Accelerometer datsheet

8/9/2019 Accelerometer datsheet

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Precision 18 g Single-/Dual-AxiMEMS Acceleromete

ADW22035/ADW220

Rev. 0Information furnished by Analog Devices is believed to be accurate and reliable. However, noresponsibility is assumed by Analog Devices for its use, nor for any infringements of patents or otherrights of third parties that may result from its use. Specifications subject to change without notice. Nolicense 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.comFax: 781.461.3113 2008 Analog Devices, Inc. All rights reserved.

FEATURESHigh performance, single-/dual-axis accelerometer

on a single IC chipLow power: 740 A at V S = 5 V (typical)High zero g bias stabilityHigh sensitivity accuracy40C to +125C temperature rangeX and Y axes aligned to within 0.1 (typical)BW adjustment with a single capacitorSingle-supply operation3500 g shock survivalRoHS-compliantCompatible with Sn/Pb- and Pb-free solder processes

5 mm 5 mm 2 mm LCC packageAPPLICATIONSVibration monitoring and compensationAbuse event detectionSports equipmentVehicle dynamic control

GENERAL DESCRIPTIONThe ADW22035/ADW22037 are high precision, low power,complete single- and dual-axisiMEMS accelerometers withsignal conditioned voltage outputs, all on a single, monolithicIC. The ADW22035/ADW22037 measure acceleration witha full-scale range of 18 g . The ADW22035/ADW22037 canmeasure both dynamic acceleration, such as vibration, andstatic acceleration, such as gravity.The user selects the bandwidth of the accelerometer usingCapacitor CX and Capacitor CY at the XOUT and YOUT pins.Bandwidths of 0.5 Hz to 2.5 kHz can be selected to suit theapplication.The ADW22035/ADW22037 are available in 5 mm 5 mm 2 mm, 8-terminal hermetic LCC packages.

FUNCTIONAL BLOCK DIAGRAMS

ADW22035

SENSOR

5V

OUTPUTAMP

COM ST X OUT

VS

CDC

CX

RFILT32k

DEMODACAMP

0 7 7 5 5

- 0 0 1

Figure 1.

ADW22037

SENSOR

5V

OUTPUTAMP

OUTPUTAMP

COM ST Y OUT

VS

CDC

C Y

RFILT32k

DEMOD

XOUTCX

RFILT32k

ACAMP

0 7 7 5 5

- 1 0 1

Figure 2.


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ADW22035/ADW22037

Rev. 0 | Page 2 of 12

TABLE OF CONTENTSFeatures .............................................................................................. 1

Applications ....................................................................................... 1

General Description ......................................................................... 1

Functional Block Diagrams ............................................................. 1 Revision History ............................................................................... 2

Specifications ..................................................................................... 3

Absolute Maximum Ratings ............................................................ 4

Thermal Resistance ...................................................................... 4

ESD Caution .................................................................................. 4

Pin Configurations and Function Descriptions ........................... 5

Typical Performance Characteristics ............................................. 6

Theory of Operation ........................................................................ 8

Performance ...................................................................

Applications Information ...................................................

Power Supply Decoupling ..............................................

Setting the Bandwidth Using CX and CY .................................. Self Test .........................................................................

Design Trade-Offs for Selecting Filter Characteristics: TNoise/BW Trade-Off ......................................................

Using the ADW22035/ADW22037 with Operating VoltaOther than 5 V ................................................................

Outline Dimensions ...........................................................

Ordering Guide ..............................................................

REVISION HISTORY10/08Revision 0: Initial Version


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ADW22035/ADW22


SPECIFICATIONSTA = 40C to +125C, VS = 5 V, CX = CY = 0.1 F, acceleration = 0 g , unless otherwise noted.

