High Performance, Wide Bandwidth Accelerometer ADXL001 Using the Analog Devices, Inc. proprietary fifth-generation iMEMs(R) process enables the ADXL001 to provide the desired dynamic range that extends from 70 g to 500 g in combination with 22 kHz of bandwidth. The accelerometer output channel passes through a wide bandwidth differential-to-singleended converter, which allows access to the full mechanical performance of the sensor. FEATURES High performance accelerometer 70 g, 250 g, and 500 g wideband ranges available 22 kHz resonant frequency structure High linearity: 0.2% of full scale Low noise: 4 mg/Hz Sensitive axis in the plane of the chip Frequency response down to dc Full differential signal processing High resistance to EMI/RFI Complete electromechanical self-test Output ratiometric to supply Velocity preservation during acceleration input overload Low power consumption: 2.5 mA typical 8-terminal, hermetic ceramic, LCC package The part can operate on voltage supplies from 3.3 V to 5 V. The ADXL001 also has a self-test (ST) pin that can be asserted to verify the full electromechanical signal chain for the accelerometer channel. The ADXL001 is available in the industry-standard 8-terminal LCC and is rated to work over the extended industrial temperature range (-40C to +125C). 15 APPLICATIONS 12 Vibration monitoring Shock detection Sports diagnostic equipment Medical instrumentation Industrial monitoring 9 RESPONSE (dB) 6 GENERAL DESCRIPTION 3 0 -3 -6 The ADXL001 is a major advance over previous generations of accelerometers providing high performance and wide bandwidth. This part is ideal for industrial, medical, and military applications where wide bandwidth, small size, low power, and robust performance are essential. 07510-102 -9 -12 -15 1 10 100 1k FREQUENCY (Hz) 10k 100k Figure 1. Sensor Frequency Response FUNCTIONAL BLOCK DIAGRAM VS VDD ADXL001 TIMING GENERATOR VDD2 MOD DIFFERENTIAL SENSOR OUTPUT AMPLIFIER DEMOD AMP XOUT COM ST 07510-001 SELF-TEST Figure 2. 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 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: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2010 Analog Devices, Inc. All rights reserved. ADXL001 TABLE OF CONTENTS Features .............................................................................................. 1 Design Principles........................................................................ 11 Applications ....................................................................................... 1 Mechanical Sensor ..................................................................... 11 General Description ......................................................................... 1 Applications Information .............................................................. 12 Functional Block Diagram .............................................................. 1 Application Circuit..................................................................... 12 Revision History ............................................................................... 2 Self-Test ....................................................................................... 12 Specifications..................................................................................... 3 Acceleration Sensitive Axis ....................................................... 12 Specifications for 3.3 V Operation ............................................. 