Precision ±2 g Dual Axis,

PWM Output Accelerometer

ADXL212

Rev. 0

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FEATURES

Dual axis accelerometer on a single IC chip

5 mm × 5 mm × 2 mm LCC package

5 mg resolution at 60 Hz

High zero g bias stability

High sensitivity accuracy

Pulse width modulated digital outputs

X- and Y-axis aligned to within 0.1° (typical)

Bandwidth adjustment with a single capacitor

Single-supply operation

3500 g shock survival

APPLICATIONS

Automotive tilt alarms

Vehicle dynamic control (VDC)/electronic stability program

(ESP) systems

Electronic chassis control

Electronic braking

Data projectors

Navigation

Platform stabilization/leveling

Alarms and motion detectors

High accuracy, 2-axis tilt sensing

GENERAL DESCRIPTION

The ADXL212 is a high precision, low power, complete dual

axis accelerometer with signal conditioned, duty cycle modulated

outputs, all on a single monolithic IC. The ADXL212 measures

acceleration with a full-scale range of ±2 g (typical). The ADXL212

measures both dynamic acceleration (such as vibration) and

static acceleration (such as gravity).

The outputs are digital signals whose duty cycles (ratio of pulse

width to period) are proportional to acceleration (12.5%/g) in

each of the two sensitive axes. The duty cycle outputs can be

directly measured by a microcontroller without an analog-to-

digital converter (ADC) or glue logic. The output period is

The typical noise floor is 500 μg/√Hz, allowing signals below

5 mg (0.3° of inclination) to be resolved in tilt sensing applica-

tions using narrow bandwidths (<60 Hz).

The user selects the bandwidth of the accelerometer using

of 0.5 Hz to 500 Hz can be selected to suit the application.

The ADXL212 is available in a 5 mm × 5 mm × 2 mm, 8-lead

hermetic LCC package.

FUNCTIONAL BLOCK DIAGRAM

ADXL212

SENSOR

32kΩ

32kΩ

OUTPUT

AMP

OUTPUT

AMP

DCM

COM

ST

DEMOD

T2

AC

AMP

t2

t1

A(g) = (t1/t2 – 0.5)/12.5%

0g = 50% DUTY CYCLE

PWM OUTPUT WAVEFORM SAMPLE

Figure 1.