View MMA1270EGR2_1280990.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

Freescale Semiconductor Technical Data
Document Number: MMA1270EG Rev 0, 04/2007
Low G Micromachined Accelerometer
The MMA series of silicon capacitive, micromachined accelerometers feature 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. Features * * * * * * * Integral Signal Conditioning Linear Output 2nd Order Bessel Filter Calibrated Self-test EPROM Parity Check Status Transducer Hermetically Sealed at Wafer Level for Superior Reliability Robust Design, High Shock Survivability
MMA1270EG
MMA1270EG: Z AXIS SENSITIVITY MICROMACHINED ACCELEROMETER 2.5g
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
EG SUFFIX (Pb-FREE) 16-LEAD SOIC CASE 475-01
ORDERING INFORMATION
Device Name MMA1270EG MMA1270EGR2 Temperature Range -40 to 105C -40 to 105C Case No. 475-01 475-01 Package SOIC-16 SOIC-16 Tape & Reel
VDD G-Cell Sensor Integrator Gain Filter Temp Comp and Gain VOUT VSS VSS VSS VOUT STATUS VDD VSS ST 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
ST Self-test
Control Logic & EPROM Trim Circuits
Oscillator
Clock Generator
VSS
STATUS
Figure 1. Simplified Accelerometer Functional Block Diagram
Figure 2. Pin Connections
(c) Freescale Semiconductor, Inc., 2007. All rights reserved.
Table 1. Maximum Ratings (Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)
Rating Powered Acceleration (all axes) Unpowered Acceleration (all axes) Supply Voltage Drop Test (1) Storage Temperature Range 1. Dropped onto concrete surface from any axis. Symbol Gpd Gupd VDD Hdrop Tstg Value 1500 2000 -0.3 to +7.0 1.2 -40 to +125 Unit g g V m C
ELECTRO STATIC DISCHARGE (ESD)
WARNING: This device is sensitive to electrostatic discharge. Although the Freescale 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 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.
MMA1270EG 2 Sensors Freescale Semiconductor
Table 2. Operating Characteristics (Unless otherwise noted: -40C TA +105C, 4.75 VDD 5.25, Acceleration = 0g, Loaded output.(1))
Characteristic Operating Range(2) Supply Voltage(3) Supply Current Operating Temperature Range Acceleration Range Output Signal Zero g (TA = 25C, VDD = 5.0 V)(4) Zero g (VDD = 5.0 V) Sensitivity (TA = 25C, VDD = 5.0 V)(5) Sensitivity (VDD = 5.0 V) Bandwidth Response Nonlinearity Noise RMS (0.1 Hz - 1.0 kHz) Spectral Density (RMS, 0.1 Hz - 1.0 KHz)(6) Self-Test Output Response (VDD = 5.0 V) Input Low Input High Input Loading(7) Response Time(8) Status(9), (10) Output Low (Iload = 100 A) Output High (Iload = 100 A) Output Stage Performance Electrical Saturation Recovery Time(11) Full Scale Output Range (IOUT = 200 A) Capacitive Load Drive(12) Output Impedance Mechanical Characteristics Transverse Sensitivity(13) Symbol VDD IDD TA gFS VOFF VOFF S S f -3dB NLOUT nRMS nSD VST VIL VIH IIN tST VOL VOH tDELAY VFSO CL ZO VXZ,YZ Min 4.75 1.1 - 40 -- 2.25 2.2 712.5 693.8 40 - 1.0 -- -- 0.9 VSS 0.7 VDD - 300 -- -- VDD - 0.8 -- VSS +0.25 -- -- -- Typ 5.00 2.1 -- 2.5 2.5 2.5 750 750 50 -- 3.5 700 1.25 -- -- - 125 10 -- -- -- -- -- 50 -- Max 5.25 3.0 +105 -- 2.75 2.8 787.5 806.3 60 +1.0 6.5 -- 1.6 0.3 VDD VDD - 50 25 0.4 -- 2.0 VDD - 0.25 100 -- 5.0 Unit V mA C g V V mV/g mV/g Hz % FSO mVrms g/Hz V V V A ms V V ms V pF % FSO
1. For a loaded output the measurements are observed after an RC filter consisting of a 1 k resistor and a 0.1 F 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 claibrated at 2g. Sensitivity limits apply to 0 Hz acceleration. 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. 10. The Status pin output latches high if the EPROM parity changes to odd. The Status pin can be reset by rising edge on self-test, unless a fault condition continues to exist. 11. Time for amplifiers to recover after an acceleration signal causes 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.
MMA1270EG Sensors Freescale Semiconductor 3