3 Operating Voltages Other Than 5 V ........................................ 12 Specifications for 5 V Operation ................................................ 4 Layout, Grounding, and Bypassing Considerations .................. 13 Recommended Soldering Profile ............................................... 5 Clock Frequency Supply Response .......................................... 13 Absolute Maximum Ratings............................................................ 6 Power Supply Decoupling ......................................................... 13 ESD Caution .................................................................................. 6 Electromagnetic Interference ................................................... 13 Pin Configuration and Function Descriptions ............................. 7 Outline Dimensions ....................................................................... 14 Typical Performance Characteristics ............................................. 8 Ordering Guide .......................................................................... 14 Theory of Operation ...................................................................... 11 REVISION HISTORY 2/10--Rev. 0 to Rev. A Added -250 and -500 models ............................................ Universal Changes to Table 1 ............................................................................ 3 Changes to Table 2 ............................................................................ 4 Added Figure 9 through Figure 18 ................................................. 8 Changes to Ordering Guide .......................................................... 14 1/09--Revision 0: Initial Version Rev. A | Page 2 of 16 ADXL001 SPECIFICATIONS SPECIFICATIONS FOR 3.3 V OPERATION TA = -40C to +125C, VS = 3.3 V 5% dc, acceleration = 0 g, unless otherwise noted. Table 1. Parameter SENSOR Nonlinearity Cross-Axis Sensitivity Resonant Frequency Quality Factor SENSITIVITY Full-Scale Range Sensitivity OFFSET Zero-g Output NOISE Noise Noise Density FREQUENCY RESPONSE -3 dB Frequency -3 dB Frequency Drift Over Temperature SELF-TEST Output Voltage Change Logic Input High Logic Input Low Input Resistance OUTPUT AMPLIFIER Output Swing Capacitive Load PSRR (CFSR) POWER SUPPLY (VS) Functional Range ISUPPLY Turn-On Time Conditions Min ADXL001-70 Typ Max 0.2 2 Includes package alignment Min ADXL001-250 Typ Max 2 0.2 2 22 2.5 IOUT 100 A 100 Hz Ratiometric -70 +70 10 Hz to 400 Hz 10 Hz to 400 Hz 1.65 -250 1.95 1.35 1.65 0.2 1000 DC to 1 MHz 2 22 2.5 +250 -500 kHz +500 g mV/g 1.95 V 2.2 1.95 1.35 1.65 % % 95 3.65 105 4.25 mg rms mg/Hz 32 2 32 2 32 2 kHz % 62 mV V V k 125 2.1 2.1 0.66 IOUT = 100 A 0.2 2 Unit 85 3.3 400 30 2 4.4 2.1 To ground ADXL001-500 Typ Max 22 2.5 16.0 1.35 Min 50 0.66 30 VS - 0.2 0.2 1000 0.9 3.135 2.5 10 50 0.66 30 VS - 0.2 0.2 1000 0.9 6 5 Rev. A | Page 3 of 16 3.135 2.5 10 50 VS - 0.2 V pF V/V 6 5 V mA ms 0.9 6 5 3.135 2.5 10 ADXL001 SPECIFICATIONS FOR 5 V OPERATION TA = -40C to +125C, VS = 5 V 5% dc, acceleration = 0 g, unless otherwise noted. Table 2. Parameter SENSOR Nonlinearity Cross-Axis Sensitivity Resonant Frequency Quality Factor SENSITIVITY Full-Scale Range Sensitivity OFFSET Zero-g Output NOISE Noise Noise Density FREQUENCY RESPONSE -3 dB Frequency -3 dB Frequency Drift Over Temperature SELF-TEST Output Voltage Change Logic Input High Logic Input Low Input Resistance OUTPUT AMPLIFIER Output Swing Capacitive Load PSRR (CFSR) POWER SUPPLY (VS) Functional Range ISUPPLY Turn-On Time