ADXL337BCPZ-RL AD | Alldatasheet
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Small, Low Power, 3-Axis ±3 g Accelerometer ADXL337 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. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2010 Analog Devices, Inc. All rights reserved.
FEATURES
Small, low profile package 3 mm × 3 mm × 1.45 mm LFCSP Low power: 300 μA (typical) Single-supply operation: 1.8 V to 3.6 V 10,000 g shock survival Excellent temperature stability Bandwidth adjustment with a single capacitor per axis RoHS/WEEE and lead-free compliant
APPLICATIONS
Cost-sensitive, low power, motion- and tilt-sensing applications Mobile devices Gaming systems Disk drive protection Image stabilization Sports and health devices GENERAL DESCRIPTION The ADXL337 is a small, thin, low power, complete 3-axis accelerometer with signal conditioned voltage outputs. The product measures acceleration with a minimum full-scale range of ±3 g. It can measure the static acceleration of gravity in tilt- sensing applications, as well as dynamic acceleration resulting from motion, shock, or vibration. The user selects the bandwidth of the accelerometer using the C X, CY, and CZ capacitors at the XOUT, YOUT, and ZOUT pins. Bandwidths can be selected to suit the application, with a range of 0.5 Hz to 1600 Hz for X and Y axes and a range of 0.5 Hz to 550 Hz for the Z axis. The ADXL337 is available in a small, low profile, 3 mm × 3 mm × 1.45 mm, 16-lead, lead frame chip scale package (LFCSP_LQ). FUNCTIONAL BLOCK DIAGRAM ADXL337 3-AXIS SENSOR DEMODULATOR OUTPUT AMPLIFIERSAC AMPLIFIER GND ST +3V ~32kΩ XOUT CX CY CZ YOUTCDC VS ZOUT ~32kΩ ~32kΩ 09358-001 Figure 1.
Rev. 0 | Page 2 of 16 TABLE OF CONTENTS Design Trade-Offs for Selecting Filter Characteristics: The
REVISION HISTORY
10/10—Revision 0: Initial Version
Rev. 0 | Page 3 of 16 SPECIFICATIONS TA = 25°C, VS = 3 V , CX = CY = CZ = 0.1 μF, acceleration = 0 g, unless otherwise noted. All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. Table 1. Parameter Test Conditions/Comments Min Typ Max Unit SENSOR INPUT Each axis Measurement Range ±3 ±3.6 g Nonlinearity % of full scale ±0.3 % Package Alignment Error ±1 Degrees Interaxis Alignment Error ±0.1 Degrees Cross-Axis Sensitivity1 ±1 % SENSITIVITY (RATIOMETRIC)2 Each axis Sensitivity at XOUT, YOUT, ZOUT V S = 3 V 270 300 330 mV/g Sensitivity Change Due to Temperature3 V S = 3 V ±0.01 %/°C 0 g BIAS LEVEL (RATIOMETRIC) 0 g Voltage at XOUT, YOUT V S = 3 V 1.35 1.5 1.65 V 0 g Voltage at ZOUT V S = 3 V 1.2 1.5 1.8 V 0 g Offset vs. Temperature XOUT, YOUT ±1.1 mg/°C 0 g Offset vs. Temperature ZOUT ±1.6 mg/°C NOISE PERFORMANCE Noise Density XOUT, YOUT 175 μg/√Hz rms Noise Density ZOUT 300 μg/√Hz rms FREQUENCY RESPONSE4 Bandwidth XOUT, YOUT5 No external filter 1600 Hz Bandwidth ZOUT5 No external filter 550 Hz RFILT Tolerance 32 ± 15% kΩ Sensor Resonant Frequency 5.5 kHz SELF TEST6 Logic Input Low 0.6 V Logic Input High 2.4 V ST Actuation Current 60 μA Output Change at XOUT Self test 0 to 1 −150 −325 −600 mV Output Change at YOUT Self test 0 to 1 +150 +325 +600 mV Output Change at ZOUT Self test 0 to 1 +150 +550 +1000 mV OUTPUT AMPLIFIER Output Swing Low No load 0.1 V Output Swing High No load 2.8 V POWER SUPPLY Operating Voltage Range7 1.8 3.0 3.6 V Supply Current VS = 3 V 300 μA Turn-On Time8 No external filter 1 ms TEMPERATURE Operating Temperature Range −40 +85 °C 1 Defined as coupling between any two axes. 2 Sensitivity is essentially ratiometric to VS. 3 Defined as the output change from ambient-to-maximum temperature or ambient-to-minimum temperature. 4 Actual frequency response controlled by user-supplied external filter capacitors (CX, CY, CZ). bandwidth = 0.5 Hz. 6 Self test response changes cubically with VS. 7 Tested at 3.0 V and guaranteed by design only (not tested) to work over the full range from 1.8 V to 3.6 V. 8 Turn-on time is dependent on CX, CY, CZ and is approximately 160 × (CX or CY or CZ) + 1, where CX, CY, and CZ are in μF and the resulting turn-on time is in ms.
