ADAS Computer

Cockpit of futuristic autonomous car

Modern vehicles are increasingly adopting AD/ADAS functions, generating more data than ever before. Processing this data is possible only through more complex E/E systems, which demand more clocks. High-speed interfaces such as PCI-Express need clocks with well controlled jitter to avoid transmission errors on the bus. Functional safety requirements put further constraints on AD/ADAS components.

SiTime MEMS oscillators offer high reliability and accuracy over temperature from -55 to 125°C in a very small package. Our solutions provide outstanding dynamic performance including excellent stability during rapid temperature change (dF/dT), resilience to shock and vibration, and low jitter. Plus, our FIT rate is up to 50x better than quartz crystal devices, facilitating the achievement of functional safety targets.

Download Application Brief

SiTime MEMS Timing Benefits

Complete MEMS clock tree

Spread spectrum oscillators

Low jitter differential oscillators

32.768-kHz XOs and TCXOs

Precision TCXOs

Most robust in real world conditions

150 fs rms jitter, excellent PSNR

Resistant to shock and vibration

Stable over wide temperature

2.2 billion hours MTBF

Integrated MEMS, easy to use

No quartz reliability issues

Reliable startup in cold temp

No cover or shielding needed

Short lead time for any frequency

ADAS Computer Block Diagram

ADAS computers require many clocks:

  • A low jitter clock is essential to ensure proper PHY operation since data input usually occurs through a PHY (such as MIPI A-PHY, FPDLink, GMSL, etc.).
  • PCI-Express is widely used for on-board, device-to-device data exchange. This requires 100-MHz differential clocks, possibly with spread spectrum – the SiT9025 is perfect for EMI reduction.
  • Multi-GB Ethernet for communications require 156.25-MHz differential, low jitter clocks.
  • SoC, processors and other devices require general purpose clocks.
  • A 32.768-kHz clock is necessary for time keeping and, in some systems, for safety functions.

See also the Application Brief on Automotive Cameras.

MEMS Timing Solutions for ADAS Computer

Devices Key Features Key Values
Single-ended Oscillator
SiT8924  1 to 110 MHz
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  • Up to -55°C to +125°C
  • ±20 ppm stability
  • 2016, 2520, 3225 packages
  • High reliability
  • Extended temperature range
  • Small footprint
Single-ended Oscillator
SiT9025  1 to 110 MHz
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  • Up to -55°C to +125°C
  • Spread spectrum
  • Configurable rise / fall times
  • 2016, 2520, 3225 packages
  • High reliability
  • Extended temperature range
  • EMI Reduction
Differential Oscillators
SiT9396  1 to 220 MHz
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SiT9397  220 to 920 MHz
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  • Low jitter: < 150 fs RMS [1]
  • ±30, ±50 ppm stability over -40 to +125°C
  • LVPECL, LVDS, HCSL, Low-power HCSL, FlexSwing™
  • 2016, 2520, 3225 packages
  • High reliability
  • Low jitter
  • Enables interfaces with demanding jitter requirements, such as PCI-Express and 10 GB Ethernet
SiT5386  1 to 60 MHz
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SiT5387  60 to 220 MHz
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  • ±0.1, ±0.2, ±0.25 ppm stability over -40 to +125°C
  • ±1 ppb/°C frequency slope
  • Low jitter: 0.31 ps RMS [1]
  • Optional voltage or digital frequency control
  • High accuracy
  • Excellent frequency stability with fast temp gradients
  • No GNSS signal loss or V2X disconnect due to micro-jumps

1 12 kHz to 20 MHz integration range

MEMS Timing Outperforms Quartz

Higher Quality

Higher Reliability

 SiTime – Higher Quality
SiTime timing devices are up to 50x more reliable than legacy quartz


Tighter Stability

Better EMI Reduction

SiTime – Tighter Stability
SiTime – Better EMI Reduction


Immune to Vibration

Better Noise Rejection

SiTime – Immune to Vibration
SiTime – Better Noise Rejection

Key concerns of designers

  • Reliability
  • Functional safety
  • High temperature requirements
  • Fast system startup time required (usually < 100 ms)
  • EMI


SiTime advantages

All SiTime devices offer the following advantages over quartz crystals, which are particularly important for automotive applications:

  • Up to 50x better reliability: Apart from reducing the amount of field failures, the better reliability translates into a lower FIT rate. This provides better Hardware Safety metrics in an FMEDA, the quantitative analysis required as part of a Functional Safety assessment.
  • Up to 100x better resilience to shock, vibration and electromagnetic interference, due to the smaller size (0.4 x 0.4 mm) and lower mass of MEMS resonators compared to crystals.
  • Better frequency stability (down to ±100 ppb) and frequency response to temperature changes dF/dT (down to < 3.5 ppb/°C). These characteristics provide better locking to GNSS and V2X, and reduced connection drops.
  • Silicon MEMS oscillators typically have a faster start-up time than crystal oscillators.
  • SiT9025 features EMI reduction features: spread spectrum and configurable rise/fall times

Watch Video: SiTime MEMS Oscillators for ADAS

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