ADXL325BCPZ

**Small, Low Power, 3-Axis ±5** _**g**_ **Accelerometer** 

**ADXL325** 

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## **FEATURES** 

## **3-axis sensing** 

**Small, low profile package** 

**4 mm × 4 mm × 1.45 mm LFCSP Low power: 350 μA typical Single-supply operation: 1.8 V to 3.6 V 10,000** _**g**_ **shock survival** 

**Excellent temperature stability Bandwidth adjustment with a single capacitor per axis RoHS/WEEE lead-free compliant** 

## **APPLICATIONS** 

**Cost-sensitive, low power, motion- and tilt-sensing applications Mobile devices Gaming systems Disk drive protection Image stabilization Sports and health devices** 

## **GENERAL DESCRIPTION** 

The ADXL325 is a small, low power, complete 3-axis accelerometer with signal conditioned voltage outputs. The product measures acceleration with a minimum full-scale range of ±5 _g_ . It can measure the static acceleration of gravity in tilt-sensing 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 ADXL325 is available in a small, low profile, 4 mm × 4 mm × 1.45 mm, 16-lead, plastic lead frame chip scale package (LFCSP_LQ). 

## **FUNCTIONAL BLOCK DIAGRAM** 

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+3V<br>VS<br>ADXL325<br>~32kΩ XOUT<br>OUTPUT AMP<br>3-AXIS CX<br>SENSOR<br>~32kΩ YOUT<br>CDC AC AMP DEMOD OUTPUT AMP<br>CY<br>~32kΩ ZOUT<br>OUTPUT AMP<br>CZ<br>COM ST<br>Figure 1.<br>07946-001<br>**----- End of picture text -----**<br>


**Rev. 0** 

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**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 ©2009 Analog Devices, Inc. All rights reserved.** 

**ADXL325* Product Page Quick Links** 

Last Content Update: 11/01/2016 

## Comparable Parts 

View a parametric search of comparable parts 

## Design Resources 

- ADXL325 Material Declaration 

- PCN-PDN Information 

## Evaluation Kits 

- ADXL325 Breakout Board 

- Quality And Reliability 

- Symbols and Footprints 

## Documentation 

## **Application Notes** 

## Discussions 

View all ADXL325 EngineerZone Discussions 

- AN-1057: Using an Accelerometer for Inclination Sensing 

- AN-688: Phase and Frequency Response of iMEMS® Accelerometers and Gyros 

## Sample and Buy 

Visit the product page to see pricing options 

## **Data Sheet** 

- ADXL325: Small, Low Power, 3-Axis ±5 _g_ Accelerometer Data Sheet 

## Technical Support 

Submit a technical question or find your regional support number 

* This page was dynamically generated by Analog Devices, Inc. and inserted into this data sheet. Note: Dynamic changes to the content on this page does not constitute a change to the revision number of the product data sheet. This content may be frequently modified. 

## **ADXL325** 

## **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 Typical Performance Characteristics ............................................. 6 Theory of Operation ...................................................................... 10 Mechanical Sensor ...................................................................... 10 

Performance ................................................................................ 10 Applications Information .............................................................. 11 Power Supply Decoupling ......................................................... 11 Setting the Bandwidth Using CX, CY, and CZ .......................... 11 Self Test ........................................................................................ 11 Design Trade-Offs for Selecting Filter Characteristics: The Noise/BW Trade-Off .................................................................. 11 Use with Operating Voltages Other Than 3 V .......................... 11 Axes of Acceleration Sensitivity ............................................... 12 Layout and Design Recommendations ................................... 13 Outline Dimensions ....................................................................... 14 Ordering Guide .......................................................................... 14 

## **REVISION HISTORY** 

## **8/09—Revision 0: Initial Version** 

Rev. 0 | Page 2 of 16 

**ADXL325** 

## **SPECIFICATIONS** 

TA = 25°C, VS = 3 V, CX = CY = CZ = 0.1 μF, acceleration = 0 _g_ , unless otherwise noted. All minimum and maximum specifications are guaranteed. Typical specifications are not guaranteed. 

