MMA6270Q Rev 1.0 2/2006 Freescale Semiconductor Technical Data ±1.5 g - 6 g Dual Axis Low-g Micromachined Accelerometer MMA6270Q The MMA6270Q low cost capacitive micromachined accelerometer features signal conditioning, a 1-pole low pass filter, temperature compensation and gSelect which allows for the selection among four 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. MMA6270Q: XY AXIS ACCELEROMETER ±1.5 g / 2 g / 4 g / 6 g Features Selectable Sensitivity (1.5 g / 2 g / 4 g / 6 g) Low Current Consumption: 500 µA Sleep Mode: 3 µA Low Voltage Operation: 2.2 V – 3.6 V 6 mm x 6 mm x 1.45 mm QFN High Sensitivity (800 mV/g @1.5 g) Fast Turn On Time Integral Signal Conditioning with Low Pass Filter Robust Design, High Shocks Survivability Pb-Free Terminations Environmentally Preferred Package Low Cost Bottom View 16 LEAD QFN 98ASA10651D Typical Applications Laptop PC: Freefall Detection, Anti-Theft Cell Phone: Image Stability, Text Scroll, Motion Dialing, E-Compass PDA: Text Scroll Navigation and Dead Reckoning: E-Compass Tilt Compensation Gaming: Tilt and Motion Sensing, Event Recorder Robotics: Motion Sensing Appliances: Vibration Sensing Package MMA6270Q – 20 to +85°C 98ASA10651D QFN-16, Tube MMA6270QR2 – 20 to +85°C 98ASA10651D QFN-16,Tape & Reel N/C 14 13 g-Select1 1 12 Sleep Mode g-Select2 2 11 N/C VDD 3 10 N/C VSS 4 9 N/C 5 6 7 8 N/C Package Drawing 15 N/C Temperature Range 16 N/C Device Name YOUT ORDERING INFORMATION XOUT Top View N/C • • • • • • • N/C • • • • • • • • • • • • Figure 1. Pin Connections © Freescale Semiconductor, Inc., 2006. All rights reserved. VDD g-Select1 g-Select2 G-Cell Sensor Sleep Mode Oscillator Clock Generator C to V Converter Gain + Filter Control Logic EEPROM Trim Circuits X-Temp Comp XOUT Y-Temp Comp YOUT VSS Figure 2. Simplified Accelerometer Functional Block Diagram Table 1. Maximum Ratings (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.) Rating Symbol Value Unit Maximum Acceleration (all axis) gmax ±2000 g Supply Voltage VDD –0.3 to +3.6 V Ddrop 1.8 m Tstg –40 to +125 °C (1) Drop Test 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 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. MMA6270Q 2 Analog Integrated Circuit Device Data Freescale Semiconductor Table 2. Operating Characteristics Unless otherwise noted: –20°C < TA < 85°C, 2.2 V < VDD < 3.6 V, Acceleration = 0 g, Loaded output(1) Characteristic Symbol Min Typ Max Unit VDD IDD IDD TA 2.2 — — –20 3.3 500 3 — 3.6 800 10 +85 V µA µA °C gFS gFS gFS gFS — — — — ±1.5 ±2.0 ±4.0 ±6.0 — — — — g g g g VOFF VOFF, TA 1.485 — 1.65 ±2 1.815 — V mg/°C S1.5g S2g S4g S6g S, TA 740 555 277.5 185 — 800 600 300 200 ±0.03 860 645 322.5 215 — mV/g mV/g mV/g mV/g %/°C f-3dB — 350 — Hz nRMS nPSD — — 4.7 350 — — mVrms µg/ Hz tRESPONSE tENABLE — — 1.0 0.5 2.0 2.0 ms ms fGCELL fCLK — — 6.0 11 — — kHz kHz VFSO VSS+0.25 — VDD–0.25 V Nonlinearity, XOUT, YOUT NLOUT –1.0 — +1.0 %FSO Cross-Axis Sensitivity(8) VXY, XZ, YZ — — 5.0 % Operating Range(2) Supply Voltage(3) Supply Current Supply Current at Sleep Mode(4) Operating Temperature Range Acceleration Range, X-Axis, Y-Axis, g-Select1 & 2: 00 g-Select1 & 2: 10 g-Select1 & 2: 01 g-Select1 & 2: 11 Output Signal Zero g (TA = 25°C, VDD = 3.3 V)(5) Zero g Sensitivity (TA = 25°C, VDD = 3.3 V) 1.5 g 2g 4g 6g Sensitivity Bandwidth Response XY Noise RMS (0.1 Hz – 1 kHz)(4) Power Spectral Density RMS (0.1 Hz – 1 kHz)(4) Control Timing Power-Up Response Time(6) Enable Response Time(7) Sensing Element Resonant Frequency XY Internal Sampling Frequency Output Stage Performance Full-Scale Output Range (IOUT = 30 µA) 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 on VDD-GND. 