ADXL320 AD | Alldatasheet
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Technical content
Small and Thin ±5 g Accelerometer ADXL320 Rev. 0 Information furn ished by An alog D evices is believed to be accurate and reliable. However, n o resp onsibility is assume d b y A nalog De vices fo r 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 p atent rights of Analog De vices. Trademarks an d registered trademarks are the property of their respective owners. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
FEATURES
4 mm × 4 mm × 1.45 mm LFCSP package 2 mg resolution at 60 Hz Wide supply voltage range: 2.4 V to 5.25 V Low power: 350 µA at VS = 2.4 V (typ) Good zero g bias stability Good sensitivity accuracy X-axis and Y-axis aligned to within 0.1° (typ) BW adjustment with a single capacitor Single-supply operation 10,000 g shock survival Compatible with Sn/Pb and Pb-free solder processes
APPLICATIONS
Cost-sensitive motion- and tilt-sensing applications Smart hand-held devices Mobile phones Sports and health-related devices PC security and PC peripherals GENERAL DESCRIPTION The ADXL320 is a low cost, low power, complete dual-axis accelerometer with signal conditioned voltage outputs, which is all on a single monolithic IC. The product measures acceleration with a full-scale range of ±5 g (typical). It can also measure both dynamic acceleration (vibration) and static acceleration (gravity). The ADXL320’s typical noise floor is 250 µg/√Hz, allowing signals below 2 mg to be resolved in tilt-sensing applications using narrow bandwidths (<60 Hz). The user selects the bandwidth of the accelerometer using capacitors CX and CY at the XOUT and YOUT pins. Bandwidths of 0.5 Hz to 2.5 kHz may be selected to suit the application. The ADXL320 is available in a very thin 4 mm × 4 mm × 1.45 mm, 16-lead, plastic LFCSP. FUNCTIONAL BLOCK DIAGRAM 04993-001 ADXL320 SENSOR +3V OUTPUT AMP OUTPUT AMP COM ST VS CDC DEMODAC AMP RFILT 32kΩ XOUT CX YOUT CY RFILT 32kΩ Figure 1.
Rev. 0 | Page 2 of 16 TABLE OF CONTENTS Design Trade-Offs for Selecting Filter Characteristics: The
REVISION HISTORY
9/04—Revision 0: Initial Version
Rev. 0 | Page 3 of 16 SPECIFICATIONS1 TA = 25°C, VS = 3 V , CX = CY = 0.1 µF, Acceleration = 0 g, unless otherwise noted. Table 1. Parameter Conditions Min Typ Max Unit SENSOR INPUT Each axis Measurement Range ±5 g Nonlinearity % of full scale ±0.2 % Package Alignment Error ±1 Degrees Alignment Error X sensor to Y sensor ±0.1 Degrees Cross Axis Sensitivity ±2 % SENSITIVITY (RATIOMETRIC)2 Each axis Sensitivity at XOUT, YOUT VS = 3 V 156 174 192 mV/g Sensitivity Change due to Temperature3 VS = 3 V 0.01 %/°C ZERO g BIAS LEVEL (RATIOMETRIC) Each axis 0 g Voltage at XOUT, YOUT VS = 3 V 1.3 1.5 1.7 V 0 g Offset Versus Temperature ±0.6 mg/°C NOISE PERFORMANCE Noise Density @ 25°C 250 µg/√Hz rms FREQUENCY RESPONSE4 CX, CY Range5 0.002 10 µF 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 Input Resistance to Ground 50 kΩ Output Change at XOUT, YOUT Self-test 0 to 1 55 mV OUTPUT AMPLIFIER Output Swing Low No load 0.3 V Output Swing High No load 2.5 V POWER SUPPLY Operating Voltage Range 2.4 5.25 V Quiescent Supply Current 0.48 mA Turn-On Time7 20 ms TEMPERATURE Operating Temperature Range −20 70 °C 1 All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. 2 Sensitivity is essentially ratiometric to VS. For VS = 2.7 V to 3.3 V, sensitivity is 154 mV/V/g to 194 mV/V/g typical. 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 capacitor (CX, CY). 6 Self-test response changes cubically with VS. 7 Larger values of CX, CY increase turn-on time. Turn-on time is approximately 160 × CX or CY + 4 ms, where CX, CY are in µF.
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 +7.0 V All Other Pins (COM − 0.3 V) to (VS + 0.3 V) Output Short-Circuit Duration (Any Pin to Common) Indefinite Operating Temperature Range −55°C to +125°C Storage Temperature −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 ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Figure 2. Pin Configuration Table 3. Pin Function Descriptions
1 NC Do Not Connect
2 ST Self-Test
3 COM Common
4 NC Do Not Connect
5 COM Common
6 COM Common
7 COM Common
8 NC Do Not Connect
9 NC Do Not Connect
10 YOUT Y Channel Output
11 NC Do Not Connect
12 XOUT X Channel Output
13 NC Do Not Connect
16 NC Do Not Connect
Figure 3. Recommended Soldering Profile Table 4. Recommended Soldering Profile
Figure 20. Output Response vs. Orientation
Rev. 0 | Page 12 of 16 For most applications, a single 0.1 µF capacitor, CDC, adequately decouples the accelerometer from noise on the power supply. However, in some cases, particularly where noise is present at the 140 kHz internal clock frequency (or any harmonic thereof), noise on the supply may cause interference on the ADXL320 output. If additional decoupling is needed, a 100 Ω (or smaller) resistor or ferrite bead may be inserted in the supply line. Additionally, a larger bulk bypass capacitor (in the 1 µF to 4.7 µF range) may be added in parallel to CDC. SETTING THE BANDWIDTH USING CX AND CY The ADXL320 has provisions for band-limiting the XOUT and YOUT pins. Capacitors must be added at these pins to implement low-pass filtering for antialiasing and noise reduction. The equation for the 3 dB bandwidth is F−3 dB = 1/(2π(32 kΩ) × C(X, Y)) or more simply, F–3 dB = 5 µF/C(X, Y) The tolerance of the internal resistor (RFILT) typically varies as much as ±15% of its nominal value (32 kΩ), and the bandwidth varies accordingly. A minimum capacitance of 2000 pF for CX and CY is required in all cases. Table 5. Filter Capacitor Selection, CX and CY VS, an electrostatic force is exerted on the accelerometer beam. circuit or connected to common (COM) in normal use. VF clamping diode between ST and VS is recommended. the measurement resolution (smallest detectable acceleration). the analog filter bandwidth at XOUT and YOUT. The output of the ADXL320 has a typical bandwidth of 2.5 kHz. values, given the rms value. Table 6. Estimation of Peak-to-Peak Noise
noise output of the ADXL320 for various CX and CY values. Table 7. Filter Capacitor Selection (CX, CY) output sensitivity is typically 135 mV/g. nominally equal to VS/2 at all supply voltages. The supply current decreases as the supply voltage decreases. current consumption at VS = 2.4 V is 350 µA. input vector to determine the orientation of an object in space. only 12.2 mg per degree of tilt, and resolution declines. vibration, shock, or other accelerations.
0.65 BSC
1.95 BSC
0.20 MIN PIN 1
0.20 MIN
0.05 MAX
0.02 NOM
Figure 21. 16-Lead Lead Frame Chip Scale Package [LFCSP]
Rev. 0 | Page 15 of 16 NOTES
Rev. 0 | Page 16 of 16 NOTES © 2004 Analo g De vices, Inc. All rights reserve d. Tra demarks and registered tra demarks are the prop erty of their respective owners . D04993–0–9/04(0)