Freescale Semiconductor Technical Data Document Number: MMA3202D Rev 4, 11/2006 Surface Mount Micromachined Accelerometer MMA3202 The MMA3202 series of dual axis (X and Y) silicon capacitive, micromachined accelerometers features signal conditioning, a 4-pole low pass filter and temperature compensation and separate outputs for the two axes. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. A full system self-test capability verifies system functionality. MMA3202D: X-Y AXIS SENSITIVITY MICROMACHINED ACCELEROMETER ±100/50g Features • • • • • • • • • Sensitivity in two separate axes: 100g X-axis and 50g Y-axis Integral Signal Conditioning Linear Output Ratiometric Performance 4th Order Bessel Filter Preserves Pulse Shape Integrity Calibrated Self-test Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status Transducer Hermetically Sealed at Wafer Level for Superior Reliability Robust Design, High Shocks Survivability D SUFFIX EG SUFFIX (Pb-FREE) 20-LEAD SOIC CASE 475A-02 Typical Applications • • • • • • • • Vibration Monitoring and Recording Impact Monitoring Appliance Control Mechanical Bearing Monitoring Computer Hard Drive Protection Computer Mouse and Joysticks Virtual Reality Input Devices Sports Diagnostic Devices and Systems ORDERING INFORMATION Device Temperature Range Case No. Package MMA3202D – 40 to +125°C 475A-02 SOIC-20 MMA3202DR2 – 40 to +125°C 475A-02 SOIC-20, Tape & Reel MMA3202EG – 40 to +125°C 475A-02 SOIC-20 MMA3202EGR2 – 40 to +125°C 475A-02 SOIC-20, Tape & Reel AVDD G-Cell Sensor ST Self-Test Integrator Control Logic & EPROM Trim Circuits Gain Filter Oscillator Temp Clock Generator Status Figure 1. Simplified Accelerometer Functional Block Diagram © Freescale Semiconductor, Inc., 2006. All rights reserved. VDD N/C 1 20 GND XOUT N/C 2 19 N/C YOUT N/C 3 18 N/C N/C 4 17 N/C ST 5 16 N/C XOUT 6 15 N/C STATUS 7 14 N/C VSS 8 13 N/C VDD 9 12 N/C AVDD 10 11 YOUT VSS Figure 2. Pin Connections Table 1. Maximum Ratings (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Rating Symbol Value Unit Powered Acceleration (all axes) Gpd 1500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD –0.3 to +7.0 V Drop Test (1) Ddrop 1.2 m Tstg –40 to +125 °C Storage Temperature Range 1. Dropped onto concrete surface from any axis. ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the accelerometers contain internal 2 kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over 2000 volts can accumulate on the human body or associated test equipment. A charge of this magnitude can alter the performance or cause failure of the chip. When handling the accelerometer, proper ESD precautions should be followed to avoid exposing the device to discharges which may be detrimental to its performance. MMA3202D 2 Sensors Freescale Semiconductor Table 2. Operating Characteristics (Unless otherwise noted: –40°C ≤ TA ≤ +105°C, 4.75 ≤ VDD ≤ 5.25, Acceleration = 0g, Loaded output.)(1) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS gFS 4.75 6 –40 — — 5.00 8 — 112.5 56.3 5.25 10 +125 — — V mA °C g g VOFF VOFF,V S S SV SV f–3dB NLOUT 2.35 0.46 VDD 19 38 3.72 7.44 360 –1.0 2.5 0.50 VDD 20 40 4 8 400 — 2.65 0.54 VDD 21 42 4.28 8.56 440 +1.0 V V mV/g mV/g mV/g/V mV/g/V Hz % FSO nRMS nPSD nCLK — — — — 110 2.0 2.8 — — mVrms µV/(Hz1/2) mVpk Self-Test Output Response Input Low Input High Input Loading(7) Response Time(8) gST VIL VIH IIN tST 9.6 VSS 0.7 × VDD –30 — 12 — — –100 2.0 14.4 0.3 × VDD VDD –300 – g V V µA ms Status(9) (10) Output Low (Iload = 100 µA) Output High (Iload = 100 µA) VOL VOH — VDD – 0.8 — — 0.4 — V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 50 — 260 kHz Output Stage Performance Electrical Saturation Recovery Time(11) Full Scale Output Range (IOUT = 200 µA) Capacitive Load Drive(12) Output Impedence tDELAY VFSO CL ZO — 0.25 — — 0.2 — — 300 — VDD– 0.25 100 — ms V pF Ω Mechanical Characteristics Transverse Sensitivity(13) Package Resonance VXZ,YZ fPKG — — — 10 5.0 — % FSO kHz (2) Operating Range Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range X-axis Acceleration Range Y-axis Output Signal Zero g (TA = 25°C, VDD = 5.0 V)(4) Zero g Sensitivity X-axis (TA = 25°C, VDD = 5.0 V)(5) Sensitivity Y-axis (TA = 25°C, VDD = 5.0 V) Sensitivity X-axis Sensitivity Y-axis Bandwidth Response Nonlinearity Noise RMS (.01 Hz – 1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 kΩ resistor and a 0.01 µF capacitor to ground. 2. These limits define the range of operation for which the part will meet specification. 3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the device may operate as a linear device but is not guaranteed to be in calibration. 4. The device can measure both + and – acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2. 5. The device is calibrated at 20g. 6. At clock frequency ≅70 kHz. 7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages. 8. Time for the output to reach 90% of its final value after a self-test is initiated. 9. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high whenever the self-test input is high, as a means to check the connectivity of the self-test and Status pins in the application. 10. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The Status pin can be reset low if the self-test pin is pulsed with a high input for at least 100 µs, unless a fault condition continues to exist. 11. Time for amplifiers to recover after an acceleration signal causing them to saturate 12. Preserves phase margin (60°) to guarantee output amplifier stability. 13. A measure of the device's ability to reject an acceleration applied 90° from the true axis of sensitivity. MMA3202D Sensors Freescale Semiconductor 3 PRINCIPLE OF OPERATION The Freescale Semiconductor, Inc. accelerometer is a surface-micromachined integrated-circuit accelerometer. The device consists of a surface micromachined capacitive sensing cell (g-cell) and a CMOS signal conditioning ASIC contained in a single integrated circuit package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined “cap'' wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as a set of beams attached to a movable central mass that move between fixed beams. The movable beams can be deflected from their rest position by subjecting the system to an acceleration (Figure 3). As the beams attached to the central mass move, the distance from them to the fixed beams on one side will increase by the same amount that the distance to the fixed beams on the other side decreases. The change in distance is a measure of acceleration. The g-cell beams form two back-to-back capacitors (Figure 3). As the central mass moves with acceleration, the distance between the beams change and each capacitor's value will change, (C = NAε/D). Where A is the area of the facing side of the beam, ε is the dielectric constant, D is the distance between the beams, and N is the number of beams. The X-Y device contains two structures at right angles to each other. The CMOS ASIC uses switched capacitor techniques to measure the g-cell capacitors and extract the acceleration data from the difference between the two capacitors. The ASIC also signal conditions and filters (switched capacitor) the signal, providing a high level output voltage that is ratiometric and proportional to acceleration. Acceleration Figure 3. Simplified Transducer Physical Model SPECIAL FEATURES Filtering The Freescale Semiconductor, Inc. accelerometers contain an onboard 4-pole switched capacitor filter. A Bessel implementation is used because it provides a maximally flat delay response (linear phase) thus preserving pulse shape integrity. Because the filter is realized using switched capacitor techniques, there is no requirement for external passive components (resistors and capacitors) to set the cutoff frequency. Ratiometricity Ratiometricity simply means that the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as you increase supply voltage the sensitivity and offset increase linearly; as supply voltage decreases, offset and sensitivity decrease linearly. This is a key feature when interfacing to a microcontroller or an A/D converter because it provides system level cancellation of supply induced errors in the analog to digital conversion process. Self-Test The sensor provides a self-test feature that allows the verification of the mechanical and electrical integrity of the accelerometer at any time before or after installation. This feature is critical in applications such as automotive airbag systems where system integrity must be ensured over the life of the vehicle. A fourth “plate'' is used in the g-cell as a selftest plate. When the user applies a logic high input to the selftest pin, a calibrated potential is applied across the self-test plate and the moveable plate. The resulting electrostatic force (Fe = 1/2 AV2/d2) causes the center plate to deflect. The resultant deflection is measured by the accelerometer's control ASIC and a proportional output voltage results. This procedure assures that both the mechanical (g-cell) and electronic sections of the accelerometer are functioning. Status Freescale accelerometers include fault detection circuitry and a fault latch. The Status pin is an output from the fault latch, OR'd with self-test, and is set high whenever one (or more) of the following events occur: • Supply voltage falls below the Low Voltage Detect (LVD) voltage threshold • Clock oscillator falls below the clock monitor minimum frequency • Parity of the EPROM bits becomes odd in number. The fault latch can be reset by a rising edge on the self-test input pin, unless one (or more) of the fault conditions continues to exist. MMA3202D 4 Sensors Freescale Semiconductor BASIC CONNECTIONS PINOUT DESCRIPTION N/C N/C GND 2 20 19 3 18 N/C ST XOUT 4 5 6 17 16 STATUS VSS VDD 7 8 9 N/C N/C N/C N/C N/C AVDD N/C 15 14 13 10 P0 A/D In ST XOUT R 1 kΩ YOUT VSS VDD N/C N/C 12 11 P1 STATUS Accelerometer 1 R 1 kΩ C 0.01 µF A/D In C 0.01 µF VSS C 0.1 µF VDD C 0.1 µF VRH C YOUT Microcontroller N/C PCB Layout 0.1 µF Power Supply Table 3. Pin Descriptions Figure 5. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller Pin No. Pin Name Description 1 thru 3 — Leave unconnected. 