**Table 1.** 

|**Table 1.**||||
|---|---|---|---|
|**Parameter**|**Conditions**|**Min**<br>**Typ**<br>**Max**|**Unit**|
|SENSOR INPUT<br>Measurement Range<br>Nonlinearity<br>Package Alignment Error<br>Interaxis Alignment Error<br>Cross-Axis Sensitivity1|Each axis<br>Percent of full scale|±5<br>±6<br>±0.2<br>±1<br>±0.1<br>±1|_g_<br>%<br>Degrees<br>Degrees<br>%|
|SENSITIVITY (RATIOMETRIC)2<br>Sensitivity at XOUT, YOUT, ZOUT<br>SensitivityChange Due to Temperature3|Each axis<br>VS= 3 V<br>VS= 3 V|156<br>174<br>192<br>±0.01|mV/_g_<br>%/°C|
|ZERO_g_BIAS LEVEL (RATIOMETRIC)<br>0_g_Voltage at XOUT, YOUT, ZOUT<br>0_g_Offset vs. Temperature|VS= 3 V|1.3<br>1.5<br>1.7<br>±1|V<br>m_g_/°C|
|NOISE PERFORMANCE<br>Noise Density XOUT, YOUT,ZOUT||250|μ_g_/√Hz rms|
|FREQUENCY RESPONSE4<br>Bandwidth XOUT, YOUT5<br>Bandwidth ZOUT5<br>RFILTTolerance<br>Sensor Resonant Frequency|No external filter<br>No external filter|1600<br>550<br>32 ± 15%<br>5.5|Hz<br>Hz<br>kΩ<br>kHz|
|SELF TEST6<br>Logic Input Low<br>Logic Input High<br>ST Actuation Current<br>Output Change at XOUT<br>Output Change at YOUT<br>Output Change at ZOUT|Self test 0 to 1<br>Self test 0 to 1<br>Self test 0 to 1|+0.6<br>+2.4<br>+60<br>−90<br>−190<br>−350<br>+90<br>+190<br>+350<br>+90<br>+320<br>+580|V<br>V<br>μA<br>mV<br>mV<br>mV|
|OUTPUT AMPLIFIER<br>Output Swing Low<br>Output SwingHigh|No load<br>No load|0.1<br>2.8|V<br>V|
|POWER SUPPLY<br>Operating Voltage Range<br>Supply Current<br>Turn-On Time7|VS= 3 V<br>No external filter|1.8<br>3.6<br>350<br>1|V<br>μA<br>ms|
|TEMPERATURE<br>Operating Temperature Range||−40<br>+85|°C|



1 Defined as coupling between any two axes. 

2 Sensitivity is essentially ratiometric to VS. 

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 filter capacitors (CX, CY, CZ). 

5 Bandwidth with external capacitors = 1/(2 × π × 32 kΩ × C). For CX, CY = 0.003 μF, bandwidth = 1.6 kHz. For CZ = 0.01 μF, bandwidth = 500 Hz. For CX, CY, CZ = 10 μF, 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 × CX or CY or CZ + 1 ms, where CX, CY, CZ are in μF. 

Rev. 0 | Page 3 of 16 

## **ADXL325** 

## **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 +3.6 V All Other Pins (COM − 0.3 V) to (VS + 0.3 V) Output Short-Circuit Duration Indefinite (Any Pin to Common) Temperature Range (Powered) −55°C to +125°C Temperature Range (Storage) −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** 

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Rev. 0 | Page 4 of 16 

**ADXL325** 

## **PIN CONFIGURATION AND FUNCTION DESCRIPTIONS** 

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16 15 14 13<br>NC 1 ADXL325 12 XOUT<br>TOP VIEW<br>ST 2 (Not to Scale) 11 NC<br>+Y<br>COM 3 +Z 10 YOUT<br>NC 4 +X 9 NC<br>5 6 7 8<br>NC = NO CONNECT<br>NC VS VS NC<br>COM COM COM ZOUT<br>07946-003<br>**----- End of picture text -----**<br>


