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Preliminary Technical Data
FEATURES
3-axis sensing Small, low-profile package 4 mm x 4 mm x 1.45 mm LFCSP Low power - 350 A (typical) Single-supply operation 1.8 V to 3.6 V 10,000 g shock survival Excellent temperature stability BW adjustment with a single capacitor per axis RoHS/WEEE lead-free compliant
Small, Low Power, 3-Axis 3 g Accelerometer ADXL335
GENERAL DESCRIPTION
The ADXL335 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 tiltsensing applications, as well as dynamic acceleration resulting from motion, shock, or vibration. The user selects the bandwidth of the accelerometer using the CX, 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 ADXL335 is available in a small, low profile, 4 mm x 4 mm x 1.45 mm, 16-lead, plastic lead frame chip scale package (LFCSP_LQ).
APPLICATIONS
Cost-sensitive, low power, motion- and tilt-sensing applications Mobile devices Gaming systems Disk drive protection Image stabilization Sports and health devices
+3V
FUNCTIONAL BLOCK DIAGRAM
Vs
ADXL335
3-Axis Sensor
CDC
Output Amp
~32k
XOUT CX
AC Amp
Demod
Output Amp Output Amp
~32k
YOUT CY
~32k
ZOUT CZ
COM
ST
Figure 1.
Rev. PrA
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)2008 Analog Devices, Inc. All rights reserved.
ADXL335 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 4 ESD Caution .................................................................................. 4 Pin Configuration and Function Descriptions ............................. 5 Theory of Operation ........................................................................ 6 Mechanical Sensor........................................................................ 6
Preliminary Technical Data
Performance ...................................................................................6 Applications........................................................................................7 Power Supply Decoupling ............................................................7 Setting the Bandwidth Using CX, CY, and CZ .............................7 Self Test ...........................................................................................7 Design Trade-Offs for Selecting Filter Characteristics: The Noise/BW Trade-Off .....................................................................7 Use with Operating Voltages Other than 3 V................................7 Axes of Acceleration Sensitivity ..................................................8 Outline Dimensions ..........................................................................9 Ordering Guide .............................................................................9
REVISION HISTORY
Rev. PrA | Page 2 of 11
Preliminary Technical Data SPECIFICATIONS
ADXL335
TA = 25C, VS = 3 V, CX = CY = CZ = 0.1 F, acceleration = 0 g, unless otherwise noted. All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. Table 1.
Parameter SENSOR INPUT Measurement Range Nonlinearity Package Alignment Error Interaxis Alignment Error Cross Axis Sensitivity1 SENSITIVITY (RATIOMETRIC)2 Sensitivity at XOUT, YOUT, ZOUT Sensitivity Change Due to Temperature3 ZERO g BIAS LEVEL (RATIOMETRIC) 0 g Voltage at XOUT, YOUT 0 g Voltage at ZOUT 0 g Offset vs. Temperature NOISE PERFORMANCE Noise Density XOUT, YOUT Noise Density ZOUT FREQUENCY RESPONSE4 Bandwidth XOUT, YOUT5 Bandwidth ZOUT5 RFILT Tolerance Sensor Resonant Frequency SELF TEST6 Logic Input Low Logic Input High ST Actuation Current Output Change at XOUT Output Change at YOUT Output Change at ZOUT OUTPUT AMPLIFIER Output Swing Low Output Swing High POWER SUPPLY Operating Voltage Range Supply Current Turn-On Time7 TEMPERATURE Operating Temperature Range
1 2 3
Conditions Each axis % of full scale
Min 3
Typ 3.6 0.3 1 0.1 1 300 0.01 1.5 1.5 1 150 300
Max
Unit g % Degrees Degrees %
Each axis VS = 3 V VS = 3 V VS = 3 V VS = 3 V
270
330
mV/g %/C V V mg/C g/Hz rms g/Hz rms Hz Hz k kHz V V A mV mV mV V V
1.35 1.2
1.65 1.8
No external filter No external filter
1600 550 32 15% 5.5 +0.6 +2.4 +60 -300 +300 +550 0.1 2.8 1.8 3.6 350 1 -40 +85
Self test 0 to 1 Self test 0 to 1 Self test 0 to 1 No load No load
VS = 3 V No external filter
V A ms C
Defined as coupling between any two axes. Sensitivity is essentially ratiometric to VS. 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). 5 Bandwidth with external capacitors = 1/(2 x x 32 k x C). For CX, CY = 0.003 F, bandwidth = 1.6 kHz. For CZ = 0.01 F, bandwidth = 500 Hz. For CX, CY, CZ = 10 F, bandwidth = 0.5 Hz. 6 Self-test response changes cubically with VS. 7 Turn-on time is dependent on CX, CY, CZ and is approximately 160 x CX or CY or CZ + 1 ms, where CX, CY, CZ are in F.
