a
Low-Cost ؎2 g Dual-Axis Accelerometer
with Duty Cycle Output
ADXL202E*
FEATURES
2-Axis Acceleration Sensor on a Single IC Chip
5 mm ؋ 5 mm ؋ 2 mm Ultrasmall Chip Scale Package
2 mg Resolution at 60 Hz
Low-Power < 0.6 mA
Direct Interface to Low-Cost Microcontrollers via
Duty Cycle Output
BW Adjustment with a Single Capacitor
3 V to 5.25 V Single Supply Operation
1000 g Shock Survival
FUNCTIONAL BLOCK DIAGRAM
3V TO 5.25V
CX
VDD
XFILT
RFILT
32k⍀
X SENSOR
OSCILLATOR
GENERAL DESCRIPTION
The ADXL202E is a low-cost, low-power, complete 2-axis accelerometer with a digital output, all on a single monolithic IC. It is an
improved version of the ADXL202AQC/JQC. The ADXL202E
will measure accelerations with a full-scale range of Ϯ2 g. The
ADXL202E can measure both dynamic acceleration (e.g., vibration) and static acceleration (e.g., gravity).
The outputs are analog voltage or digital signals whose duty cycles
(ratio of pulsewidth to period) are proportional to acceleration.
The duty cycle outputs can be directly measured by a microprocessor counter, without an A/D converter or glue logic. The
duty cycle period is adjustable from 0.5 ms to 10 ms via a single
resistor (RSET).
Y SENSOR
COM
ANALOG
TO
DUTY
CYCLE
(ADC)
ADXL202E
DEMOD
APPLICATIONS
2-Axis Tilt Sensing with Faster Response than
Electrolytic, Mercury, or Thermal Sensors
Computer Peripherals
Information Appliances
Alarms and Motion Detectors
Disk Drives
Vehicle Security
XOUT
DEMOD
CDC
SELF-TEST
RFILT
32k⍀
YOUT
YFILT
C
O
U
N P
T
E
R
T2
CY
RSET
T2
T1
A(g) = (T1/T2 – 0.5)/12.5%
0g = 50% DUTY CYCLE
T2 = RSET/125M⍀
The typical noise floor is 200 g√Hz, allowing signals below
2 mg (at 60 Hz bandwidth) to be resolved.
The bandwidth of the accelerometer is set with capacitors CX and
CY at the XFILT and YFILT pins. An analog output can be reconstructed by filtering the duty cycle output.
The ADXL202E is available in 5 mm ϫ 5 mm ϫ 2 mm 8-lead
hermetic LCC package.
*Patents Pending
REV. A
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
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Tel: 781/329-4700
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Fax: 781/326-8703
© Analog Devices, Inc., 2000