Table 1.Parameter Conditions Min 1 Typ Max 1 Unit

SENSOR INPUT Each axisMeasurement Range2 18 gNonlinearity % of full scale 0.2 1.25 %Package Alignment Error 1 DegreesAlignment Error (ADW22037) X sensor to Y sensor 0.1 DegreesCross-Axis Sensitivity 1.5 3 %

SENSITIVITY (RATIOMETRIC)3 Each axisSensitivity at XOUT, YOUT VS = 5 V 94 100 106 mV/g Sensitivity Change Due to Temperature4 VS = 5 V 0.3 %

ZEROg BIAS LEVEL (RATIOMETRIC) Each axis0 g Voltage at XOUT, YOUT VS = 5 V 2.4 2.5 2.6 VInitial 0g Output Deviation from Ideal VS = 5 V, 25C 125 mg

0 g Offset vs. Temperature 1 mg/CNOISE PERFORMANCEOutput Noise


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ADW22035/ADW22037


ABSOLUTE MAXIMUM RATINGSTable 2.Parameter RatingAcceleration (Any Axis, Unpowered) 3500g

Acceleration (Any Axis, Powered) 3500g Drop Test (Concrete Surface) 1.2 mVS 0.3 V to +7.0 VAll Other Pins (COM 0.3 V) to

(VS + 0.3 V)Output Short-Circuit Duration

(Any Pin to Common) IndefiniteTemperature Range (Powered) 55C to +125CTemperature Range (Storage) 65C to +150C

Stresses above those listed under Absolute Maximum Ratingsmay cause permanent damage to the device. This is a stress

rating only; functional operation of the device at these or anyother conditions above those indicated in the operationalsection of this specification is not implied. Exposure to absolutemaximum rating conditions for extended periods may affectdevice reliability.

THERMAL RESISTANCEJA is specified for the worst-case conditions, that is, a devsoldered in a circuit board for surface-mount packages.

Table 3. Thermal ResistancePackage Type JA JC Device Weight8-Terminal Ceramic LCC 120C/W 20C/W


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ADW22035/ADW22


PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

7

6

54

8

3

2

1STDNC

COM

VS

DNC

+X

ADW22035TOP VIEW

(Not to Scale)

DNC = DO NOT CONNECT

XOUT

DNC

DNC

0 7 7 5 5

- 0 0 3

Figure 4. ADW22035 Pin Configuration

Table 4. ADW22035 Pin Function DescriptionsPin No. Mnemonic Description1 ST Self Test2 DNC Do Not Connect3 COM Common4 DNC Do Not Connect5 DNC Do Not Connect6 DNC Do Not Connect7 XOUT X Channel Output8 VS 3 V to 6 V

7

6

54

8

3

2

1ST

DNC

COM

VS

DNC

+X

+Y

DNC = DO NOT CONNECT

XOUT

YOUT

DNC

0 7 7 5 5

- 0 0 4

ADW22037TOP VIEW

(Not to Scale)

Figure 5. ADW22037 Pin Configuration

Table 5. ADW22037 Pin Function DescriptionsPin No. Mnemonic Description1 ST Self Test2 DNC Do Not Connect3 COM Common4 DNC Do Not Connect5 DNC Do Not Connect6 YOUT Y Channel Output7 XOUT X Channel Output

8 VS 3 V to 6 V


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ADW22035/ADW22037


TYPICAL PERFORMANCE CHARACTERISTICSVS = 5 V for all graphs, unless otherwise noted.