PRINCIPLE OF OPERATION
The Freescale 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 3). 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 4). As the center plate moves with acceleration, the distance between the plates changes and each capacitor's value will change, (C = A/D). Where A is the area of the plate, 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. SPECIAL FEATURES Filtering The Freescale 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 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 the following event occurs: * Parity of the EPROM bits becomes odd in number. * The fault latch can be reset by a rising edge on the selftest input pin, unless one (or more) of the fault conditions continues to exist.
Acceleration
Figure 3. Transducer Physical Model
Figure 4. Equivalent Circuit Model
MMA1270EG 4 Sensors Freescale Semiconductor
BASIC CONNECTIONS
Pinout Description PCB Layout
STATUS Accelerometer ST VOUT VSS VDD R 1 k C 0.1 F VRH C 0.1 F P1 Microcontroller P0 A/D In C 0.1 F
VSS VSS VSS VOUT STATUS VDD VSS ST
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
VSS C 0.1 F VDD
Table 3. Pin Descriptions
Pin No. 1 thru 3 4 5 6 7 8 9 thru 13 14 thru 16 Pin Name VSS VOUT STATUS VDD VSS ST Trim pins -- Description Redundant connections to the internal VSS and may be left unconnected. Output voltage of the accelerometer. Logic output pin used to indicate fault. The power supply input. The power supply ground. Logic input pin used to initiate self-test. Used for factory trim. Leave unconnected. No internal connection. Leave unconnected.
Power Supply
Figure 6. Recommended PCB Layout for Interfacing Accelerometer to Microcontroller NOTES: 1. Use a 0.1 F capacitor on VDD to decouple the power source. 2. Physical coupling distance of the accelerometer to the microcontroller should be minimal. 3. 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. 4. Use an RC filter of 1 k and 0.1 F on the output of the accelerometer to minimize clock noise (from the switched capacitor filter circuit). 5. PCB layout of power and ground should not couple power supply noise.
VDD LOGIC INPUT C1 0.1 F 1 2 3
8 6
MMA1270EG ST VDD VSS VSS VSS 7 VSS VOUT
5 R1 1 k C2 0.1 F
STATUS
6. Accelerometer and microcontroller should not be a high current path. 7. 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.
4
OUTPUT SIGNAL
Figure 5. SOIC Accelerometer with Recommended Connection Diagram
MMA1270EG Sensors Freescale Semiconductor 5
ACCELERATION SENSING DIRECTIONS
DYNAMIC ACCELERATION
VSS VSS VSS VOUT STATUS VDD VSS ST 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
+g
-g
16-Pin SOIC Package N/C pins are recommended to be left FLOATING
STATIC ACCELERATION
Direction of Earth's gravity field(1)
+1g
VOUT = 3.25 V
0g
VOUT = 2.50 V
0g
VOUT = 2.50 V
-1g
VOUT = 1.75 V
1. When positioned as shown, the Earth's gravity will result in a positive 1g output
MMA1270EG 6 Sensors Freescale Semiconductor
PACKAGE DIMENSIONS
PAGE 1 OF 2
CASE 475-01 ISSUE C 16-LEAD SOIC
MMA1270EG Sensors Freescale Semiconductor 7
PACKAGE DIMENSIONS
PAGE 2 OF 2
CASE 475-01 ISSUE C 16-LEAD SOIC
MMA1270EG 8 Sensors Freescale Semiconductor
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 support.japan@freescale.com 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 support.asia@freescale.com 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 LDCForFreescaleSemiconductor@hibbertgroup.com
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. FreescaleTM and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. (c) Freescale Semiconductor, Inc., 2007. All rights reserved.
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. For information on Freescale's Environmental Products program, go to http://www.freescale.com/epp.
MMA1270EG Rev. 0 04/2007

▲Up To Search▲

Price & Availability of MMA1270EGR2

	To Download MMA1270EGR2 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .