KIT1925MMA1270D

Freescale Semiconductor, Inc.    Order this document by MMA1270D/D SEMICONDUCTOR TECHNICAL DATA      The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 2–pole low pass filter and temperature compensation. 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. MMA1270D: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER ±2.5g Features • Integral Signal Conditioning • Linear Output Freescale Semiconductor, Inc... • 2nd Order Bessel Filter • Calibrated Self–test • EPROM Parity Check Status 16 • Transducer Hermetically Sealed at Wafer Level for Superior Reliability 9 • Robust Design, High Shock Survivability 1 Typical Applications 8 • Vibration Monitoring and Recording 16 LEAD SOIC CASE 475–01 • Appliance Control • Mechanical Bearing Monitoring • Computer Hard Drive Protection • Computer Mouse and Joysticks Pin Assignment • Virtual Reality Input Devices '$$ • Sports Diagnostic Devices and Systems '$$ '$$ '!&% ORDERING INFORMATION Device Temperature Range MMA1270D –40 to +105°C Case No. Package Case 475–01 SOIC–16 $%%&$ ' '$$ $%                   SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM '  $ $!# $% $%$%  %#%!#  ! %#! !  "#! %# #&%$ %# !$%!# %" !"   !   '!&% '$$ $%%&$ Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 Motorola Sensor Device Data  Motorola, Inc. 2002 For More Information On This Product, Go to: www.freescale.com  1 Freescale Semiconductor, Inc. MAXIMUM RATINGS (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Symbol Value Unit Powered Acceleration (all axes) Rating gpd 1500 g Unpowered Acceleration (all axes) gupd 2000 g Supply Voltage VDD –0.3 to +7.0 V Hdrop 1.2 m Tstg –40 to +125 °C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. Freescale Semiconductor, Inc... ELECTRO STATIC DISCHARGE (ESD) WARNING: This device is sensitive to electrostatic discharge. Although the Motorola accelerometers contain internal 2kV ESD protection circuitry, extra precaution must be taken by the user to protect the chip from ESD. A charge of over  2 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. For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. 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 4.75 1.1
40 — 5.00 2.1 — 2.5 5.25 3.0 +105 — V mA °C g VOFF VOFF S S f–3dB NLOUT 2.25 2.2 712.5 693.8 40
1.0 2.5 2.5 750 750 50 — 2.75 2.8 787.5 806.3 60 +1.0 V V mV/g mV/g Hz % FSO Noise RMS (0.1 Hz – 1.0 kHz) Spectral Density (RMS, 0.1 Hz – 1.0 kHz)(6) nRMS nSD — — 3.5 700 6.5 — mVrms µg/√Hz Self–Test Output Response (VDD = 5.0 V) Input Low Input High Input Loading(7) Response Time(8)
VST VIL VIH IIN tST 0.9 VSS 0.7 VDD
50 — 1.25 — —
125 10 1.6 0.3 VDD VDD
300 25 V V V µA ms Status(12)(13) Output Low (Iload = 100 µA) Output High (Iload = –100 µA) VOL VOH — VDD
0.8 — — 0.4 — V V Output Stage Performance Electrical Saturation Recovery Time(9) Full Scale Output Range (IOUT = –200 µA) Capacitive Load Drive(10) Output Impedance tDELAY VFSO CL ZO — VSS+0.25 — — — — — 50 2.0 VDD
0.25 100 — ms V pF Ω Mechanical Characteristics Transverse Sensitivity(11) VXZ,YZ — — 5.0 % FSO Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Freescale Semiconductor, Inc... Output Signal Zero g (TA = 25°C, VDD = 5.0 V)(4) Zero g (VDD = 5.0 V) Sensitivity (TA = 25°C, VDD = 5.0 V)(5) Sensitivity(VDD = 5.0 V) Bandwidth Response Nonlinearity NOTES: 1. For a loaded output the measurements are observed after an RC filter consisting of a 1 kΩ resistor and a 0.1 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. Sensitivity limits apply to 0 Hz acceleration. 6. At clock frequency  35 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. Time for amplifiers to recover after an acceleration signal causing them to saturate. 10. Preserves phase margin (60°) to guarantee output amplifier stability. 11. A measure of the device’s ability to reject an acceleration applied 90° from the true axis of sensitivity. 12. 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. 13. The Status pin output latches high if the EPROM parity changes to odd. The Status pin can be reset by a rising edge on self–test, unless a fault condition continues to exist. Motorola Sensor Device Data For More Information On This Product, Go to: www.freescale.com  3 Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. PRINCIPLE OF OPERATION SPECIAL FEATURES The Motorola 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 two stationary plates with a moveable plate in–between. The center plate can be deflected from its rest position by subjecting the system to an acceleration (Figure 2). When the center plate deflects, the distance from it to one fixed plate will increase by the same amount that the distance to the other plate decreases. The change in distance is a measure of acceleration. The g–cell plates form two back–to–back capacitors (Figure 3). As the center plate moves with acceleration, the distance between the plates changes and each capacitor’s value will change, (C = Aε/D). Where A is the area of the plate, ε is the dielectric constant, and D is the distance between the plates. 