0

10

20

30

40

50

60

5 0

4 0

3 0

2 0

1 0 0 1

0 2 0

3 0

4 0

5 0

P E R C E N T O F P O P U L A T I O N

(mV) 0 7 7 5 5

- 0 0 5

Figure 6. X-Axis Zero g Bias Deviation from Ideal at 25C

0

5

10

15

20

25

30

35

3

. 0

2

. 5

2

. 0

1

. 5

1

. 0

0

. 5 0 0

. 5 1

. 0 1

. 5 2 . 0

2 . 5

3 . 0

3 . 5


(m g /C) 0 7 7 5 5

- 0 0 6

Figure 7. X-Axis Zero g Bias Tempco

0

5

10

15

20

25

9 7

9 8

9 9

1 0 0

1 0 1

1 0 2

1 0 3

P E R C E

N T O F P O P U L A T I O N

(mV/ g) 0 7 7 5 5

- 0 0 7

Figure 8. X-Axis Sensitivity at 25C

0

10

20

30

40

50

60

5 0

4 0

3 0

2 0

1 0 0 1

0 2 0

3 0

4 0

5 0


(mV) 0 7 7 5 5

- 0 0 8

Figure 9. Y-Axis Zerog Bias Deviation from Ideal at 25C

0

5

10

15

20

25

30

35

3

. 0

2

. 5

2

. 0

1

. 5

1

. 0

0

. 5 0 0

. 5 1

. 0 1

. 5 2

. 0 2

. 5 3

. 0


(m g /C) 0 7 7 5 5

- 0 0 9

Figure 10. Y-Axis Zerog Bias Tempco

0

5

10

15

20

25

9 7

9 8

9 9

1 0 0

1 0 1

1 0 2

1 0 3


(mV/ g) 0 7 7 5 5

- 0 1 0

Figure 11. Y-Axis Sensitivity at 25C


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ADW22035/ADW22


0

5

10

15

20

25

30

35

40

0 . 0

6 0

0 . 0

6 5

0 . 0

7 0

0 . 0

7 5

0 . 0

8 0

0 . 0

8 5

0 . 0

9 0

0 . 0

9 5

0 . 1

0 0


(V) 0 7 7 5 5

- 0 1 1

Figure 12. X-Axis Self-Test Response at 25C

97.5

98.0

98.5

99.0

99.5

100.0

100.5

101.0

50 25 0 25 50 75 100 125

S E N S I T I V I T Y ( m V )

TEMPERATURE (C) 0 7 7 5 5

- 0 1 2

Figure 13. Sensitivity vs. Temperature; Parts Soldered to PCB

0

10

20

30

40

50

60

70

80

90

6 8 0

7 0 0

7 2 0

7 4 0

7 6 0

7 8 0

8 0 0

8 2 0

8 4 0

8 6 0

8 8 0

9 0 0

9 2 0

9 4 0

9 6 0


(A)

25C 105C

0 7 7 5 5

- 0 1 3

Figure 14. Supply Current vs. Temperature

0

5

10

15

20

25

30

35

40

45

0 . 0

6 0

0 . 0

6 5

0 . 0

7 0

0 . 0

7 5

0 . 0

8 0

0 . 0

8 5

0 . 0

9 0

0 . 0

9 5

0 . 1

0 0


(V) 0 7 7 5 5

- 0 1 4

Figure 15. Y-Axis Self-Test Response at 25C

0 7 7 5 5

- 0 1 5

TIME (2ms/DIV)

V O L T A G E ( V )

Figure 16. Turn-On Time: C X , C Y = 0.1 F, Time Scale = 2 ms/div


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ADW22035/ADW22037


THEORY OF OPERATIONThe ADW22035/ADW22037 is a complete accelerationmeasurement system on a single, monolithic IC. TheADW22035/ADW22037 is a dual-axis accelerometer. Thisdevice contains a polysilicon surface-micromachined sensorand signal conditioning circuitry to implement an open-loopacceleration measurement architecture. The output signals areanalog voltages proportional to acceleration. The ADW22035/ADW22037 are capable of measuring both positive and negativeaccelerations to at least 18 g .The sensor is a surface-micromachined polysilicon structurebuilt on top of the silicon wafer. Polysilicon springs suspend thestructure over the surface of the wafer and provide a resistanceagainst acceleration forces. Deflection of the structure is measuredusing a differential capacitor that consists of independent fixedplates and plates attached to the moving mass. The fixed platesare driven by 180 out-of-phase square waves. Acceleration deflects

the beam and unbalances the differential capacitor, resulting inan output square wave whose amplitude is proportional to acce-leration. Phase-sensitive demodulation techniques are thenused to rectify the signal and determine the direction of theacceleration.