_Figure 2. Pin Configuration_ 

**Table 3. Pin Function Descriptions** 

|**Pin No.**|**Mnemonic**|**Description**|
|---|---|---|
|1<br>2<br>3<br>4<br>5<br>6<br>7<br>8<br>9<br>10<br>11<br>12<br>13<br>14<br>15<br>16<br>EP|NC<br>ST<br>COM<br>NC<br>COM<br>COM<br>COM<br>ZOUT<br>NC<br>YOUT<br>NC<br>XOUT<br>NC<br>VS<br>VS<br>NC<br>Exposedpad|No Connect (or Optionally Ground)<br>Self Test<br>Common<br>No Connect<br>Common<br>Common<br>Common<br>Z Channel Output<br>No Connect (or Optionally Ground)<br>Y Channel Output<br>No Connect<br>X Channel Output<br>No Connect<br>Supply Voltage (1.8 V to 3.6 V)<br>Supply Voltage (1.8 V to 3.6 V)<br>No Connect<br>Not internallyconnected. Solder for mechanical integrity.|



Rev. 0 | Page 5 of 16 

## **ADXL325** 

## **TYPICAL PERFORMANCE CHARACTERISTICS** 

N > 1000 for all typical performance plots, unless otherwise noted. 

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50<br>40<br>30<br>20<br>10<br>0<br>1.46 1.47 1.48 1.49 1.5 1.51 1.52 1.53 1.54<br>OUTPUT (V)<br>POPULATION (%)<br>07946-005<br>**----- End of picture text -----**<br>


_Figure 3. X-Axis Zero_ g _Bias at 25°C, VS = 3 V_ 

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40<br>30<br>20<br>10<br>0<br>1.46 1.47 1.48 1.49 1.50 1.51 1.52 1.53 1.54<br>OUTPUT (V)<br>Figure 4. Y-Axis Zero  g  Bias at 25°C, VS = 3 V<br>30<br>25<br>20<br>15<br>10<br>5<br>0<br>1.46 1.47 1.48 1.49 1.50 1.51 1.52 1.53 1.54<br>OUTPUT (V)<br>POPULATION (%)<br>07946-006<br>POPULATION (%)<br>07946-007<br>**----- End of picture text -----**<br>


_Figure 5. Z-Axis Zero_ g _Bias at 25°C, VS = 3 V_ 

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60<br>50<br>40<br>30<br>20<br>10<br>0<br>–0.22 –0.20 –0.18 –0.16 –0.14 –0.12<br>VOLTAGE (V)<br>POPULATION (%)<br>07946-008<br>**----- End of picture text -----**<br>


_Figure 6. X-Axis Self Test Response at 25°C, VS = 3 V_ 

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60<br>50<br>40<br>30<br>20<br>10<br>0<br>0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.20 0.21 0.22<br>VOLTAGE (V)<br>Figure 7. Y-Axis Self Test Response at 25°C, VS = 3 V<br>60<br>50<br>40<br>30<br>20<br>10<br>0<br>0.26 0.27 0.28 0.29 0.30 0.31 0.32 0.33 0.34 0.35 0.36<br>VOLTAGE (V)<br>Figure 8. Z-Axis Self Test Response at 25°C, VS = 3 V<br>POPULATION (%)<br>07946-009<br>POPULATION (%)<br>07946-010<br>**----- End of picture text -----**<br>


Rev. 0 | Page 6 of 16 

**ADXL325** 

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50<br>45<br>40<br>35<br>30<br>25<br>20<br>15<br>10<br>5<br>0<br>–1.4 –1.0 –0.6 –0.2 0.2 0.6 1.0 1.4<br>TEMPERATURE COEFFICIENT (mg/°C)<br>Figure 9. X-Axis Zero  g  Bias Temperature Coefficient, VS = 3 V<br>POPULATION (%)<br>07946-011<br>**----- End of picture text -----**<br>


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50<br>40<br>30<br>20<br>10<br>0<br>–1.4 –1.0 –0.6 –0.2 0.2 0.6 1.0 1.4<br>TEMPERATURE COEFFICIENT (mg/°C)<br>POPULATION (%)<br>07946-012<br>**----- End of picture text -----**<br>