Rev. PrA | Page 3 of 11
ADXL335 ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Acceleration (Any Axis, Unpowered) Acceleration (Any Axis, Powered) VS All Other Pins Output Short-Circuit Duration (Any Pin to Common) Temperature Range (Powered) Temperature Range (Storage) Rating 10,000 g 10,000 g -0.3 V to +3.6 V (COM - 0.3 V) to (VS + 0.3 V) Indefinite -55C to +125C -65C to +150C
Preliminary Technical Data
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.
TP RAMP-UP
tP
CRITICAL ZONE TL TO TP
TEMPERATURE
TL
TSMAX TSMIN
tL
tS
PREHEAT
RAMP-DOWN
05677-002
t25C TO PEAK
TIME
Figure 2. Recommended Soldering Profile
Table 3. Recommended Soldering Profile
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) Time (tL) Peak Temperature (TP) Time within 5C of Actual Peak Temperature (tP) Ramp-Down Rate Time 25C to Peak Temperature Sn63/Pb37 3C/s max 100C 150C 60 s to 120 s 3C/s max 183C 60 s to 150 s 240C + 0C/-5C 10 s to 30 s 6C/s max 6 minutes max Pb-Free 3C/s max 150C 200C 60 s to 180 s 3C/s max 217C 60 s to 150 s 260C + 0C/-5C 20 s to 40 s 6C/s max 8 minutes max
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.
Rev. PrA | Page 4 of 11
Preliminary Technical Data PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
NC NC NC Vs
0.50 MAX 0.65 4 0.325
ADXL335
16 NC ST NC NC 1 2 3 4 5
15
14
13 12 11 XOUT NC
4 1.95 0.35 MAX 0.65
ADXL335
TOP VIEW
(Not to Scale)
+Z
+Y 10 +X 9 7 8 YOUT NC
0.325 CENTER PAD IS NOT INTERNALLY CONNECTED BUT SHOULD BE SOLDERED FOR MECHANICAL INTEGRITY
6
COM
ZOUT
NC
NC
1.95 DIMENSIONS SHOWN IN MILLIMETERS
05677-032
Figure 3. Pin Configuration
Figure 4. Recommended PCB Layout
Table 4. Pin Function Descriptions
Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
1
Mnemonic NC ST NC NC COM NC NC ZOUT NC YOUT NC XOUT NC NC VS NC
Description No Connect (or optionally ground) Self Test No Connect1 No Connect1 Common No Connect1 No Connect1 Z Channel Output No Connect (or optionally ground) Y Channel Output No Connect1 X Channel Output No Connect1 No Connect1 Supply Voltage (1.8 V to 3.6 V) No Connect1
NC pins are not internally connected and can be tied to Vs or Common unless otherwise noted.
Rev. PrA | Page 5 of 11
ADXL335 THEORY OF OPERATION
The ADXL335 is a complete 3-axis acceleration measurement system. The ADXL335 has a measurement range of 3 g minimum. It contains a polysilicon surface micromachined sensor and signal conditioning circuitry to implement an openloop 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 k resistor. The user then sets the signal bandwidth of the device by adding a capacitor. This filtering improves measurement resolution and helps prevent aliasing.
