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
Low power: 700 μA at V
S
= 5 V (typical)
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
adjustable from 0.5 ms to 10 ms via a single resistor (R
SET
).
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
Capacitors C
X
and C
Y
at the X
FILT
and Y
FILT
pins. Bandwidths
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
09804-001
ADXL212
SENSOR
32kΩ
32kΩ
+
S
OUTPUT
AMP
OUTPUT
AMP
DCM
COM ST X
FILT
Y
FILT
V
S
DC
C
X
DEMOD
C
Y
T2
Y
OUT
X
OUT
R
SET
AC
AMP
t2
t1
A(g) = (t1/t2 – 0.5)/12.5%
0g = 50% DUTY CYCLE
t2(sec) = R
SET
/125MΩ
PWM OUTPUT WAVEFORM SAMPLE
Figure 1.
