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Low Noise, High Frequency MEMS Accelerometers Data Sheet ADXL1001/ADXL1002 Rev. 0 Document Feedback 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 ©2017 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com
FEATURES
Single in plane axis accelerometer with analog output Linear frequency response range from dc to 11 kHz (3 dB point) Resonant frequency of 21 kHz Ultralow noise density 30 µg/√Hz in ±100 g range (ADXL1001) 25 µg/√Hz in ±50 g range (ADXL1002) Overrange sensing plus dc coupling allows fast recovery time Complete electromechanical self-test Sensitivity performance Sensitivity stability over temperature 5% Linearity to ±0.1% of full-scale range Cross axis sensitivity ±1% (ZX), ±1% (YX), Single-supply operation Output voltage ratiometric to supply Low power consumption 1.0 mA Power saving standby operation mode with fast recovery RoHS compliant −40°C to +125°C temperature range 5 mm × 5 mm × 1.80 mm LFCSP package
APPLICATIONS
Health usage monitoring system (HUMS) FUNCTIONAL BLOCK DIAGRAM Figure 1. GENERAL DESCRIPTION The ADXL1001/ADXL1002 deliver ultralow noise density over an extended frequency range with two full-scale range options, and are optimized for industrial condition monitoring. The ADXL1001 (±100 g) and the ADXL1002 (±50 g) have typical noise densities of 30 µg/√Hz and 25 µg/√Hz, respectively. Both accelerometer devices have stable and repeatable sensitivity, which is immune to external shocks up to 10,000 g. The ADXL1001/ADXL1002 have an integrated full electrostatic self test (ST) function and an overrange (OR) indicator that allow advanced system level features and are useful for embedded applications. With low power and single-supply operation of 3.3 V to 5.25 V, t h e ADXL1001/ADXL1002 also enable wireless sensing product design. The ADXL1001/ ADXL1002 are available in a 5 mm × 5 mm × 1.80 mm LFCSP package, and are rated for operation over a −40°C to +125°C temperature range. TIMING GENERATOR ADXL1001/ADXL1002 VOUT OR SENSORMOD AMP SELF TEST ST VSS OUTPUT AMPLIFIERDEMOD OVERRANGE DETECTION VDD STANDBY 07510-001
ADXL1001/ADXL1002 Data Sheet Rev. 0 | Page 2 of 14 TABLE OF CONTENTS
REVISION HISTORY
3/2017—Revision 0: Initial Version
Data Sheet ADXL1001/ADXL1002 Rev. 0 | Page 3 of 14 SPECIFICATIONS TA = 25°C, VDD = 5.0 V , acceleration = 0 g, unless otherwise noted. Table 1. Test Conditions/ ADXL1001 ADXL1002 Parameter1 Comments Min Typ Max Min Typ Max Unit SENSOR Measurement Range ±100 ±50 g Linearity Percentage of full scale ±0.1 ±0.1 % Cross Axis Sensitivity2 ZX cross axis ±1.0 ±1.0 % YX cross axis ±1.0 ±1.0 % SENSITIVITY (RATIOMETRIC TO VDD) Sensitivity DC 20 40 mV/g Sensitivity Change Due to Temperature3 ZERO g OFFSET (RATIOMETRIC TO VDD) 0 g Output Voltage VDD/2 VDD/2 V 0 g Output Range over Temperature4 −40°C to +125°C 5 5 g NOISE Noise Density 100 Hz to 10 kHz 30 25 µg/√Hz 1/f Frequency Corner 0.1 0.1 Hz FREQUENCY RESPONSE Sensor Resonant Frequency 21 21 kHz 5% Bandwidth5 4.7 4.7 kHz 3 dB Bandwidth5 11 11 kHz SELF TEST Output Change (Ratiometric to VDD) ST low to ST high 235 275 510 545 mV Input Level High, VIH VDD × 0.7 VDD × 0.7 V Low, VIL VDD × 0.3 VDD × 0.3 V Input Current 25 25 µA OUTPUT AMPLIFIER Short-Circuit Current 3 3 mA Output Impedance <0.1 <0.1 Ω Maximum Resistive Load 20 20 MΩ Maximum Capacitive Load6 No external resistor 100 100 pF With external resistor 22 22 nF POWER SUPPLY ( VDD) Quiescent Supply Current 1.0 1.15 1.0 1.15 mA Standby Current 225 285 225 285 µA Standby Recovery Time (Standby to Measure Mode) Output settled to 1% of final value <50 <50 µs Turn On Time7 <550 <550 µs OPERATING TEMPERATURE RANGE −40 +125 −40 +125 °C 1 All minimum and maximum specifications are guaranteed. Typical specifications may not be guaranteed. 2 Cross axis sensitivity is defined as the coupling of excitation along a perpendicular axis onto the measured axis output. 3 Includes package hysteresis from 25°C. 4 Difference between maximum and minimum values in temperature range. 5 Specified as frequency range that is within a deviation range relative to dc sensitivity, range is limited by an increase in response due to response gain at the sensor resonant frequency. 6 For capacitive loads larger than 100 pF, an external series resistor must be connected (minimum 8 kΩ). The output capacitance must not exceed 22 nF. 7 Measured time difference from the instant VDD reaches half its value to the instant at which the output settles to 1% of its final value.
