CAS200 series (Dual-axis, in-plane) high-performance dual-axis linear accelerometer

Choose the lowest range that still covers the maximum expected acceleration, transient load and engineering margin without clipping. The CAS211 provides ±0.85g with a digital scale factor of 33,500 LSB/g and noise of up to 50 µg/√Hz, making it suitable for small motions, tilt and low-g measurement, while the CAS212 and CAS213 extend the range to ±2.5g and ±10g. The CAS214 and CAS215 cover ±30g and ±96g, but their digital scale factors fall to 1,050 and 300 LSB/g and their noise levels increase. The 1,000g operational shock rating is a survival specification and does not increase the measurable acceleration range or provide measurement headroom. Select the variant based first on measurable dynamics and overload margin, and then compare its noise, resolution and scale factor with the application requirements.

Use SPI when the host processor needs direct digital acceleration, temperature and status data, or when eliminating an external ADC simplifies the design. The interface is a 4-wire SPI Mode 0 slave using 48-bit messages, with a recommended message rate of 1 kHz, an allowed range from 1 Hz to 10 kHz and a nominal 1 MHz clock within a 100 kHz to 8 MHz range. Sampling above 500 Hz is recommended to reduce aliasing, although the digital sensor bandwidth remains above 170 Hz. Choose the analogue outputs when the design benefits from bandwidth above 250 Hz or already includes a suitable acquisition chain; because the outputs are ratiometric, ADC-reference and supply behaviour must be considered together. Interface selection should account for filtering, synchronisation and built-in-test handling rather than bandwidth alone.

The sensor operates functionally from 2.7 to 3.6 V, but all specified performance limits assume a tighter 3.15 to 3.45 V supply across the full -40°C to +125°C operating range. Current consumption is typically 3 mA, with a specified maximum of 5 mA. Fit a 100 nF X7R ceramic decoupling capacitor at the main supply, add a nearby 10 µF bulk capacitor and use separate 100 nF X7R capacitors for the Vdd_Cap and Vref_Cap connections. Avoid routing signal or power tracks beneath the capacitive sensor package where possible because they can introduce acceleration-bias offsets. These provisions reduce supply coupling and limit the compensation required during completed-system calibration.

The CAS200 operates from -40°C to +125°C and has a storage range of -55°C to +150°C, allowing it to be designed into equipment exposed to broad thermal cycles. Its hermetically sealed ceramic package provides resistance to humidity, while the stated absolute limit is 90% RH under non-condensing conditions. The operational shock rating is 1,000g for a 1 ms half-sine pulse. Non-operational survival is 6,500g for the CAS211 through CAS213 and 10,000g for the CAS214 and CAS215, using a 0.1 ms half-sine pulse. These values are survival limits rather than measurable ranges, and the PCB, solder joints and surrounding assembly still require application-level shock and vibration qualification.

The digital and analogue signal paths provide bandwidths above 170 Hz and 250 Hz respectively, but usable resolution depends strongly on the selected variant and the bandwidth retained after filtering. As a first-order white-noise estimate, RMS noise is calculated by multiplying noise spectral density by the square root of measurement bandwidth. Across a 100 Hz bandwidth, the CAS211 noise value of 50 µg/√Hz corresponds to approximately 0.5 mg RMS, while the CAS215 value of 1,200 µg/√Hz corresponds to approximately 12 mg RMS. Narrower filtering can reduce integrated noise when the application does not require the full response bandwidth. Engineers should therefore select the acceleration range and signal bandwidth together rather than treating them as independent requirements.

Yes, the integrated temperature channel can support host-level thermal compensation and operating-condition monitoring. The digital output has a typical scale factor of 11 LSB/°C with an offset of 2,380 LSB at +25°C, while the analogue output provides 5 mV/°C with an offset of approximately 1.49 V at +25°C. The stated temperature repeatability is within ±5°C, so the channel should not replace a calibrated external sensor where precise ambient-temperature measurement is required. It is most useful for correlating acceleration bias and scale-factor behaviour with the sensor’s own thermal state. Establish compensation curves on the completed assembly because PCB layout, mounting stress and local heating can affect the final system response.

The matching CAS21x evaluation board can confirm the selected measurement range and interface before the host PCB design is finalised. The board measures 34 × 26 mm, operates from 3.3 V and provides access to both analogue outputs and the SPI bus for CAS21x variants spanning ±0.85g to ±96g. It supports early checks of scaling, bandwidth, noise, message handling and temperature data using the intended device. The board is intended for evaluation rather than integration as a permanent subsystem, so its mechanical, EMC and environmental behaviour should not be transferred directly to the final assembly. A production design still requires the recommended decoupling, controlled PCB layout, validated mounting process and system-level calibration.