MOTOROLA Order this document by MMA2201D/D SEMICONDUCTOR TECHNICAL DATA MMA2201D Surface Mount Micromachined Accelerometer The MMA series of silicon capacitive, micromachined accelerometers features signal conditioning, a 4–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. Features MMA2201D: X AXIS SENSITIVITY MICROMACHINED ACCELEROMETER ± 40g • Integral Signal Conditioning • Linear Output • Ratiometric Performance 16 • 4th Order Bessel Filter Preserves Pulse Shape Integrity 9 • Calibrated Self–test 1 • Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status 8 • Transducer Hermetically Sealed at Wafer Level for Superior Reliability 16 LEAD SOIC CASE 475–01 • Robust Design, High Shocks Survivability Typical Applications • Vibration Monitoring and Recording • Appliance Control • Mechanical Bearing Monitoring • Computer Hard Drive Protection • Computer Mouse and Joysticks • Virtual Reality Input Devices • Sports Diagnostic Devices and Systems SIMPLIFIED ACCELEROMETER FUNCTIONAL BLOCK DIAGRAM VDD G–CELL SENSOR VST SELF–TEST INTEGRATOR GAIN CONTROL LOGIC & EPROM TRIM CIRCUITS FILTER OSCILLATOR TEMP COMP VOUT CLOCK GEN. VSS STATUS Figure 1. Simplified Accelerometer Functional Block Diagram REV 0 Motorola Sensor Device Data Motorola, Inc. 2000 1 MMA2201D 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 500 g Unpowered Acceleration (all axes) Gupd 2000 g Supply Voltage VDD –0.3 to +7.0 V Ddrop 1.2 m Tstg – 40 to +105 °C Drop Test(1) Storage Temperature Range NOTES: 1. Dropped onto concrete surface from any axis. 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. Motorola Sensor Device Data MMA2201D OPERATING CHARACTERISTICS (Unless otherwise noted: –40°C v TA v +85°C, 4.75 v VDD v 5.25, Acceleration = 0g, Loaded output(1)) Characteristic Symbol Min Typ Max Unit VDD IDD TA gFS 4.75 4.0 40 — 5.00 5.0 — 38 5.25 6.0 +85 — V mA °C g VOFF VOFF,V S SV f –3dB NLOUT 2.3 0.44 VDD 47.5 9.3 360 1.0 2.5 0.50 VDD 50 10 400 — 2.7 0.56 VDD 52.5 10.7 440 +1.0 V V mV/g 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 10 VSS 0.7 x VDD 30 — 14 0.3 x VDD VDD 300 10 g V V µA ms Status(12)(13) Output Low (Iload = 100 µA) Output High (Iload = 100 µA) VOL VOH — VDD .8 — — 0.4 — V V Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V fmin 150 — 400 kHz 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 — 0.3 — — 0.2 — — 300 — VDD 0.3 100 — ms V pF Ω Mechanical Characteristics Transverse Sensitivity(11) Package Resonance VZX,YX fPKG — — — 10 5.0 — % FSO kHz Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Output Signal Zero g (VDD = 5.0 V)(4) Zero g Sensitivity (TA = 25°C, VDD = 5.0 V)(5) Sensitivity Bandwidth Response Nonlinearity Noise RMS (.01–1 kHz) Power Spectral Density Clock Noise (without RC load on output)(6) Clock Monitor Fail Detection Frequency * * * * 12 — — 110 2.0 * * * NOTES: 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. 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 a Low Voltage Detection or Clock Frequency failure occurs, or 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 3 MMA2201D PRINCIPLE OF OPERATION 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. Acceleration Figure 2. Transducer Physical Model 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. 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. 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 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. BASIC CONNECTIONS Figure 3. Equivalent Circuit Model Pinout Description SPECIAL FEATURES N/C Filtering The Motorola 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 cut–off frequency. N/C N/C 4 ST VOUT N/C VSS VDD 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 N/C 9 N/C N/C N/C N/C N/C N/C N/C Motorola Sensor Device Data MMA2201D PCB Layout 1 thru 3 — No internal connection. Leave unconnected. 4 ST Logic input pin used to initiate self–test. 5 VOUT 6 — Description Output voltage of the accelerometer. No internal connection. Leave unconnected. 7 VSS The power supply ground. 8 VDD The power supply input. 9 thru 13 Trim pins 14 thru 16 — VDD No internal connection. Leave unconnected. LOGIC INPUT 6 4 ST 8 VDD VOUT C1 0.1 µF 7 VSS 5 STATUS R1 1 kΩ OUTPUT SIGNAL C2 0.01 µF Figure 4. SOIC Accelerometer with Recommended Connection Diagram Motorola Sensor Device Data P1 ST VOUT VSS VDD P0 A/D IN R 1 kΩ C 0.01 µF C 0.1 µF VRH C Used for factory trim. Leave unconnected. MMA2201D STATUS ACCELEROMETER Pin Name MICROCONTROLLER Pin No. VSS C 0.1 µF VDD 0.1 µF POWER SUPPLY Figure 5. Recommend PCB Layout for Interfacing Accelerometer to Microcontroller NOTES: • 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. 5 MMA2201D Positive Acceleration Sensing Direction N/C –X N/C N/C AXIS ORIENTATION (ACCELERATION FORCE VECTOR) SELF TEST XOUT N/C +X VSS VDD 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 N/C N/C N/C N/C N/C N/C N/C N/C 16–Pin SOIC Package N/C pins are recommended to be left FLOATING 8 7 6 5 4 3 2 1 Direction of Earth’s gravity field.* 9 10 11 12 13 14 15 16 * When positioned as shown, the Earth’s gravity will result in a positive 1g output ORDERING INFORMATION Device MMA2201D 6 Temperature Range *40 to +85°C Case No. Case 475–01 Package SOIC–16 Motorola Sensor Device Data MMA2201D PACKAGE DIMENSIONS –A– 16 9 P 8 PL 0.13 (0.005) –B– 1 M T A B M M 8 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.13 (0.005) TOTAL IN EXCESS OF D DIMENSION AT MAXIMUM MATERIAL CONDITION. D 16 PL 0.13 (0.005) M T A M B M R X 45 _ K J C –T– SEATING PLANE K G F M DIM A B C D F G J K M P R MILLIMETERS MIN MAX 10.15 10.45 7.40 7.60 3.30 3.55 0.35 0.49 0.76 1.14 1.27 BSC 0.25 0.32 0.10 0.25 0_ 7_ 10.16 10.67 0.25 0.75 INCHES MIN MAX 0.400 0.411 0.292 0.299 0.130 0.140 0.014 0.019 0.030 0.045 0.050 BSC 0.010 0.012 0.004 0.009 0_ 7_ 0.400 0.420 0.010 0.029 CASE 475–01 ISSUE A 16 LEAD SOIC Motorola Sensor Device Data 7 MMA2201D Motorola reserves the right to make changes without further notice to any products herein. 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