Preliminary Technical Data
MECHANICAL SENSOR
The ADXL335 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, of course, be calibrated out at the system level.
PERFORMANCE
Rather than using additional temperature compensation circuitry, innovative design techniques ensure high performance is built-in to the ADXL335. As a result, there is neither quantization error nor nonmonotonic behavior, and temperature hysteresis is very low (typically less than 3 mg over the -25C to +70C temperature range).
Rev. PrA | Page 6 of 11
Preliminary Technical Data APPLICATIONS
POWER SUPPLY DECOUPLING
For most applications, a single 0.1 F capacitor, CDC, placed close to the ADXL335 supply pins adequately decouples the accelerometer from noise on the power supply. However, in applications where noise is present at the 50 kHz internal clock frequency (or any harmonic thereof), additional care in power supply bypassing is required as this noise can cause errors in acceleration measurement. If additional decoupling is needed, a 100 (or smaller) resistor or ferrite bead can be inserted in the supply line. Additionally, a larger bulk bypass capacitor (1 F or greater) can be added in parallel to CDC. Ensure that the connection from the ADXL335 ground to the power supply ground is low impedance because noise transmitted through ground has a similar effect as noise transmitted through VS.
ADXL335
Never 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.
DESIGN TRADE-OFFS FOR SELECTING FILTER CHARACTERISTICS: THE NOISE/BW TRADE-OFF
The selected accelerometer bandwidth ultimately determines the measurement resolution (smallest detectable acceleration). Filtering can be used to lower the noise floor to improve the resolution of the accelerometer. Resolution is dependent on the analog filter bandwidth at XOUT, YOUT, and ZOUT. The output of the ADXL335 has a typical bandwidth of greater than 500 Hz. The user must filter the signal at this point to limit aliasing errors. The analog bandwidth must be no more than half the analog-to-digital sampling frequency to minimize aliasing. The analog bandwidth can be further decreased to reduce noise and improve resolution. The ADXL335 noise has the characteristics of white Gaussian noise, which contributes equally at all frequencies and is described in terms of g/Hz (the noise is proportional to the square root of the accelerometer bandwidth). The user should limit bandwidth to the lowest frequency needed by the application to maximize the resolution and dynamic range of the accelerometer. With the single-pole, roll-off characteristic, the typical noise of the ADXL335 is determined by
rms Noise = Noise Density x ( BW x 1.6 )
SETTING THE BANDWIDTH USING CX, CY, AND CZ
The ADXL335 has provisions for band limiting the XOUT, YOUT, and ZOUT 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/(2(32 k) x C(X, Y, Z)) or more simply F-3 dB = 5 F/C(X, Y, Z) The tolerance of the internal resistor (RFILT) typically varies as much as 15% of its nominal value (32 k), and the bandwidth varies accordingly. A minimum capacitance of 0.0047 F for CX, CY, and CZ is recommended in all cases. Table 5. Filter Capacitor Selection, CX, CY, and CZ
Bandwidth (Hz) 1 10 50 100 200 500 Capacitor (F) 4.7 0.47 0.10 0.05 0.027 0.01
Often, the peak value of the noise is desired. Peak-to-peak noise can only be estimated by statistical methods. Table 6 is useful for estimating the probabilities of exceeding various peak values, given the rms value. Table 6. Estimation of Peak-to-Peak Noise
Peak-to-Peak Value 2 x rms 4 x rms 6 x rms 8 x rms % of Time that Noise Exceeds Nominal Peak-to-Peak Value 32 4.6 0.27 0.006
SELF TEST
The ST pin controls the self test feature. When this pin is set to VS, an electrostatic force is exerted on the accelerometer beam. The resulting movement of the beam allows the user to test if the accelerometer is functional. The typical change in output is -500 mg (corresponding to -150 mV) in the X-axis, 500 mg (or 150 mV) on the Y-axis, and -200 mg (or -60 mV) on the Z-axis. This ST pin may be left open circuit or connected to common (COM) in normal use.