_Figure 10. Y-Axis Zero_ g _Bias Temperature Coefficient, VS = 3 V_ 

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40<br>35<br>30<br>25<br>20<br>15<br>10<br>5<br>0<br>–3.5 –3.0 –2.5 –2.0 –1.5 –1.0 –0.5 0 0.5 1.0 1.5 2.0 2.5<br>TEMPERATURE COEFFICIENT (m g /°C)<br>Figure 11. Z-Axis Zero  g  Bias Temperature Coefficient, VS = 3 V<br>POPULATION (%)<br>07946-013<br>**----- End of picture text -----**<br>


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1.55<br>N = 8<br>1.54<br>1.53<br>1.52<br>1.51<br>1.50<br>1.49<br>1.48<br>1.47<br>1.46<br>1.45<br>–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100<br>TEMPERATURE (°C)<br>OUTPUT (V)<br>07946-014<br>**----- End of picture text -----**<br>


_Figure 12. X-Axis Zero_ g _Bias vs. Temperature, Eight Parts Soldered to PCB_ 

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1.55<br>N = 8<br>1.54<br>1.53<br>1.52<br>1.51<br>1.50<br>1.49<br>1.48<br>1.47<br>1.46<br>1.45<br>–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100<br>TEMPERATURE (°C)<br>Figure 13. Y-Axis Zero  g  Bias vs. Temperature, Eight Parts Soldered to PCB<br>OUTPUT (V)<br>07946-015<br>**----- End of picture text -----**<br>


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1.54 N = 8<br>1.52<br>1.50<br>1.48<br>1.46<br>1.44<br>1.42<br>1.40<br>–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100<br>TEMPERATURE (°C)<br>OUTPUT (V)<br>07946-016<br>**----- End of picture text -----**<br>


_Figure 14. Z-Axis Zero_ g _Bias vs. Temperature, Eight Parts Soldered to PCB_ 

Rev. 0 | Page 7 of 16 

## **ADXL325** 

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30<br>25<br>20<br>15<br>10<br>5<br>0<br>0.164 0.166 0.168 0.170 0.172 0.174 0.176 0.178 0.180 0.182<br>SENSITIVITY (V/ g )<br>Figure 15. X-Axis Sensitivity at 25°C, VS = 3 V<br>POPULATION (%)<br>07946-017<br>**----- End of picture text -----**<br>


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40<br>35<br>30<br>25<br>20<br>15<br>10<br>5<br>0<br>0.164 0.166 0.168 0.170 0.172 0.174 0.176 0.178 0.180 0.182<br>SENSITIVITY (V/ g )<br>Figure 16. Y-Axis Sensitivity at 25°C, VS = 3 V<br>35<br>30<br>25<br>20<br>15<br>10<br>5<br>0<br>0.164 0.166 0.168 0.170 0.172 0.174 0.176 0.178 0.180 0.182<br>SENSITIVITY (V/ g )<br>Figure 17. Z-Axis Sensitivity at 25°C, VS = 3 V<br>POPULATION (%)<br>07946-018<br>POPULATION (%)<br>07946-019<br>**----- End of picture text -----**<br>


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N = 8<br>0.187<br>0.182<br>0.177<br>0.172<br>0.167<br>0.162<br>0.157<br>–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100<br>TEMPERATURE (°C)<br>Figure 18. X-Axis Sensitivity vs. Temperature,<br>Eight Parts Soldered to PCB, VS = 3 V<br>N = 8<br>0.187<br>0.182<br>0.177<br>0.172<br>0.167<br>0.162<br>0.157<br>–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100<br>TEMPERATURE (°C)<br>Figure 19. Y-Axis Sensitivity vs. Temperature,<br>Eight Parts Soldered to PCB, VS = 3 V<br>0.187<br>N = 8<br>0.182<br>0.177<br>0.172<br>0.167<br>0.162<br>0.157<br>–40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100<br>TEMPERATURE (°C)<br>) g<br>SENSITIVITY (V/<br>07946-020<br>) g<br>SENSITIVITY (V/<br>07946-021<br>SENSITIVITY (V/g)<br>07946-022<br>**----- End of picture text -----**<br>


_Figure 20. Z-Axis Sensitivity vs. Temperature, Eight Parts Soldered to PCB, VS = 3 V_ 

Rev. 0 | Page 8 of 16 

**ADXL325** 

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600<br>CH4: Z O UT, 500mV/DIV<br>500<br>CH3: Y O UT, 500mV/DIV<br>400<br>CH2: X OUT , 500mV/DIV<br>300 4<br>3<br>200 2 CH1: POWER, 2V/DIV<br>100<br>1 OUTPUTS ARE OFFSET<br>FOR CL A RITY<br>0<br>1.5 2.0 2.5 3.0 3.5 4.0 TIME (1ms/DIV)<br>SUPPLY (V)<br>CURRENT (µA)<br>07946-024<br>07946-023<br>**----- End of picture text -----**<br>


_Figure 21. Typical Current Consumption vs. Supply Voltage_ 

_Figure 22. Typical Turn-On Time, VS = 3 V, CX = CY = CZ = 0.0047 μF_ 

Rev. 0 | Page 9 of 16 

## **ADXL325** 

## **THEORY OF OPERATION** 

The ADXL325 is a complete 3-axis acceleration measurement system. The ADXL325 has a measurement range of ±5 _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. 

## **MECHANICAL SENSOR** 

The ADXL325 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 that high performance is built-in to the ADXL325. As a result, there is neither quantization error nor nonmonotonic behavior, and temperature hysteresis is very low (typically <3 m _g_ over the −25°C to +70°C temperature range). 

The demodulator output is amplified and brought off-chip through a 32 kΩ resistor. The user then sets the signal bandwidth of the device by adding a capacitor. This filtering improves measurement resolution and helps prevent aliasing. 

Rev. 0 | Page 10 of 16 

**ADXL325** 

## **APPLICATIONS INFORMATION POWER SUPPLY DECOUPLING** 

For most applications, a single 0.1 μF capacitor, CDC, placed close to the ADXL325 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 because this noise can cause errors in acceleration measurement. If additional decoupling is needed, a 100 Ω (or smaller) resistor or ferrite bead can be inserted in the supply line. Additionally, a larger bulk bypass capacitor (1 μF or greater) can be added in parallel to CDC. Ensure that the connection from the ADXL325 ground to the power supply ground is low impedance because noise transmitted through ground has a similar effect as noise transmitted through VS. 

## **SETTING THE BANDWIDTH USING CX, CY, AND CZ** 

The ADXL325 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 3 dB bandwidth equation is 

_f_ −3 dB = 1/(2π(32 kΩ) × _C_ ( _X_ , _Y, Z_ )) 

or more simply 

## _f_ –3 dB = 5 μF/ _C_ ( _X_ , _Y, Z_ ) 

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 0.0047 μF for CX, CY, and CZ is recommended in all cases. 

## **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 ADXL325 has a typical bandwidth 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 ADXL325 noise has the characteristics of white Gaussian noise, which contributes equally at all frequencies and is described in terms of μ _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 ADXL325 is determined by 

_rms Noise_ = _Noise Density_ × ( _BW_ × 1.6 ) 

Often, the peak value of the noise is desired. Peak-to-peak noise can only be estimated by statistical methods. Table 5 is useful for estimating the probabilities of exceeding various peak values, given the rms value. 

**Table 5. Estimation of Peak-to-Peak Noise** 

**Table 4. Filter Capacitor Selection, CX, CY, and CZ** 

|**Bandwidth (Hz)**|**Capacitor (μF)**|
|---|---|
|1<br>10<br>50<br>100<br>200<br>500|4.7<br>0.47<br>0.10<br>0.05<br>0.027<br>0.01|



## **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 whether the accelerometer is functional. The typical change in output is −1.08 _g_ (corresponding to −190 mV) in the X axis, +1.08 _g_ (+190 mV) on the Y axis, and +1.83 _g_ (+320 mV) on the Z axis. This ST pin can be left open circuit or connected to common (COM) in normal use. 