4 — No internal connection. Leave unconnected. 5 ST Logic input pin used to initiate self-test. 6 XOUT Output voltage of the accelerometer. X Direction. 7 STATUS 8 VSS The power supply ground. 9 VDD The power supply input. 10 AVDD Power supply input (Analog). 11 YOUT Output voltage of the accelerometer. Y Direction. 12 thru 16 — Used for factory trim. Leave unconnected. 17 thru 19 — No internal connection. Leave unconnected. 20 GND Logic output pin to indicate fault. Ground. MMA3202D VDD Logic Input C1 0.1 µF 5 7 Status ST 9 VDD XOUT 10 AVDD 8 NOTE: • Use a 0.1 µF capacitor on VDD to decouple the power source. • Physical coupling distance of the accelerometer to the microcontroller should be minimal. • Place a ground plane beneath the accelerometer to reduce noise, the ground plane should be attached to all of the open ended terminals shown in Figure 5. • Use an RC filter of 1 kΩ and 0.01 µF on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). • PCB layout of power and ground should not couple power supply noise. • Accelerometer and microcontroller should not be a high current path. • A/D sampling rate and any external power supply switching frequency should be selected such that they do not interfere with the internal accelerometer sampling frequency. This will prevent aliasing errors. R1 1 kΩ 6 X Output Signal C2 0.01 µF VSS YOUT 11 R2 1 kΩ Y Output Signal C3 0.01 µF Figure 4. SOIC Accelerometer with Recommended Connection Diagram MMA3202D Sensors Freescale Semiconductor 5 Dynamic Acceleration Sensing Direction +Y N/C N/C Acceleration of the package in the +X and +Y direction (center plates move in the −X and −Y direction) will result in an increase in the X and Y outputs. N/C N/C ST +X XOUT STATUS VSS VDD AVDD 1 2 3 4 5 6 20 19 GND 18 17 N/C N/C N/C 16 15 14 7 8 9 10 N/C N/C 13 N/C N/C 12 11 N/C YOUT −X Activation of Self test moves the center plates in the −X and −Y direction, resulting in an increase in the X and Y outputs. −Y 20-Pin SOIC Package N/C pins are recommended to be left FLOATING Top View Static Acceleration Sensing Direction 10 9 8 7 6 5 4 3 2 1 Direction of Earth’s gravity field.* 11 12 13 14 15 16 17 18 19 20 Front View Side View * When positioned as shown, the Earth’s gravity will result in a positive 1g output in the X channel. MMA3202D 6 Sensors Freescale Semiconductor MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct 0.380 in. 9.65 mm footprint, the packages will self-align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads. 0.050 in. 1.27 mm 0.024 in. 0.610 mm 0.080 in. 2.03 mm Figure 6. Footprint SOIC-20 (Case 475A-01) MMA3202D Sensors Freescale Semiconductor 7 PACKAGE DIMENSIONS PAGE 1 OF 2 CASE 475A-02 ISSUE C 20-LEAD SOIC MMA3202D 8 Sensors Freescale Semiconductor PACKAGE DIMENSIONS PAGE 2 OF 2 CASE 475A-02 ISSUE C 20-LEAD SOIC MMA3202 Sensors Freescale Semiconductor 9 How to Reach Us: Home Page: www.freescale.com Web Support: http://www.freescale.com/support USA/Europe or Locations Not Listed: Freescale Semiconductor, Inc. Technical Information Center, EL516 2100 East Elliot Road Tempe, Arizona 85284 +1-800-521-6274 or +1-480-768-2130 www.freescale.com/support Europe, Middle East, and Africa: Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muenchen, Germany +44 1296 380 456 (English) +46 8 52200080 (English) +49 89 92103 559 (German) +33 1 69 35 48 48 (French) www.freescale.com/support Japan: Freescale Semiconductor Japan Ltd. Headquarters ARCO Tower 15F 1-8-1, Shimo-Meguro, Meguro-ku, Tokyo 153-0064 Japan 0120 191014 or +81 3 5437 9125 [email protected] Asia/Pacific: Freescale Semiconductor Hong Kong Ltd. Technical Information Center 2 Dai King Street Tai Po Industrial Estate Tai Po, N.T., Hong Kong +800 2666 8080 [email protected] For Literature Requests Only: Freescale Semiconductor Literature Distribution Center P.O. Box 5405 Denver, Colorado 80217 1-800-441-2447 or 303-675-2140 Fax: 303-675-2150 [email protected] MMA3202D Rev. 5 11/2006 Information in this document is provided solely to enable system and software implementers to use Freescale Semiconductor products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. Freescale Semiconductor reserves the right to make changes without further notice to any products herein. Freescale Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Freescale Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters that may be provided in Freescale Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals”, must be validated for each customer application by customer’s technical experts. Freescale Semiconductor does not convey any license under its patent rights nor the rights of others. Freescale Semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur. Should Buyer purchase or use Freescale Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold Freescale Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Freescale Semiconductor was negligent regarding the design or manufacture of the part. Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2006. All rights reserved.