Precision 2 g Dual Axis, PWM Output Accelerometer ADXL212 FEATURES GENERAL DESCRIPTION Dual axis accelerometer on a single IC chip The ADXL212 is a high precision, low power, complete dual 5 mm 5 mm 2 mm LCC package axis accelerometer with signal conditioned, duty cycle modulated 5 mg resolution at 60 Hz outputs, all on a single monolithic IC. The ADXL212 measures Low power: 700 A at V = 5 V (typical) S acceleration with a full-scale range of 2 g (typical). The ADXL212 High zero g bias stability measures both dynamic acceleration (such as vibration) and High sensitivity accuracy static acceleration (such as gravity). Pulse width modulated digital outputs The outputs are digital signals whose duty cycles (ratio of pulse X- and Y-axis aligned to within 0.1 (typical) width to period) are proportional to acceleration (12.5%/g) in Bandwidth adjustment with a single capacitor each of the two sensitive axes. The duty cycle outputs can be Single-supply operation directly measured by a microcontroller without an analog-to- 3500 g shock survival digital converter (ADC) or glue logic. The output period is adjustable from 0.5 ms to 10 ms via a single resistor (RSET). APPLICATIONS Automotive tilt alarms The typical noise floor is 500 g/Hz, allowing signals below Vehicle dynamic control (VDC)/electronic stability program 5 mg (0.3 of inclination) to be resolved in tilt sensing applica- (ESP) systems tions using narrow bandwidths (<60 Hz). Electronic chassis control The user selects the bandwidth of the accelerometer using Electronic braking Capacitors CX and CY at the XFILT and YFILT pins. Bandwidths Data projectors of 0.5 Hz to 500 Hz can be selected to suit the application. Navigation The ADXL212 is available in a 5 mm 5 mm 2 mm, 8-lead Platform stabilization/leveling hermetic LCC package. Alarms and motion detectors High accuracy, 2-axis tilt sensing FUNCTIONAL BLOCK DIAGRAM +V S C Y Y V S FILT ADXL212 32k OUTPUT Y OUT AMP C DC AC DEMOD DCM AMP OUTPUT X OUT AMP SENSOR 32k COM ST X T2 FILT C R X SET PWM OUTPUT WAVEFORM SAMPLE t2 t1 A(g) = (t1/t2 0.5)/12.5% 0g = 50% DUTY CYCLE t2(sec) = R /125M SET Figure 1. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 09804-001ADXL212 TABLE OF CONTENTS Features .............................................................................................. 1 Applications Information .............................................................. 10 Applications....................................................................................... 1 Power Supply Decoupling ......................................................... 10 General Description ......................................................................... 1 Setting the Bandwidth Using CX and CY ................................. 10 Functional Block Diagram .............................................................. 1 Self Test ........................................................................................ 10 Revision History ............................................................................... 2 Design Trade-Offs for Selecting Filter Characteristics: Noise vs. Bandwidth ............................................................................. 10 Specifications..................................................................................... 3 Using the ADXL212 with Operating Voltages Other Than 5 V Absolute Maximum Ratings............................................................ 4 ....................................................................................................... 11 Thermal Resistance ...................................................................... 4 Using the ADXL212 as a Dual Axis Tilt Sensor..................... 11 ESD Caution.................................................................................. 4 Outline Dimensions....................................................................... 12 Pin Configuration and Function Descriptions............................. 5 Ordering Guide .......................................................................... 12 Typical Performance Characteristics ............................................. 6 Theory of Operation ........................................................................ 9 Performance .................................................................................. 9 REVISION HISTORY 5/11Revision 0: Initial Version Rev. 0 Page 2 of 12