Low Cost ±1.2
g
Dual
Axis Accelerometer
ADXL213
Rev. A
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FEATURES
Dual axis accelerometer on a single IC chip
5 mm × 5 mm × 2 mm LCC package
1 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 axes aligned to within 0.1° (typical)
BW adjustment with a single capacitor
Single-supply operation
3500 g shock survival
Qualified for automotive applications
APPLICATIONS
Automotive tilt alarms
Data projectors
Navigation
Platform stabilization/leveling
Alarms and motion detectors
High accuracy, 2-axis tilt sensing
GENERAL DESCRIPTION
The ADXL213 is a low cost, low power, complete dual axis
accelerometer with signal conditioned, duty cycle modulated
outputs, all on a single monolithic IC. The ADXL213 measures
acceleration with a full-scale range of ±1.2 g (typical). The
ADXL213 can measure both dynamic acceleration (e.g.,
vibration) and static acceleration (e.g., gravity).
The outputs are digital signals whose duty cycles (ratio of pulse
width to period) are proportional to acceleration (30%/g). The
duty cycle outputs can be directly measured by a microcontrol-
ler without an A/D converter or glue logic.
Innovative design techniques are used to ensure high zero g bias
stability (typically better than 0.25 mg/°C), as well as tight sensi-
tivity stability (typically better than 50 ppm/°C).
The typical noise floor is 160 µg/√
Hz
, allowing signals below
1 mg (0.06° 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 250 Hz may be selected to suit the application.
The ADXL213 is available in a 5 mm × 5 mm × 2 mm, 8-pad
hermetic LCC package.
FUNCTIONAL BLOCK DIAGRAM
04742-0-001
ADXL213
SENSOR
32kΩ
32kΩ
+V
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
A(g) = (T1/T2 – 0.5)/30%
0g = 50% DUTY CYCLE
T2(s) = R
SET
/125MΩ
T2
T1
Figure 1.