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. Filtering The Motorola accelerometers contain an onboard 2–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 cut–off frequency. 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 self– test plate. When the user applies a logic high input to the self–test 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. Acceleration Status Motorola 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 the following event occurs: Figure 2. Transducer Physical Model  4 Figure 3. Equivalent Circuit Model • 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. For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PCB Layout BASIC CONNECTIONS '!&% $%%&$ ' '$$ $%    $%%&$        '$$ '$$         " $% " '!&% # '$$ +Ω '     µ   µ '#         '$$ '$$   µ '  µ Figure 4. Pinout Description Freescale Semiconductor, Inc... "!(# $&""* Pin No. Pin Name Description 1 thru 3 VSS Redundant connections to the internal VSS and may be left unconnected. 4 VOUT 5 STATUS 6 VDD The power supply input. 7 VSS The power supply ground. NOTES: 8 ST Logic input pin used to initiate self– test. 9 thru 13 Trim pins Used for factory trim. Leave unconnected. • Use a 0.1 µF capacitor on VDD to decouple the power source. 14 thru 16 — No internal connection. Leave unconnected. ' !  "&% Output voltage of the accelerometer. Figure 6. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller Logic output pin used to indicate fault.    $%  '   µ  '$$ '!&%  • 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 internal VSS terminals shown in Figure 4. $%%&$ # +Ω !&%"&% $    µ Figure 5. SOIC Accelerometer with Recommended Connection Diagram Motorola Sensor Device Data • Use an RC filter of 1 kΩ and 0.1 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. For More Information On This Product, Go to: www.freescale.com  5 Freescale Semiconductor, Inc. ACCELERATION SENSING DIRECTIONS DYNAMIC ACCELERATION '$$ '$$ '$$ +g '!&% $%%&$ ' '$$ $%                   16–Pin SOIC Package N/C pins are recommended to be left FLOATING Freescale Semiconductor, Inc... –g STATIC ACCELERATION Direction of Earth’s gravity field.* +1g '!&%   ' 0g 0g '!&%   ' '!&%   ' –1g '!&%   ' * When positioned as shown, the Earth’s gravity will result in a positive 1g output  6 For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data Freescale Semiconductor, Inc. PACKAGE DIMENSIONS A A G/2 2 PLACES, 16 TIPS G
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      M    CASE 475–01 ISSUE B 16 LEAD SOIC Motorola Sensor Device Data For More Information On This Product, Go to: www.freescale.com  7 Freescale Semiconductor, Inc... Freescale Semiconductor, Inc. Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola 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 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. Motorola does not convey any license under its patent rights nor the rights of others. Motorola 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 Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola 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 Motorola was negligent regarding the design or manufacture of the part. Motorola and the Stylized M Logo are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer. MOTOROLA and the Stylized M Logo are registered in the US Patent & Trademark Office. All other product or service names are the property of their respective owners.
Motorola, Inc. 2002. How to reach us: USA/EUROPE/Locations Not Listed: Motorola Literature Distribution; P.O. Box 5405, Denver, Colorado 80217. 1–303–675–2140 or 1–800–441–2447 JAPAN: Motorola Japan Ltd.; SPS, Technical Information Center, 3–20–1, Minami–Azabu. Minato–ku, Tokyo 106–8573 Japan. 81–3–3440–3569 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Centre, 2 Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong. 852–26668334 Technical Information Center: 1–800–521–6274 HOME PAGE: http://www.motorola.com/semiconductors/  8 ◊For More Information On This Product, Go to: www.freescale.com Motorola Sensor Device Data MMA1270D/D