USE WITH OPERATING VOLTAGES OTHER THAN 3 V
The ADXL335 is tested and specified at VS = 3 V; however, it can be powered with VS as low as 1.8 V or as high as 3.6 V. Note that some performance parameters change as the supply voltage is varied.
Rev. PrA | Page 7 of 11
ADXL335
The ADXL335 output is ratiometric, therefore, the output sensitivity (or scale factor) varies proportionally to the supply voltage. At VS = 3.6 V, the output sensitivity is typically 360 mV/g. At VS = 2 V, the output sensitivity is typically 195 mV/g. The zero g bias output is also ratiometric, so 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 voltage increases. This is because the scale factor (mV/g) increases while the noise voltage remains constant. At VS = 3.6 V, the X- and Y-axis noise density is typically 120 g/Hz, while at VS = 2 V, the X- and Y-axis noise density is typically 270 g/Hz. Self test response in g is roughly proportional to the square of the supply voltage. However, when ratiometricity of sensitivity is factored in with supply voltage, the self test response in volts is roughly proportional to the cube of the supply voltage. For example, at VS = 3.6 V, the self test response for the ADXL335 is approximately -275 mV for the X-axis, +275 mV for the Y-axis, and -100 mV for the Z-axis.
XOUT = -1g YOUT = 0g ZOUT = 0g
Preliminary Technical Data
At VS = 2 V, the self test response is approximately -60 mV for the X-axis, +60 mV for the Y-axis, and -25 mV for the Z-axis. The supply current decreases as the supply voltage decreases. Typical current consumption at VS = 3.6 V is 375 A, and typical current consumption at VS = 2 V is 200 A.
AXES OF ACCELERATION SENSITIVITY
AZ
AY
TOP
AX
Figure 5. Axes of Acceleration Sensitivity, Corresponding Output Voltage Increases When Accelerated Along the Sensitive Axis
TOP
GRAVITY
XOUT = 0g YOUT = 1g ZOUT = 0g XOUT = 0g YOUT = -1g ZOUT = 0g
TOP
TOP
TOP
XOUT = 1g YOUT = 0g ZOUT = 0g
TOP
Figure 6. Output Response vs. Orientation to Gravity
Rev. PrA | Page 8 of 11
05677-031
XOUT = 0g YOUT = 0g ZOUT = 1g
XOUT = 0g YOUT = 0g ZOUT = -1g
05677-030
Preliminary Technical Data OUTLINE DIMENSIONS
0.20 MIN 0.20 MIN
13 16 1
ADXL335
PIN 1 INDICATOR 2.43 1.75 SQ 1.08
PIN 1 INDICATOR
TOP VIEW
4.15 4.00 SQ 3.85 0.65 BSC
12
BO TTOM VIEW
9 8 5 4
0.55 0.50 0.45 1.50 1.45 1.40 SEATING PLANE 0.05 MAX 0.02 NOM 0.35 0.30 0.25 COPLANARITY 0.05
1.95 BSC
*STACKED DIE WITH GLASS SEAL.
Figure 7. 16-Lead Lead Frame Chip Scale Package [LFCSP_LQ] 4 mm x 4 mm Body, 1.45mm Thick Quad (CP-16-5a*) Dimensions shown in millimeters
ORDERING GUIDE
Model ADXL335BCPZ1 ADXL335BCPZ-RL1 ADXL335BCPZ-RL71 EVAL-ADXL335Z1
1
Measurement Range 3 g 3 g 3 g
Specified Voltage 3V 3V 3V
Temperature Range -40C to +85C -40C to +85C -40C to +85C
Package Description 16-Lead LFCSP_LQ 16-Lead LFCSP_LQ 16-Lead LFCSP_LQ Evaluation Board
072606-A
Package Option CP-16-5a CP-16-5a CP-16-5a
Z = Pb-free part.
Rev. PrA | Page 9 of 11
ADXL335 NOTES
Preliminary Technical Data
Rev. PrA | Page 10 of 11
Preliminary Technical Data NOTES
ADXL335
(c)2008 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. PR07808-0-9/08(PrA)
Rev. PrA | Page 11 of 11

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