Top of Rack Switch / Leaf Switch

top rack switch leaf hero image

IEEE 1588 is becoming the de facto standard for better performance in data centers. As Synchronous Ethernet (SyncE) replaces Ethernet, use of a TCXO or OCXO reference clock in top-of-rack and leaf switch is needed. SiTime offers a complete MEMS-based clock tree solution that performs better in real-world operating conditions.

Elite Platform® Super-TCXOs® and Emerald OCXOs provide essential stability and reduce time error through better frequency over temperature slope. Cascade™ network synchronizers / jitter cleaners / clock generators, used to filter jitter in recovered clocks, have an integrated resonator that simplifies development and reduces field failures. When SyncE and IEEE 1588 are not needed, SiTime differential oscillators offer sub-100-femtosecond jitter and low power. Together they offer a complete and robust clock tree.

Download Application Brief

SiTime MEMS Timing Benefits

Complete MEMS clock tree

Integrated MEMS

Stratum 3E MEMS OCXO


More robust in real world conditions

4x better dF/dT for best time sync

70 fs rms jitter, excellent PSNR

Resistant to airflow, heat, vibration

Integrated MEMS, easy to use

No external quartz

No quartz reliability issues

No cover or shielding needed

Top of Rack Switch / Leaf Switch Block Diagrams

MEMS Timing Solutions with SyncE and IEEE 1588

MEMS Timing Solutions without SyncE and IEEE 1588

MEMS XO + Buffer Alternative Timing Solution

MEMS Timing Solutions

Devices Function Key Features
SiT535x  1 to 220 MHz
Reference clock for jitter cleaner and IEEE1588 ±100 ppb, ±1 ppb/°C 105°C
SiT57xx  1 to 60 MHz
Reference clock for jitter cleaner and IEEE1588 ±5 ppb, ±0.04 ppb/°C
Clock Generator
SiT9514x  8 kHz to 2.1 GHz
Ethernet 4-in, 11-out, 4-PLL
Network Synchronizer
SiT9514x  8 kHz to 2.1 GHz
Ethernet, processor 4-in, 11-out, 4-PLL
Differential XO
SiT9501  25 to 644.53125 MHz
Buy Now
SiT9375  25 to 644.53125 MHz
Buy Now
Ethernet, FPGA 0.07 to 0.25 ps jitter, 105°

What is a Top of Rack (ToR) Switch?

A leaf switch (or top-of-rack ToR switch) aggregates server traffic between the spine switches and either the core network or servers in the data-center campus. As bandwidth increases in next-gen deployments, higher performance is specified by IEEE 1588, placing a greater demand for high-performance timing solutions that withstand airflow, heat, and vibration. 

TOR Leaf Switch – Data Center diagram

MEMS Timing Outperforms Quartz

Better Stability

Better Frequency Slope

SiTime – Better Stability
SiTime – Better Frequency Slope


Better Vibration Resistance

Better Allan Deviation

SiTime – Better Vibration Resistance
SiTime – Better Allan Deviation


Excellent Phase Noise, 156.25 MHz

Better PSNR (Power Supply Noise Rejection)

SiTime – Excellent Phase Noise 156.25 MHz
SiTime – Better PSNR (Power Supply Noise Rejection)

Watch Video: SiTime Elite Super-TCXO Dynamic Performance vs. Quartz TCXO

contact support 2

Need samples or more information?

Contact Us Request Samples