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 1.5 g 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. MMA6270Q Analog Integrated Circuit Device Data Freescale Semiconductor 3 PRINCIPLE OF OPERATION The 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 the center beam moves with acceleration, the distance between the beams changes and each capacitor's value will change, (C = Aε/D). Where A is the area of the beam, ε is the dielectric constant, and D is the distance between the beams. The 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 g-Select The g-Select feature allows for the selection among 4 sensitivities present in the device. Depending on the logic input placed on pins 1 and 2, the device internal gain will be changed allowing it to function with a 1.5 g, 2 g, 4 g, or 6 g sensitivity (Table 3). This feature is ideal when a product has applications requiring different sensitivities for optimum performance. The sensitivity can be changed at anytime during the operation of the product. The g-Select1 and gSelect2 pins can be left unconnected for applications requiring only a 1.5 g sensitivity as the device has an internal pull-down to keep it at that sensitivity (800 mV/g). Table 3. g-Select Pin Descriptions g-Select2 g-Select1 g-Range Sensitivity 0 0 1.5 g 800 mV/g 0 1 2g 600 mV/g 1 0 4g 300 mV/g 1 1 6g 200 mV/g Sleep Mode The dual axis accelerometer provides a Sleep Mode that is ideal for battery operated products. When Sleep Mode is active, the device outputs are turned off, providing significant reduction of operating current. A low input signal on pin 12 (Sleep Mode) will place the device in this mode and reduce the current to 3 uA typ. For lower power consumption, it is recommended to set g-Select1 and g-Select2 to 1.5 g mode. By placing a high input signal on pin 12, the device will resume to normal mode of operation. Filtering The dual axis accelerometer contains onboard single-pole switched capacitor filters. 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. Ratiometricity Ratiometricity simply means the output offset voltage and sensitivity will scale linearly with applied supply voltage. That is, as supply voltage is increased, 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. MMA6270Q 4 Analog Integrated Circuit Device Data Freescale Semiconductor BASIC CONNECTIONS Connection Diagram Pin Descriptions PCB Layout XOUT YOUT NC 16 15 14 13 POWER SUPPLY g-Select1 1 12 Sleep Mode g-Select2 2 11 NC VDD VDD 3 10 NC VSS Sleep Mode VSS 4 6 7 8 NC NC NC Figure 4. Pinout Description Accelerometer 5 NC 9 NC C C g-Select1 VRH VDD P0 VSS P1 g-Select2 P2 XOUT R YOUT R C A/DIN C Microcontroller NC Top View Table 4. Pin Descriptions Pin No. Pin Name 1 g-Select1 Logic input pin to select g level. 2 g-Select2 Logic input pin to select g level. 3 VDD Power Supply Input 4 VSS Power Supply Ground 5-7 N/C No internal connection. Leave unconnected. 8 - 11 N/C Unused for factory trim. Leave unconnected. 12 Sleep Mode 13 N/C 14 YOUT Y direction output voltage. 15 XOUT X direction output voltage. 16 N/C Logic Inputs Description Logic input pin to enable product or Sleep Mode. No internal connection. Leave unconnected No internal connection. Leave unconnected. 