Conditions Min ADXL001-70 Typ Max 0.2 2 Includes package alignment Min ADXL001-250 Typ Max 2 0.2 2 22 2.5 IOUT 100 A 100 Hz Ratiometric -70 +70 10 Hz to 400 Hz 10 Hz to 400 Hz 2.5 -250 3.00 2.00 2.5 0.2 1000 DC to 1 MHz 2 22 2.5 +250 -500 kHz +500 g mV/g 3.00 V 3.3 3.00 2.00 2.5 % % 60 2.35 70 2.76 mg rms mg/Hz 32 2 32 2 32 2 kHz % 217 mV V V k 445 3.3 3.3 0.66 IOUT = 100 A 0.2 2 Unit 55 2.15 1435 30 2 6.7 3.3 To ground ADXL001-500 Typ Max 22 2.5 24.2 2.00 Min 50 0.66 30 VS - 0.2 0.2 1000 0.9 3.135 4.5 10 50 0.66 30 VS - 0.2 0.2 1000 0.9 6 9 3.135 Rev. A | Page 4 of 16 4.5 10 50 VS - 0.2 V pF V/V 6 9 V mA ms 0.9 6 9 3.135 4.5 10 ADXL001 RECOMMENDED SOLDERING PROFILE Table 3. Soldering Profile Parameters Profile Feature Average Ramp Rate (TL to TP) Preheat Minimum Temperature (TSMIN) Maximum Temperature (TSMAX) Time (TSMIN to TSMAX), ts TSMAX to TL Ramp-Up Rate Time Maintained Above Liquidous (tL) Liquidous Temperature (TL) Liquidous Time (tL) Peak Temperature (TP) Time Within 5C of Actual Peak Temperature (tP) Ramp-Down Rate Time 25C to Peak Temperature (tPEAK) Sn63/Pb37 3C/sec maximum Pb-Free 3C/sec maximum 100C 150C 60 sec to 120 sec 150C 200C 60 sec to 150 sec 3C/sec 3C/sec 183C 60 sec to 150 sec 240C + 0C/-5C 10 sec to 30 sec 6C/sec maximum 6 minute maximum 217C 60 sec to 150 sec 260C + 0C/-5C 20 sec to 40 sec 6C/sec maximum 8 minute maximum Soldering Profile Diagram CRITICAL ZONE TL TO TP tP TP tL TSMAX TSMIN tS PREHEAT RAMP-DOWN tPEAK TIME (t) Figure 3. Soldering Profile Diagram Rev. A | Page 5 of 16 07510-022 TEMPERATURE (T) RAMP-UP TL ADXL001 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter Acceleration (Any Axis, Unpowered and Powered) Supply Voltage, VS Output Short-Circuit Duration (VOUT to GND) Storage Temperature Range Operating Temperature Range Soldering Temperature (Soldering, 10 sec) Drops onto hard surfaces can cause shocks of greater than 4000 g and can exceed the absolute maximum rating of the device. Exercise care during handling to avoid damage. Rating 4000 g -0.3 V to +7.0 V Indefinite -65C to +150C -55C to +125C 245C ESD CAUTION 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. Rev. A | Page 6 of 16 ADXL001 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS DNC 1 DNC 2 COM 3 8 7 VDD 6 XOUT 5 DNC 4 DNC = DO NOT CONNECT ST ADXL001 TOP VIEW (Not to Scale) Figure 4. Pin Configuration Table 5. Pin Function Descriptions Pin No. 1, 2, 5 3 4 6 7 8 Mnemonic DNC COM ST XOUT VDD VDD2 Description Do Not Connect. Common. Self-Test Control (Logic Input). X-Axis Acceleration Output. 3.135 V to 6 V. Connect to VDD2. 3.135 V to 6 V. Connect to VDD. Rev. A | Page 7 of 16 07510-004 VDD2 10 5 0 Figure 7. ADXL001-70, Sensitivity Distribution (mV/g) Rev. A | Page 8 of 16 25 20 15 10 5 4.50 4.48 4.46 4.44 4.54 30 4.56 Figure 9: ADXL001-250, Sensitivity Distribution 4.52 (mV/g) 4.54 07510-025 15 4.52 25 4.50 Figure 6. Zero-g Bias Deviation from Ideal (TA = 125C) 4.48 VOLTS 4.46 5 0 07510-024 10 4.44 15 4.42 20 4.40 VOLTS 4.42 25 4.40 30 4.38 40 4.38 45 4.36 Figure 5. Zero-g Bias Deviation from Ideal 4.36 16.8 16.7 16.6 16.5 16.4 16.3 16.2 16.1 16.0 15.9 15.8 15.7 15.6 15.5 0 07510-008 10 15.4 PERCENT OF POPULATION 20 15.3 15.2 07510-005 30 4.34 35 PERCENT OF POPULATION 0.07 40 4.32 0 4.30 5 07510-006 0.06 0.05 0.04 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 -0.04 -0.05 50 4.34 20 PERCENT OF POPULATION 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 -0.01 -0.02 -0.03 -0.04 -0.05 -0.07 -0.06 PERCENT OF POPULATION 60 4.32 0 07510-007 -0.07 -0.06 PERCENT OF POPULATION 0 4.30 16.8 16.7 16.6 16.5 16.4 16.3 16.2 16.1 16.0 15.9 15.8 15.7 15.6 15.5 15.4 15.3 15.2 PERCENT OF POPULATION ADXL001 TYPICAL PERFORMANCE CHARACTERISTICS VS = 3.3 V, TA = 25C, unless otherwise noted. 