Precision ± ± g Dual Axis,
PWM Output Accelerometer
ADXL±1±
FEATURES
GENERAL DESCRIPTION
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 VS = 5 V (typical)
High zero g bias stability
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).
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
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 (RSET).
3500 g shock survival
APPLICATIONS
Automotive tilt alarms
Vehicle dynamic control (VDC)/electronic stability program
(ESP) systems
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).
Electronic chassis control
Electronic braking
Data projectors
The user selects the bandwidth of the accelerometer using
Capacitors CX and CY at the XFILT and YFILT pins. Bandwidths
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
hermetic LCC package.
Platform stabilization/leveling
Alarms and motion detectors
High accuracy, 2-axis tilt sensing
FUNCTIONAL BLOCK DIAGRAM
+V
V
S
C
Y
Y
FILT
S
ADXL212
32kΩ
32kΩ
OUTPUT
AMP
Y
X
OUT
OUT
C
DC
AC
AMP
DEMOD
DCM
OUTPUT
AMP
SENSOR
COM
ST
X
T2
FILT
C
R
SET
X
PWM OUTPUT WAVEFORM SAMPLE
t2
t1
A(g) = (t1/t2 – 0.5)/12.5%
0g = 50% DUTY CYCLE
t2(sec) = R
/125MΩ
SET
Figure 1.
Rev. 0
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