SiTime’s new Endura Oscillator Families, precision timing for Aerospace and Defence

27th January 2023
Sheryl Miles

SiTime,the precision timing company, has announced two new Endura precision timing oscillator families.

These ruggedised devices are engineered to deliver high performance in extreme conditions in aerospace-defence applications such as Positioning, Navigation and Timing (PNT), tactical communications, network synchronisation and surveillance.

The devices include the Endura ultra-stable Super-TCXO and the Endura low-jitter differential oscillator. Both families deliver 10x better environmental resilience. In addition, the Endura Super-TCXO family delivers up to 5x better stability, while the differential oscillator family delivers the best jitter.

“Timing technology is ever more crucial in aerospace and defence applications where extreme conditions are the norm,” said Fari Assaderaghi, EVP, Technology and Engineering, SiTime. “Today, in these systems, timing is a major source of performance challenges during system verification, qualification, and field operation. This leads to significant engineering time spent in troubleshooting and/or negotiating waivers with end customers. With the drive to higher performance and positioning accuracy, timing requirements for new aerospace-defence electronics are only getting more stringent. It is difficult to foresee how legacy timing devices will continue to perform well in these new systems.”

“SiTime Endura precision timing solutions deliver a dramatically better user experience,” continued Assaderaghi. “Not only can designers count on the performance and reliability of Endura-based timing systems, but they can also save valuable development time that would have otherwise been spent in troubleshooting. The SiTime Endura family is fast becoming the preferred timing choice for aerospace and defence engineers.”

SiTime’s innovative MEMS, analogue and systems technologies enable many features that simplify design. For example, frequencies are programmable up to 6 decimal places of accuracy and ensure that the designer can select the exact frequency they want, to enhance system performance. With a frequency stability specification as low as ±10 ppb, designers can replace large OCXOs with Super-TCXOs.

With power-supply noise rejection (PSNR) specification, SiTime devices are very resistant to power supply noise, which is a common problem in the dense electrical environments of aerospace-defence electronics.

Key specifications of the Endura SiT5541 ultra-stable super-TCXOs

  • 1 to 60MHz
  • -40°C to +105°C operating temperature range, enables use in extreme temperatures
  • ±10 ppb frequency stability over the full temperature range, highest amongst TCXOs, and able to replace more expensive, power-hungry, and less-reliable OCXOs
  • 0.01 ppb/g g-sensitivity per MIL-PRF-55310
  • 110 mW (typ.) power consumption, 2 to 10x lower than ±10 ppb OCXOs
  • ±0.5 ppb/°C dF/dT (frequency slope), resistant to thermal shock and airflow
  • ±300 ppb 20-year aging at 85°C, eliminates expensive in-factory calibration that is required with less stable devices
  • Small 7.0 x 5.0mm ceramic package, insensitive to board bending stress, reducing board layout constraints

Key specifications of the Endura SiT9551/SiT9356/SiT9357 ultra-low-jitter differential oscillators

Endura differential oscillators enable low data error rates and uninterrupted communications for on-the-ground, mounted, dismounted and airborne conditions.

  • SiT9551, 15 different frequencies from 25 to 644.5MHz, 70fs RMS typical IPJ (integrated phase jitter, 12kHz to 20MHz integration range)
  • SiT9346, 1 to 220MHz frequency range, 150fs RMS typical IPJ
  • SiT9347, 220 to 920MHz frequency range, 150fs RMS typical IPJ
  • 9fs/mV power supply noise rejection (PSNR) ensures peak performance in the presence of power-supply noise, which is a common issue in dense aerospace-defence electronics
  • -55°C to +125°C operating temperature range, enables use in extreme temperatures
  • 0.04 ppb/g g-sensitivity per MIL-PRF-55310
  • ±20 to ±50 ppm frequency stability over the full temperature range
  • 26mA no load current (typ.) with LVDS, 1.8, 2.5 or 3.3V supply voltage
  • Available in 2016, 2520 and 3225 QFN packages


Both device families are sampling now.

Volume production for Endura SiT5541 ultra-stable Super-TCXO is expected in March 2023, and for Endura SiT9551 low-jitter differential oscillators in July 2023.

Upon release, all Endura precision timing solutions will be available on SiTimeDirect for quick configuration and 48-hour shipments.

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