25 20 15 10 5 Figure 8. ADXL001-70, Sensitivity Distribution (TA = 125C) (mV/g) 35 30 25 20 15 10 Figure 10: ADXL001-250, Sensitivity Distribution (TA = 125C) (mV/g) 25 15 10 5 0 (mV) Figure 13. ADXL001-70, Self-Test Delta Rev. A | Page 9 of 16 Figure 12. ADXL001-500, Sensitivity Distribution (TA = 125C) 56 57 58 59 60 61 62 63 (mA) Figure 16. ISUPPLY Distribution 64 65 (mV/g) Figure 15. ADXL001-500, Self-Test Delta 30 25 20 15 10 5 66 67 2.900 (mV) 2.825 07510-010 55 2.750 5 2.675 5 0 07510-029 10 2.600 15 2.525 (mV/g) 2.450 30 2.375 Figure 11. ADXL001-500, Sensitivity Distribution 142 140 138 136 134 132 130 128 126 124 122 120 118 0 07510-028 5 116 10 114 15 PERCENT OF POPULATION 20 112 110 07510-026 25 2.300 20 PERCENT OF POPULATION 2.27 25 2.225 0 07510-027 30 2.150 20 PERCENT OF POPULATION 2.29 2.26 2.25 2.24 2.23 2.22 2.21 2.20 2.19 2.18 2.17 PERCENT OF POPULATION 30 2.075 0 07510-009 2.28 2.27 2.26 2.25 2.24 2.23 2.22 2.21 2.20 2.19 2.18 2.17 PERCENT OF POPULATION 0 2.000 440 435 430 425 420 415 410 405 400 395 390 385 380 375 370 365 360 PERCENT OF POPULATION ADXL001 20 15 10 5 (mV) Figure 14. ADXL001-250, Self-Test Delta 40 25 35 30 25 20 15 10 ADXL001 40 30 25 20 15 07510-011 5 07510-012 10 CH1 500mV BW CH2 500mV BW 3.000 2.925 2.850 2.775 2.700 2.625 2.550 2.475 2.400 2.325 2.250 2.175 0 2.100 PERCENT OF POPULATION 35 T M10.0s 42.80% A CH2 1.38V (mA) Figure 18. Turn-On Characteristic (10 s per DIV) Figure 17. ISUPPLY at 125C Rev. A | Page 10 of 16 ADXL001 THEORY OF OPERATION DESIGN PRINCIPLES MECHANICAL SENSOR The ADXL001 accelerometer provides a fully differential sensor structure and circuit path for excellent resistance to EMI/RFI interference. The ADXL001 is built using the Analog Devices SOI MEMS sensor process. The sensor device is micromachined in-plane in the SOI device layer. Trench isolation is used to electrically isolate, but mechanically couple, the differential sensing elements. Single-crystal silicon springs suspend the structure over the handle wafer and provide resistance against acceleration forces. MOVABLE FRAME PLATE CAPACITORS UNIT SENSING CELL FIXED PLATES UNIT FORCING CELL MOVING PLATE ANCHOR Figure 19. Simplified View of Sensor Under Acceleration Rev. A | Page 11 of 16 07510-019 Figure 19 is a simplified view of one of the differential sensor cell blocks. Each sensor block includes several differential capacitor unit cells. Each cell is composed of fixed plates attached to the device layer and movable plates attached to the sensor frame. Displacement of the sensor frame changes the differential capacitance. On-chip circuitry measures the capacitive change. ANCHOR ACCELERATION This latest generation SOI MEMS device takes advantage of mechanically coupled but electrically isolated differential sensing cells. This improves sensor performance and size because a single proof mass generates the fully differential signal. The sensor signal conditioning also uses electrical feedback with zero-force feedback for improved accuracy and stability. This force feedback cancels out the electrostatic forces contributed by the sensor circuitry. ADXL001 APPLICATIONS INFORMATION APPLICATION CIRCUIT ACCELERATION SENSITIVE AXIS Figure 20 shows the standard application