The output of the demodulator is amplified and brought off-cthrough a 32 k resistor. At this point, the user can set thesignal bandwidth of the device by adding a capacitor. Thisfiltering improves measurement resolution and helps prevealiasing.PERFORMANCERather than using additional temperature compensation circuinnovative design techniques ensure that high performancis built in to these devices. As a result, there is essentially quantization error or nonmonotonic behavior, and temperaturhysteresis is very low (typically less than 15 m g over the 40Cto +125C temperature range).Figure 17 demonstrates the typical sensitivity shift over temature for VS = 5 V. Sensitivity stability is optimized for VS = 5 V,but is still very good over the specified range; it is typicalbetter than 1% over temperature at VS = 3 V.

EARTH'S SURFACE

TOP VIEW(Not to Scale)

PIN 8XOUT = 2.5V

YOUT = 2.4V

XOUT = 2.5V YOUT = 2.5V

PIN 8XOUT = 2.5V

YOUT = 2.6V

PIN 8XOUT = 2.4V

YOUT = 2.5V

PIN 8XOUT = 2.6V

YOUT = 2.5V

0 7 7 5 5

- 0 2 1

Figure 17. Output Response vs. Orientation


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ADW22035/ADW22


APPLICATIONS INFORMATIONPOWER SUPPLY DECOUPLINGFor most applications, a single 0.1 F capacitor, CDC, adequatelydecouples the accelerometer from noise on the power supply.

However in some cases, particularly where noise is present atthe 140 kHz internal clock frequency (or any harmonic thereof),noise on the supply can cause interference on the ADW22037output. If additional decoupling is needed, a 100 (or smaller)resistor or ferrite beads can be inserted in the supply line of theADW22035/ADW22037. Additionally, a larger bulk bypasscapacitor (in the 1 F to 22 F range) can be added in parallelto CDC.SETTING THE BANDWIDTH USING CX AND CY The ADW22035/ADW22037 have provisions for band limitingthe XOUT and YOUT pins. Capacitors must be added at these pinsto implement low-pass filtering for antialiasing and noise reduc-

tion. The equation for the 3 dB bandwidth isF 3dB = 1/(2(32 k) C ( X , Y ))

or more simply,F 3dB = 5 F/C ( X , Y )

The tolerance of the internal resistor (R FILT) can vary typically asmuch as 25% of its nominal value (32 k); thus, the bandwidth varies accordingly. A minimum capacitance of 2000 pF for CX andCY is required in all cases.

Table 6. Filter Capacitor Selection, C X and C Y Bandwidth (Hz) Capacitor (F)

1 4.710 0.4750 0.10100 0.05200 0.027500 0.01

SELF TESTThe ST pin controls the self-test feature. When this pin is setto VS, an electrostatic force is exerted on the beam of the accele-rometer. The resulting movement of the beam allows the userto test if the accelerometer is functional. The typical change in

output is 800 m g (corresponding to 80 mV). This pin can beleft open-circuit or connected to common in normal use.The ST pin should never be exposed to voltage greater thanVS + 0.3 V. If the system design is such that this conditioncannot be guaranteed (that is, multiple supply voltages arepresent), a low VF clamping diode between ST and VS isrecommended.

DESIGN TRADE-OFFS FOR SELECTING FILTERCHARACTERISTICS: THE NOISE/BW TRADE-OFFThe accelerometer bandwidth selected ultimately detethe measurement resolution (smallest detectable accelFiltering can be used to lower the noise floor, improviresolution of the accelerometer. Resolution is dependeanalog filter bandwidth at XOUT and YOUT.The output of the ADW22035/ADW22037 has a typicwidth of 2.5 kHz. The user must filter the signal at thislimit aliasing errors. The analog bandwidth must be nothan half the analog-to-digital sampling frequency to maliasing. The analog bandwidth can be further decreasreduce noise and improve resolution.The ADW22035/ADW22037 noise has the characteriof white Gaussian noise, which contributes equally at quencies and is described in terms of g /Hz (that is, the noiseis proportional to the square root of the accelerometer baThe user should limit bandwidth to the lowest frequencythe application to maximize the resolution and dynamithe accelerometer.With the single pole roll-off characteristic, the typical the ADW22035/ADW22037is determined by

)6.1BW()Hz/130(rmsNoise = g

At 100 Hz, the noise is

g g m64.1)6.1100()Hz/130(rmsNoise ==

Often, the peak value of the noise is desired. Peak-to-can only be estimated by statistical methods.Table 7 is usefulfor estimating the probabilities of exceeding various pgiven the rms value.

