Top of Rack Switch / Leaf Switch
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.
SiTime MEMS Timing Benefits
Complete MEMS clock treeIntegrated MEMS Stratum 3E MEMS OCXO MEMS clock IC/PLL |
More robust in real world conditions4x better dF/dT for best time sync 70 fs rms jitter, excellent PSNR Resistant to airflow, heat, vibration |
Integrated MEMS, easy to useNo 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 |
|---|---|---|
|
Super-TCXO
SiT535x 1 to 220 MHz
|
Reference clock for jitter cleaner and IEEE1588 | ±100 ppb, ±1 ppb/°C 105°C |
|
OCXO
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
SiT9375 25 to 644.53125 MHz
|
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.
MEMS Timing Outperforms Quartz
Better Stability |
Better Frequency Slope |
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Better Vibration Resistance |
Better Allan Deviation |
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Excellent Phase Noise, 156.25 MHz |
Better PSNR (Power Supply Noise Rejection) |
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Watch Video: SiTime Elite Super-TCXO Dynamic Performance vs. Quartz TCXO
Application Notes and Papers
- Synchronization System Performance Benefits of Precision MEMS TCXOs under Environmental Stress Conditions
- AN10063 TCXO and OCXO Stability and System Impact Beyond Rated Temperature
- AN10064 Improved System Performance with Digital Frequency Tuning in Precision Super-TCXOs
- AN20003 SiT9514x Power Supply Noise Rejection
- AN20011 SiT9514x Dynamic Control of Outputs
- AN10052 IEEE 1088 Precision Time Protocol (PTP) in ITU-T Standards
- See full list of related applications notes