circuit for the ADXL001. Note that VDD and VDD2 should always be connected together. The output is shown connected to a 1000 pF output capacitor for improved EMI performance and can be connected directly to an ADC input. Use standard best practices for interfacing with an ADC and do not omit an appropriate antialiasing filter. The ADXL001 is an x-axis acceleration and vibration-sensing device. It produces a positive-going output voltage for vibration toward its Pin 8 marking. CVDD 0.1F VDD2 VDD 8 DNC 1 2 COM Figure 21. XOUT Increases with Acceleration in the Positive X-Axis Direction 7 ADXL001 DNC 07510-002 VS PIN 8 TOP VIEW (Not to Scale) 3 OPERATING VOLTAGES OTHER THAN 5 V XOUT 6 5 COUT 1nF DNC XOUT The ADXL001 is specified at VS = 3.3 V and VS = 5 V. Note that some performance parameters change as the voltage is varied. 4 In particular, the XOUT output exhibits ratiometric offset and sensitivity with supply. The output sensitivity (or scale factor) scales proportionally to the supply voltage. At VS = 3.3 V, the output sensitivity is typically 16 mV/g. At VS = 5 V, the output sensitivity is nominally 24.2 mV/g. XOUT zero-g bias is nominally equal to VS/2 at all supply voltages. SELF-TEST The fixed fingers in the forcing cells are normally kept at the same potential as that of the movable frame. When the digital self-test input is activated, the ADXL001 changes the voltage on the fixed fingers in these forcing cells on one side of the moving plate. This potential creates an attractive electrostatic force, causing the sensor to move toward those fixed fingers. The entire signal channel is active; therefore, the sensor displacement causes a change in XOUT. The ADXL001 self-test function verifies proper operation of the sensor, interface electronics, and accelerometer channel electronics. Do not expose the ST pin to voltages greater than VS + 0.3 V. If this cannot be guaranteed due to the system design (for instance, if there are multiple supply voltages), then a low VF clamping diode between ST and VS is recommended. 3.5 3.0 NOMINAL ZERO-g HIGH LIMIT 2.5 2.0 LOW LIMIT 1.5 1.0 3.2 07510-016 Figure 20. Application Circuit ZERO-g BIAS (V) DNC = DO NOT CONNECT 07510-023 ST ST 3.7 4.2 4.7 5.2 5.7 SUPPLY VOLTAGE (V) Figure 22. Typical Zero-g Bias Levels Across Varying Supply Voltages Self-test response in gravity is roughly proportional to the cube of the supply voltage. For example, the self-test response for the ADXL001-70 at VS = 5 V is approximately 1.4 V. At VS = 3.3 V, the self-test response for the ADXL001-70 is approximately 400 mV. To calculate the self-test value at any operating voltage other than 3.3 V or 5 V, the following formula can be applied: (ST @ VX) = (ST @ VS) x (VX/VS)3 where: VX is the desired supply voltage. VS is 3.3 V or 5 V. Rev. A | Page 12 of 16 ADXL001 LAYOUT, GROUNDING, AND BYPASSING CONSIDERATIONS CLOCK FREQUENCY SUPPLY RESPONSE In any clocked system, power supply noise near the clock frequency may have consequences at other frequencies. An internal clock typically controls the sensor excitation and the signal demodulator for micromachined accelerometers. If the power supply contains high frequency spikes, they may be demodulated and interpreted as acceleration signals. A signal appears at the difference between the noise frequency and the demodulator frequency. If the power supply noise is 100 Hz away from the demodulator clock, there is an output term at 100 Hz. If the power supply clock is at exactly the same frequency