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, there are multiple supply voltages), then a low VF clamping diode between ST and VS is recommended. 

|**Peak-to-Peak Value**|**% of Time That Noise Exceeds**<br>**Nominal Peak-to-Peak Value**|
|---|---|
|2 × rms<br>4 × rms<br>6 × rms<br>8 × rms|32<br>4.6<br>0.27<br>0.006|



## **USE WITH OPERATING VOLTAGES OTHER THAN 3 V** 

The ADXL325 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. 

The ADXL325 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 209 mV/ _g_ . At VS = 2 V, the output sensitivity is typically 116 mV/ _g_ . 

The zero _g_ bias output is also ratiometric; therefore, 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 200 μ _g_ /√Hz, while at VS = 2 V, the X- and Y-axis noise density is typically 300 μ _g_ /√Hz. 

Rev. 0 | Page 11 of 16 

## **ADXL325** 

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 ADXL325 is approximately −328 mV for the X-axis, +328 mV for the Y axis, and +553 mV for the Z axis. At VS = 2 V, the self test response is approximately −56 mV for the X axis, +56 mV for the Y axis, and −95 mV for the Z axis. 

The supply current decreases as the supply voltage decreases. Typical current consumption at VS = 3.6 V is 375 μA, and typical current consumption at VS = 2 V is 300 μA. 

## **AXES OF ACCELERATION SENSITIVITY** 

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AZ<br>AY<br>AX<br>TOP<br>07946-025<br>**----- End of picture text -----**<br>


_Figure 23. Axes of Acceleration Sensitivity (Corresponding Output Voltage Increases When Accelerated Along the Sensitive Axis)_ 

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XOUT = –1 g<br>YOUT = 0 g<br>ZOUT = 0 g<br>TOP<br>GRAVITY<br>XOUT = 0 g XOUT = 0 g<br>YOUT = 1 g TOP TOP YOUT = –1 g<br>ZOUT = 0 g ZOUT = 0 g<br>TOP<br>XOUT = 1 g<br>YOUT = 0 g<br>ZOUT = 0 g<br>XOUT = 0 g XOUT = 0 g<br>YOUT = 0 g YOUT = 0 g<br>ZOUT = 1 g ZOUT = –1 g<br>TOP<br>07946-026<br>**----- End of picture text -----**<br>


_Figure 24. Output Response vs. Orientation to Gravity_ 

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**ADXL325** 

## **LAYOUT AND DESIGN RECOMMENDATIONS** 

The recommended soldering profile is shown in Figure 25, followed by a description of the profile features in Table 6. The recommended PCB layout or solder land drawing is shown in Figure 26. 

|**tP**<br>**tL**<br>**t25°C TO PEAK**<br>**tS**<br>**PREHEAT**<br>**CRITICAL ZONE**<br>**TL TO TP**<br>**TEMPERATURE**<br>**TIME**<br>**RAMP-DOWN**<br>**RAMP-UP**<br>**TSMIN**<br>**TSMAX**<br>**TP**<br>**TL**<br>07946-002<br>_Figure 25. Recommended Soldering Profile_<br>**Table 6. Recommended Soldering Profile**|**tP**<br>**tL**<br>**t25°C TO PEAK**<br>**tS**<br>**PREHEAT**<br>**CRITICAL ZONE**<br>**TL TO TP**<br>**TEMPERATURE**<br>**TIME**<br>**RAMP-DOWN**<br>**RAMP-UP**<br>**TSMIN**<br>**TSMAX**<br>**TP**<br>**TL**<br>07946-002<br>_Figure 25. Recommended Soldering Profile_<br>**Table 6. Recommended Soldering Profile**||
|---|---|---|
|**Profile Feature**|**Sn63/Pb37**|**Pb-Free**|
|Average Ramp Rate (TLto TP)<br>Preheat<br>Minimum Temperature (TSMIN)<br>Maximum Temperature (TSMAX)<br>Time (TSMINto TSMAX), tS<br>TSMAXto TL<br>Ramp-Up Rate<br>Time Maintained Above Liquidous (TL)<br>Liquidous Temperature (TL)<br>Time (tL)<br>Peak Temperature (TP)<br>Time Within 5°C of Actual Peak Temperature (tP)<br>Ramp-Down Rate<br>Time 25°C to Peak Temperature|3°C/sec maximum<br>100°C<br>150°C<br>60 sec to 120 sec<br>3°C/sec maximum<br>183°C<br>60 sec to 150 sec<br>240°C + 0°C/−5°C<br>10 sec to 30 sec<br>6°C/sec maximum<br>6 minutes maximum|3°C/sec maximum<br>150°C<br>200°C<br>60 sec to 180 sec<br>3°C/sec maximum<br>217°C<br>60 sec to 150 sec<br>260°C + 0°C/−5°C<br>20 sec to 40 sec<br>6°C/sec maximum<br>8 minutes maximum|