Rev. 0 | Page 4 of 16 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Rating Acceleration (Any Axis, Unpowered) 10,000 g Acceleration (Any Axis, Powered) 10,000 g VS −0.3 V to +3.6 V All Other Pins (GND − 0.3 V) to (VS + 0.3 V) Output Short-Circuit Duration (Any Pin to Common) Indefinite Temperature Range (Powered) −55°C to +125°C Temperature Range (Storage) −65°C to +150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ESD CAUTION
- EXPOSED PAD IS NOT INTERNALLY
Figure 2. Pin Configuration Table 3. Pin Function Descriptions 1, 3 RES Reserved. This pin must be connected to GND or left open. 6, 7 GND Must be connected to ground. 8 to 13 NC Not internally connected. 14 V S Supply Voltage (3.0 V typical). 15 V S Supply Voltage (3.0 V typical). EPAD Exposed Pad. Not internally connected but should be soldered for mechanical integrity.
Rev. 0 | Page 10 of 16 THEORY OF OPERATION The ADXL337 is a complete 3-axis acceleration measurement system. The ADXL337 has a measurement range of ±3 g minimum. It contains a polysilicon surface micromachined sensor and signal conditioning circuitry to implement an open-loop acceleration measurement architecture. The output signals are analog voltages that are proportional to acceleration. The accelerometer can measure the static acceleration of gravity in tilt-sensing applications as well as dynamic acceleration resulting from motion, shock, or vibration. The sensor is a polysilicon surface micromachined structure built on top of a silicon wafer. Polysilicon springs suspend the structure over the surface of the wafer and provide a resistance against acceleration forces. Deflection of the structure is measured using a differential capacitor that consists of independent fixed plates and plates attached to the moving mass. The fixed plates are driven by 180° out-of-phase square waves. Acceleration deflects the moving mass and unbalances the differential capacitor resulting in a sensor output whose amplitude is proportional to acceleration. Phase-sensitive demodulation techniques are then used to determine the magnitude and direction of the acceleration. The demodulator output is amplified and brought off chip through a 32 kΩ resistor. The user then sets the signal bandwidth (BW) of the device by adding a capacitor. This filtering improves measurement resolution and helps prevent aliasing. MECHANICAL SENSOR The ADXL337 uses a single structure for sensing the X, Y , and Z axes. As a result, the three axes sense directions are highly orthogonal with little cross-axis sensitivity. Mechanical misalignment of the sensor die to the package is the chief source of cross-axis sensitivity. Mechanical misalignment can be calibrated out at the system level. PERFORMANCE Rather than using additional temperature compensation circuitry, innovative design techniques ensure that high performance is built into the ADXL337. As a result, there is neither quantization error nor nonmonotonic behavior, and temperature hysteresis is very low (typically less than 3 mg over the −25°C to +85°C temperature range).
similar effect as noise transmitted through VS. CY, and CZ is recommended in all cases. Table 4. Filter Capacitor Selection, CX, CY, and CZ VS, an electrostatic force is exerted on the accelerometer beam. diode between ST and VS is recommended. the measurement resolution (smallest detectable acceleration). analog filter bandwidth at XOUT, YOUT, and ZOUT. the analog-to-digital sampling frequency to minimize aliasing. the resolution and dynamic range of the accelerometer. Table 5. Estimation of Peak-to-Peak Noise
0.05 MAX
0.02 NOM
0.152 REF
0.20 MIN
Figure 27. 16-Lead Lead Frame Chip Scale Package [LFCSP_LQ]
Rev. 0 | Page 15 of 16 NOTES
Rev. 0 | Page 16 of 16 NOTES ©2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the prop erty of their respective owners. D09358-0-10/10(0)