ADXL202 DATASHEET PDF
ADXL datasheet, ADXL circuit, ADXL data sheet: AD – Low Cost +-2 g/+ g Dual Axis iMEMS Accelerometers with Digital Output,alldatasheet. ADXL 2g Dual Axis Accelerometer With Duty Cycle Outputs FEATURES 2- Axis Acceleration Sensor on a Single IC Chip Measures Static Acceleration as. ADXL Accelerometers are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for ADXL Accelerometers.
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Documents Flashcards Grammar checker. The outputs are analog voltage or digital signals whose duty cycles ratio of pulsewidth to period are proportional to acceleration. The duty cycle period is adjustable from 0. An analog output can be reconstructed by filtering the duty cycle output.
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One Technology Way, P. BoxNorwood, MAU. Supply 0 g Offset vs. Specifications subject to change without notice. This is a stress rating only; functional operation of the device at these or any other conditions above those indicate in the opera tional sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Care should be exercised in handling to avoid damage.
Electrostatic charges as high as V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADXLE datazheet proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high-energy electrostatic discharges.
Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Typical Supply Current vs. Typical X-Axis Zero g vs. Output for 16 Parts REV. Typical Y-Axis Zero g vs.
Datadheet Length of the total cycle. It contains a polysilicon surfacemicromachined sensor and signal conditioning circuitry to implement an open loop acceleration measurement architecture.
The accelerometer can measure static acceleration forces such as gravity, allowing it to be used as a tilt sensor. The sensor is a surface micromachined polysilicon structure built on top of the silicon wafer.
Polysilicon springs suspend the structure over the surface of the wafer and provide a resistance against acceleration forces. Deflection of the structure is measured using a differential capacitor that consists of independent fixed plates and central plates attached to the moving mass. An acceleration will deflect the beam and unbalance the differential capacitor, resulting in an output square wave whose amplitude is proportional to acceleration.
Phase sensitive demodulation techniques are then used to rectify the signal and determine the direction of the acceleration. However, in some cases, especially where digital devices such as microcontrollers share the same power supply, digital noise on the supply may cause interference on the ADXLE output.
At this point a pin is available on each channel to allow the user to set the datashete bandwidth of the device by adding a capacitor. This filtering improves measurement resolution and helps prevent aliasing. A single resistor sets the period for a complete cycle T2which can be set between 0.
A proper design will take into account the application requirements for bandwidth, signal resolution and acquisition time, as discussed in the following sections. Capacitors must be datashret at these pins to implement low-pass filtering for antialiasing and noise reduction. The equation for the 3 dB bandwidth is: ST The ST pin controls the self-test feature. When this pin is set to VDD, an electrostatic force is exerted on the beam of the accelerometer.
The resulting movement of the beam allows the user to test if the accelerometer is functional. This pin may be left open circuit or connected to datasehet in normal use.
A minimum capacitance of pF for C X, Y is required in all cases. T2 does not have to be measured for every measurement cycle. It need only be updated to account for changes due to temperature, a relatively slow process. Decoding algorithms for various microcontrollers have been developed. Consult the appropriate Application Note.
ADXL Data Sheet
The equation for the period is: The device is designed adl202 operate at duty cycle periods between 0. Its higher sensitivity Specific code sets, reference designs, and application notes are available from the factory. This section will outline a general design procedure and discuss the various trade-offs that need to be considered. With the single pole roll-off characteristic, the typical noise of the ADXLE is determined by the following equation: The designer should adx,202 some idea of the required performance of the system in terms of: Often the peak value of the noise is desired.
Peak-to-peak noise can only be estimated by statistical methods. Table III is useful for estimating the probabilities of exceeding various peak values, given the rms value. These requirements will help to determine the accelerometer bandwidth, the speed of the datasheer clock and the length of the Dagasheet period.
Estimation of Peak-to-Peak Noise When selecting a microcontroller it is helpful to have a counter timer port available. The microcontroller should have dataheet for software calibration. The easiest way to null this offset is with a calibration factor saved on the microcontroller or by a user calibration for zero g. Filtering can be used to lower the noise floor and improve the resolution of the accelerometer.
The user must filter the signal at this point to limit aliasing errors. This will result in greater dynamic error generated at the DCM.
The analog bandwidth may be further decreased to reduce noise and improve resolution. It is recommended that the user limit bandwidth to the lowest frequency needed by the application, to maximize the resolution and dynamic range of the accelerometer. The second relates to the measurement resolution of the counter when decoding the duty cycle output.
ADXL202 Data Sheet
The actual resolution of the acceleration signal is, however, limited by the time resolution of the counting devices used to decode the duty cycle. The faster the counter clock, the higher the resolution of the duty cycle and the shorter the T2 period can be for a given resolution. The following datssheet shows some of the trade-offs.
When one sensor is reading a maximum change in output per degree, the other is at its minimum. An accelerometer uses the force of gravity as an input vector to determine orientation of an object in space. An accelerometer is most sensitive to tilt when its sensitive axis is perpendicular to the force of gravity, i. At this orientation its adlx202 to changes in tilt is highest.
When the accelerometer is oriented on axis to gravity, i. When the accelerometer is perpendicular to gravity, its output will change nearly Duty Sdxl202 Filtering An analog output can be reconstructed by filtering the duty cycle output. This technique requires only passive components. The analog output signal will be ratiometric to the supply voltage. The advantage of this method is an output scale factor datasheey approximately double the analog output.
ADXL Datasheet and Product Info | Analog Devices
An op amp follower may be required to buffer this pin. The advantage of this method is that the full 5 kHz bandwidth of the accelerometer is available to the user.
A capacitor still must be added datashest this point for filtering.
Note that the accelerometer offset and sensitivity are adcl202 to the supply voltage. The offset and sensitivity are nominally: The ADXLE architecture has been designed so that these calibrations take place in the software of the microcontroller used to decode the duty cycle signal. Some key points are presented here. Power Cycle the accelerometer. Run the accelerometer at a Lower Voltage, Down to 3 V. Running the part at 3 V datashedt reduce the supply current from 0.
A buffer amplifier is recommended, and satasheet be required in any case to amplify the analog output to give enough resolution with an 8-bit ratasheet bit converter. Power Cycling When Using the Digital Output An alternative is to run the microcontroller at a higher clock rate and put it into shutdown between readings, allowing the use of the digital output. The concept is to acquire a reading as quickly as possible and then shut down the ADXLE and the microcontroller until the next sample is needed.
For low g applications, the force of gravity is the most stable, accurate and convenient acceleration reference available. The sensitivity can be determined by the two measurements. Using the two readings, the sensitivity is: Application notes outlining algorithms for calculating acceleration from duty cycle and automated calibration routines are available from the factory.
In either of the above approaches, the ADXLE can be turned on and off directly using a digital port pin on the microcontroller to power the accelerometer without additional components. Outline of the Declaration xdxl202 Independence. Thomas Jefferson, Declaration of Independence.