PCB thermal design is required. the junction to case thermal resistance. Table 3. Package Characteristics
1 Thermal impedance simulated values are based on a JEDEC 2S2P thermal
test board with nine thermal vias. See JEDEC JESD51. Figure 2. Recommended Soldering Profile Table 4. Recommended Soldering Profile
Figure 3. Pin Configuration Table 5. Pin Function Descriptions 1 to 9, 31, 32 NIC Not Internally Connected. DNC Do Not Connect. Leave unconnected. 12 VDD 3.3 V to 5.25 V Supply Voltage. 13, 14, 27, 28 VSS Supply Ground. 15 STANDBY Standby mode Input, Active High. 16 ST Self Test Input, Active High. identifies significant overrange activity. This pin is not latched. 30 VOUT Analog Output Voltage. 33 EPAD Exposed Pad. The exposed pad on the bottom of the package must be connected to ground.
- NIC = NOT INTERNALLY CONNECTED.
- DNC = NO NOT CONNECT. LEAVE THIS PIN UNCONNECTED.
- THE EXPOSED PAD ON THE BOTTOM OF THE PACKAGE MUST BE CONNECTED TO GROUND.
- AXIS OF SENSITIVITY IS IN-PLANE TO THE PACKAGE AND HORIZONTAL AS SHOWN.
24 DNC
23 DNC
22 DNC
21 DNC
19 DNC
18 DNC
17 DNC
Data Sheet ADXL1001/ADXL1002 Rev. 0 | Page 9 of 14 THEORY OF OPERATION The ADXL1001/ADXL1002 are high frequency, low noise single- axis microelectromechanical systems (MEMS) accelerometers that provide an analog output that is proportional to mechanical vibration. The ADXL1001/ADXL1002 have high g ranges of 100 g and 50 g and are suitable for vibration measurements in high bandwidth applications such as vibration analysis systems that monitor and diagnose machine or system health. The low noise and high frequency bandwidth allows the measurement of vibration patterns caused by small moving parts, such as internal bearings, and the high g range provides the dynamic range to be used in high vibration environments such as heating, ventilation, and air conditioning (HV AC) and heavy machine equipment. To achieve proper performance, be aware of system noise, mounting, and signal conditioning. System noise is affected by supply voltage noise. The analog output of the ADXL1001/ADXL1002 is a ratiometric output; therefore, supply voltage modulation affects the output. Use a properly decoupled stable supply voltage to power the ADXL1001/ ADXL1002 and to provide a reference voltage for the digitizing system. The output signal is impacted by an overrange stimulus. An overload indicator output feature is provided to indicate a condition that is critical for an intelligent measurement system. For more information about the overrange features, see the Overrange section. Proper mounting is required to ensure full mechanical transfer of vibration to accurately measure the desired vibration rather than vibration of the measurement system, including the sensor. A common technique for high frequency mechanical coupling is to utilize a sensor stud mount system while considering the mechanical interface of fixing the ADXL1001/ADXL1002 in the stud. For lower frequencies (below the full capable bandwidth of the sensor), it is possible to use magnetic or adhesive mounting. Proper mounting technique ensures proper and repeatable results that are not influenced by measurement system mechanical resonances and/or damping at the desired frequency, and represents an efficient and proper mechanical transfer to the system being monitored. Proper application specific signal conditioning is require to achieve optimal results. An understanding of measurement frequency range and managing overload condition is important to achieve accurate results. The electrical output signal of the ADXL1001/ADXL1002 requires some band limiting and proper digitization bandwidth. See the Interfacing Analog Output Below 10 kHz section and the Interfacing Analog Output Beyond 10 kHz section for more information. MECHANICAL DEVICE OPERATION The moving component of 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 differential capacitors that consist of independent fixed plates and plates attached to the moving mass. Acceleration deflects the structure and unbalances the differential capacitor, resulting in a sensor output with an amplitude proportional to acceleration. Phase- sensitive demodulation determines the magnitude and polarity of the acceleration. OPERATING MODES The ADXL1001/ADXL1002 have two operating modes: measurement mode and standby mode. Measurement mode provides a continuous analog output for active monitoring. Standby mode is a nonoperational, low power mode. Measurement Mode Measurement mode is the normal operating mode of the ADXL1001/ADXL1002. In this mode, the accelerometer actively measures acceleration along the axis of sensitivity and consumes 1.0 mA (typical) using a 5.0 V supply. Standby Placing the ADXL1001/ADXL1002 in standby mode suspends the measurement with internal reduction of current consumption to 225 μA (typical for 5.0 V supply). The transition time from standby to measurement mode is <50 μs. The transition from standby to measure mode is shown in Figure 18. BANDWIDTH The ADXL1001/ADXL1002 circuitry supports an output signal bandwidth beyond the resonant frequency of the sensor, measuring acceleration over a bandwidth comparable to the resonant frequency of the sensor. The output response is a combination of the sensor response and the output amplifier response. Therefore, external band limiting or filtering is required; see the Interfacing Analog Output Below 10 kHz section and the Interfacing Analog Output Beyond 10 kHz section for more information. When using the ADXL1001/ADXL1002 beyond 10 kHz, consider the nonlinearity due to the resonance frequency of the sensor, the additional noise due to the wideband output of the amplifier, and the discrete frequency spurious tone due to coupling of the internal 200 kHz clock. Aliased interferers in the desired band cannot be removed, and observed performance degrades. A combination of high speed sampling and appropriate band limiting filtering is required for optimal performance.
band beyond the resonance frequency range of the sensor. resonant frequency of the sensor. critical in cases when measuring greater than a few kilohertz. output response to an input stimulus peaks, as shown in Figure 4. responses, additional external low-pass filtering is required. not to affect the analysis of results. Figure 26. ADXL1001/ADXL1002 Behavior During a Continuous Overrange
Figure 29. 32-Lead Lead Frame Chip Scale Package (LFCSP)
0.05 MAX
0.02 NOM
0.203 REF
0.20 MIN
3.50 REF
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