as the accelerometer clock, the term appears as an offset. If the difference frequency is outside the signal bandwidth, the output filter attenuates it. However, both the power supply clock and the accelerometer clock may vary with time or temperature, which can cause the interference signal to appear in the output filter bandwidth. The ADXL001 addresses this issue in two ways. First, the high clock frequency, 125 kHz for the output stage, eases the task of choosing a power supply clock frequency such that the difference between it and the accelerometer clock remains well outside the filter bandwidth. Second, the ADXL001 has a fully differential signal path, including a pair of electrically isolated, mechanically coupled sensors. The differential sensors eliminate most of the power supply noise before it reaches the demodulator. Good high frequency supply bypassing, such as a ceramic capacitor close to the supply pins, also minimizes the amount of interference. The clock frequency supply response (CFSR) is the ratio of the response at the output to the noise on the power supply near the accelerometer clock frequency or its harmonics. A CFSR of 0.9 V/V means that the signal at the output is half the amplitude of the supply noise. This is analogous to the power supply rejection ratio (PSRR), except that the stimulus and the response are at different frequencies. POWER SUPPLY DECOUPLING For most applications, a single 0.1 F capacitor, CDC, adequately decouples the accelerometer from noise on the power supply. However, in some cases, particularly where noise is present at the 1 MHz internal clock frequency (or any harmonic thereof), noise on the supply can cause interference on the ADXL001 output. If additional decoupling is needed, a 50 (or smaller) resistor or ferrite bead can be inserted in the supply line. Additionally, a larger bulk bypass capacitor (in the 1 F to 4.7 F range) can be added in parallel to CDC. ELECTROMAGNETIC INTERFERENCE The ADXL001 can be used in areas and applications with high amounts of EMI or with components susceptible to EMI emissions. The fully differential circuitry of the ADXL001 is designed to be robust to such interference. For improved EMI performance, especially in automotive applications, a 1000 pF output capacitor is recommended on the XOUT output. Rev. A | Page 13 of 16 ADXL001 OUTLINE DIMENSIONS 0.094 0.078 0.062 0.22 0.15 0.08 (R 4 PLCS) 0.030 0.020 DIA 0.010 1 7 0.183 0.177 SQ 0.171 R 0.008 (4 PLCS) 0.055 0.050 0.045 (PLATING OPTION 1, SEE DETAIL A FOR OPTION 2) 0.108 0.100 0.092 0.075 REF R 0.008 (8 PLCS) TOP VIEW 0.010 0.006 0.002 5 3 BOTTOM VIEW 0.082 0.070 0.058 0.019 SQ DETAIL A (OPTION 2) 111808-C 0.208 0.197 SQ 0.188 0.031 0.025 0.019 Figure 23. 8-Terminal Ceramic Leadless Chip Carrier [LCC] (E-8-1) Dimensions shown in inches ORDERING GUIDE Model 1 ADXL001-70BEZ ADXL001-70BEZ-R7 ADXL001-250BEZ ADXL001-250BEZ-R7 ADXL001-500BEZ ADXL001-500BEZ-R7 EVAL-ADXL001-250Z EVAL-ADXL001-500Z EVAL-ADXL001-70Z 1 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C g Range 70 g 70 g 250 g 250 g 500 g 500 g Z = RoHS Compliant Part. Rev. A | Page 14 of 16 Package Description 8-Terminal LCC 8-Terminal LCC 8-Terminal LCC 8-Terminal LCC 8-Terminal LCC 8-Terminal LCC Evaluation Board Evaluation Board Evaluation Board Package Option E-8-1 E-8-1 E-8-1 E-8-1 E-8-1 E-8-1 ADXL001 NOTES Rev. A | Page 15 of 16 ADXL001 NOTES (c)2010 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D07510-0-2/10(A) Rev. A | Page 16 of 16