express Gen1 through Gen5 clock distribution.
• High-speed data acquisition systems requiring low jitter.
• Telecommunications infrastructure timing.
• Level translation between different voltage domains (e.g., 3.3V to 1.8V).

Clock Buffers, Drivers Procurement Notes

Verify the specific ordering suffix 'N' against the manufacturer's official documentation to confirm package type and tape/reel specifications. Ensure the required output voltage levels (3.3 V, 2.5 V, or 1.8 V) match the system design constraints for both core and output supplies.

Clock Buffers, Drivers Selection Notes

Select this component when applications require distributing a high-frequency clock signal (>1 GHz) with minimal added jitter. Consider the available input types (differential vs. single-ended/crystal) and the required output logic families (LVPECL, LVDS, HCSL, LVCMOS). Verify that the PCB layout can accommodate the 48-pin QFN package and proper thermal dissipation.

Clock Buffers, Drivers Part Context

The SIT92211 belongs to SiTime's high-performance clock buffer family, specifically engineered for demanding digital systems. It replaces traditional quartz-based buffers by offering lower jitter, smaller form factors, and greater flexibility in input/output configurations. The AI suffix typically denotes an industrial temperature range (-40°C to 85°C) and specific quality grades.

Clock Buffers, Drivers Replacement Considerations

Direct pin-to-pin replacements may not exist due to the specific 48-pin QFN footprint and unique control pin configuration. Evaluate other SiTime models like the SiT92216 or SiT92315 if pin count or output configuration differs. Cross-check electrical parameters such as maximum frequency and jitter specs before substituting.

Clock Buffers, Drivers FAQ

What are the supported input clock types?

The SiT92211 accepts two universal clock inputs (CLKin0/1) which can be differential or single-ended, operating up to 2.1 GHz. It also has a dedicated crystal input (OSCIN) for crystals between 8 MHz and 50 MHz or single-ended clocks.

Can the output drivers be mixed within the same bank?

No, the output drivers in Bank A and Bank B must be configured uniformly. Each bank can be set to LVPECL, LVDS, HCSL, or Hi-Z mode via control pins, but all outputs within a single bank share the same configuration.

How is the LVCMOS output synchronized?

The LVCMOS output (REFOUT) is synchronized to the selected clock input. It can be enabled or disabled in a glitch-free manner using the REFOUT_EN pin, ensuring clean transitions during state changes.