Datasheet ADXL212 (Analog Devices)

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 μA at VS = 5 V (typical)
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
APPLICATIONS
adjustable from 0.5 ms to 10 ms via a single resistor (RSET).
Automotive tilt alarms
The typical noise floor is 500 μg/√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 Platform stabilization/leveling
The ADXL212 is available in a 5 mm × 5 mm × 2 mm, 8-lead
Alarms and motion detectors
hermetic LCC package.
High accuracy, 2-axis tilt sensing FUNCTIONAL BLOCK DIAGRAM +VS CY V Y S FILT ADXL212 32kΩ OUTPUT Y C AMP OUT DC AC DEMOD DCM AMP OUTPUT X SENSOR AMP OUT 32kΩ COM ST XFILT T2 CX RSET PWM OUTPUT WAVEFORM SAMPLE t2 t1
1
A(g ) = (t1/t2 – 0.5)/12.5%
-00
0g = 50% DUTY CYCLE
804
t2(sec) = RSET/125MΩ
09 Figure 1.
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION PERFORMANCE APPLICATIONS INFORMATION POWER SUPPLY DECOUPLING SETTING THE BANDWIDTH USING CX AND CY SELF TEST DESIGN TRADE-OFFS FOR SELECTING FILTER CHARACTERISTICS: NOISE vs. BANDWIDTH USING THE ADXL212 WITH OPERATING VOLTAGES OTHER THAN 5 V USING THE ADXL212 AS A DUAL AXIS TILT SENSOR Dual Axis Tilt Sensor: Converting Acceleration to Tilt OUTLINE DIMENSIONS ORDERING GUIDE