Table 7. Estimation of Peak-to-Peak Noise

Peak-to-Peak Value% of Time That Noise ExceedsNominal Peak-to-Peak Value

2 rms 324 rms 4.66 rms 0.278 rms 0.006


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ADW22035/ADW22037


Peak-to-peak noise values provide the best estimate of theuncertainty in a single measurement. Peak-to-peak noise isestimated by 6 rms.Table 8 gives the typical noise outputof the ADW22035/ADW22037 for various CX and CY values.

Table 8. Filter Capacitor Selection (C X , CY)

Bandwidth (Hz)CX, CY (F)

RMS Noise(m g )

Peak-to-Peak NoiseEstimate (m g )

10 0.47 0.5 3.050 0.1 1.2 7.2100 0.047 1.6 9.6500 0.01 3.7 22.2

USING THE ADW22035/ADW22037 WITHOPERATING VOLTAGES OTHER THAN 5 VThe ADW22035/ADW22037 are tested and specified at VS = 5 V;however, it can be powered with VS as low as 3 V or as high as6 V. Some performance parameters change as the supply voltage

is varied.

The ADW22035/ADW22037 output is ratiometric, thus thoutput sensitivity (or scale factor) varies proportionally tosupply voltage. At VS = 3 V the output sensitivity is typically56 mV/ g .The zero g bias output is also ratiometric, thus the zero g output

is nominally equal to VS/2 at all supply voltages.The output noise is not ratiometric but is absolute in volts;therefore, the noise density decreases as the supply voltagincreases. This is because the scale factor (mV/ g ) increaseswhile the noise voltage remains constant. At VS = 3 V, the noisedensity is typically 240 g /Hz.Self-test response in g is roughly proportional to the square ofthe supply voltage. However, when ratiometricity of sensitis factored in with supply voltage, self-test response in volroughly proportional to the cube of the supply voltage. That VS = 3 V, the self-test response is approximately equivale15 mV or equivalent to 270 m g (typical).


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ADW22035/ADW22


OUTLINE DIMENSIONS

0 9 1 3 0 7 - B

BOTTOM VIEW

1

35

7

TOP VIEW

0.075 REF

R 0.008(4 PLCS)

0.2030.197 SQ0.193

0.200.150.10

(R 4 PLCS )0.1800.177 SQ0.174

0.0870.0780.069

0.0080.0060.004

0.0770.0700.063

0.0540.0500.046

0.0300.0250.020

0.0280.020 DIA0.012

0.1060.1000.094R 0.008

(8 PLCS)

Figure 18. 8-Terminal Ceramic Leadless Chip Carrier [LCC]

(E-8-1)Dimensions shown in inches

ORDERING GUIDE

Model Numberof Axes SpecifiedVoltage (V) Temperature Range Package Description PackageOptionADW22035Z1 1 5 40C to +125C 8-Terminal Ceramic Leadless Chip Carrier [LCC] E-ADW22035Z-RL1 1 5 40C to +125C 8-Terminal Ceramic Leadless Chip Carrier [LCC] E-ADW22035Z-RL71 1 5 40C to +125C 8-Terminal Ceramic Leadless Chip Carrier [LCC) EADW22037Z1 2 5 40C to +125C 8-Terminal Ceramic Leadless Chip Carrier [LCC] EADW22037Z-RL1 2 5 40C to +125C 8-Terminal Ceramic Leadless Chip Carrier [LCC] E-ADW22037Z-RL71 2 5 40C to +125C 8-Terminal Ceramic Leadless Chip Carrier [LCC] E-

1 Z = RoHS Compliant Part.

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