1 g-Select1 MMA6270Q 3 VDD A/DIN Figure 6. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller NOTES: 1. Use 0.1 µF capacitor on VDD to decouple the power source. Do not exceed capacitor values of 2.2 or 3.3 µF. 2. Physical coupling distance of the accelerometer to the microcontroller should be minimal. 3. Flag underneath package is connected to ground. 4. 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 6. 5. Use an RC filter with 1.0 kΩ and 0.1 µF on the outputs of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). 6. PCB layout of power and ground should not couple power supply noise. 7. Accelerometer and microcontroller should not be a high current path. 2 g-Select2 VDD C YOUT 14 0.1 µF 1 kΩ 8. 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 (11 kHz for the sampling frequency). This will prevent aliasing errors. 0.1 µF 4 12 VSS XOUT 15 Sleep Mode Logic Input 1 kΩ 0.1 µF Figure 5. Accelerometer with Recommended MMA6270Q Analog Integrated Circuit Device Data Freescale Semiconductor 5 DYNAMIC ACCELERATION Top View Side View +Y 14 13 12 2 11 3 10 4 9 +X -X 5 6 7 Bottom 15 Top 16 1 Z direction (For reference only) 8 -Y : Arrow indicates direction of mass movement. 16-Pin QFN Package STATIC ACCELERATION Direction of Earth’s gravity field.* Top View Side View [email protected] 0g = 1.65 V YOUT @ -1g = 0.85 V XOUT @ +1g = 2.45 V YOUT @ 0g = 1.65 V XOUT @ 0g = 1.65 V YOUT @ 0g = 1.65 V XOUT @ -1g = 0.85 V YOUT @ 0g = 1.65 V XOUT @ 0g = 1.65 V YOUT @ 0g = 1.65 V XOUT @ 0g = 1.65 V YOUT @ +1g = 2.45 V * When positioned as shown, the Earth’s gravity will result in a positive 1 g output. MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS MMA6270Q 6 Analog Integrated Circuit Device Data Freescale Semiconductor 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 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. 6.0 0.55 4.25 9 6.0 8 13 12 5 16 0.50 1.00 1 4 Solder areas Pin 1 ID (non metallic) PACKAGE DIMENSIONS For the most current package revision, visit www.freescale.com and perform a keyword search using the “98A” listed below. 6 PIN 1 INDEX AREA DETAIL G A M 0.1 C 2X 0.10 C 0.08 C 1.45±0.1 5 6 (0.203) (0.102) C SEATING PLANE DETAIL G 2X M 0.10 C B (0.5) (1) 4 0.1 C A B 16X 4.24 4.04 EXPOSED DIE ATTACH PAD 13 VIEW ROTATED 90˚ CLOCKWISE (45˚) 0.1 DETAIL M PIN 1 INDEX 16 DETAIL M 12 4.24 4.04 1 0.5 NOTES: 1. ALL DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. THIS DIMENSION APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25MM AND 0.30MM FROM TERMINAL TIP. 4. THIS DIMENSION REPRESENTS TERMINAL FULL BACK FROM PACKAGE EDGE UP TO 0.1MM IS ACCEPTABLE. 5. COPLANARITY APPLIES TO THE EXPOSED HEAT SLUG AS WELL AS THE TERMINAL. 6. RADIUS ON TERMINAL IS OPTIONAL. 7. MINIMUM METAL GAP 0.2MM. 0.1 C A B 9 4 12X 8 16X 1 5 0.63 0.43 16X VIEW M-M 0.60 0.40 0.1 M C A B 0.05 M C 3 98ASA10651D ISSUE O 16-LEAD QFN MMA6270Q Sensors Freescale Semiconductor 7 How to Reach Us: Home Page: www.freescale.com E-mail: [email protected] RoHS-compliant and/or Pb-free versions of Freescale products have the functionality and electrical characteristics of their non-RoHS-compliant and/or non-Pb-free counterparts. For further information, see http://www.freescale.com or contact your Freescale sales representative. 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