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0.50 4<br>MAX<br>0.65 0.325<br>0.35<br>MAX<br>0.65<br>4<br>1.95<br>0.325<br>CENTER PAD IS NOT<br>INTERNALLY CONNECTED<br>BUT SHOULD BE SOLDERED<br>FOR MECHANICAL INTEGRITY<br>1.95<br>DIMENSIONS SHOWN IN MILLIMETERS<br>07946-004<br>**----- End of picture text -----**<br>


_Figure 26. Recommended PCB Layout_ 

Rev. 0 | Page 13 of 16 

## **ADXL325** 

## **OUTLINE DIMENSIONS** 

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0.20 MIN PIN 1<br>0.20 MIN INDICATOR<br>13 16<br>INDICATORPIN 1 4.15 12 EXPOSED 1 2.43<br>TOP VIEW 4.00 SQ PAD 1.75 SQ<br>3.85 0.65 BSC (BOTTOM VIEW) 1.08<br>9 4<br>8 5<br>0.55<br>0.50<br>0.45<br>1.95 BSC<br>0.05 MAX FOR PROPER CONNECTION OF<br>1.50 0.02 NOM THE EXPOSED PAD, REFER TO<br>1.451.40 SEATING 0.350.30 COPLANARITY0.05 THE PIN CONFIGURATION ANDFUNCTION DESCRIPTIONSSECTION OF THIS DATA SHEET.<br>PLANE 0.25<br>*STACKED DIE WITH GLASS SEAL.<br>Figure 27. 16-Lead Lead Frame Chip Scale Package [LFCSP_LQ]<br>4 mm × 4 mm Body, 1.45 mm Thick Quad<br>(CP-16-5a*)<br>**----- End of picture text -----**<br>


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112008-A<br>**----- End of picture text -----**<br>


_Dimensions shown in millimeters_ 

## **ORDERING GUIDE** 

|**Model**|**Measurement Range **|**Specified Voltage**|**Temperature Range **|**Package Description**|**Package Option**|
|---|---|---|---|---|---|
|ADXL325BCPZ1<br>ADXL325BCPZ–RL1<br>ADXL325BCPZ–RL71<br>EVAL-ADXL325Z1|±5_g_<br>±5_g_<br>±5_g_|3 V<br>3 V<br>3 V|−40°C to +85°C<br>−40°C to +85°C<br>−40°C to +85°C|16-Lead LFCSP_LQ<br>16-Lead LFCSP_LQ<br>16-Lead LFCSP_LQ<br>Evaluation Board|CP-16-5a<br>CP-16-5a<br>CP-16-5a|



1 Z = RoHS Compliant Part. 

Rev. 0 | Page 14 of 16 

**ADXL325** 

## **NOTES** 

Rev. 0 | Page 15 of 16 

**ADXL325** 

## **NOTES** 

**Analog Devices offers specific products designated for automotive applications; please consult your local Analog Devices sales representative for details. Standard products sold by Analog Devices are not designed, intended, or approved for use in life support, implantable medical devices, transportation, nuclear, safety, or other equipment where malfunction of the product can reasonably be expected to result in personal injury, death, severe property damage, or severe environmental harm. Buyer uses or sells standard products for use in the above critical applications at Buyer's own risk and Buyer agrees to defend, indemnify, and hold harmless Analog Devices from any and all damages, claims, suits, or expenses resulting from such unintended use.** 

**©2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.** 

**D07946-0-8/09(0)** 

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