ADXL212 Datasheet, PDF (1/12 Pages) Analog Devices – Precision ±2 g Dual Axis, PWM Output Accelerometer

Precision ±2 g Dual Axis,
PWM Output Accelerometer
ADXL212
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
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
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 (RSET).
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 CX and CY at the XFILT and YFILT 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
+V_S
V_S
C_Y
Y_FILT
ADXL212
C_DC
AC
AMP
DEMOD
OUTPUT ^32kΩ
AMP
DCM
Y_OUT
SENSOR
OUTPUT
AMP _32kΩ
X_OUT
COM
ST
X_FILT
C_X
T2
R_SET
PWM OUTPUT WAVEFORM SAMPLE
t2
t1
Figure 1.
A(g) = (t1/t2 – 0.5)/12.5%
0g = 50% DUTY CYCLE
t2(sec) = R_SET/125MΩ
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
www.analog.com
Fax: [phone]
©2011 Analog Devices, Inc. All rights reserved.