MMA7260QRev 1, 06/2005Freescale SemiconductorTechnical Data© Freescale Semiconductor, Inc., 2005. All rights reserved.±1.5g - 6g Three Axis Low-g Micromachined AccelerometerThe MMA7260Q low cost capacitive micromachined accelerometer features signal conditioning, a 1-pole low pass filter, temperature compensation and g-Select which allows for the selection among 4 sensitivities. Zero-g offset full scale span and filter cut-off are factory set and require no external devices. Includes a Sleep Mode that makes it ideal for handheld battery powered electronics.Features• Selectable Sensitivity (1.5g/2g/4g/6g)• Low Current Consumption: 500 µA• Sleep Mode: 3 µA• Low Voltage Operation: 2.2 V – 3.6 V• 6mm x 6mm x 1.45mm QFN• High Sensitivity (800 mV/g @1.5 g)• Fast Turn On Time• High Sensitivity (1.5 g) • Integral Signal Conditioning with Low Pass Filter• Robust Design, High Shocks Survivability• Pb-Free Terminations• Environmentally Preferred Package•Low CostTypical Applications• HDD MP3 Player : Freefall Detection• Laptop PC : Freefall Detection, Anti-Theft• Cell Phone : Image Stability, Text Scroll, Motion Dialing, E-Compass• Pedometer : Motion Sensing• PDA : Text Scroll• Navigation and Dead Reckoning : E-Compass Tilt Compensation• Gaming : Tilt and Motion Sensing, Event Recorder• Robotics : Motion SensingORDERING INFORMATIONDevice Name Temperture Range Case No. PackageMMA7260Q– 20 to +85°C 1622-01 QFN-16, TubeMMA7260QR2– 20 to +85°C 1622-01 QFN-16,Tape & ReelMMA7260QMMA7260Q: XYZ AXISACCELEROMETER±1.5g/2g/4g/6g16 LEADQFNCASE 1622-0116 1514 13567812341211109g-Select1g-Select2VDDVSSSleep ModeN/CN/CN/CN/CN/CN/CN/CN/CXOUTYOUTZOUTBottom ViewFigure 1. Pin ConnectionsTop ViewMMA7260QSensors2 Freescale SemiconductorFigure 2. Simplified Accelerometer Functional Block DiagramELECTRO STATIC DISCHARGE (ESD)WARNING: This device is sensitive to electrostatic discharge.Although the Freescale accelerometer contains internal 2000 V 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.Table 1. Maximum Ratings(Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)Rating Symbol Value UnitMaximum Acceleration (all axis) gmax±2000 gSupply Voltage VDD–0.3 to +3.6 VDrop Test(1)1. Dropped onto concrete surface from any axis.Ddrop1.8 mStorage Temperature Range Tstg–40 to +125 °CVSSZOUTYOUTXOUTg-Select1g-Select2Sleep ModeVDDG-CellSensorOscillatorClockGeneratorX-TempCompY-TempCompZ-TempCompC to VConverterGain+FilterControl LogicEEPROM Trim CircuitsMMA7260QSensorsFreescale Semiconductor 3Table 2. Operating Characteristics Unless otherwise noted: –20°C < TA < 85°C, 2.2 V < VDD < 3.6 V, Acceleration = 0g, Loaded output(1)Characteristic Symbol Min Typ Max UnitOperating Range(2)Supply Voltage(3)Supply CurrentSupply Current at Sleep Mode(4)Operating Temperature RangeAcceleration Range, X-Axis, Y-Axis, Z-Axisg-Select1 & 2: 00g-Select1 & 2: 10g-Select1 & 2: 01g-Select1 & 2: 11VDDIDDIDDTAgFSgFSgFSgFS2.2——–20————3.35003—±1.5±2.0±4.0±6.03.680010+85————VµAµA°CggggOutput SignalZero g (TA = 25°C, VDD = 3.3 V)(5)Zero gSensitivity (TA = 25°C, VDD = 3.3 V)1.5g2g4g6gSensitivityBandwidth ResponseXYZVOFFVOFF, TAS1.5gS2gS4gS6gS,TAf-3dBf-3dB1.485—740555277.5185———1.65±2800600300200±0.033501501.815—860645322.5215———Vmg/°CmV/gmV/gmV/gmV/g%/°CHzHzNoiseRMS (0.1 Hz – 1 kHz)(4)Power Spectral Density RMS (0.1 Hz – 1 kHz)(4)nRMSnPSD——4.7350——mVrmsµg/Control TimingPower-Up Response Time(6)Enable Response Time(7)Sensing Element Resonant FrequencyXYZInternal Sampling FrequencytRESPONSEtENABLEfGCELLfGCELLfCLK—————1.00.56.03.4112.02.0———msmskHzkHzkHzOutput Stage PerformanceFull-Scale Output Range (IOUT = 30 µA) VFSOVSS+0.25 — VDD–0.25 VNonlinearity, XOUT, YOUT, ZOUTNLOUT–1.0 — +1.0 %FSOCross-Axis Sensitivity(8)VXY, XZ, YZ—— 5.0 %1. For a loaded output, the measurements are observed after an RC filter consisting of a 1.0 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 2.2 and 3.6 V, 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. This value is measured with g-Select in 1.5g mode.5. 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. For negative acceleration, the output will decrease below VDD/2.6. The response time between 10% of full scale Vdd input voltage and 90% of the final operating output voltage.7. The response time between 10% of full scale Sleep Mode input voltage and 90% of the final operating output voltage.8. A measure of the device’s ability to reject an acceleration applied 90° from the true axis of sensitivity.HzMMA7260QSensors4 Freescale SemiconductorPRINCIPLE OF OPERATIONThe Freescale accelerometer is a surface-micromachined integrated-circuit accelerometer.The device consists of two surface micromachined capacitive sensing cells (g-cell) and a signal conditioning ASIC contained in a single integrated circuit package. The sensing elements are 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
View Full Document
Unlocking...